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Characidium pumarinri n. sp. is described from the affluents of Rio Huallaga, a tributary of Rio Maranon that drains the eastern slopes of the Andes, in the Peruvian Amazon. The new species has a deep body (24-31% in LS ), 11-17 well-marked dark bars and remarkable sexual dimorphism related to colour pattern, in which males have darker anal, dorsal, pectoral and pelvic fins than females. C. pumarinri resembles some species allocated in Clade C4, mainly by having a high number of transversal bars and a deep body. In addition, a thorough review and further descriptions of the secondary sexual characteristics in Characidium are provided.

Characidium xavante da Graça, Pavanelli & Buckup, 2008: 319, fig. 4. Paratypes: 4 lots, 39 specimens —NUP 3887, 18, 21.9–28.2 mm SL; NUP 4107, 1 (f) c&s, 24.0 mm SL; NUP 4108, 1 (m) c&s, 22.8 mm SL: Brazil, Mato Grosso, Primavera do Leste, córrego Xavante, on the road from MT-130 to Culuene dam, upper rio Xingu basin, 14°38’24”S, 53°55’38”W, L. Casatti, F. Gibran, A. Melo & H. Santos, 18 Jan 2002. NUP 3888, 19, 19.5–24.4 mm SL: Brazil, Mato Grosso, Paranatinga, first stream after rio Culuene bridge, from Paranatinga to Canarana, upper rio Xingu basin, 13°55’43”S, 53°41’45”W, L. Casatti, F. Gibran, A. Melo & H. Santos, 20 Jan 2002., Published as part of De Oliveira, Rianne C., Ota, Renata R., Deprá, Gabriel C., Zawadzki, Cláudio H., Pavanelli, Carla S. & Da Graça, Weferson J., 2022, Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil, pp. 1-43 in Zootaxa 5128 (1) on page 5, DOI: 10.11646/zootaxa.5128.1.1, http://zenodo.org/record/6479497, {"references":["da Graca, W. J., Pavanelli, C. S. & Buckup, P. A. (2008) Two new species of Characidium (Characiformes: Crenuchidae) from Paraguay and Xingu river basins, state of Mato Grosso, Brazil. Copeia, 2008 (2), 326 - 332. https: // doi. org / 10.1643 / CI- 06 - 167"]}

Characidium xanthopterum Silveira, Langeani, da Graça, Pavanelli & Buckup, 2008: 170, fig. 1. Paratypes: 2 lots, 17 specimens —NUP 4414, 15, 32.8–40.4 mm SL; NUP 4415, 2 c&s, 37.6–42.0 mm SL: Brazil, Goiás, Corumbaíba, córrego Gameleira, tributary to left margin of rio Corumbá, 17°59’S, 48°29’W, Nupélia staff, 12 Oct 1996., Published as part of De Oliveira, Rianne C., Ota, Renata R., Deprá, Gabriel C., Zawadzki, Cláudio H., Pavanelli, Carla S. & Da Graça, Weferson J., 2022, Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil, pp. 1-43 in Zootaxa 5128 (1) on page 5, DOI: 10.11646/zootaxa.5128.1.1, http://zenodo.org/record/6479497, {"references":["Silveira, L. G., Langeani, F., da Graca, W. J., Pavanelli, C. S. & Buckup, P. A. (2008) Characidium xanthopterum (Ostariophysi: Characiformes: Crenuchidae): a new species from the central Brazilian Plateau. Neotropical Ichthyology, 6 (2), 169 - 174. https: // doi. org / 10.1590 / S 1679 - 62252008000200003"]}

Characidium heirmostigmata da Graça & Pavanelli, 2008: 54, fig. 1. Paratypes: 5 lots, 18 specimens —NUP 1411, 4, 42.5–46.5 mm SL; NUP 5333, 2 c&s, 38.9–44.6 mm SL: Brazil, Paraná, Cândido de Abreu, rio Nestor, tributary to right margin of rio Ivaí, upper rio Paraná basin, approx. 24°28’S, 50°54’W, Nupélia staff, 22 Nov 1994. NUP 1381, 8, 40.2–45.6 mm SL; NUP 1393, 3, 45.3–50.0 mm SL; NUP 5334, 1 c&s, 37.5 mm SL: Brazil, Paraná, Jussara, rio Abelha, tributary to left margin of rio Ivaí, upper rio Paraná basin, approx. 23°36’S, 52°28’W, Nupélia staff, 17 Nov 1994. Remarks: The correct coordinates of the type-locality are 25°04’55”S, 51°10’35”W., Published as part of De Oliveira, Rianne C., Ota, Renata R., Deprá, Gabriel C., Zawadzki, Cláudio H., Pavanelli, Carla S. & Da Graça, Weferson J., 2022, Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil, pp. 1-43 in Zootaxa 5128 (1) on page 4, DOI: 10.11646/zootaxa.5128.1.1, http://zenodo.org/record/6479497

Characidium papachibe Peixoto & Wosiacki, 2013: 53, fig. 1. Paratype: 1 lot, 1 specimen — NUP 14153, 1, 20.6 mm SL: Brazil, Pará, Juruti, unnamed stream left tributary to rio Aruã, left tributary to rio Arapiuns, itself a left tributary to rio Tapajós, 02°34’31.9”S, 55°54’16.1”W, L.A.W. Peixoto, R. D. Raiol, C.S. Ramos & N.C. Castro, 4 Jun 2010., Published as part of De Oliveira, Rianne C., Ota, Renata R., Deprá, Gabriel C., Zawadzki, Cláudio H., Pavanelli, Carla S. & Da Graça, Weferson J., 2022, Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil, pp. 1-43 in Zootaxa 5128 (1) on page 4, DOI: 10.11646/zootaxa.5128.1.1, http://zenodo.org/record/6479497, {"references":["Peixoto, L. A. W. & Wosiacki, W. B. (2013) A new species of Characidium (Characiformes: Crenuchidae) from the Lower Amazon. Copeia, 2013 (1), 52 - 57. https: // doi. org / 10.1643 / CI- 12 - 080"]}

Characidium nupelia da Graça, Pavanelli & Buckup, 2008: 327, fig. 1. Paratypes: 7 lots, 108 specimens —NUP 2155, 15, 19.4–25.8 mm SL: Brazil, Mato Grosso, Rosário do Oeste, córrego Forquilha, tributary to rio Manso (downstream from Manso Reservoir), upper rio Paraguai basin, 14°44’58”S 56°07’39”W, Nupélia staff, 24 Mar 2001; NUP 982, 25, 16.2–26.0 mm SL: same locality and collectors as previous, Mar/ Apr 2000. NUP 4106, 1 (m) c&s, 23.8 mm SL: same locality and collectors as previous, Mar/ Apr 2000. NUP 3331, 21, 21.4–31.9 mm SL: Brazil, Mato Grosso, Chapada dos Guimarães, Córrego Lajinha, tributary to Rio Manso (upstream from Manso Reservoir), 14°57’18”S, 55°41’15”W, Nupélia staff, 19 Jul 2002. NUP 1959, 31, 14.5–26.7 mm SL: Brazil, Mato Grosso, Chapada dos Guimarães, córrego Sujo, tributary to Manso Reservoir, approx. 14°52’S, 55°47’W, S. Veríssimo, 20 May 2000. NUP 2156, 14, 22.7–30.1 mm SL: Brazil, Mato Grosso, Chapada dos Guimarães, córrego São Joaquim, tributary to rio Manso (upstream from Manso Reservoir), approx. 14°56’S, 55°39’W, Nupélia staff, 19 Jul 2002. NUP 3332, 1, 27.3 mm SL: Brazil, Mato Grosso, Nobres, córrego Cancela, tributary to rio Cuiabá, 14°42’30”S, 56°15’51”W, Nupélia staff, 20 Jul 2002., Published as part of De Oliveira, Rianne C., Ota, Renata R., Deprá, Gabriel C., Zawadzki, Cláudio H., Pavanelli, Carla S. & Da Graça, Weferson J., 2022, Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil, pp. 1-43 in Zootaxa 5128 (1) on page 4, DOI: 10.11646/zootaxa.5128.1.1, http://zenodo.org/record/6479497, {"references":["da Graca, W. J., Pavanelli, C. S. & Buckup, P. A. (2008) Two new species of Characidium (Characiformes: Crenuchidae) from Paraguay and Xingu river basins, state of Mato Grosso, Brazil. Copeia, 2008 (2), 326 - 332. https: // doi. org / 10.1643 / CI- 06 - 167"]}

Characidium chicoi da Graça, Ota & Domingues, 2019: 1481, fig. 1. Paratypes: 5 lots, 28 specimens — NUP 21237, 6, 17.1–18.7 mm SL: Brazil, Mato Grosso, Itiquira, rio Comprido, tributary of the rio Correntes, rio Paraguai basin, 17°32’4.4”S, 54°25’38.9”W, Nupélia staff, 15 Mar 2019. NUP 21238, 4, 15.2–18.0 mm SL: same locality and collectors as previous, 31 Aug 2018. NUP 21239, 13, 14.9–17.2 mm SL: same locality and collectors as previous, 12 Feb 2019. NUP 21284, 1 c&s, 18.7 mm SL: same locality and collectors as previous, 31 Aug 2018. NUP 21285, 4 c&s, 16.4–17.0 mm SL: same locality and collectors as previous, 12 Feb 2019., Published as part of De Oliveira, Rianne C., Ota, Renata R., Deprá, Gabriel C., Zawadzki, Cláudio H., Pavanelli, Carla S. & Da Graça, Weferson J., 2022, Catalog of type specimens of the fish collection of the Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (NUP), Universidade Estadual de Maringá Paraná, Brazil, pp. 1-43 in Zootaxa 5128 (1) on page 4, DOI: 10.11646/zootaxa.5128.1.1, http://zenodo.org/record/6479497, {"references":["da Graca, W. J., Ota, R. R. & Domingues, W. M. (2019) A new species of miniature Characidium (Characiformes: Crenuchidae) from the upper Rio Paraguay basin, Mato Grosso state, Brazil. Journal of Fish Biology, 95 (6), 1480 - 1485. https: // doi. org / 10.1111 / jfb. 14169"]}

Characidium xavante was described from two tributaries of the Culuene River drainage, in the upper Xingu River basin. New samplings recorded the species for streams from the Kaaiapó River drainage (Teles Pires River drainage, upper Tapajós River basin) with additional specimens also recorded in the Xingu River basin, Paranatinga municipality, Mato Grosso State, Brazil. The new records represent an extension of the geographical distribution of the species, that from now on fits in a pattern of distribution known to be shared with other ca. 20 species of fishes. We suggest that Characidium xavante could be classified as Least Concern (LC), according to the International Union for Conservation of Nature Standards and Petitions Committee (IUCN).

A new miniature species of Characidium is described from the upper Rio Paraguay basin, Brazil. The new species can be diagnosed from all congeners by the presence of a dark-brown humeral blotch, vertically elongated (spanning 5 to 7 horizontal scale rows), with the shape of an upside-down acute triangle. Additionally, it can be diagnosed by a short lateral line (6 to 8 perforated scales), the absence of a conspicuous peduncular blotch, a lower number of principal caudal-fin rays (14-16) and by absence of the adipose fin. The new species is the smallest species of the genus; the largest specimen was 19.3 mm standard length.

The extraordinary species diversity of the Neotropical freshwater fish fauna is world renown. Yet, despite rich species diversity, taxonomic and genetic resources for its Cerrado ichthyofauna remain poorly developed. We provide a reference library of 149 DNA barcodes for 39 species/lineages of Cerrado headwater stream fishes from the Brazilian Distrito Federal and nearby areas and test the utility of distance-based criteria, tree-based criteria and minibarcodes for specimen identification. Mean Kimura 2-parameter genetic distances within species to orders ranged 1·8-12·1%. However, mean intraspecific v. congeneric-interspecific distances (0·9-1·3%) overlapped extensively and distance-based barcoding failed to achieve correct identifications due to c. 4-12·1% error rates and 19·5% ambiguous identifications related to the presence of singletons. Overlap was reduced and best-match success rates improved drastically to 83·5% when Characidium barcodes representing potential misidentifications or undescribed species were removed. Tree-based monophyly criteria generally performed similarly to distance methods, correctly differentiating up to c. 85% of species/lineages despite neighbour-joining and Bayesian tree errors (random lineage-branching events, long-branch attraction). Five clusters (Ancistrus aguaboensis, Characidium spp., Eigenmannia trilineata, Hasemania hanseni and Hypostomus sp. 2) exhibited deep intraspecific divergences or para-/polyphyly and multiple Barcode Index Number assignments indicative of putative candidate species needing taxonomic re-examination. Sliding-window analyses also indicated that a 200 bp minibarcode region performed just as well at specimen identification as the entire barcode gene. Future DNA barcoding studies of Distrito Federal-Cerrado freshwater fishes will benefit from increased sampling coverage, as well as consideration of minibarcode targets for degraded samples and next-generation sequencing.

The Araguaia River basin has the highest fish biodiversity within the Cerrado biome (Brazilian savannah), with many endemic and threatened species by human activities. Despite growing efforts to catalog Neotropical freshwater fish biodiversity, many regions are still undersampled. Our objective is to complement the information about stream fish in two hydrographic basins in the Cerrado. We sampled 72 streams with 50 m stretch in the Upper Araguaia (n = 32) and Middle Rio das Mortes (n = 40) basins. We collected 14,887 individuals distributed in 137 species, 81 genera, 30 families, and six orders. Characidae, Loricariidae, and Cichlidae were the families richer in species. We found a high diversity of rare fish species in the streams sampled, ca. 71.5% of the species had at least five individuals collected, and 18 species had only one collected specimen. The most frequent species were Astyanax cf. goyacensis, Knodus cf. breviceps, and Characidium cf. zebra. Both basins shared around 43% of the species. We caught 76 species in Upper Araguaia and 120 species in Middle Rio das Mortes. Seventeen exclusive fish species occurred in Upper Araguaia, whereas 61 were found in the Middle Rio das Mortes basin. Our analysis showed lower diversity of fish in Upper Araguaia than in the Middle Rio das Mortes basin. Considering the exclusive fish species of both basins, the human threats in those regions, and the few existent protected areas, we need a better look at the aquatic biodiversity conservation of this ecosystem. Resumo: A bacia do rio Araguaia apresenta a maior diversidade de peixes no bioma Cerrado, muitas dessas são endêmicas e ameaçadas pelas atividades antropogênicas. Apesar dos crescentes esforços para catalogar a diversidade de peixes neotropicais muitas regiões ainda permanecem subamostradas. O objetivo do nosso estudo é complementar a informação sobre peixes de riachos para duas importantes bacias hidrográficas no Cerrado. Amostramos um total de 72 trechos de 50 metros em riachos nas bacias alto rio Araguaia (n = 32) e médio Rio das Mortes (n = 40). Coletamos um total de 14.887 indivíduos distribuídos em 137 espécies, 81 gêneros, 30 famílias e seis ordens. As famílias Characidae, Loricariidae e Cichlidae foram as tiveram maior número de espécies. Encontramos uma grande raridade de espécies de peixes nos riachos amostrados, cerca de 71,5% das espécies apresentaram ao menos até cinco indivíduos coletados e 18 espécies tiveram apenas um único exemplar. As espécies com maior ocorrência nos riachos foram, Astyanax cf. goyacensis Knodus cf. breviceps e Characidium cf. zebra. As duas bacias compartilham aproximadamente 43% das espécies de peixes coletadas. Encontramos 76 espécies para o alto rio Araguaia e 120 espécies para médio Rio das Mortes. Observamos 17 espécies exclusivas para a bacia do alto rio Araguaia e 61 espécies exclusivas para bacia do Médio Rio das Mortes. Nossas análises mostraram que a diversidade de peixes é menor na bacia do alto rio Araguaia quando comparada a bacia do médio Rio das Mortes. Considerando as ameaças antrópicas, o baixo número unidades de conservação e o elevado número de espécies exclusivas presentes em ambas as bacias, existe uma necessidade urgente concentrar esforços na conservação desses ecossistemas.

Made available in DSpace on 2021-07-14T10:50:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-11. Added 1 bitstream(s) on 2021-07-14T11:39:12Z : No. of bitstreams: 1 S1679-62252021000200201.pdf: 1151343 bytes, checksum: afd408656f80e8c8228301fccbff138c (MD5) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Characidium sp. aff. C. vidali é uma espécie encontrada em riachos costeiros do sudeste do Brasil, que apresenta elementos cariotípicos elucidativos quanto à ocorrência de variações microestruturais, conservando a macroestrutura cromossômica do gênero. O objetivo deste estudo foi aplicar ferramentas citomoleculares para identificar características no cariótipo de Characidium sp. aff. C. vidali, que contribuam para a definição citogenética desta espécie, agregando informações quanto à evolução da estruturação cromossômica do grupo. A espécie apresentou 2n = 50 cromossomos, além de 1 a 4 microcromossomos B por célula. A FISH mostrou os genes de histona H3 e H4 sintênicos no braço curto do par 10, e os microssatélites (CA)15, (CG)15, (GA)15 e (TTA)10 clusterizados nas porções subteloméricas de todos os cromossomos do complemento A, com grande acúmulo nos supranumerários. A sonda telomérica identificou marcações terminais em todos os cromossomos, além de quatro pares marcados intersticialmente, chamados de sítios ITS, e dois pares com duas marcações intersticiais, chamados de double-ITS. O bandamento C revelou que os cromossomos supranumerários são completamente heterocromáticos, que os sítios ITS são banda C positivos, mas os sítios double-ITS são banda C negativos. Então, ao longo da evolução de Characidium, eventos genômicos estão ocorrendo e reestruturando cromossomos nas populações. Characidium sp. aff. C. vidali is a species found in coastal streams in southeastern Brazil, which has karyotypic explanatory elements as the occurrence of microstructural variations, keeping the chromosomal macrostructure of the genus. The objective of this study was to apply cytomolecular tools in the chromosomes of Characidium sp. aff. C. vidali to identify characteristics in their karyotype contributing to cytogenetic definition of this species, adding information about the evolution of the chromosomal structure of the group. The species showed 2n = 50 chromosomes and from 1 to 4 additional B microchromosomes. FISH technique showed histone H3 and H4 genes in the short arm of pair 10, and microsatellites (CA)15, (CG)15, (GA)15 and (TTA)10 clustered in the subtelomeric portions of all A chromosomes, with total accumulation by supernumerary. The telomeric probe marked terminal regions of all chromosomes, in addition to the interstitial portion of four pairs, called ITS sites, with these markings being duplicated in two pairs, hence the double-ITS classification. C-banding revealed that supernumerary chromosomes are completely heterochromatic, that ITS sites are C-banding positive, but double-ITS sites are C-banding negative. So, throughout the evolution to Characidium, genomic events are occurring and restructuring chromosomes in populations. Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Departamento de Biologia Estrutural e Funcional Fundação Educacional de Penápolis Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Departamento de Biologia Estrutural e Funcional FAPESP: 2018/20610–1 FAPESP: 2016/09204–6 FAPESP: 2014/26508–3 CNPq: 306054/2006–0

Characidium wangyapoik, new species urn:lsid:zoobank.org:act: 1EBB34BE-431E-4D03-A343- 6E8132EE810C Figures 1A, 11–12 Characidium n. sp. ‘Ireng’.— Lujan et al., 2020: 1216 [locality information]. Holotype.— CSBD F-3615 (ex AUM 67118), 1 (1mo/me, 1gm), 72.6 mm SL, Guyana (border with Brazil), Potaro-Siparuni (Region 8), Amazon River basin, Ireng River, first shoal upriver from split with Sukwabi Creek, 5.07711, –59.97423, N. K. Lujan, J. W. Armbruster, D. C. Werneke, M. Ram, 8 January 2016. Paratypes.— All specimens Guyana (border with Brazil), Potaro-Siparuni (Region 8), Amazon River basin, Ireng River basin (known as the Rio Mau in Brazil): ANSP 207526, 3 (1mo/me, 3gm), 42.6–56.8 mm SL, AUM 67036, 26 (5mo/ me, 26gm, 4cs), 22.0– 59.9 mm SL, CSBD F-3616, 3 (1mo/me, 3gm), 37.7–52.2 mm SL, INPA ICT-059496, 3 (0mo/me, 3gm), 52.6–54.6 mm SL, ROM 111286, 3 (0mo/me, 3gm), 47.7–53.8 mm SL, Ireng River, at Orinduik Falls, between upper and lower falls, 4.72536, –60.03852, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram, 2 January 2016; AUM 67046, 16 (0), 17.8–46.4 mm SL, Ireng River, below lower Orinduik Falls, 4.71898, –60.03507, N. K. Lujan, J. W. Armbruster, D. C. Werneke, M. Ram, 3 January 2016; AUM 67068, 18 (0), 25.2–43.5 mm SL, Ireng River, at Branana Rapids, shoals downstream of Orinduik Falls, 4.67585, –60.06046, D. C. Werneke, J. W. Armbruster, D. I. Brooks, M. Ram, 4 January 2016; AUM 67076, 4 (0), 36.0– 40.4 mm SL, Ireng River, at Orinduik Falls, between upper and lower falls, 4.72536, –60.03852, D. C. Werneke, J. W. Armbruster, D. I. Brooks, M. Ram, N. K. Lujan, 4 January 2016; AUM 67077, 20 (0mo/me, 13gm), 31.8–51.9 mm SL, Ireng River, at Orinduik Falls, around halfway between upper and lower falls, 4.72176, –60.03703, D. C. Werneke, J. W. Armbruster, D. I. Brooks, M. Ram, N. K. Lujan, 4 January 2016; AUM 67094, 1 (0), 30.2 mm SL, Ireng River, just above Orinduik Falls, 4.72798, –60.03597, N. K. Lujan, J. W. Armbruster, D. C. Werneke, D. I. Brooks, M. Ram, 5 January 2016; AUM 67118, 14 (4mo/me, 7gm, 2cs), 49.4–76.1 mm SL, INPA ICT-059497, 2 (1mo/me, 2gm), 60.6–62.6 mm SL, first shoal upriver from split with Sukwabi Creek, 5.07711, –59.97423, N. K. Lujan, J. W. Armbruster, D. C. Werneke, M. Ram, 8 January 2016; AUM 67143, 6 (0mo/me, 6gm), 44.8–67.7 mm SL, Ireng River, shoals at mouth of Monkey Creek, Kaibarupai, 5.04398, –59.97717, N. K. Lujan, J. W. Armbruster, D. C. Werneke, 9 January 2016; AUM 67181, 9 (3mo/me, 9gm), 49.1–68.8 mm SL, ROM 111287, 2 (2mo/me, 2gm), 60.6–61.3 mm SL, Ireng River, shoals at mouth of Monkey Creek, Kaibarupai, 5.04398, –59.97717, J. W. Armbruster, N. K. Lujan, D. I. Brooks, 12 January 2016; AUM 67189, 2 (0mo/ me, 2gm), Sukwabi Creek, East Fork, downstream of Wotowanda Falls, 5.08867, –59.96952, J. W. Armbruster, N. K. Lujan, D. I. Brooks, D. C. Werneke, P. Peters, R. Daniel, local fishermen, 13 January 2016; AUM 67196, 12 (0mo/me, 11gm), 28.1–67.9 mm SL, Ireng River, downstream of Kaibarupai, 5.02404, –59.97763, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram, D. I. Brooks, 14 January 2016; AUM 67199, 2 (0), 19.7–23.2 mm SL, Ireng River, at Sand Hill shoals, 4.96554, –59.99411, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram, D. I. Brooks, 14 January 2016; AUM 67204, 12 (5mo/me), 17.1–72.0 mm SL, Ireng River, at Waipa Landing, 4.93345, –59.99514, D. C. Werneke, J. W. Armbruster, N. K. Lujan, M. Ram, D. I. Brooks, 14 January 2016. Diagnosis.— Characidium wangyapoik can be distinguished from all crenuchids except C. crandellii, C. declivirostre, and C. duplicatum by having venter without scales from the isthmus to the pelvic girdle (vs. maximally to pectoral insertion) and from most species of Characidium by having a very large pectoral fin with first three unbranched pectoral-fin rays thickened and first pectoral-fin ray bent at an oblique angle (vs. pectoral-fin rays not thickened and first pectoral-fin ray either straight or slightly convex). Characidium wangyapoik differs from C. crandellii, C. declivirostre, and C. duplicatum by having at least the ventral region of flank with thin bars becoming contiguous across body at larger sizes (vs. ventral area with almost square blotches), having lateral-line canal in most of scales very short (~ 25% of scale length), and having canal pores covered by preceding scales (vs. canal at least 33% of scale length and pores not covered by preceding scales); from C. crandellii by having 10 circumpeduncular scales (vs. 12), having two or more thin dark bands consisting of spots on rays in dorsal and pectoral fins (vs. a median wide dark band with pigment concentrated on membranes in dorsal fin and pectoral fin either entirely dark or dark with lighter middle), having an almost square dorsal fin with slightly concave distal margin (vs. falcate), having adipose fin located above middle of anal-fin base (vs. anterior edge of adipose fin at or behind vertical through posteriormost anal-fin insertion), by having dentary and premaxillary teeth narrow, peg-like, and maximally tricuspid with only central cusp well developed (vs. wide and tri- to pentacuspid, central cusp longest), by having zero to two (total) teeth in second dentary row (vs. 8 or more); by a preanal length/SL ratio of 77.4–82.3% (vs. 72.9–76.6%), and anal–apex length/SL ratio of 94.6–100.3% (vs. 89.4–94.0%); from C. declivirostre by having the flanks with 10 or more narrow bars (vs. less than 10 almost square blotches); and from C. duplicatum by having one leading unbranched pelvic ray (vs. two). Characidium wangyapoik is most similar in color to C. amaila from the upper Kuribrong River, but it has bands in the dorsal and pectoral fins (vs. no bands in C. amaila) and the unbranched pectoral-fin rays are greatly thickened (vs. only slightly thickened). Description.— Measurements based on 21 specimens (Table 2); meristics based on 20 specimens (reported below). Dorsal profile of body forms convex arc from tip of snout to posterior end of supraoccipital, then becomes steeper and longer convex arc from supraoccipital to end of dorsal fin (highest point of arc at dorsal-fin origin); dorsal profile relatively straight and ventrally angled from dorsal fin to adipose fin, then forming concave arc to caudal fin. Ventral profile straight to anal fin, then forming concave arc to caudal fin. Body depth greatest at dorsal origin and least at middle of caudal peduncle. Body oval in cross section anteriorly (flattened ventrally) and oval with dorsal and ventral surfaces somewhat flattened on caudal peduncle. Eye diameter 52.5–69.0% snout length, decreasing in size with SL (Fig. 3), oval, angled with anterior vertex ventral to posterior vertex; dorsal rim of orbit slightly higher than interorbital surface. Snout broadly rounded. Gill membranes united across isthmus. Tubercles present in both sexes dorsally on head and anterodorsal scales. Scales cycloid with most scales having 10–30 short, parallel striae (most on first postdorsal scale). Lateral line complete with canal occupying approximately 1/4 of scale length and pores covered by previous scales; 30 (1), 31 (4), 32 (12), or 33 (3) lateral-line scales; lateral-line scales distinctly smaller anteriorly; naked area between anterior lateral-line scales and pectoral-fin base; lateral line continues onto scales covering caudal base. 4 scales above lateral line and 2 scales below lateral line; 10 circumpeduncular scales. Scales covering anterior 1/5 of caudal fin. 7 (2), 8 (14), or 9 (4) predorsal scales. Venter unscaled on isthmus and posteriorly to 4 to 5 scales anterior to pelvic-fin origin. Dorsal fin with 2 unbranched and 8 (1) or 9 (19) branched rays (ii,8–9); first unbranched ray about 1/3 length of second; first unbranched ray longest and last shortest; fin roughly rectangular. Pectoral fin with 3 unbranched and 10 (19) or 11 (1) branched rays (iii,10–11); unbranched rays and first branched ray with thick pads of tissue anteriorly; first unbranched ray strongly curved; first branched ray longest and last shortest; pectoral fin oriented obliquely on body with posteriormost insertion located posterodorsally to origin. Pelvic fin with 1 leading unbranched ray, 6 (19) or 7 (1) branched rays, and 1 posterior unbranched ray (i,6–7,i); first branched ray longest; 2 to 3 pelvic axillary scales present with complex covering ~ half of pelvic-fin base. Anal fin with 2 unbranched rays and 5 branched rays (ii,5); first unbranched ray slightly less than 1/3 length of second, closely adhered; fin margin curved with second unbranched ray longest and last branched ray shortest. Caudal fin with 1 unbranched and 8 (4) or 9 (16) branched rays in upper lobe and 8 (16), or 9 (4) branched and 1 unbranched ray in lower lobe (i,8–9,8–9,i); forked with upper and lower lobes coequal. Adipose fin present with base centered on vertical through middle of anal-fin base. Rays of paired, dorsal, and anal fins with thick flaps of skin dorsally (paired fins) and laterally (dorsal and anal fins) that overlap successive rays in adpressed fins; flaps widest and longest anteriorly, decreasing in size and width posteriorly, flaps usually absent on posterior rays. Teeth tricuspid, narrow and peg-like with median cusp round and lateral cusps poorly developed. 6 (4), 7 (12), or 8 (4) premaxillary teeth. 9 (3), 10 (6), 11 (6), 12 (4), or 14 (1) teeth in outer dentary row. Inner dentary row comprising many small, unicuspid teeth; teeth may be poorly visible or absent in smaller specimens. Ectopterygoid with two rows of approximately 10 (lateral) and 5–10 (medial) minute teeth. Branchiostegal rays 4; 1 ray attached to posterior ceratohyal; 3 rays attached to anterior ceratohyal. Gill rakers 2–3 on dorsal limb, 1 on angle, 6–7 on ventral limb of anterior branchial arch. One supraorbital present; crescent shaped; from dorsal midpoint of orbit to dorsal ~ 1/4 of anterior scleral ossicle. All elements of infraorbital series, except infraorbital 1, without laminar component. Parietal branch of supraorbital sensory canal extending less than 1/4 into parietal. Parietal fontanel reduced to tiny triangle at posterior borders of parietals, almost absent in some; smallest specimens with gap between parietals. Frontal foramina above supraorbital canal 3–4 with some posterior foramina sometimes combined, wide, circular. Total number of vertebrae 33 (3). Vertebral centra 2–4 fused, without ventral processes. Rib of centrum 4 distally expanded, extending anteriorly toward lateral process of centrum 2. Posterior chamber of swim bladder extremely reduced, about length of one vertebral centrum. Supraneurals between neural spine of fourth centrum and anterior dorsal-fin pterygiophore 4 (4), 5 (1). Epurals 3 (5). Uroneural present, about 1/2 as long as urostyle. Coloration in life.— (Fig. 11) Base color tan with slight yellow tinge (particularly on head, fins, and dorsally). Dorsal surface with many (~ 10) diffuse saddles that seem to subdivide in larger specimens. Faint stripe present along lateral line. Numerous narrow bars below lateral line (1–1.5 scale rows wide). These may extend above lateral line and join with dorsal saddles (particularly in larger specimens). Color generally concentrated on scales with each scale having lighter edges, but either anterior or posterior edges may be light. Ventral surface gray with ventral bars almost meeting midventrally. Iridescent yellow-green stripe noticeable in some specimens between midlateral stripe and dorsal surface; stripe located below dark pigment and fades at insertion of posteriormost dorsal-fin ray. Head with dorsal saddle that extends to near ventral margin of opercle (posterior margin of opercle gray to yellow). Large dark blotches present below and behind eye. Wide stripe present from eye to snout. Dark bands present between orbits and down snout. Amount of melanin on head varies, some individuals with large gray to yellow patches and some almost entirely dark. Iridescent green spot present in some specimens located dorsal to postorbital dark spot. Dorsal fin with dark distal margin, gray band that changes to yellow proximally, then black band made of spots on rays that covers ~ 1/4 width of fin (interradial membranes gray along band), then narrow gray to yellow band, and finally proximal black band made of roughly triangular spots with longest edges along anterior margins of rays and sloping posteroventrally to posterior margin of rays (interradial membranes gray to yellow); all bands more diffuse anteriorly. Pectoral fin with gray distal margin changing to yellow proximally; dark spots present in two bands distally; distalmost dark band with spots only on rays, but some spots bleed onto membranes in proximal band; dark band at base of pectoral fin may be present; pectoral-fin colors more diffuse ventrally, generally gray with fleshy pads of unbranched and first branched rays almost white. Pelvic fin colored similarly to pectoral with single median band that includes melanophores on interradial membranes and band at base of fin. Anal fin as pelvic fin, but no basal band. Adipose fin yellow to gray proximally and dark distally with dark color confluent with saddle below it. Base color of caudal fin dark with pigment concentrated at junctions of lepidotrichia; two yellow spots present at base (just above and just below midline), single median spot located along midline just after proximal spots, rest of fin with large yellow blotches proximally and large gray blotches distally (gray blotches may fade into base color). Coloration in alcohol.— (Fig. 12) As in life but yellows and grays become tan and iridescence is lost. Distribution.— (Fig. 9) Characidium wangyapoik is only known from the upper Ireng River basin (Amazon River) along the Brazil / Guyana border (known as the Rio Mau in Brazil). Specimens were collected from below Orinduik Falls to the upper falls on the Ireng and its equal tributary, the Sukwabi River, but not above the Uluk Tuwuk or Wotawanda falls of the upper Ireng and Sukwabi Rivers (see Lujan et al., 2020, for a more detailed map and description of this area). Etymology.— Wangyapoik is the Patamona word for the species, and it is used as a noun in apposition. Wang means ‘honey’ and yapoik means ‘seated,’ perhaps in reference to the yellowish color. The Patamona also refer to the species by the English common name of ‘‘fallsfish.’&rsquo

Characidium crandellii Steindachner, 1915 Figures 1B, 4–6 Characidium crandellii Steindachner 1915: 32, Rio Miang, tributary Cotingo, Tacutu; Boa Vista, Rio Branco, Brazil. Specimens examined.— Brazil: syntypes: NMW 62673, 5 (2gm), 69260, 2 (1gm), Amazon River basin, Rio Miang, tributary Cotingo, Tacutu; Boa Vista, Rio Branco, Brazil. Guyana: AUM 28034, 3 (0mo/me, 3 gm), 26.8–33.3 mm SL, Potaro-Siparuni, Essequibo River basin, Potaro River, Tumatumari cataract, S bank below old hydroelectric plant, 5.36333, –59.00111; AUM 28139, 1 (0), 24.4 mm SL, Potaro-Siparuni, Essequibo River basin, Potaro River, Waratuk cataract, 5.25889, –59.40028; AUM 28184, 1 (1mo/me, 1gm), 37.1 mm SL, Potaro-Siparuni, Essequibo River basin, Potaro River and tributaries, at Tukeit cataract, 4.99889, –59.53889; AUM 35582, 7 (2mo, 1me), 26.4–29.1 mm SL, Cuyuni-Mazaruni (Region 7), Mazaruni River basin, Whitewater Creek 6.8 km SW Bartica, 6.378, –58.67374; AUM 36957, 12 (1mo/me, 8gm), 25.1–45.2 mm SL, Upper Demerara-Berbice (Region 10), Essequibo River basin, Essequibo River at Kurukupari, E bank, 4.66149, –58.67519; AUM 36958, 7 (0) 20.0– 23.6 mm SL, Upper Takutu-Upper Essequibo (Region 9), Amazon River basin, Pirara River, tributary of the Ireng River, 3.5 km NNW Pirara, 3.6487, –59.68897; AUM 36959, 1 (1mo/me, 1gm), 34.6 mm SL, Upper Takutu-Upper Essequibo (Region 9), Amazon River basin, Moco-Moco River at Moco-Moco Hydro Power Station 18.8 km SE Lethem, 3.29672, –59.64466; AUM 36960, 5 (2mo/me, 2gm), 47.4–48.6 mm SL, Upper Demerara-Berbice (Region 10), Essequibo River basin, Essequibo River at Kurukupari, E bank, 4.66149, –58.67519; AUM 45273, 1 (0), 30.0 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Essequibo River, side channel in rapids, 4.4215, –58.48623; AUM 45348, 1 (0), 23.7 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Essequibo River, side channel in rapids, 4.4215, –58.48623; AUM 45371, 4 (0mo/ me, 4gm), 23.8–27.0 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Essequibo River, side channel in rapids, 4.4215, –58.48623; AUM 62834, 1 (0), Potaro-Siparuni (Region 8), Essequibo River basin, Kuribrong River, in rapids at Grass Shoals, 5.40791, –59.53179; AUM 62874, 7 (0mo, 4me, 4gm), 37.2–43.8 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Kuribrong River, at Ram Sheep Rapids, 5.44236, –59.50201; AUM 62889, 1 (0), Potaro-Siparuni (Region 8), Essequibo River basin, Grass Falls Creek [Kiwikparu Creek], just upstream from mouth of Kuribrong River, 5.4065, –59.53361; AUM 62898, 76 (8mo, 6me, 24gm, 6cs), 41.7–56.5 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Grass Falls Creek [Kiwikparu Creek], near top of falls, 5.40532, –59.5439; AUM 63165, 2 (0), 23.1–24.3 mm SL, Upper Takutu-Upper Essequibo (Region 9), Amazon River basin, Ireng River, 6.9 km WSW Karasabai, 4.01957, –59.6017; AUM 67037, 3 (2mo, 3me, 3gm, 1cs), 47.4–72.5 mm SL, Potaro-Siparuni (Region 8), Amazon River basin, Ireng River, at Orinduik Falls, between upper and lower falls, 4.72536, –60.03852, 2 January 2016; AUM 67142, 1 (1mo, 1me, 1gm), 106.9 mm SL, Potaro-Siparuni (Region 8), Amazon River basin, Ireng River, shoals at mouth of Monkey Creek, Kaibarupai, 5.04398, –59.97717, 9 January 2016; ROM 91332, 3 (0), Potaro-Siparuni (Region 8), Essequibo River basin, Sheetrock Creek at crossing of Wailang-Powis tractor trail, 5.47473, –59.43770; ROM 91410, 1 (0), Potaro-Siparuni (Region 8), Essequibo River basin, Mikobe Creek approximately 0.5 km upstream from mouth, at rapids beyond first rapid blocking upstream boat movement, 5.41396, –59.47025, October 201; ROM 110044, 2 (0), Potaro-Siparuni (Region 8), Essequibo River basin, Sheetrock Creek at crossing of road between Wailang and Mona Falls, 5.47494, –59.43769; ROM 101902, 1 (0), Cuyuni-Mazaruni (Region 7), Mazaruni River basin, no common locality given, 6.13585, –60.0745. Venezuela: AUM 39466, 1 (1mo, 1me, 1gm), 49.4 mm SL, Amazonas, Orinoco River basin, Río Ventuari, above Salto Tencua, 58 km ESE of San Juan de Manapiare, 5.04777, –65.61583; AMNH 91171, 21 (0mo/me, 10gm), Bolivar, Orinoco River basin, Río Carapo, at third rapids above camp along left bank, 5.71333, –63.53333 (coordinates per Armbruster and Taphorn, 2013). Diagnosis.— Characidium crandellii can be distinguished from all crenuchids except C. declivirostre, C. duplicatum, new species, and C. wangyapoik, new species, by having the venter without scales from the isthmus to the pelvic girdle (vs. maximally to pectoral-fin insertion) and from most species of Characidium by having a very large pectoral fin with the first four unbranched pectoral-fin rays thickened, and the first pectoral-fin ray bent at an oblique angle (vs. pectoral-fin rays not thickened and first ray either straight or slightly convex). Characidium crandellii can be distinguished from C. declivirostre, C. duplicatum, new species, and C. wangyapoik, new species, by having the dorsal fin strongly falcate or concave (vs. largely rectangular with slightly convex edge); dorsal fin with a terminal hyaline band followed by a wide, dark band approximately 25% or greater the width of the fin, another wide hyaline band ~ 50% of the width of the fin, and a basal, dark band with all dark colors present on rays and membranes (vs. two or more thin dark bands much less than 25% of fin width, spots forming bands present only on fin rays); by having the pectoral fin either uniformly dark or with a lighter middle (vs. having spots forming two or more bands), by having the adipose fin inserted directly above insertion of the posteriormost anal-fin ray or slightly behind (vs. over the middle of the anal-fin base), by having 12 circumpeduncular scales (vs. 10), having dentary and premaxillary teeth wide and tri- to pentacuspid (central cusp longest; vs. teeth narrow and peg-like, and maximally tricuspid with only the central cusp well developed), by many teeth (.5) in the posterior dentary row (vs. usually zero but up to two total); and by an anal–apex length/SL ratio of 89.4–94.0 (vs. 93.9–100.3); from C. declivirostre and C. wangyapoik, new species, by having four branched pectoral-fin rays (vs. 3) and a preanal length/SL ratio of 72.9–76.6 (vs. 76.9–82.3); and from C. duplicatum, new species, by having one anterior branched pelvic-fin ray and ray count of i,6,i (vs. two, and ray count of ii,5,i). In addition, infraorbitals 3–4 are reduced to just ossification around the infraorbital canal in C. crandellii, while there is some laminar bone dorsal and ventral to the canal in C. declivirostre, C. duplicatum, new species, and C. wangyapoik, new species. Description.— Measurements (Table 1) and meristics (reported below) based on 20 specimens. Dorsal profile of body convex arc from tip of snout to posterior end of dorsal fin (highest point of arc at dorsal-fin origin); body then relatively straight and angled ventrally to adipose fin, then shallowly concave to caudal fin. Ventral profile straight to anal fin, then concave arc to caudal fin. Body depth greatest at dorsal-fin origin and least at middle of caudal peduncle. Body oval in cross section anteriorly with ventral surface flattened and oval with dorsal and ventral surfaces somewhat flattened on caudal peduncle. Eye diameter 45.8–97.3% snout length, decreasing with SL (Fig. 3); oval, angled with anterior vertex ventral to posterior vertex; dorsal rim of orbit slightly higher than interorbital surface. Snout broadly rounded. Gill membranes united across isthmus. Tubercles absent. Scales cycloid, mostly smooth, some with numerous (~ 20– 30) weak, parallel striae. Lateral line complete with anterior segments within each scale occupying approximately one-third length of each scale and pores visible laterally, vs. posterior segments occupying less than one-quarter length of each scale and pores covered by previous scale; 30 (2), 31 (3), 32 (8), 33 (6), or 36 (1) lateral-line scales; lateral-line scales distinctly smaller anteriorly; naked area located between anterior lateral-line scales and pectoral-fin base; lateral line continues onto scales covering caudal base. 4 (12) or 5 (8) scales above lateral line, 1 (2) or 2 (18) scales below lateral line, 12 circumpeduncular scales. Scales covering anterior 20% of caudal fin. 8 (2), 9 (6), 10 (9), or 11 (3) predorsal scales. Venter unscaled on isthmus and posteriorly to about 2 scales before pelvic-fin origin. Dorsal fin with 2 unbranched and 8 (9) or 9 (11) branched rays (ii,8–9); first unbranched ray about half length of second; first branched ray longest with shortest ray in middle making fin falcate. Pectoral fin with 4 unbranched and 11 (11) or 12 (9) branched rays (iv,11–12); unbranched rays and first unbranched ray with thick pads of tissue anteriorly; first unbranched ray strongly bent in middle to form oblique angle; first branched ray longest and last shortest; pectoral fin oriented obliquely on body with insertion of posteriormost fin ray located posterodorsally to origin. Pelvic fin with 1 leading unbranched ray, 6 branched rays, and 1 posterior unbranched ray (i,6,i); first branched ray longest; 2 or 3 pelvic axillary scales present with complex covering about half of pelvic-fin base. Anal fin with 2 unbranched rays and 5 (4) or 6 (16) branched rays (ii,5–6); first unbranched ray approximately one-third length of second, closely adhered; fin falcate with first unbranched ray longest and last shortest. Caudal fin with 1 unbranched and 9 (17) or 10 (3) branched rays in upper lobe and 7 (6), 8 (12), or 9 (2) branched and 1 unbranched ray in lower lobe (i,9–10,7–9,i); forked with upper and lower lobes equal. Adipose fin present with base centered on vertical over last ray of anal fin. Rays of paired, dorsal, and anal fins with thick flaps of skin dorsally (paired fins) and laterally (dorsal and anal fins) that overlap successive rays in folded fin; flaps widest and longest anteriorly, decreasing in size and width posteriorly and usually absent on posterior rays. Teeth tri- to pentacuspid, wide with edges sharp. 5 (3), 6 (6), 7 (8), or 8 (3) premaxillary teeth. 5 (1), 6 (1), 7 (4), 8 (3), 9 (5), 10 (2), 11 (2), or 12 (2) teeth in outer dentary row. Inner dentary row made up of many small, unicuspid teeth. Ectopterygoid with 2 rows of approximately 8–10 minute teeth per row. Branchiostegal rays 4; 1 ray attached to posterior ceratohyal; 3 rays attached to anterior ceratohyal. Gill rakers 3–5 on dorsal limb, 1 on angle, 7–8 on ventral limb of anterior branchial arch. One supraorbital present; moderately crescent shaped with ventral edge almost straight; from dorsal midpoint of orbit to dorsal ~ 1/4–1/3 anterior scleral ossicle; one individual had the posterior portion of each supraorbital present as three separate ossifications in addition to main anterior ossification. All elements of infraorbital series, except infraorbital 1, without laminar component; infraorbitals 3–4 no more than ossification around canal. Parietal branch of supraorbital sensory canal extending to middle or about 3/4 of parietal. Parietal fontanel variable from tiny triangle at posterior borders of parietals to narrow opening at posterior borders of parietals that widens in posterior ~ 1/3 of parietals then narrows to contact with frontals. Frontal foramina above supraorbital canal 4, wide, circular. Total number of vertebrae 35 (2), 36 (2), 37 (2). Vertebral centra 2 þ 3 fused, without ventral processes. Rib of centrum 4 distally expanded, extending anteriorly toward lateral process of centrum 2. Posterior chamber of swim bladder absent. Supraneurals between neural spine of fourth centrum and anterior dorsal-fin pterygiophore 4 (4), 5 (1). Epurals 2. Uroneural present, about 60% as long as urostyle. Coloration in life.— (Figs. 4, 5) Background color generally light tan on body to yellow on fins occasionally with some green iridescence. Background color of largest specimen (AUM 67142) golden with gold filling lighter areas of fins and gold present on ventral surface (although lighter) from anterior of the pelvic fins to caudal peduncle. Dark midlateral stripe generally present from opercle to caudal fin; scales within stripe darkest in their centers making stripe appear to be made out of chevrons with distal portions of some of these chevrons bleeding into scales above and below (darker above than below); stripe widens to large spot on caudal peduncle. About seven dorsal saddles present, first two in nuchal area, third below anterior portion of dorsal fin, fourth and fifth in interdorsal area, and sixth and seventh between adipose and caudal fin. Scales in lighter areas between saddles have posterior halves dark with darker colors dorsally. Irregular blotches present below lateral stripe and often contiguous with dorsal saddles. Light areas of body rich tan above midlateral stripe and pale yellow below; tan above stripe fades to pale yellow posteriorly. Head with mottled dark patch above roof of cranium, dark line behind the eye, dark line leading from near snout tip to posterior of eye, mottling dorsally on the snout with pale yellow spot located anterodorsally to eye, and lighter areas of the cheek and opercle speckled with melanophores. All fins gray at distal margins and yellow proximally; gray and yellow portions bleed into one another along fin rays. Membranes and some parts of rays between gray and yellow regions dark; most intense dark marks on dorsal fin, ventral portion of caudal fin, and at bases of pectoral and adipose fins. Unbranched pectoral and pelvic rays (and less so following branched rays) with darkest colors centrally along rays and increasing distally, with anterior margins gray and posterior margins yellow. Ventrally, colors more muted; thickened, unbranched and anterior branched rays of pectoral and pelvic fins light gray. Dark areas located at bases of all fins. Largest specimen (AUM 67142) differs from this general pattern in that light areas golden and dark areas more intense, lateral stripe absent, and iris brick red (vs. reddish but mottled with black). Coloration in alcohol.— Similar to color in life, but dark areas more intense and wider and light areas light gray or tan. Distribution.— Characidium crandellii has been found mostly in the upper Branco River (Amazon River) basins of Brazil and Guyana and the middle and lower Essequibo River of Guyana (Fig. 6). The type locality is a tributary of the Cotinga River (tributary of the Takutu/Branco) in the vicinity of Boa Vista (Fig. 6). We have examined two collections of the species from the Orinoco River basin. One specimen is from above Tencua Falls (Salto Tencua), the first major barrier to navigation and a major faunal break between the middle and upper Ventuari River (Lujan et al., 2018), and the other collection is from south of Tepuy Guaiquinima in the Paragua/Caroni River basin, also above a series of rapids, including Uraima Falls located just north of the tepui. The Tencua specimen differs from other C. crandellii sensu stricto by having a series of small, vertical spots below the midline and just posterior to the pectoral fin and only the faint remnant of a lateral stripe. The Río Paragua specimens appear more similar to the specimens from the Amazon and Essequibo than to the Tencua specimen. Remarks.— One specimen from the Ireng River (AUM 67142; 106.9 mm SL; Fig. 4) is the largest specimen of Characidium ever examined and far larger than any other specimens. Its golden color seems to suggest that it is a nuptial male, but we did not confirm with dissection because the specimen is unique., Published as part of Armbruster, Jonathan W., Lujan, Nathan K. & Bloom, Devin D., 2021, Redescription of the Guiana Shield Darter Species Characidium crandellii and C. declivirostre (Crenuchidae) with Descriptions of Two New Species, pp. 102-122 in Ichthyology & Herpetology 109 (1) on pages 103-108, DOI: 10.1643/i2019299, http://zenodo.org/record/7846669, {"references":["Steindachner, F. 1915. Beitrage zur Kenntniss der Flufische Sudamerikas. V. Denkschriften der Kaiserlichen Akademie der Wissenschaften in Wien, Mathematisch-Naturwissenschaftliche Klasse 93: 15 - 106.","Armbruster, J. W., and D. C. Taphorn. 2013. Description of Neblinichthys peniculatus, a new species of loricariid catfish from the Rio Paragua. Neotropical Ichthyology 11: 65 - 72.","Lujan, N. K., J. W. Armbruster, and N. R. Lovejoy. 2018. Multilocus phylogeny, diagnosis and generic revision of the Guiana Shield endemic suckermouth armored catfish tribe Lithoxini (Loricariidae: Hypostominae). Zoological Journal of the Linnean Society 184: 1169 - 1186."]}

Characidium declivirostre Steindachner, 1915 Figures 2A, 7–9 Characidium declivirostre Steindachner 1915: 31, Río Coquenan, tributary of Río Caroni, Venezuela. Melanocharacidium pectorale (sic).— Conway et al., 2012: figs. 6C, D, H, and J, and other mentions [fin pad description]. Specimens examined.— Venezuela: AMNH 91168, 1 (0), Bolivar, Orinoco River basin, Río Carapo, at first rapids along right bank, 5.69750, –63.54167 (coordinates per Armbruster and Taphorn, 2013); AMNH 91169, 4 (0), Bolivar, Orinoco River basin, Río Carapo, at third rapids above camp along left bank, 5.71333, –63.53333 (coordinates per Armbruster and Taphorn, 2013); AMNH 91170, 17 (0), Río Paragua, at Gusano Rapids, ca. 1–1.5 hours upriver from Río Carapo mouth, ~ 5.5037, –63.5941 (coordinates placed at first large rapids complex upstream of Río Carapo, 1 March 1990; AMNH 232950, 8 (0), Amazonas, Orinoco River basin, Río Cuao at Guacamaya Raudal, 13 km upstream from Raudal del Danto, 5.12861, –67.52556; AMNH 232982, 2 (0), Amazonas, Orinoco River basin, Río Cuao at Raudal Piapoco, 21.5 km upstream from Raudal del Danto, 5.18250, –67.51361; AMNH 233000, 26 (0), Amazonas, Orinoco River basin, Río Cuao, Raudal Cielo, west side of Isla del Cielo, 15 minutes by foot from SAS-01-04 basecamp, 7 March 2001; AMNH 233025, 1 (0), Amazonas, Orinoco River basin, Río Cuao at Raudal Pauji, W side of Isla del Cielo, ca. 10 minutes by boat downstream from SAS-01-04 basecamp, 5.14861, –67.53639; AMNH 233084, 14 (0), Amazonas, Orinoco River basin, Caño Pawa ca. 30 minutes by foot upstream from mouth into Río Cuao, ca. 30 minutes downstream from Puerto Nuevo, 5.29194. –67.32889; AUM 22310, 1 (0), Bolivar, Orinoco River basin, Río Chaviripa, at base of falls, ca. 2 km SE Caicara-Puerto Ayacucho Rd., 7.11389, –66.47306; AUM 22318, 1 (0mo/me, 1gm), 34.9 mm SL, Bolivar, Orinoco River basin, Tributary of Río Caripo, ca. 16 km ESE Los Pijiguaos, Caicara-Puerto Ayacucho Rd., 6.57361, –66.93417; AUM 36625, 4 (3mo/me, 4gm), 43.4–50.2 mm SL, Bolivar, Orinoco River basin, Río San Ignacio, km 258, 5.01015, –61.13694; AUM 36638, 8 (3mo/3me, 4gm), 37.0– 56.2 mm SL, Bolivar, Orinoco River basin, tributary to Río Yuruani, km 255, 5.01888, –61.11447; AUM 36660, 2 (0), 41.7–45.7 mm SL, Bolivar, Orinoco River basin, Río Samey, 57.5 km WSW of Santa Elena, 6 km S. of El Piaje, on foot path, 4.42296, –61.59586; AUM 36674, 7 (2mo/me, 7gm), 33.0– 47.5 mm SL, Bolivar, Orinoco River basin, Río Mapuari, km 268, 38 km N of Santa Elena, 4.94401, –61.12099; AUM 37137, 2 (0), 29.6– 32.7 mm SL, Bolivar, Orinoco River basin, Río Paragua, 66.9 km SSW of La Paragua, at Uraima Falls, 6.30117, –63.62427; AUM 39296, 5 (0), 19.1–20.5 mm SL, Amazonas, Orinoco River basin, Río Manapiare, 14.5 km NW of San Juan de Manapiare, 5.42863, –66.13616; AUM 39468, 2 (0mo/me, 2gm), 34.5–36.3 mm SL, Amazonas, Orinoco River basin, Río Ventuari, above Salto Tencua, 58 km ESE of San Juan de Manapiare, 5.04777, –65.61583; AUM 39539, 1 (0mo/me, 1gm), 38.6 mm SL, Amazonas, Orinoco River basin, Río Ventuari, at Raudales Tencua, 56 km ESE of San Juan de Manapiare, 5.04968, –65.62722; AUM 39601, 1 (0), Amazonas, Orinoco River basin, Río Manapiare, 17 km NW of San Juan de Manapiare, 5.44198, –66.1507; AUM 40191, 44 (6mo/me, 20gm, 4cs), 18.4–57.2 mm SL, Amazonas, Orinoco River basin, tributary to Orinoco, 30 km S of Puerto Ayacucho, 5.38659, –67.61556; AUM 43381, 3 (0mo/me, 1gm), 58.4 mm SL, Amazonas, Orinoco River basin, Río Iguapo, 12.6 km ENE of La Esmeralda, 3.19988, –65.43582, 7 March 2005; AUM 43461, 1 (0), Amazonas, Orinoco River basin, Río Casiquiare, bedrock in stream, 73 km NE of San Carlos de Río Negro, 2.35258, –66.57521; AUM 43497, 6 (0), Amazonas, Amazon River basin, Río Siapa, raudales, 154 km E of San Carlos de Río Negro, 1.60339, –65.71587; AUM 43519, 1 (1mo/me, 1gm), 58.7 mm SL, Amazonas, Amazon River basin, Caño Aracamoní, 156 km ESE of San Carlos de Río Negro, 1.55669, –65.72533; AUM 43924, 11 (0), Amazonas, Orinoco River basin, Río Iguapo, 12.8 km ENE of Esmeralda, 3.19544, –65.43908; AUM 43943, 1 (0), Amazonas, Orinoco River basin, Caño Tama Tama, 31 km WNW of Esmeralda, 3.21294, –65.82502; AUM 44072, 1 (0), Amazonas, Orinoco River basin, Río Orinoco, Punto de Maraya, 80.8 km E of San Fernando de Atabapo, Isla Maraya, 4.02303, –66.97189; AUM 53418, 1 (0mo/me, 1gm), 53.9 mm SL, Amazonas, Orinoco River basin, Cano Pasa, 98 km S of the Puerto Ayacucho airport, 5.06119, –67.77957; AUM 54195, 1 (0), Amazonas, Orinoco River basin, Río Cataniapo, at Gavilan community, 5.54902, –67.38808; AUM 54207, 26 (0), Amazonas, Orinoco River basin, Río Cataniapo, at Sardi community, 5.53375, –67.37395; AUM 56680, 27 (5mo/me, 11gm, 2cs), 50.5–55.5 mm SL, Amazonas, Orinoco River basin, Río Cuao, at Raudales Danto, 69.3 km S of Puerto Ayacucho, 5.04409, –67.56045; AUM 56762, 2 (0), Amazonas, Orinoco River basin, Caño Soromoni, 11.8 km WNW of La Esmeralda, 3.1938, –65.65197; NMW 62442, 4 (3gm), syntypes, Orinoco River basin, Río Coquenan, tributary of Río Caroni. Diagnosis.— Characidium declivirostre can be distinguished from all crenuchids except C. crandellii, C. duplicatum, new species, and C. wangyapoik, new species, by having venter without scales from isthmus to pelvic girdle (vs. maximally to insertion of posteriormost pectoral-fin ray) and from most species of Characidium by having a very large pectoral fin with first three, unbranched pectoral-fin rays thickened, and first pectoral-fin ray bent at an oblique angle (vs. pectoral-fin rays not thickened and first ray either straight or slightly curved). Characidium declivirostre differs from C. crandellii and C. duplicatum, new species, by having three unbranched pectoral rays (vs. four); from C. crandellii by having ten circumpeduncular scales (vs. 12), by having two or more thin dark bands consisting of spots on rays in the dorsal and pectoral fins (vs. a median wide dark band with pigment concentrated on membranes in the dorsal fin and the pectoral fin either entirely dark or dark with a lighter middle), by having an almost square dorsal fin with slightly concave distal edge (vs. falcate), by having the adipose fin above the middle of the anal-fin base (vs. anterior edge of the adipose fin above or behind a vertical through the insertion of the posterior most anal-fin ray), by having dentary and premaxillary teeth narrow and peg-like, and maximally tricuspid with only the central cusp well developed (vs. wide and tri- to pentacuspid, central cusp longest), by having zero to two (total) teeth in the second dentary row (vs. 8 or more), by a preanal length/SL ratio of 76.9–80.6% (vs. 72.9–76.6%), and an anal–apex length/SL ratio of 93.9–97.8% (vs. 89.4– 94.0%); from C. duplicatum, new species, by having one leading unbranched pelvic ray (vs. two); and from C. wangyapoik, new species, by having the ventral portion of the flanks with less than ten almost square blotches (vs. 10 or more narrow bars), by having lateral-line canals at least 33% of scale length and pores not covered by preceding scales (vs. lateral-line canals very short in scale, less than 25%, and pores covered by preceding scales). Description.— Measurements (Table 1) and meristics (reported below) based on 20 specimens. Dorsal profile of body forms convex arc from tip of snout to adipose fin (slight change in conformation at insertion of posteriormost dorsal-fin ray) then concave arc to caudal fin. Ventral profile straight to anal fin, then concave arc to caudal fin. Body depth greatest at dorsal-fin origin and least at middle of caudal peduncle. Body oval in cross section anteriorly (flattened ventrally) and oval with dorsal and ventral surfaces somewhat flattened on caudal peduncle. Eye 57.6–78.8% snout length, decreasing in size with SL (Fig. 3), oval, angled with anterior vertex ventral to posterior vertex; dorsal rim of orbit slightly higher than interorbital surface. Snout pointed. Gill membranes united across isthmus. Tubercles present in both sexes, distributed dorsally on head and anterodorsal scales. Scales cycloid, generally flat with about 6 striae in first postdorsal scale. Lateral line complete with canal in scales running approximately 33% of scales and pores visible laterally just posterior to previous scales; 30 (1), 31 (13), 32 (3), 33 (2), or 35 (1) lateral-line scales; lateral-line scales distinctly smaller anteriorly; naked area between anterior lateral-line scales and pectoral-fin base; lateral line continues onto scales covering caudal base. 3 (3) or 4 (17) scales above lateral line and 2 scales below lateral line, 10 circumpeduncular scales. Scales covering anterior 20% of caudal fin. 8 (10), 9 (9), or 10 (1) predorsal scales. Venter unscaled on isthmus and posteriorly to about two to three scales anterior to pelvic-fin origin. Dorsal fin with 2 unbranched and 9 branched rays (ii,9); first unbranched ray about one-half length of second, closely adhered; first branched ray longest and last shortest; fin roughly rectangular. Pectoral fin with 3 unbranched and 9 (1), 10 (17), or 11 (2) branched rays (iii,9–11); unbranched rays and first branched ray with thick pads of tissue anteriorly; first unbranched ray forming curve; first branched ray longest and last shortest; pectoral fin oriented obliquely on body with insertion of posteriormost ray located posterodorsally to origin. Pelvic fin with 1 leading unbranched ray, 6 branched rays, and 1 posterior unbranched ray (i,6,i); first branched ray longest; 2 to 3 pelvic axillary scales present with complex covering approximately half of pelvic-fin base. Anal fin with 2 unbranched rays and 5 (15) or 6 (5) branched rays (ii,5–6); first unbranched ray approximately one-third length of second, closely adhered; fin margin almost straight with second unbranched or first branched ray longest; anal fin fits into space made available by steep, concave profile of venter starting at anal-fin origin. Caudal fin with 1 unbranched and 9 branched rays in upper lobe and 7 (1) or 8 (19) branched and one unbranched ray in lower lobe (i,9,7–8,i); forked with upper and lower lobes coequal. Adipose fin present with base centered on vertical through middle of anal-fin base. Rays of paired, dorsal, and anal fins with thick flaps of skin dorsally (paired fins) and laterally (dorsal and anal fins) that overlap successive rays of adpressed fin; flaps widest and longest anteriorly, decreasing in size and width posteriorly and often absent on middle and posterior rays. Teeth tricuspid, narrow and peg-like with median cusp round and lateral cusps poorly developed. 5 (1), 6 (9), 7 (3), 8 (4), 9 (2), or 10 (1) premaxillary teeth. 6 (2), 7 (1), 8 (6), 9 (3), 10 (3), 11 (1), or 12 (4) teeth in outer dentary row. Inner dentary row made up of many small, unicuspid teeth; teeth may be absent or not readily visible in smaller specimens. Ectopterygoid usually with 2 rows of approximately 10 (lateral) and 5–10 (medial) minute teeth, some specimens having only lateral row. Branchiostegal rays 4, 1 attached to posterior ceratohyal, 3 attached to anterior ceratohyal. Gill rakers 1–3 on dorsal limb, 1 on angle, 6–7 on ventral limb of anterior branchial arch. 1 supraorbital present; crescent shaped; from dorsal midpoint of orbit to dorsal 1/3 of anterior scleral ossicle. All elements of infraorbital series, except infraorbital 1, without laminar component. Parietal branch of supraorbital sensory canal extending to middle of parietal. Parietal fontanel reduced to tiny triangle at posterior borders of parietals. Frontal foramina above supraorbital canal 3 wide, circular. Total number of vertebrae 33 (1), 34 (1), 35 (2), 36 (2). Vertebral centra 2–4 fused, without ventral processes. Rib of centrum 4 distally expanded, extending anteriorly toward lateral process of centrum 2. Posterior chamber of swim bladder extremely reduced, about length of one vertebral centrum. Supraneurals between neural spine of fourth centrum and anterior dorsal-fin pterygiophore 4 (3), 5 (3). Epurals 2 (1), 3 (5). Uroneural present, about 50% as long as urostyle. Coloration in life.— (Fig. 7) Base color tan with very slight yellow tinge (particularly on head and fins). Dorsal surface with six saddles considerably darker than light intervening regions (light regions from head to dorsal fin have spots centrally [dorsoventrally] and distally [anteroposteriorly] located on scales); first dorsal saddle located on nape, second anterior to dorsal-fin origin, third directly under dorsal fin, fourth in interdorsal region, fifth posterior to adipose-fin base, and sixth at end of caudal peduncle and continuing on to scales covering base of caudal fin. Faint lateral stripe made of spotted scales present along lateral line (spots always located along center lines, but may be posterior on scale (anterior body), central on scales (middle body), or anterior on scales (posterior body); lateral stripe covers lateral-line scales and one row above. Approximately 8 roughly square blotches located below lateral line (usually 2–2.5 scale rows wide, but some blotches smaller, particularly in smaller specimens). These blotches terminate in lateral stripe. Faint, iridescent yellow-green area noticeable above pectoral-fin base. Head mottled with dark patches on tan to yellow background. Dark patch located on center of opercle, patch fading anteriorly; posterodorsal corner of opercle tan. Large, diffuse, dark blotches present below and behind eye. Wide stripe present from eye to snout. Dark bands present between orbits and down snout. Amount of melanin on head variable, some individuals with large light gray to yellow patches and some almost entirely dark gray. Dorsal fin with alternating dark and light bands; bands better developed anteriorly. Distal band dark, pigment concentrated on rays. Second band gray (membranes) and tan (rays). Third band black, pigment concentrated on membranes. Fourth band wide gray (membranes) and tan (rays) band. Fifth (most proximal) band black, band covering rays and membranes. Pectoral fin with yellow to gray base color with dark spots centered on rays in two to three distal and one basal band; bands irregular; some spots bleeding onto membranes; ventrally, pectoral-fin colors more diffuse, generally gray with fleshy pads of unbranched and first branched rays almost white. Pelvic fin colored similarly to pectoral with single median band including melanophores on interradial membranes, and diffuse dark band at base of fin. Anal fin as pelvic fin, but no basal band, and band much wider anteriorly. Adipose fin yellow to gray proximally and dark distally with dark color confluent with saddle below it. Base color of caudal fin dark with pigment particularly concentrated at branching points of lepidotrichia; 2 yellow spots present at base (just above and below midline); dorsal and ventral spots may bleed into one another across center; rest of fin with large yellow blotches. Coloration in alcohol.— (Fig. 8) As in life but yellows and grays change to tan to light brown, spots on scales less distinct and numerous, and iridescence absent. Juveniles colored similarly to adults, but may have more and narrower ventral blotches, generally lighter in color overall. Some populations considerably lighter with greater contrast between light and dark areas, narrower bands, and smaller spots on fins. Distribution.— (Fig. 9) Characidium declivirostre is known from throughout the Orinoco River basin and the upper Negro River basin. The type locality is the Río Coquenán (also spelled Kukenan), a tributary of the upper Caroni River in Venezuela, We collected and examined material from near this locality (AUM 37137). Its range likely also includes leftbank clear or blackwater tributaries of the Orinoco River in Colombia and rivers draining the southern slope of the western Guiana Shield in Brazil. Our collections of this species were mostly from bedrock shoals in medium to largesized streams. Remarks.— In their investigation of the microanatomy of paired-fin pads in ostariophysan fishes, Conway et al. (2012: figs. 6C, D, H, and J) described the pectoral- and pelvic-fin pads of this species (AUM 40191, misidentified therein as Melanocharacidium pectorale). The pads were described as Type I pads where the epidermis is thickened without contribution from the subepidermal layers. They found the epidermis to be thicker ventrally than dorsally (60 vs. 30 lm), the subdermal layer thicker dorsally than ventrally (30 vs. 10 lm), keratinized unculi present on the ventral surfaces of the fin-ray pads, and alarm substance cells and mucocytes present and common on dorsal and ventral surfaces except the ventral surfaces of the pads., Published as part of Armbruster, Jonathan W., Lujan, Nathan K. & Bloom, Devin D., 2021, Redescription of the Guiana Shield Darter Species Characidium crandellii and C. declivirostre (Crenuchidae) with Descriptions of Two New Species, pp. 102-122 in Ichthyology & Herpetology 109 (1) on pages 109-113, DOI: 10.1643/i2019299, http://zenodo.org/record/7846669, {"references":["Steindachner, F. 1915. Beitrage zur Kenntniss der Flufische Sudamerikas. V. Denkschriften der Kaiserlichen Akademie der Wissenschaften in Wien, Mathematisch-Naturwissenschaftliche Klasse 93: 15 - 106.","Conway, K. W., N. K. Lujan, J. G. Lundberg, R. L. Mayden, and D. S. Siegel. 2012. Microanatomy of the paired-fin pads of ostariophysan fishes (Teleostei: Ostariophysi). Journal of Morphology 273: 1127 - 1149.","Armbruster, J. W., and D. C. Taphorn. 2013. Description of Neblinichthys peniculatus, a new species of loricariid catfish from the Rio Paragua. Neotropical Ichthyology 11: 65 - 72."]}

Characidium duplicatum, new species urn:lsid:zoobank.org:act: 11B1C6B7-9273-4C91-959A-31FDF3C0797B Figure 10 Leptocharacidium sp. — Hardman et al., 2002: 235 [locality record]. Holotype.— CSBD F-3614 (ex AUM 62835), 1 (1mo/me, 1gm), 39.4 mm SL, Guyana, Region 8 (Potaro-Siparuni), Potaro- Essequibo River basin, Kuribrong River, in rapids at Grass Shoals, 05.40791, –059.53179, J. W. Armbruster, D. C. Werneke, E. A. Liverpool, D. P. Fernandes, D. C. Taphorn, 12 March 2014. Paratypes.— Guyana: AUM 28124, 1 (1mo/me), 25.2 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Potaro River, Amatuk cataract and beach just below cataract, 5.30389, –59.31111, L. M. Page, J. W. Armbruster, M. H. Sabaj, M. Hardman, J. H. Knouft, W. S. Prince, 25 October 1998; AUM 28135, 5 (5mo/me, 5gm, 1cs), 19.6–22.6 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Potaro River, Waratuk cataract, 5.25889, –59.40028, L. M. Page, J. W. Armbruster, M. H. Sabaj, M. Hardman, J. H. Knouft, W. S. Prince, 26 October 1998; AUM 62835, 1 (1mo/me, 1gm), 38.9 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Kuribrong River, in rapids at Grass Shoals, 5.40791, –59.53179, J. W. Armbruster, D. C. Werneke, E. A. Liverpool, D. P. Fernandes, D. C. Taphorn, 12 March 2014; AUM 72308, 1 (0mo, 1me, 1gm), 29.9 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Kuribrong River, at Ram Sheep Rapids, 5.44236, –59.50201, D. C. Taphorn, J. W. Armbruster, D. C. Werneke, E. A. Liverpool, D. P. Fernandes, M. Benjamin, 13 March 2014; ROM 61496, 13 (5mo/me, 7gm), 19.5–28.9 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Potaro River, Amatuk Falls, side channel of Potaro River near portage, 5.30421, –59.31051, E. Holm, 2 October 1990; ROM 110060, 1 (1mo/me, 1 gm), 36.2 mm SL, Potaro-Siparuni (Region 8), Essequibo River basin, Sheetrock Creek at crossing of road between Wailang and Mona Falls, 5.47494, –59.43769, N. K. Lujan, E. Liverpool, D. Gordon, M. Benjamen, L. Ziccardi, O. Williams, 29 April 2013. Other specimens examined.— Guyana: AUM 38991, 1 (1mo/ me, 1gm), 25.2 mm SL, Upper Takutu-Upper Essequibo (Region 9), Essequibo River basin, Essequibo River at Kassi- Attae Rapids, 5.5 km SE mouth of Kuyuwini River, 2.22654, –58.29379, J. W. Armbruster, M. H. Sabaj, M. Hardman, D. Arjoon, N. K. Lujan, L. S. de Souza, 10 November 2003; AUM 39024, 7 (6mo, 7me, 6gm, 1cs), 25.0–30.0 mm SL, Upper Takutu-Upper Essequibo (Region 9), Essequibo River basin, Essequibo River at Yukanopito Falls, 44.5 km SW mouth of Kuyuwini River, 1.91461, –58.52046, J. W. Armbruster, M. H. Sabaj, M. Hardman, D. Arjoon, N. K. Lujan, L. S. de Souza, 9 November 2003. Diagnosis.— Characidium duplicatum can be distinguished from all other crenuchids except Leptocharacidium by having two anterior unbranched pelvic rays, and from all crenuchids except C. crandellii, C. declivirostre, and C. wangyapoik, new species, by having venter without scales from the isthmus to pelvic girdle (vs. maximally to posteriormost pectoral-fin ray insertion), and from most species of Characidium by having a very large pectoral fin with first four unbranched pectoral-fin rays thickened, and first pectoral-fin ray bent at oblique angle (vs. pectoral-fin rays not thickened and first ray either straight or slightly convex). Characidium duplicatum further differs from C. declivirostre and C. wangyapoik, new species, by having four unbranched pectoral-fin rays (vs. three); from C. crandellii by having nine branched pectoral-fin rays (vs. 10– 11); pelvic fin ii,5,i (vs. i,6,i), by having ten circumpeduncular scales (vs. 12), by having two or more thin dark bands consisting of spots on dorsal- and pectoral-fin rays (vs. a median wide dark band with pigment concentrated on dorsal- and pectoral-fin membranes, membranes either entirely dark or lighter at center), by having an almost square dorsal fin with slightly concave distal margin (vs. falcate), by having adipose fin above middle of anal-fin base (vs. origin of adipose fin above or behind vertical through posteriormost anal-fin ray insertion), by having dentary and premaxillary teeth narrow, peg-like, maximally tricuspid with only central cusp well developed (vs. wide and tri- to pentacuspid, central cusp longest), by having no teeth in the second dentary row (vs. 8 or more), and by an anal–apex length/SL ratio of 94.5–100.0% (vs. 89.4–94.0%). In addition, the anterior border of the pectoral girdle is convex such that it is deepest at the midline in C. duplicatum, while the anterior border is slightly notched (deepest lateral of midline) in C. declivirostre and C. wangyapoik, new species, and deeply notched in C. crandellii. Description.— Measurements based on 20 specimens (Table 2); meristics based on 23 specimens. Dorsal profile of body convex arc from tip of snout to posterior end of supraoccipital, then beginning steeper and longer concave arc from supraoccipital to end of dorsal fin (highest point of arc at dorsal-fin origin); body then relatively straight and angled ventrally to end of caudal peduncle. Ventral profile straight to end of pelvic base, rises slightly to anal fin, then concave arc to caudal fin. Body deepest at dorsal-fin origin and shallowest at middle of caudal peduncle. Body oval in cross section anteriorly and oval with dorsal and ventral surfaces somewhat flattened on caudal peduncle. Eye diameter 78.8– 118.0% snout length, decreasing in size with SL (Fig. 3), oval, angled with anterior vertex ventral to posterior vertex; dorsal rim of orbit significantly higher than interorbital surface. Snout broadly rounded. Gill membranes united across isthmus, but width of membrane greater in larger specimens. Tubercles absent. Scales cycloid with approximately 10 parallel striae in first postdorsal scale. Lateral line complete with canal in most scales occupying approximately 33–50% of scales and pores exposed just posterior to previous scale (some scales with pore at or near posterior end of scale); 28 (1), 29 (10), 30 (3), or 31 (3) lateral-line scales; lateral-line scales distinctly smaller anteriorly; naked area between anterior lateral-line scales and pectoral-fin base; lateral line continues onto scales covering caudal-fin base. 4 scales above lateral line and 1 (3) or 2 (14) scales below lateral line, 10 circumpeduncular scales. Scales covering anterior 20% of caudal fin. 8 (5), 9 (9), 10 (2), or 11 (1) predorsal scales. Venter unscaled on isthmus and posteriorly to approximately 2 scales before pelvic-fin origin. Dorsal fin with 2 unbranched and 8 (1), 9 (20) or 10 (2) branched rays (ii,8–10); first unbranched ray slightly less than one-half length of second, closely adhered; first branched ray longest and antepenultimate shortest, making fin slightly concave. Pectoral fin with 4 unbranched and 8 (2), 9 (19), or 10 (2) branched rays (iv,8–10); unbranched rays with thick pads of tissue anteriorly; first unbranched ray strongly curved posteriorly; fourth unbranched ray longest and last branched ray shortest; pectoral fin oriented obliquely on body with posteriormost insertion located dorsal to origin. Pelvic fin with 2 leading unbranched rays, 5 branched rays, and 1 posterior unbranched ray (ii,5,i); second branched ray longest; 2 to 3 pelvic axillary scales present with complex covering ~ half of pelvic-fin base. Anal fin with 2 unbranched rays and 3 (1) or 5 (22) branched rays (ii,3 or 5); first unbranched ray less than 1/3 length of second, closely adhered; fin slightly falcate with second branched ray longest, first unbranched ray considerably shorter, rays then becoming shorter to last; anal fin fits into concavity made by steep, concave margin of ventral profile starting at anal-fin origin. Caudal fin with 1 unbranched and 10 (22) branched rays in upper lobe and 9 (22) branched and 1 unbranched ray in lower lobe (i,10,9,i; one specimen had caudal fin too damaged to count rays); forked with upper and lower lobes equal. Adipose fin present with base centered on vertical over middle of anal-fin base. Rays of paired, dorsal, and anal fins with thick flaps of skin dorsally (paired fins) and laterally (dorsal and anal fins) that overlap successive rays of adpressed fin; flaps widest and longest anteriorly, decreasing in size and width posteriorly, sometimes absent on posterior rays. Teeth tricuspid, narrow and peg-like with median cusp round and lateral cusps poorly developed. 5 (3), 6 (14), or 7 (6) premaxillary teeth. 3 (1), 5 (4), 6 (6), 7 (10), 8 (1), or 9 (1) teeth in outer dentary row. No teeth observed on inner dentary row. Ectopterygoid with single row of approximately 10 minute teeth. Branchiostegal rays 4; 1 ray attached to posterior ceratohyal; 3 rays attached to anterior ceratohyal. Gill rakers 1–3 on dorsal limb, 1 on angle, 3–5 on ventral limb of anterior branchial arch. One supraorbital present; approximately crescent shaped with ventral side almost straight; from dorsal midpoint of orbit to dorsal ~ 1/3 of anterior scleral ossicle. All elements of infraorbital series, except infraorbital 1, without laminar component. Parietal branch of supraorbital sensory canal extending to middle of parietal. Parietal fontanel absent; however, parietals do not meet along midline, perhaps due to small size of cleared and stained specimens. Frontal foramina above supraorbital canal 3 wide, circular. Total number of vertebrae 33 (2). Vertebral centra 2–4 fused, without ventral processes. Rib of centrum 4 distally expanded, extending anteriorly toward lateral process of centrum 2. Swim bladder was not examined. Supraneurals between neural spine of fourth centrum and anterior dorsal-fin pterygiophore 4(2). Epurals 3(2). Uroneural present, about 3/4 as long as urostyle. Color in life.— (Fig. 10) Body with yellow base color dorsally fading to gray ventrally. Dorsal surface covered with eight dark saddles, first on posterior of head, three between head and dorsal-fin origin (middle band lighter), one under dorsal fin, one between dorsal and adipose fins, one beginning under posterior half of adipose and continuing on caudal peduncle, and one at end of the caudal peduncle. Lighter spaces between saddles with yellow pigment covered by brown dorsally. Lateral stripe faintly visible, formed by scales in stripe with spot of color that leaves anterior edges of scales yellow-gray. Scales with spots covering all except anterior edge of scales present in all regions of body; spots more distinct on caudal peduncle. Several long wide blotches below lateral line with those between posteriormost pectoral-fin ray insertion and anal-fin origin most distinct. Dorsal fin with two distalmost bands formed from spots on rays with interspaces on rays yellow and fin membranes gray; proximal band of dorsal fin similar to others, but anterior end of band with large spot that covers both rays and membranes. Pectoral fin with three bands consisting of spots on branched rays; unbranched rays with central column of black surrounded by gray; interradial membranes gray; large dark spot present above most of pectoral fin and yellow spot present just above pectoral-fin origin; anterior base of pectoral fin to opercle gray with some patches of black melanophores. Pelvic fin colored similar to dorsal fin but with two bands; base of pelvic fin yellow. Anal fin with one medial dark band made of spots centered on rays and bleeding into interradial membranes; rest of anal fin gray. Adipose fin with yellow-gray base and dark tip contiguous with dorsal saddles below. Caudal fin with mostly gray membranes and alternating dark and yellow patches; dark patches longer than yellow patches on central rays and distally on all rays; dorsal- and ventralmost three or four rays with two to three large yellow spots surrounded by black; yellows and blacks fading distally. Head mostly mottled with black and dusky yellow; black interorbital bar present, continuing ventrally along anterior border of eye; large, dark crescent anterior of eye with small connection to interorbital bar; large black spot below eye that widens and fades ventrally; large dark spot on opercle, preopercle, and posterior infraorbitals. Some iridescent green and yellow spots present posterior to eye. Color in alcohol.— (Fig. 10) Similar to life except with iridescence absent and grays and yellows converted to tan. Holotype and specimen collected with it (AUM 62835) considerably darker than all other specimens. Distribution.— (Fig. 9) Found throughout the Essequibo River basin, but has been rarely encountered during our surveys. Most locations are in the lower Potaro and Kuribrong, but two localities are in the upper Essequibo upstream of the mouth of the Kuyuwini River. Remarks.— Because Characidium duplicatum is distributed in both the lower and upper Essequibo with no collections in between, we excluded the upper Essequibo localities from the type series to be more certain that the types contain a single species. Although similar to Characidium declivirostre in color pattern, C. duplicatum has extra unbranched pectoral and leading pelvic rays. The fourth unbranched pectoral and second unbranched pelvic rays are more similar in appearance to the first unbranched rays than to other branched rays, suggesting that the extra unbranched fin rays were gained via conversion of anterior branched rays. This is further supported by the fact that the pectoral and pelvic fins have the same total number of rays (usually 13 and 8, respectively) in C. duplicatum and C. declivirostre. The fourth unbranched pectoral ray and second unbranched pelvic rays are also the longest in their respective fins, while the first branched ray is the longest in C. declivirostre and C. wangyapoik, new species. The only other crenuchid with two unbranched pelvic rays is Leptocharacidium omospilus. Etymology.— Duplicatum is Latin for double and is a neuter adjective. In reference to the presence of two unbranched anal-fin rays., Published as part of Armbruster, Jonathan W., Lujan, Nathan K. & Bloom, Devin D., 2021, Redescription of the Guiana Shield Darter Species Characidium crandellii and C. declivirostre (Crenuchidae) with Descriptions of Two New Species, pp. 102-122 in Ichthyology & Herpetology 109 (1) on pages 113-116, DOI: 10.1643/i2019299, http://zenodo.org/record/7846669, {"references":["Hardman, M., L. M. Page, M. H. Sabaj, J. W. Armbruster, and J. H. Knouft. 2002. A comparison of fish surveys made in 1908 and 1998 of the Potaro, Essequibo, Demerara, and coastal river drainages of Guyana. Ichthyological Exploration of Freshwaters 13: 225 - 238."]}

Based on collections made in the western Guiana Shield over the last 21 years, Characidium crandellii and C. declivirostre are redescribed and two similar species are described from Guyana. These species all have enlarged paired fins with three to four rays thickened ventrally on the pectoral fin and two rays thickened on the pelvic fin. The species can be separated from all other Characidium and Melanocharacidium by having the venter unscaled from the isthmus to the pelvic origin. Characidium crandellii is found in the Essequibo and Takutu River systems and in an isolated population above Tencua Falls in the Ventuari River and the upper Paragua River (Orinoco River basin). Characidium declivirostre is found throughout the right-bank, shield tributaries of the Orinoco River system and in the upper Negro River. Characidium duplicatum, new species, appears to be rare but widely distributed in the Essequibo River system. Characidium wangyapoik, new species, is only known from the upper Ireng River, Branco River basin, along the border between Brazil and Guyana.

KEY TO SPECIES OF THE FAST-WATER CHARACIDIUM OF THE GUIANA SHIELD 1a. Twelve circumpeduncular scales. Dorsal fin falcate with a medial dark band and terminal white band (Figs. 4, 5). Origin of adipose fin centered at vertical above insertion of posteriormost anal-fin ray (Figs. 4, 5). Pectoral fin uniformly dark or peripherally dark with lighter center. Proximal dentary and premaxillary teeth wide and tri- to pentacuspid (central cusp longest) _________ Characidium crandellii 1b. Ten circumpeduncular scales. Dorsal fin only slightly concave along distal margin and with two or more thin dark bands (Figs. 7, 8, 10–12). Origin of adipose fin at vertical over center of anal-fin base or more anterior. Pectoral fin light with at least one (usually two or three) dark bands made of separate elongate spots (Figs. 7, 8, 10–12). Proximal dentary and premaxillary teeth narrow, peg-like, tricuspid, but only central cusp conspicuous ___________________________________ 2 2a. Pelvic fin with two unbranched rays. Pectoral fin with four unbranched rays (Fig. 1B) _________________________________ _____________________________________________ C. duplicatum, new species 2b. Pelvic fin with one unbranched ray. Pectoral fin with three unbranched rays (Fig. 1A) ______________________________ 3 3a. Dorsal coloration consisting of prominent saddles that extend to a faint midlateral stripe that may appear as a series of blotches (stripe most prominent in preserved specimens). No accessory bars between saddles. Ventral portion of sides with few, rectangular to square blotches that do not extend dorsal to midlateral stripe (Figs. 7, 8) _________________ C. declivirostre 3b. Dorsal saddles not prominent in adults, and usually confluent with thin bands from below midlateral stripe, which is usually demarcated by a faint stripe made of zig-zag lines with the stripe most prominent in smaller individuals. Thin bars also present in lighter interspaces between saddles, some of which extend below midlateral stripe (Figs. 11, 12). Ventral portion of sides with numerous narrow bars that extend above midlateral stripe (in juveniles, only some bars may continue dorsal to midlateral stripe; Figs. 11, 12) ____ C. wangyapoik, new species

A new species of Characidium is described from the Cerrado biome, in Brasília, Distrito Federal, Central Brazil. The new species can be readily diagnosed by the presence of two or three longitudinal rows of dots along the body sides, absence of bars, by the short pectoral fin, which does not reach the vertical through the dorsal fin origin. Additional useful diagnostic characters are the scaled isthmus, absence of the adipose fin, and the terminal mouth. The new species is only known from the córrego Taquara and its tributaries, a tributary of ribeirão do Gama, upstream from lago Paranoá, in the upper rio Paraná basin. In accordance to the IUCN Red List Categories and Criteria, the new species is categorized as Critically Endangered. RESUMO Uma nova espécie de Characidium é descrita do bioma Cerrado em Brasília, Distrito Federal, Brasil Central. A nova espécie pode ser diagnosticada pela presença de duas ou três fileiras longitudinais de pontos no corpo, ausência de barras e nadadeira peitoral curta, que não alcança a vertical que passa pela origem da nadadeira dorsal. Caracteres adicionais úteis na diagnose são o istmo escamado, a ausência da nadadeira adiposa e a boca terminal. A nova espécie é conhecida apenas do córrego Taquara e seus tributários, tributário do ribeirão do Gama a montante do Lago Paranoá, na bacia do alto rio Paraná. De acordo com os Critérios e Categorias para Listas Vermelhas da IUCN, a nova espécie é categorizada como uma Criticamente Ameaçada.

A new species of Characidium is described from the tributaries of the rio Tocantinzinho, rio Tocantins basin, located in the southern portion of the Chapada dos Veadeiros, at about 1,200 meters of elevation, Goiás, Brazil. The new species can be diagnosed by an unusual combination of two apomorphic features present in distinct clades of Characidium, the presence of a scaleless isthmus in allied to with a single row of dentary teeth. Additionally, the new species has a unique color pattern of inconspicuous vertical bars disconnected from the dorsal midline, forming seven to nine square blotches along body sides, and the presence of a dark saddle-shaped mark at the dorsal-fin base. Osteologically, it can be diagnosed by having the first and second anal-fin proximal radials fused and contacting the third hemal spine, which is branched. The new species also has a peculiar, unusual variation of fin-ray counts among its congeners. Resumo Uma nova espécie de Characidium é descrita dos riachos tributários do rio Tocantins, bacia do rio Tocantins, localizados na vertente sul da Chapada dos Veadeiros, a aproximadamente 1.200 metros de altitude, Goiás, Brasil. A nova espécie pode ser diagnosticada pela combinação não usual de dois caracteres apomórficos presentes em clados distintos de Characidium, a presença do istmo sem escama em conjunto com uma única série de dentes no dentário. Adicionalmente, a nova espécie tem um padrão de coloração único de barras verticais desconectadas na região dorsal, formando sete a nove manchas quadradas ao longo do lado do corpo, e pela presença de uma mancha em forma de sela na base da nadadeira dorsal. Osteologicamente, ela pode ser diagnosticada por possuir o primeiro e segundo radiais da nadadeira anal fusionados e em contato com o terceiro espinho hemal, que é ramificado. A espécie nova também possui uma variação peculiar e pouco usual no número de raios das nadadeiras entre os congêneres.

During a parasitological survey of fishes at Iguazu National Park, Argentina, specimens belonging to the allocreadiid genus Auriculostoma were collected from the intestine of Characidium heirmostigmata. The erection of the new species is based on a unique combination of morphological traits as well as on phylogenetic analysis. Auriculostoma guacurarii n. sp. resembles four congeneric species – Auriculostoma diagonale, Auriculostoma platense, Auriculostoma tica and Auriculostoma totonacapanensis – in having smooth and oblique testes, but can be distinguished by a combination of several morphological features, hosts association and geographic distribution. Morphologically, the new species can be distinguished from both A. diagonale and A. platense by the egg size (bigger in the first and smaller in the last); from A. tica by a shorter body length, the genital pore position and the extension of the caeca; and from A. totonacapanensis by the size of the oral and ventral sucker and the post-testicular space. Additionally, one specimen of Auriculostoma cf. stenopteri from the characid Charax stenopterus (Characiformes) from La Plata River, Argentina, was sampled and the partial 28S rRNA gene was sequenced. The phylogenetic analysis revealed that A. guacurarii n. sp. clustered with A. tica and these two as sister taxa to A. cf. stenopteri. The new species described herein is the tenth species in the genus and the first one parasitizing a member of the family Crenuchidae.

3.2 | Characidium tatama new species Figures 3, 4 and 5, and Table 1. urn:lsid:zoobank.org:act:4170703E80D7-4170-9212-10B5918D3E79. Characidium sp. 2 ��� Pacifico ��� ��� Agudelo-Zamora et al., 2020, p. 14 (material examined). 3.3 | Holotype IMCN 8925, 38.1 mm L S, Colombia, Choc��, San Jos�� Del Palmar, r��o Ingar�� by the bridge, 04 55 ' 13.39 '' N, 76 12 ' 21.48 '' W, A. Ortega-Lara. 09 September 2018. Abbreviations: DO, dorsal origin; AO, anal origin; HL, head length; S.D; standard deviation; LS, standard length; TL, total length. 3.4 | Paratypes All from Colombia. IMCN 8924, 1 C&S female, 36.0 mm L S; CHIFF 0011, 2, 27.9 ��� 36.3 mm L S, all collected with the holotype. IMCN 8926, 1 (AOL 138 tissue), 36 mm L S, Colombia, Choc��, San Jos�� Del Palmar, r��o Cruces tributary of r��o Ingar��, A. Ortega-Lara. 09 September 2018; IMCN 8927, 1 (AOL 139 tissue), 32.5 mm L S, Colombia, Choc��, San Jos�� Del Palmar, quebrada Corcobado, 4 54 ' 54.9 '' N, 76 13 ' 3.6 '' W, A. Ortega-Lara, 09 September 2018; CIRUV 010-19, 1, 30.5 mm L S, Colombia, Valle del Cauca, Buenaventura, quebrada La Brea, tributary of r��o Calima, 3 59 ' 25.7 '' N, 76 58 ' 23.3 '' W. D��az & Serna. 16 May 2010. 3.5 | Diagnosis Characidium tatama is distinguished from all Characidium, except C. alipioi Travassos 1955, C. amaila Lujan et al., 2013, C. boavistae Steindachner 1915, C. bolivianum Pearson 1924, C. crandellii Steindachner 1915, C. declivirostre Steindachner 1915, C. gomesi Travassos 1956, C. grajahuense Travassos 1944, C. japuhybense Travassos 1949, C. kamakan Zanata & Camelier, 2015, C. lauroi Travassos 1949, C. pterostictum Gomes 1947, C. purpuratum Steindachner 1882, C. timbuiense Travassos, 1946, C. travassosi Melo et al., 2016, C. vidali Travassos 1967 and the clade members of C. fasciatum or clade C1 (sensu Buckup, 1992) for having the isthmus without scales (Figure 3). Also, C. tatama is distinguished from C. helmeri Zanata, Sarmento- Soares & Martins-Pinheiro 2015, C. oiticicai Travassos 1967 and C. travassossi Melo et al., 2016 by the presence of an adipose fin (vs. adipose fin absence). Additionally, C. tatama n. sp. is distinguished among clade C1 congeners by having a rounded point in the midline of the upper scales of the lateral line (Figure 4); it is distinguished from C. amaila by having a lower number of scales on the lateral line (32 ��� 33 vs. 34 ��� 36) and by the shape of its swim bladder (wide bilobed anterior chamber and small posterior thin chamber vs. anterior chamber as wide as the posterior, and the posterior chamber long and thin); from C. crandellii and C. declivirostre by having free branchiostegal rays (vs. joined branchiostegal rays [see Lujan et al., 2013, p. 455); from C. boavistae, C. bolivianum, C. gomesi, C. grajahuensis, C. japuhybense, C. kamakan, C. lauroi, C. purpuratum, C. pterostictum, C. schubarti and C. timbuiense for having the caudal and anal fins without bands on the rays (vs. caudal and anal fins with dark pigment or with some type of band) (see Lujan et al., 2013, p. 458; Zanata & Camelier, 2015, p. 488). 3.6 | Description Morphometric data can be seen in Table 1, the largest known specimen not exceeding 45 mm L S Body slightly compressed laterally, strongly convex dorsal profile from snout to supraoccipital fontanelle, ascending slightly convex arc to dorsal-fin origin; descending through base of dorsal fin, and to first caudal-fin procurrent ray. Ventral profile concave from dentary to pelvic fin, vertex located from this point to caudal peduncle straight. Greatest body depth at, or just above, dorsal-fin origin. Snout strongly rounded tip, at level of ventral margin of orbit. Maxillary long and extending beyond anterior margin of orbit. Circular orbit larger than snout length, smaller than maxilla. Iris round. Dorsal-fin rays ii8(1), 9(5), 10*(1); anal-fin rays ii6*(7); pectoral-fin rays ii6(1), 7*(2) ii8(4); pelvic-fin rays i7(6), 8*(1); principal caudal-fin rays in dorsal lobe 8(1), 9*(5), in ventral lobe 8*(7). Scales cycloid. Lateral line complete; pored lateral-line scales 32(2), 33*(5). Scales above lateral line 3(1), 4*(6), below 2*(7). Predorsal scales 11*(7). Circumpeduncular scales 10(1), 11*(4). Isthmus and area between pectoral fins without scales. Mesethmoid bone separated from frontal, parietal fontanel absent, postcleitrum (PC) I absent, PC II and III present. Medial process of first rib with ventral concave curvature in hook shape decreasing in width to the tip of belly, dorsal upper process triangular with concave space between process and base to vertebral joint (Figure 8a). Swimbladder with two chambers, anterior chamber bilobate and short, posterior chamber slim, its base wider than the tip (Figure 8b). 3.7 | Colour in alcohol Dark colouration on head due to the high concentration of chromatophores divided longitudinally by a black lateral band that crosses the eye. Ventral region silver and divided by the lateral line. Body crossed by longitudinal band that ends in the caudal region with a dark bar on the base of the caudal fin, basicaudal spot in medial rays of the caudal fin. Dorsal region brown with the edges of the scales black, forming a pattern of chainrings, which extend beyond the longitudinal band. Pectoral, pelvic and anal fins hyaline; caudal fin in smaller specimens (L S,) also hyaline, but larger specimens with scattered chromatophores not clustered or forming bands. Dorsal-fin base with dark black stripe. Chromatophores forming a band at the base of the dorsal fin. Unpigmented belly, except on caudal peduncle, which has a last dark transversal body band. 3.8 | Ecology The Ingar�� River (type locality) has U-shaped banks (sensu Parsons et al., 2002) with abundant riparian coverage on both sides, and a predominance of a rocky substrate and some large ridges, which makes it a torrential river with few pools or backwaters (Figure 5). 3.9 | Distribution Characidium tatama is endemic to the Choc�� biogeographic region and inhabits rivers tributaries of the upper San Juan and Calima river (Figure 1). 3.10 | Etymology A noun in apposition to the Tatam�� National Natural Park created in 1987 and the place where most of the type specimens were collected. The word Tatam�� in Embera-Cham�� language means the grandfather of the rivers. 3.11 | Conservation assessment Characidium tatama is so far known from two localities in tributaries of the San Juan and Calima Rivers. The EOO estimated for the species is 5.419. 3 km 2, and the AOO estimated is 74 km 2 (sensu Bachman et al., 2011). Additional collecting efforts should be conducted in the region to better understand the geographic distribution of the species and the existent threats. From the points assessed here for the distribution of C. tatama, the species is tentatively categorized as Vulnerable (VU) D2 under the geospatial aspect because the population is restricted to less than 20 km 2 and the number of localities is less than five (IUCN Standards and Petitions Subcommittee, 2019), with accelerated deforestation inside Colombian national parks (Clerici et al., 2020)., Published as part of Agudelo���Zamora, Henry D., Tavera, Jos��, Murillo, Yiskar D. & Ortega���Lara, Armando, 2020, The unknown diversity of the genus Characidium (Characiformes: Crenuchidae) in the Choc�� biogeographic region, Colombian Andes: Two new species supported by morphological and molecular data, pp. 1-14 in Journal of Fish Biology 97 (4) on pages 5-7, DOI: 10.1111/jfb.14527, http://zenodo.org/record/4058131, {"references":["Agudelo-Zamora, H., Ortega-Lara, A., & Taphorn, D. (2020). Characidium chancoense, a new species of south American darter from the Rio Cauca drainage, Colombia (Characiformes: Crenuchidae). Zootaxa, 4768 (2), 249 - 263. https: // doi. org / 10.11646 / zootaxa. 4768.2.6.","Lujan, N. K., Agudelo-Zamora, H., Taphorn, D. C., Booth, P. N., & Lopez- Fernandez, H. (2013). Description of a new, narrowly endemic south American darter (Characiformes: Crenuchidae) from the central Guiana shield highlands of Guyana. Copeia, 2013 (3), 454 - 463. https: // doi. org / 10.1093 / molbev / msy 096.","Zanata, A. M., & Camelier, P. (2015). Two new species of Characidium Reinhardt (Characiformes: Crenuchidae) from northeastern Brazilian coastal drainages. Neotropical Ichthyology, 13 (3), 487 - 498. https: // doi. org / 10.1590 / 1982 - 0224 - 20140106.","Travassos, 1946 (Characiformes: Crenuchidae), com descriC ~ ao de uma especie nova para o Caparao, Sudeste do Brasil. (Masters thesis). http: // portais 4. ufes. br / posgrad / teses / tese _ 8576 _ Maridiesse %","Melo, M. R. S., Buckup, P. A., & Oyakawa, O. T. (2016). A new species of Characidium Reinhardt, 1867 (Characiformes: Crenuchidae) endemic to the Atlantic Forest in Parana state, southern Brazil. Neotropical Ichthyology, 14 (3), e 160014.","Buckup, P. A. (1992). Redescription of Characidium fasciatum, type species of the Characidiinae (Teleostei, Characiformes). Copeia, 1992, 1066 - 1073. https: // doi. org / 10.2307 / 1446639.","Parsons, M., Thoms, M. and Norris, R., 2002, Australian River Assessment System: Review of Physical River Assessment Methods - A Biological Perspective, Monitoring River Health Initiative Technical Report no 21, Commonwealth of Australia and University of Canberra, Canberra.","Bachman, S., Moat, J., Hill, A. W., de la Torre, J., & Scott, B. (2011). Supporting red list threat assessments with GeoCAT: geospatial conservation assessment tool. ZooKeys, 150, 117 - 126.","Clerici, N., Armenteras, D., Kareiva, P., Botero, R., Ramirez-Delgado, J. P., Forero-Medina, G., et al. (2020). Deforestation in Colombian protected areas increased duringpost-conflict periods. Scientific Reports, 10 (1), 1 - 10."]}

3.12 | Characidium dule, new species urn:lsid:zoobank.org:act:FFF769BD-AA23-4FEC- AF33-1770A612D41D. Characidium sp. 4 ��� Arquia ��� ��� Agudelo-Zamora et al., 2020, p. 14 (material examined). 3.13 | Holotype IMCN 8941, 37.4 mm L S, Colombia, Choc��, Unguia, r��o Arqu��a, at the village of Arqu��a, 08 00 ' 07.1 '' N, 77 06 ' 56.2 '' W, A. Ortega-Lara. 05 April 2017. 3.14 | Paratypes All from Colombia. IMCN 8929, 7 + 1 C&S female, 32.8 ��� 44.7 mm L S from the same locality of the holotype; IMCN 8942, 1, 30.9 mm L S from the same locality of the holotype; CHIFF 0012, 1, 31.3 mm L S, Colombia, Choc��, Quibd��, Tutunendo river, 5 44 ' 39.7 '' N, 76 31 ' 54.2 '' W. A. Ortega-Lara, N. Lujan. 01 August 2019. 3.15 | Diagnosis Characidium dule can be differentiated from all other Characidium species by having a unique colour pattern in the humeral region that consists of a small marking, similar to a black line, between the supraoccipital and the beginning of the opercle, followed by a light point (golden in live specimens or white in preserved specimens), and a humeral round blotch which is formed by two to three scales (Figures 5, 6), in addition to a triangular blotch at the end of the caudal peduncle where pigmentation varies in size starting at �� scale, followed by 1 scale and its base is 2 scales. In mature specimens (recognized by their purplish colour) the caudal triangular point is less visible. It is distinguished from C. purpuratum Steindachner 1882 and C. marshi Breder 1925 by having lower number of dorsal (7 ��� 9 vs. 11) and anal (6 ��� 7 vs. 8 in C. purpuratum and 7 ��� 9 in C. marshi) fin rays. It is also distinguished from C. purpuratum by the presence of scales in the isthmus and the area between the pectorals (vs. isthmus and area between the pectoral without scales). It is also distinguished from C. marshi by having a smaller number of scales in the lateral line (30 ��� 33 vs. 31 ��� 35) and by the absence of postcleithrum I (vs. presence of postcleithrum). 3.16 | Description Morphometric data can be seen in Table 2, the largest known specimen not exceeding 44.7 mm L S. Body slightly compressed laterally with slightly convex dorsal profile from snout to supraoccipital fontanelle, ascending slightly convex to origin of dorsal fin, and ascending at another convex angle from beginning of dorsal to adipose fin, descends slightly in a straight line and right angle from adipose to first procuring radius of tail fin. Slightly concave ventral profile, vertex on pelvic fin, ends dentary at anterior part and ventral procurrent rays at posterior. Greatest body depth is at or just before origin of dorsal fin. Slightly convex pointed snout from dorsal margin of orbit. Maxilla short, just barely exceeding anterior margin of orbital, exceeding posterior nostril. Circular orbit larger than snout length, similar in size to maxilla; iris round. Dorsal base fin with chromatophores forming a band. Abbreviations: DO, dorsal origin; AO, anal origin; HL, head length; S.D; standard deviation; LS, standard length; TL, total length. Dorsal-fin rays ii7(1), 9*(8); anal-fin rays i6(7), 7*(2); pectoral-fin rays iii7 (1), 8*(6), 9(2); pelvic-fin rays i6(1), 7*(8); principal caudal-fin rays in dorsal lobe 9*(9), in ventral lobe 8*(9). Scales cycloid. Lateral line complete; pored lateral-line scales 30(2), 31*(2), 32(3), 33(2) Scales above lateral line 4*(9), below 2*(9). Predorsal scales 8*(4), 9(5). Circumpeduncular scales 11*(2), 12*(7). Isthmus and area between the pectoral with scales. Mesethmoid bone separated from frontal, parietal fontanel reduced width size of the post-parietal bars, postcleitrum (PC) I absent but PC II and III present. Medial process of first rib with ventral vertex paddle-shaped, wider in vertex which decreases ventrally to tip of rib, dorsal upper process has an L shape without concave space between process and base to vertebral join (Figure 8c.); swimbladder with two chambers, anterior bilobulated and laterally wider than that of C. tatama, posterior chamber shorter than anterior chamber and rounded (Figure 8d.). 3.17 | Colour in live specimens Mature specimens purplish. This colour is observed predominantly on dorsal, anal, adipose, caudal and pelvic fins, extending also over ventral area (Figure 9). Lateral line with golden shades predominantly between pelvic and anal fins. Head, with golden line behind eye, followed by a black line and golden point at end of opercle, as well as a black humeral blotch. First portion of dorsal fin (first two rays) golden in colour. Head with a band that is smaller than pupil, extending from front edge of eye to beginning of maxillary bone. 3.18 | Colour in alcohol Mature specimens purple with 7 ��� 8 bars, with highly pigmented dorsal, anal and caudal fins (Figures 6 and 8). In all the specimens, transverse band present and smaller in size (1/2 scale) than humeral and caudal spots. Unmarked belly. Humeral blotch reaching two to three scales and concave extension towards pectoral fin, being faint in immature specimens and dark in mature specimens and coming into contact with last rays of the pectoral fin (Figure 7). Dorsal anterior portion of maxilla pigmented forming a line reaching the eye, ventral posterior portion of maxilla without pigment. 3.19 | Ecology The Arqu��a River (type locality) is a tributary of steep banks with large slopes, with good riparian coverage on both flanks and a predominance of a rocky substrate with large edges, which allow the formation of backwaters and small pools where sand and organic materials are deposited. A tributary of transparent waters (Figure 10). 3.20 | Distribution Characidium dule is endemic to the Choc�� biogeographical region and inhabits rivers or streams tributaries to the Atrato River, from its upper reaches to near the mouth into the Urab�� Gulf (Figure 1). 3.21 | Etymology A noun in apposition dedicated to the Dule (Kuna) ethnic group of Maggilagundiwala or Resguardo de Arqu��a in the Colombian Choc��, whose language is under a high risk of extinction and where most of the type specimens were collected. 3.22 | Conservation assessment Characidium dule is so far known from two localities in tributaries of the Atrato River. The EOO estimated for the species is 5.701. 2 km 2, and the AOO estimated is 21 km 2 (sensu Bachman et al., 2011). Additional collecting efforts should be conducted in the region to better understand the geographic distribution of the species and the existent threats. From the points assessed here for the distribution of C. dule, the species is tentatively categorized as Vulnerable (VU) D2 under the geospatial aspect because the population is restricted to less than 20 km 2 and the number of localities is less than five (IUCN Standards and Petitions Subcommittee, 2019), with accelerated deforestation inside Colombian national parks (Clerici et al., 2020)., Published as part of Agudelo���Zamora, Henry D., Tavera, Jos��, Murillo, Yiskar D. & Ortega���Lara, Armando, 2020, The unknown diversity of the genus Characidium (Characiformes: Crenuchidae) in the Choc�� biogeographic region, Colombian Andes: Two new species supported by morphological and molecular data, pp. 1-14 in Journal of Fish Biology 97 (4) on pages 8-10, DOI: 10.1111/jfb.14527, http://zenodo.org/record/4058131, {"references":["Agudelo-Zamora, H., Ortega-Lara, A., & Taphorn, D. (2020). Characidium chancoense, a new species of south American darter from the Rio Cauca drainage, Colombia (Characiformes: Crenuchidae). Zootaxa, 4768 (2), 249 - 263. https: // doi. org / 10.11646 / zootaxa. 4768.2.6.","Bachman, S., Moat, J., Hill, A. W., de la Torre, J., & Scott, B. (2011). Supporting red list threat assessments with GeoCAT: geospatial conservation assessment tool. ZooKeys, 150, 117 - 126.","Clerici, N., Armenteras, D., Kareiva, P., Botero, R., Ramirez-Delgado, J. P., Forero-Medina, G., et al. (2020). Deforestation in Colombian protected areas increased duringpost-conflict periods. Scientific Reports, 10 (1), 1 - 10."]}

3.2 | Characidium tatama new species Figures 3, 4 and 5, and Table 1. urn:lsid:zoobank.org:act:4170703E80D7-4170-9212-10B5918D3E79. Characidium sp. 2 “ Pacifico ” – Agudelo-Zamora et al., 2020, p. 14 (material examined). 3.3 | Holotype IMCN 8925, 38.1 mm L S, Colombia, Chocó, San José Del Palmar, río Ingará by the bridge, 04 55 ' 13.39 '' N, 76 12 ' 21.48 '' W, A. Ortega-Lara. 09 September 2018. Abbreviations: DO, dorsal origin; AO, anal origin; HL, head length; S.D; standard deviation; LS, standard length; TL, total length. 3.4 | Paratypes All from Colombia. IMCN 8924, 1 C&S female, 36.0 mm L S; CHIFF 0011, 2, 27.9 – 36.3 mm L S, all collected with the holotype. IMCN 8926, 1 (AOL 138 tissue), 36 mm L S, Colombia, Chocó, San José Del Palmar, río Cruces tributary of río Ingará, A. Ortega-Lara. 09 September 2018; IMCN 8927, 1 (AOL 139 tissue), 32.5 mm L S, Colombia, Chocó, San José Del Palmar, quebrada Corcobado, 4 54 ' 54.9 '' N, 76 13 ' 3.6 '' W, A. Ortega-Lara, 09 September 2018; CIRUV 010-19, 1, 30.5 mm L S, Colombia, Valle del Cauca, Buenaventura, quebrada La Brea, tributary of río Calima, 3 59 ' 25.7 '' N, 76 58 ' 23.3 '' W. Díaz & Serna. 16 May 2010. 3.5 | Diagnosis Characidium tatama is distinguished from all Characidium, except C. alipioi Travassos 1955, C. amaila Lujan et al., 2013, C. boavistae Steindachner 1915, C. bolivianum Pearson 1924, C. crandellii Steindachner 1915, C. declivirostre Steindachner 1915, C. gomesi Travassos 1956, C. grajahuense Travassos 1944, C. japuhybense Travassos 1949, C. kamakan Zanata & Camelier, 2015, C. lauroi Travassos 1949, C. pterostictum Gomes 1947, C. purpuratum Steindachner 1882, C. timbuiense Travassos, 1946, C. travassosi Melo et al., 2016, C. vidali Travassos 1967 and the clade members of C. fasciatum or clade C1 (sensu Buckup, 1992) for having the isthmus without scales (Figure 3). Also, C. tatama is distinguished from C. helmeri Zanata, Sarmento- Soares & Martins-Pinheiro 2015, C. oiticicai Travassos 1967 and C. travassossi Melo et al., 2016 by the presence of an adipose fin (vs. adipose fin absence). Additionally, C. tatama n. sp. is distinguished among clade C1 congeners by having a rounded point in the midline of the upper scales of the lateral line (Figure 4); it is distinguished from C. amaila by having a lower number of scales on the lateral line (32 – 33 vs. 34 – 36) and by the shape of its swim bladder (wide bilobed anterior chamber and small posterior thin chamber vs. anterior chamber as wide as the posterior, and the posterior chamber long and thin); from C. crandellii and C. declivirostre by having free branchiostegal rays (vs. joined branchiostegal rays [see Lujan et al., 2013, p. 455); from C. boavistae, C. bolivianum, C. gomesi, C. grajahuensis, C. japuhybense, C. kamakan, C. lauroi, C. purpuratum, C. pterostictum, C. schubarti and C. timbuiense for having the caudal and anal fins without bands on the rays (vs. caudal and anal fins with dark pigment or with some type of band) (see Lujan et al., 2013, p. 458; Zanata & Camelier, 2015, p. 488). 3.6 | Description Morphometric data can be seen in Table 1, the largest known specimen not exceeding 45 mm L S Body slightly compressed laterally, strongly convex dorsal profile from snout to supraoccipital fontanelle, ascending slightly convex arc to dorsal-fin origin; descending through base of dorsal fin, and to first caudal-fin procurrent ray. Ventral profile concave from dentary to pelvic fin, vertex located from this point to caudal peduncle straight. Greatest body depth at, or just above, dorsal-fin origin. Snout strongly rounded tip, at level of ventral margin of orbit. Maxillary long and extending beyond anterior margin of orbit. Circular orbit larger than snout length, smaller than maxilla. Iris round. Dorsal-fin rays ii8(1), 9(5), 10*(1); anal-fin rays ii6*(7); pectoral-fin rays ii6(1), 7*(2) ii8(4); pelvic-fin rays i7(6), 8*(1); principal caudal-fin rays in dorsal lobe 8(1), 9*(5), in ventral lobe 8*(7). Scales cycloid. Lateral line complete; pored lateral-line scales 32(2), 33*(5). Scales above lateral line 3(1), 4*(6), below 2*(7). Predorsal scales 11*(7). Circumpeduncular scales 10(1), 11*(4). Isthmus and area between pectoral fins without scales. Mesethmoid bone separated from frontal, parietal fontanel absent, postcleitrum (PC) I absent, PC II and III present. Medial process of first rib with ventral concave curvature in hook shape decreasing in width to the tip of belly, dorsal upper process triangular with concave space between process and base to vertebral joint (Figure 8a). Swimbladder with two chambers, anterior chamber bilobate and short, posterior chamber slim, its base wider than the tip (Figure 8b). 3.7 | Colour in alcohol Dark colouration on head due to the high concentration of chromatophores divided longitudinally by a black lateral band that crosses the eye. Ventral region silver and divided by the lateral line. Body crossed by longitudinal band that ends in the caudal region with a dark bar on the base of the caudal fin, basicaudal spot in medial rays of the caudal fin. Dorsal region brown with the edges of the scales black, forming a pattern of chainrings, which extend beyond the longitudinal band. Pectoral, pelvic and anal fins hyaline; caudal fin in smaller specimens (L S,) also hyaline, but larger specimens with scattered chromatophores not clustered or forming bands. Dorsal-fin base with dark black stripe. Chromatophores forming a band at the base of the dorsal fin. Unpigmented belly, except on caudal peduncle, which has a last dark transversal body band. 3.8 | Ecology The Ingará River (type locality) has U-shaped banks (sensu Parsons et al., 2002) with abundant riparian coverage on both sides, and a predominance of a rocky substrate and some large ridges, which makes it a torrential river with few pools or backwaters (Figure 5). 3.9 | Distribution Characidium tatama is endemic to the Chocó biogeographic region and inhabits rivers tributaries of the upper San Juan and Calima river (Figure 1). 3.10 | Etymology A noun in apposition to the Tatamá National Natural Park created in 1987 and the place where most of the type specimens were collected. The word Tatamá in Embera-Chamí language means the grandfather of the rivers. 3.11 | Conservation assessment Characidium tatama is so far known from two localities in tributaries of the San Juan and Calima Rivers. The EOO estimated for the species is 5.419. 3 km 2, and the AOO estimated is 74 km 2 (sensu Bachman et al., 2011). Additional collecting efforts should be conducted in the region to better understand the geographic distribution of the species and the existent threats. From the points assessed here for the distribution of C. tatama, the species is tentatively categorized as Vulnerable (VU) D2 under the geospatial aspect because the population is restricted to less than 20 km 2 and the number of localities is less than five (IUCN Standards and Petitions Subcommittee, 2019), with accelerated deforestation inside Colombian national parks (Clerici et al., 2020).

3.12 | Characidium dule, new species urn:lsid:zoobank.org:act:FFF769BD-AA23-4FEC- AF33-1770A612D41D. Characidium sp. 4 “ Arquia ” – Agudelo-Zamora et al., 2020, p. 14 (material examined). 3.13 | Holotype IMCN 8941, 37.4 mm L S, Colombia, Chocó, Unguia, río Arquía, at the village of Arquía, 08 00 ' 07.1 '' N, 77 06 ' 56.2 '' W, A. Ortega-Lara. 05 April 2017. 3.14 | Paratypes All from Colombia. IMCN 8929, 7 + 1 C&S female, 32.8 – 44.7 mm L S from the same locality of the holotype; IMCN 8942, 1, 30.9 mm L S from the same locality of the holotype; CHIFF 0012, 1, 31.3 mm L S, Colombia, Chocó, Quibdó, Tutunendo river, 5 44 ' 39.7 '' N, 76 31 ' 54.2 '' W. A. Ortega-Lara, N. Lujan. 01 August 2019. 3.15 | Diagnosis Characidium dule can be differentiated from all other Characidium species by having a unique colour pattern in the humeral region that consists of a small marking, similar to a black line, between the supraoccipital and the beginning of the opercle, followed by a light point (golden in live specimens or white in preserved specimens), and a humeral round blotch which is formed by two to three scales (Figures 5, 6), in addition to a triangular blotch at the end of the caudal peduncle where pigmentation varies in size starting at ½ scale, followed by 1 scale and its base is 2 scales. In mature specimens (recognized by their purplish colour) the caudal triangular point is less visible. It is distinguished from C. purpuratum Steindachner 1882 and C. marshi Breder 1925 by having lower number of dorsal (7 – 9 vs. 11) and anal (6 – 7 vs. 8 in C. purpuratum and 7 – 9 in C. marshi) fin rays. It is also distinguished from C. purpuratum by the presence of scales in the isthmus and the area between the pectorals (vs. isthmus and area between the pectoral without scales). It is also distinguished from C. marshi by having a smaller number of scales in the lateral line (30 – 33 vs. 31 – 35) and by the absence of postcleithrum I (vs. presence of postcleithrum). 3.16 | Description Morphometric data can be seen in Table 2, the largest known specimen not exceeding 44.7 mm L S. Body slightly compressed laterally with slightly convex dorsal profile from snout to supraoccipital fontanelle, ascending slightly convex to origin of dorsal fin, and ascending at another convex angle from beginning of dorsal to adipose fin, descends slightly in a straight line and right angle from adipose to first procuring radius of tail fin. Slightly concave ventral profile, vertex on pelvic fin, ends dentary at anterior part and ventral procurrent rays at posterior. Greatest body depth is at or just before origin of dorsal fin. Slightly convex pointed snout from dorsal margin of orbit. Maxilla short, just barely exceeding anterior margin of orbital, exceeding posterior nostril. Circular orbit larger than snout length, similar in size to maxilla; iris round. Dorsal base fin with chromatophores forming a band. Abbreviations: DO, dorsal origin; AO, anal origin; HL, head length; S.D; standard deviation; LS, standard length; TL, total length. Dorsal-fin rays ii7(1), 9*(8); anal-fin rays i6(7), 7*(2); pectoral-fin rays iii7 (1), 8*(6), 9(2); pelvic-fin rays i6(1), 7*(8); principal caudal-fin rays in dorsal lobe 9*(9), in ventral lobe 8*(9). Scales cycloid. Lateral line complete; pored lateral-line scales 30(2), 31*(2), 32(3), 33(2) Scales above lateral line 4*(9), below 2*(9). Predorsal scales 8*(4), 9(5). Circumpeduncular scales 11*(2), 12*(7). Isthmus and area between the pectoral with scales. Mesethmoid bone separated from frontal, parietal fontanel reduced width size of the post-parietal bars, postcleitrum (PC) I absent but PC II and III present. Medial process of first rib with ventral vertex paddle-shaped, wider in vertex which decreases ventrally to tip of rib, dorsal upper process has an L shape without concave space between process and base to vertebral join (Figure 8c.); swimbladder with two chambers, anterior bilobulated and laterally wider than that of C. tatama, posterior chamber shorter than anterior chamber and rounded (Figure 8d.). 3.17 | Colour in live specimens Mature specimens purplish. This colour is observed predominantly on dorsal, anal, adipose, caudal and pelvic fins, extending also over ventral area (Figure 9). Lateral line with golden shades predominantly between pelvic and anal fins. Head, with golden line behind eye, followed by a black line and golden point at end of opercle, as well as a black humeral blotch. First portion of dorsal fin (first two rays) golden in colour. Head with a band that is smaller than pupil, extending from front edge of eye to beginning of maxillary bone. 3.18 | Colour in alcohol Mature specimens purple with 7 – 8 bars, with highly pigmented dorsal, anal and caudal fins (Figures 6 and 8). In all the specimens, transverse band present and smaller in size (1/2 scale) than humeral and caudal spots. Unmarked belly. Humeral blotch reaching two to three scales and concave extension towards pectoral fin, being faint in immature specimens and dark in mature specimens and coming into contact with last rays of the pectoral fin (Figure 7). Dorsal anterior portion of maxilla pigmented forming a line reaching the eye, ventral posterior portion of maxilla without pigment. 3.19 | Ecology The Arquía River (type locality) is a tributary of steep banks with large slopes, with good riparian coverage on both flanks and a predominance of a rocky substrate with large edges, which allow the formation of backwaters and small pools where sand and organic materials are deposited. A tributary of transparent waters (Figure 10). 3.20 | Distribution Characidium dule is endemic to the Chocó biogeographical region and inhabits rivers or streams tributaries to the Atrato River, from its upper reaches to near the mouth into the Urabá Gulf (Figure 1). 3.21 | Etymology A noun in apposition dedicated to the Dule (Kuna) ethnic group of Maggilagundiwala or Resguardo de Arquía in the Colombian Chocó, whose language is under a high risk of extinction and where most of the type specimens were collected. 3.22 | Conservation assessment Characidium dule is so far known from two localities in tributaries of the Atrato River. The EOO estimated for the species is 5.701. 2 km 2, and the AOO estimated is 21 km 2 (sensu Bachman et al., 2011). Additional collecting efforts should be conducted in the region to better understand the geographic distribution of the species and the existent threats. From the points assessed here for the distribution of C. dule, the species is tentatively categorized as Vulnerable (VU) D2 under the geospatial aspect because the population is restricted to less than 20 km 2 and the number of localities is less than five (IUCN Standards and Petitions Subcommittee, 2019), with accelerated deforestation inside Colombian national parks (Clerici et al., 2020).

Characidium barbosai, new species (Figs. 1-2, 3A) Holotype: ZUEC 17139 (42.5 mm SL): Brazil, Mato Grosso, Vila Bela da Santíssima Trindade, córrego Longa Vida, tributary of rio Guaporé, Serra da Borda, 14º45’35’’S, 59º42’14’’W; F.A. Machado, N.E. Silva & C.M.C. Leite, 3 June 2005. Paratypes: All from Brazil, Mato Grosso, Vila Bela da Santíssima Trindade, rio Guaporé basin, Serra da Borda. ZUEC 171140 (17, 21.0– 43.7 mm SL); ANSP 207590 (5, 32.3–42.2 mm SL); CAS 247209 (5, 28.8–37.7 mm SL): same data as holotype. ZUEC 17145 (17, 21.3–39.8 mm SL); FMNH 144645 (5, 26.3–33.5 mm SL); MCZ 174158 (5, 30.8–36.4 mm SL): Córrego Longa Vida, 14º45’31’’S, 59º42’28’’W, 580 meters a.s.l.; F.A. Machado, N.E. Silva & C.M.C. Leite, 3 June 2005. ZUEC 17144 (194, 8 CS, 17.3–40.9 mm SL); CPUFMT 6778 (5, 29.6–35.7 mm SL); INPA 59043 (5, 28.5–36.1 mm SL); LBP 29207 (5, 27.0– 35.4 mm SL); MCP 54289 (5, 25.9–36.4 mm SL); MHNG 2784.070 (5, 30.4–33.5 mm SL); MNRJ 51745 (5, 32.0– 38.1 mm SL); MZUSP 125671 (5, 28.4–38.1 mm SL): Córrego Longa Vida, immediately below dam, 14º48’42’’S, 59º39’43’’W, 635 meters a.s.l.; F.A. Machado & N. Flausino Jr., 11 Sept 2005. MZUSP 84775 (91, 24.1–55.1 mm SL); UF 245019 (10, 26.4–48.6 mm SL): Córrego Cabeceira, c. 14º50’S, 59º40’W; F.A. Machado & N.E. Silva, 8 May 2004. ZUEC 17149 (4, 32.2–34.9 mm SL): Córrego Cabeceira, Mineradora Santa Elina, c. 14º50’S, 59º40’W; F.A. Machado, N.E. Silva & C.M.C. Leite, 2 June 2005. ZUEC 14735 (9, 18.5–43.5 mm SL): Córrego Cabeceira, c. 14º50’S, 59º40’W; F.A. Machado, N.E. Silva & C.M.C. Leite, 2 Jun 2005. ZUEC 14736 (49, 16.7–35.4 mm SL): Córrego Longa Vida (trib. rio Guaporé), 14º48’42’’S, 59º39’43’’W, 635 meters a.s.l.; F.A. Machado, N.E. Silva & C.M.C. Leite, 2 Jun 2005. Diagnosis. Characidium barbosai can be diagnosed from all congeners, except from C. summus, by lacking a preorbital stripe. It can be diagnosed from C. summus by the presence of 10–12 bars along the body (vs. bars absent), basicaudal spot inconspicuous (vs. basicaudal spot conspicuous), humeral blotch inconspicuous (vs. conspicuous), by having 12 scales around caudal peduncle (vs. 14), and by an adipose fin present (vs. absent). In addition, C. barbosai further differs its congeners except C. bahiense Almeida, C. chicoi da Graça, Ota & Domingues, C. clistenesi Melo & Espíndola, C. interruptum Pellegrin, C. lagosantense Travassos, C. lanei Travassos, C. laterale (Boulenger), C. litorale Leitão & Buckup, C. mirim Netto-Ferreira, Birindelli & Buckup, C. nana Mendonça & Netto-Ferreira, C. nupelia da Graça, Pavanelli & Buckup, C. orientale Buckup & Reis, C. rachovii Regan, C. satoi Melo & Oyakawa, C. stigmosum Melo & Buckup, C. vestigipinne Buckup & Hahn, and C. xavante da Graça, Pavanelli & Buckup by the presence of a single row of dentary teeth (vs. two rows); among those species, it differs from C. bahiense, C. chicoi, C. interruptum, C. lagosantense, C. lanei, C. laterale, C. mirim, C. nana, C. nupelia, C. orientale, C. rachovii, C. stigmosum, C. vestigipinne, and C. xavante by the presence of the parietal branch of the supraorbital canal (vs. absent); it differs from C. clistenesi, along with C. bahiense, C. bimaculatum, C. laterale, C. nana, C. nupelia and C. xavante, by the absence of a conspicuous peduncular blotch, and from C. litorale and C. satoi by having one or two scales between anus and anal-fin origin (vs. four or five in C. litorale and four to seven in C. satoi). See the Discussion for further comments on the diagnosis of the new species. Description. Morphometric data summarized in Table 1. Largest specimen examined reaching 45.2 mm SL. Body moderately elongated. Dorsal profile convex between tip of snout and posterior naris, gently convex from latter point to dorsal-fin origin, straight along dorsal-fin basis, slightly convex to straight from dorsal-fin terminus to anteriormost dorsal procurrent dorsal-fin ray. Ventral profile gently convex between tip of dentary and isthmus, gently convex to straight between latter point and anal-fin origin, slightly convex at anal-fin base; almost straight between anal-fin terminus and anteriormost ventral procurrent caudal-fin ray. Greatest body depth at dorsal-fin origin. Snout short, roughly triangular in lateral view. Mouth small, terminal. Tip of maxilla reaching level of anterior margin of orbit. Margin of orbit free, with narrow eyelid. Cheek narrow, its depth less than one third of eye diameter. Nares distinctly separated. Dermal flap surrounding anterior naris, and at anterior margin of posterior naris. Temporal and parietal branches of supraorbital laterosensory canal present; parietal branch elongated, reaching the parietal bone. Fontanel limited anteriorly by frontals, laterally by parietals and posteriorly by supraoccipital. TABLE I. Morphometric data for Characidium barbosai. Range includes values of holotype and paratypes. N = Number of specimens examined; SD = standard deviation. Dentary teeth 9 (3), 10(4), 12(1), arranged in single row; teeth crown triangular, lacking noticeable cusps, increasing in size toward symphysis. Premaxillary teeth 5(1), 6(11), 7*(42), 8(12) arranged in single row; teeth crown triangular, lacking noticeable cusps, increasing in size towards symphysis. Maxillary teeth absent. Ectopterygoid teeth arranged in single row; teeth minute and conical, numbering 1(2), 3(2), 4(1), 5(1), 6 (1), 7(1). Mesopterygoid teeth absent. Branchiostegal rays 4 (8); three attached to ceratohyal (8), one attached to epihyal (8). Total gill rakers on first arch 10(1), 11(2), 12 (1), 13(1), 14(1); gill rakers attached to epibranchial 4(2), 5 (5), 6(1); gill rakers attached to ceratobranchial 4(1), 5(4), 6 (1), 7(2); gill rakers attached to basibranchial 0(2) or 1(6). Scales cycloid; 11-15 parallel radii present on posterior field of scale, circuli restricted to anterior field of scales. Lateral line complete, all scales perforated; lateral-line scales 30(1), 31(1), 32(2), 33(5), 34*(42), 35(17), or 36(1). Scales above lateral line 4*(69). Scales below lateral line 4*(69). Scales around caudal peduncle 12*(66) or 13(2). Pre-dorsal scales series regularly arranged, except at its anterior portion, where often misaligned; scales on pre-dorsal series 9(3), 10(34), 11*(23), 12(6). Scales between anus and anal fin 1(39), 2*(26). Isthmus scaled. Pectoral fin short, not reaching vertical that pass through dorsal-fin origin. Origin of dorsal fin at level slight anterior to pelvic-fin origin. Pectoral-fin rays iii,7,i* (5), iii,8,i (62), iii,9,i (2). Pelvic-fin rays i,6,i (3), i,7,i* (64), i,8,i (1). Dorsal-fin rays iii,8 (1), ii,9* (67); supranumerary element on first pterygiophore of dorsal fin 1 (8). Analfin rays iii, 6(1), ii,7* (65); supranumerary element on first pterygiophore of anal fin 1 (8). Principal caudal-fin rays i,8,7,i (1), i,8,9,i* (55); upper procurrent rays 8 (1), 9(2); lower procurrent rays 8(1), 9(1). Adipose fin present. Precaudal vertebrae 20 (3), 21 (5); total vertebrae 33 (5), 34(3). Supraneurals 5 (1), 6(6), 7 (1). Hypurals numbering 6, hypurals 4, 5, and 6 not fused (8). Epurals 2(4), 3 (4). Posterior chamber of swim bladder larger than anterior chamber, 25.2–25.8 % in SL (2). Coloration of preserved specimens. Ground color of head and trunk light brown, darker dorsally, lighter ventrally. Sides of head and opercle light brown, with minute, numerous evenly-spaced melanophores. Dorsal portion of snout and head light brown. Preorbital and postorbital stripes absent. Humeral blotch present, vertically elongated, situated immediately behind upper corner of opercle, extending vertically one scale row and half above lateral line dorsally, reaching or falling short of reaching, lateral line, ventrally. Midlateral stripe conspicuous, narrow, extending from immediately behind humeral blotch to caudal peduncle, diffuse anteriorly and posteriorly not reaching end of caudal peduncle. Midlateral stripe anteriorly at level of lower portion of scale row immediately above lateral line and dorsal portion of lateral line scale row, gradually lowering to central portion of lateral-line scale row. Basicaudal spot present, small and inconspicuous, more noticeable in small specimens, but little discernible or absent in specimens larger than 41.0 mm SL. Peduncular spot absent. Bars alongside body 10-12, relatively broad dorsally, tapering ventrally; bars on midbody more conspicuous, first and second bars typically not extending ventrally from longitudinal stripe, middle bars not extending to abdominal region, last two bars very narrow. Bars limits becoming blurred ontogenetically and absent from specimens equal or larger than 41.0 mm SL, which have a reticulated color pattern, with pigmentation concentrated on distal portion of scales. Pectoral, pelvic, dorsal, anal, and caudal fins mostly hyaline; melanophores present only on fin-rays lepidotrichia, and forming a subdued medial stripe at dorsal fin. Sexual dimorphism. Tiny hooks are present on the pelvic-fin rays of a few specimens (ZUEC 17144, 7, 29.7–35.3 mm SL), on first to fifth branched rays, numbering 3–12 per fin ray. No fin hooks were observed on the pectoral-, anal-, dorsal- or caudal-fin rays. One of the specimens bearing hooks was dissected and identified as a mature male with well-developed testicles. Only three females could be positively identified by the possession of well-developed ovaries (discernible through the abdominal cavity wall, and confirmed through dissection; ZUEC 17144, 3, 31.6–34.7 mm SL). These females do not have hooks on pelvic-fin rays. Distribution. Characidium barbosai is only known from the headwaters of two tributaries of the Rio Guaporé, the Córrego Longa Vida and the Córrego Cabeceira, at the Serra da Borda, an isolated plateau with altitudes ranging between 300–800 meters a.s.l., rio Madeira drainage, Amazon basin, Mato Grosso, Brazil (Fig. 3). Ecological notes. The streams from Serra da Borda plateau possess clearwater and range from intermittent small streams only flowing during the rainy season (November to April), to the relatively large and perennial Córrego Longa Vida. Riparian vegetation at these streams range from open cerrado savannah, buritizais – wetlands dominated by the buriti palm, Mauritia flexuosa –, and semideciduous, submontane forest. Characidium barbosai occurs at the intermittent streams and become restricted to the remaining water pools during the dry season, but is more abundant at the perennial Córrego Longa Vida. These streams located in the upper Serra da Borda Plateu are virtually isolated from their lower sections in the surrounding lowlands by steeps waterfalls. Unlike its congeners, Characidium barbosai is a midwater fish, picking food items drifted by the current or at the surface, much like several characid fishes as Astyanax spp. with a similar pelagic feeding behavior. During the night, specimens were observed motionless at the water column or, more rarely, at the bottom. Only a few fish species, all silurifoms, were collected syntopically with C. barbosai at the Córrego Longa Vida: Callichthys callichthys (Callichthyidae), an unidentified species of Ancistrus (Loricariidae), and an unidentified species of Trichomycterus (Trichomycteridae). Gut contents of eleven examined specimens (ZUEC 14735, 1; 14736, 2; 17144, 8) were mostly empty, but a single specimen possessed a few arthropods remains. Conservation status. Characidium barbosai is so far only known from a restrict area, the stretches of the Córrego Longa Vida and Córrego Cabeceira crossing the Serra da Borda plateau, where the species seems to be common. Gold mining in the Serra da Borda (originally called Serra de São Vicente) started in the 1730’s with the establishment of the Arraial de São Francisco Xavier, one of the first colonial settlements in the Mato Grosso state, and was abandoned by the end of the XIX century with the demise of the alluvial gold in the region (Póvoas, 1995). Intensive gold mining using modern techniques was resumed in the last twenty years in the area. The upper portion of the Córrego Longa Vida was dammed in 2005 forming a small reservoir, related to the gold mining activities in the area. It is unclear how the damming impacted C. barbosai, but specimens were collected in both the lake above the dam and in the stream stretch below it in 2005 (F.A Machado and N. Flausino Junior, pers. obs.). Besides the damming, it seems that little disturbance has taken place so far at the Córrego Longa Vida. On the other hand, the Córrego Cabeceira, the other headwater tributary from where C. barbosai is known, was intensely disturbed since 2005, with large tailing dams build at its upper course, where untreated sewage is also being disposed of. Unregulat- ed, intensive illegal gold mining has been occurring intermittently at the eastern versant of the Serra da Borda since 2015 and has completely ravaged some headwater streams draining into the rio Galera (a tributary of rio Guaporé), but the Córrego Longa Vida and its tributaries, which drain the western versant of the Serra da Borda, directly into the rio Guaporé, seem to have been spared so far from the devastation. As the extent of occurrence of C. barbosai is not well documented, nor the potential impacts at its habitat, we prefer at the moment to consider C. barbosai as Data Deficient (DD) following IUCN’s criteria (International Union for Conservation of Nature, 2012). Etymology. The specific epithet honors Gerson Natalício Barbosa, a District Attorney from Mato Grosso state, for his commitment in the enforcement of the environmental laws, and for being one of the conceivers of the project “Água para o Futuro”, which is surveying, protecting and restoring springs in the urban area of Cuiabá, the capital of Mato Grosso. A patronymic adjective.

Made available in DSpace on 2020-12-10T20:06:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-17 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) A new species of Characidium is described from headwater tributaries of the upper rio Guapore, Rio Madeira basin, Mato Grosso state, Brazil. The new species can be diagnosed from all congeners, except Characidium summus, for lacking the preorbital and postorbital stripes. It can be diagnosed from the latter species by having 12 circumpeduncular scales (vs. 14), by an adipose fin present (vs. adipose fin absent), and 10-12 bars along the body (vs. absence of bars), among other characters. The new species is so far only known from direct tributaries of the Rio Guapore at the Serra da Borda, an isolated plateau 300-800 meters above sea level, and possess a behavior very uncommon within the genus, being a mid-water pelagic fish, instead of the benthic behavior of most congeners. Comments on the putative phylogenetic relationships of the new species, as well as some remarks on its unusual behavior within the genus, are presented. Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Rua Prof Doutor Antonio Celso Wagner Zanin 250, BR-18618689 Botucatu, SP, Brazil Univ Estadual Campinas Adao Jose Cardoso, Museu Zool, Caixa Postal 6109, BR-13083863 Campinas, SP, Brazil Univ Fed Mato Grosso, Inst Biociencias, Dept Biol & Zool, Av Fernando Correia da Costa 2367, BR-78060900 Cuiaba, MT, Brazil Univ Sao Paulo, Inst Oceanog, Dept Oceanog Biol, Praca Oceanog 191, BR-05508120 Sao Paulo, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Rua Prof Doutor Antonio Celso Wagner Zanin 250, BR-18618689 Botucatu, SP, Brazil FAPESP: 2011/51532-7 FAPESP: 2013/20936-0 FAPESP: 2017/12909-4 CNPq: 433050/2016-0

Characidium cacah, new species, apparently endemic to the rio das Velhas sub-basin, upper rio São Francisco basin, Brazil, is described. The new species is easily distinguished from congeners, except C. chicoi, C. helmeri, C. mirim, C. nana, C. nupelia, C. stigmosum and C. xavante, by having an incomplete lateral line and for lacking an adipose fin. The new species can be diagnosed from the aforementioned species by a series of characters, including the presence of 12 circumpeduncular scales, the isthmus completely scaled, a thin inconspicuous or dashed midlateral dark stripe, the absence of a conspicuous peduncular blotch, and humeral blotch and basicaudal spot variably marked.

Two new species of Characidium, C. tatama and C. dule, are described from the biogeographic Choco region in western Colombia. Both new species are supported by both morphological and molecular data. C. tatama from the San Juan River in the Pacific and C. dule from the Atrato River in the Caribbean portion of Colombia are both distributed in the upper and lower portions of these basins. An extensive comparison with other trans- and cis-Andean species of Characidium was made, in addition to species delimitation, using COI sequences by distinct methods (GMYC, ABGD, bPTP).

Characidium chancoense, new species (Figs. 1, 2f, 3; Table 1) urn:lsid:zoobank.org:act: DD25AADA-BFDC-46CA-88C9-37AA76784503 Characidium sp.— Roman-Valencia & Garcia, 2006:22, fig. 1A (morphogeometry; specimens from Zanjón Bagazal, Rio Cauca basin, Colombia; comparison with Characidium caucanum). Holotype. IMCN 4528, 50.5 mm SL, Colombia, Valle del Cauca, Ansermanuevo, upper Río Cauca drainage, Río Chanco, 4°46’30.14”N 76°0’8.62”W, A. Ortega-Lara, 26 Nov 2000. Paratypes. All from Colombia. Departamento Valle del Cauca, Río Cauca drainage: IMCN 4474, 11, 40.8–49.5 mm SL, Ansermanuevo, Río Chanco, 4°46’30.14”N 76°0’8.62”W, A. Ortega-Lara, 26 Nov 2000; IMCN 4527, 20 + 3 C&S, 34.7–44.6 mm SL, Ansermanuevo, Río Chanco, km 4 road to El Águila and the Ansermanuevo city, Bellavista farm, A. Ortega-Lara, 27 Nov 2000; IMCN 4823, 2, 44.9–45.2 mm SL, Ansermanuevo, Río Chanco, 4°46’30.14”N 76°0’8.62”W, A. Ortega-Lara, 26 Nov 2000; IMCN 4480, 3, 42.1–47.3 mm SL, Ansermanuevo, Río Chanco, 4°44’37”N 76°03’30”W, A. Ortega-Lara, 8 Nov 2000; IMCN 4530, 7, 40.3–49.2 mm SL, Ansermanuevo, Río Chanco, Bellavista farm, 4°46’30.14”N 76°0’8.62”W, A. Ortega-Lara, 26 Nov 2000; IMCN 4491, 3, 33.7–46.9 mm SL, Ansermanuevo, Río Chanco, 4°46’30.14”N 76°0’8.62”W, A. Ortega-Lara, 22 Nov 2000. Departamento Quindío: IUQ 3778, 2, 43.1–47.1 mm SL, Río Portugal de Piedras (upper Río Cauca drainage), 4°03’09.9”N 76°21’16.8”W, M. Ramírez and J. Arcila, 22 Oct 2008. Non-types. All from Colombia, Río Cauca basin. CIUA 268, 1, 53.1 mm SL, Antioquia, Anorí, Quebrada Boquerón, tributary of Porce III dam, 7°0’29.02”N 75°3’51.98”W, A. Bermúdez, 03 Jun 2005; CIUA 705, 2, 42.6–48.4 mm SL, Antioquia, Barbosa, Quebrada Las Lajas at I-62 route, 6°28’16.2”N 75°17’29.9”W, J. G. Ospina-Pabón, 03 Jun 2007; CIUA 799, 1, 39.5 mm SL, Cauca, Buenos Aires, Río Cauca, near to Vereda La Balsa, 03°05’10.9”N 76°35’36.8”W, J. G. Ospina-Pabón and L. Ochoa, 01 Jan 2005. Diagnosis. Characidium chancoense can be distinguished from its trans-Andean congeners, except females of C. caucanum, by its pigmentation pattern and internal morphology. It has a vertically elongate spot between the posterior edge of the opercle and the humeral blotch which abuts a yellow gap (live specimens) or white gap (preserved specimens) that ends at the humeral blotch, and 7–12 vertical bars that occupy completely the scales on which they occur; anteriormost 6–11 bars are cuneate shaped with their vertices reaching to, or one scale row below, the lateral-line scale series, posteriormost 1–4 bars (counted from the caudal-fin base) reach past the lateral line to the ventral margin of the caudal peduncle. Vertical bars are absent in males of C. caucanum, and present in C. sanctjohanni and C. cf. zebra but only occupy the scale margins, leaving the center unpigmented, creating a chain pattern. Characidium phoxocephalum has spots and vertical bars above, on and below the lateral stripe. Characidium chancoense lacks a well-defined dark caudal-peduncle spot but does have the middle caudal-fin rays pigmented only near their bases by the continuation of the lateral stripe, and the rest of the fin hyaline. In C. phoxocephalum and C. caucanum the middle caudal-fin rays are pigmented along their entire length. Characidium cf. zebra has a small, well-defined dark caudal-peduncle spot located slightly posterior to the caudal-fin base and the rest of the fin is hyaline (Fig. 1). Characidium chancoense females differ from those of C. caucanum by the length and shape of the vertical bars (only the posterior bars cross the lateral line and they are not sinuous vs. vertical bars crossing the lateral line and sinuous) (Fig. 2e, f). Lastly, a review of Eigenmann’s (1922: 315) illustration of C. phoxocephalum and C. caucanum shows notable differences in the shapes of the caudal-fin lobes: a forked caudal fin with pointed lobes, which has also been confirmed by examination of topotypic specimens and which differs from the rounded caudal-fin lobes of C. chancoense (Fig 1, 2c, d, e.). See additional comments on the diagnosis of the species in the Discussion, below. Description. Morphometric data given in Table 1. Body slightly compressed laterally. Dorsal profile moderately convex from snout to anterior naris, slightly convex from there to tip of supraoccipital, then moderately convex to dorsal-fin origin; roughly straight and posteroventrally inclined through dorsal-fin base to adipose-fin origin; slightly concave from latter point to first procurrent caudal-fin ray. Ventral profile moderately convex to pectoral fin insertion, then gently convex to anal-fin base; posterodorsally inclined along anal-fin, almost straight along caudal peduncle. Greatest body depth at or just anterior to dorsal-fin origin. Snout with rounded tip, at level of ventral margin of orbit. Maxilla relatively short, reaching posterior naris but not anterior margin of eye. Orbit circular, about equal to snout length; iris round. ......continued on the next page Dorsal-fin rays ii+8 (3), ii+9* (48) or ii+10 (2); anal-fin rays ii+ 6+i (10) or ii+7+i* (43); pectoral-fin rays iii+10+i* (31), iii+11+i (20) or iii+12+i (2); pelvic-fin rays i+7 (6), i+8* (44) or i+9 (3); principal caudal-fin rays (upper and lowermost simple) i+8+7+i (2), i+8+8+i (2), i+8+9+i (13), i+9+8+i* (34) or i+9+9+i (2). Adipose fin present, situated at vertical through posterior end of anal-fin base. Scales cycloid. Lateral line complete, pored lateral-line scales: 31(1), 34(7), 35*(7), 36(23), 37(14), 39(1). Scale rows above lateral line 3(1), 4*(52), and below lateral line 2*(37), 3(16). Scales around caudal peduncle 10(9), 11*(23), 12(21). Predorsal scales series arranged in single, regular row; scales in predorsal series 10(17), 11*(35), 12(1). Isthmus scaled. Outer premaxillary tooth series with two bicuspid teeth and six (2) to seven (1) conic teeth (Fig. 4a). Maxilla edentulous. Dentary with ten (3) teeth, decreasing in size posterolaterally with posteriormost teeth only 1/3 the height of anteriormost; anteriormost five teeth tricuspid, remaining teeth conical (Fig. 4b). Gill rakers on ventral lobe of first gill arch numbering 9 (3), first two very small and rudimentary. Four branchiostegal rays. Lower process of dentary with sensorial canal that begins at symphysis and extends to posterior tip. Posterior tip of dentary ending in sharp point. Anguloarticular triangular with base longer than unequal sides, upper vertex of articular truncate, anterior vertex pointed. Anguloarticular joint with quadrate concave with dorsally curved posterior process. Retroarticular elongate with rounded posterior margin, boot-shaped. Quadrate joint with anguloarticular rounded, postero-inferior process of quadrate articulating with symplectic and postero-superior process pointed; upper margin convex, anterior margin straight up to articulation. Metapterygoid butterfly shaped. Mesopterygoid shaped as inverted trapezoid. Ectopterygoid with 11+14 conical teeth (1) or 11+11 (1). Palatine rectangular. Maxilla with upper margin straight or slightly concave, lower margin convex with two antero-superior foramina; posterior tip rounded, anterior tip sharply pointed. Dorsal lamina of mesethmoid bone considerably narrower anteriorly than posteriorly and attached to the frontal (see Buckup 1993b: 230); portion of mesethmoid contacting premaxila ending in three rounded lobes. Optic nerve foramen in pterosphenoid with opening oriented antero–posteriorly. Fontanel trapezoidal, bordered anteriorly by frontals, laterally by parietals and posteriorly by supraoccipital (one specimen with anterior margin forming vertex between parietals). Vertebrae 36–38 (2). Ribs 17 (2). Dorsal fin with 10 (2) or 11 pterygiophores (1). Anal fin with eight (2) or nine (1) pterygiophores (1). Swimbladder with posterior chamber much longer than anterior chamber (Fig. 5c). Color in alcohol. Overall color of head and body tan or yellowish-tan. Dorsal midline with faint brown stripe from tip of supraoccipital to dorsal-fin base, and from posterior margin of dorsal-fin base to adipose-fin origin. Dorsum with two additional, narrower stripes (sometimes broken into rows of tightly packed dots), one extending from rear of head to slightly posterior to dorsal-fin origin, the other from rear of head to adipose fin. Diffuse gray midlateral stripe originating on the upper lip and very faintly continuing posteriorly across the snout, eye, infraorbitals, and upper opercle, absent from the posterior opercular margin and anterior to well-defined, rounded humeral blotch posterior to upper margin of opercle. Dark, well-defined midlateral stripe extending from immediately behind humeral blotch to base of middle caudal fin rays (width approximately 7/8 of scale height). Stripe darkest where overlain by the 7–12 vertical, cuneate-shaped bars. In faded specimens bars fainter and tips of their vertices more noticeable. Dorsal fin dusky gray with band of pigment concentrated on rays passing through middle of fin. Adipose fin light proximally, dusky gray distally. Caudal fin with dark pigmentation concentrated on first three or four upper and lowermost procurrent rays and middle rays. Anal fin with irregular band of melanophores concentrated on membranes. Pelvic and pectoral fins hyaline or light yellow. Color in life. Dorsum olivaceous from rear of head to caudal fin, venter white blending with reddish color (specimens from quebrada Dopo at finca Los Chorros, tributary of río Cauca, vereda los Chorros, Yotoco, Valle del Cauca) from base of pelvic fin to caudal fin. Fin rays yellowish, distal parts of fins hyaline. Iridescent band present under black lateral line located over lateral-line scales. Base of each caudal-fin lobe with olivaceous or reddish spots separated by black basicaudal spot (Fig. 1b). Sexual dimorphism. None observed. Etymology. Named after its type locality, the Río Chanco. To be treated as a Latinized geographic adjective. Distribution. This species occurs in tributaries of the Río Cauca system, Cauca, Valle del Cauca and Antioquia Departments, Colombia (Fig. 3).

Characidium chancoense new species, is described from the transandean upper Río Cauca drainage in Colombia. It can be distinguished from all congeners by its pigmentation pattern that consists of 7–12 vertical bars, most of which are cuneate-shaped with the vertex ending on or just below the lateral-line scale series, except for the last 1–4, which are dorsoventrally elongate rectangular bars that extend well below the lateral line. Characidium chancoense is sympatric with C. caucanum Eigenmann, C. phoxocephalum Eigenmann, C. cf. zebra Eigenmann and C. cf. boavistae Steindachner. Unlike C. caucanum and C. cf. boavistae, C. chancoense does not appear to be sexually dimorphic.

Key to the Characidium species from the trans-Andean basins of Colombia 1a. Isthmus and chest lacking scales........................................... Characidium cf. boavistae (Figs. 2k, l) 1b. Isthmus and chest scaled............................................................................... 2 2a. Sides of body with well-defined black spots located on, above and below a dark lateral stripe; dorsum crossed by 7���10 vertical bars that do not reach below lateral stripe......................................... C. phoxocephalum (Figs. 2b, d) 2b. Sides of body without well-defined black spots; dorsum without vertical bars (in adult males of C. caucanum) or with 6���18 vertical bars crossing dorsum (mean = 11), some of which reaching well below the horizontal lateral stripe... 3 (Fig. 2a, c, e) 3a. Caudal-fin mark not forming a well-defined spot on peduncle, but dark pigment present on middle caudal-fin rays........................................................................................... 4 (Figs. 2a, b, c, g, e, f) 3b. Caudal-fin mark present as well-defined spot on peduncle, dark pigment not extending onto middle caudal-fin rays.......................................................................................... 5 (Figs. 2g, h, i, j, k, l) 4a. Vertical bars on body narrow (1/2���1 scale wide) and sinuous, not cuneate-shaped, usually 11 or more in juveniles and females, or sides of body without vertical bars in adult males............................ Characidium caucanum (Fig. 2a, c, e) 4b. Vertical bars on body wide (up to four scales wide at widest dorsal end), anteriormost cuneate-shaped with vertex pointing down and reaching to, or just below, lateral line, posterior bars (1���4 counted from caudal-fin base) reaching well below the lateral line to ventral margin of caudal peduncle, usually fewer than 12 vertical bars present on sides of body (range 7���12)................................................................ Characidium chancoense, new species (Fig. 2f) 5a. Sides of body with 9���10 wide vertical bars, none cuneate-shaped; body depth at origin of dorsal fin 19.9���25.8 % in SL, mean 25.5.................................................................. Characidium sanctjohanni (Fig. 2h, j) 5b. Sides of the body with 6���16 thin vertical bars, all passing well below narrow horizontal stripe, none cuneate-shaped; body slender, body depth at origin of dorsal fin 17.8���27.4 % in SL, mean 23.4............... Characidium cf. zebra (Fig. 2g, i), Published as part of Agudelo-Zamora, Henry D., Ortega-Lara, Armando & Taphorn, Donald C., 2020, Characidium chancoense, a new species of South American darter from the R��o Cauca drainage, Colombia (Characiformes: Crenuchidae), pp. 249-263 in Zootaxa 4768 (2) on pages 260-261, DOI: 10.11646/zootaxa.4768.2.6, http://zenodo.org/record/3779748

Characidium iaquira, a new species from the upper rio Juruena, rio Tapajos basin, Brazil, is described. The new species can be promptly distinguished from all congeners by having a unique v-shaped dark mark lying along the caudal-fin extension, in medium- and large-sized specimens, and a remarkable iridescent green colouration in life. Characidium iaquira is closely related to Characidium crandellii and Characidium declivirostre by sharing unambiguous synapomorphies such as branchiostegal membranes united to each other across the isthmus, a scaleless area extending from the isthmus to the pectoral girdle, and dermal flaps surrounding anterior and posterior naris independent, but touching each other distally. Morphological specializations of the paired fins in the three riffle-dwellers species are discussed, including the wing-like shape, robustness, and inclination of the pectoral fin.

Eukaryotic genomes consist of several repetitive DNAs, including dispersed DNA sequences that move between chromosome sites, tandem repeats of DNA sequences, and multigene families. In this study, repeated sequences isolated from the genome of Characidium gomesi were analyzed and mapped to chromosomes in Characidium zebra and specimens from two populations of C. gomesi. The sequences were transposable elements (TEs) named retroelement of Xiphophorus (Rex); multigene families of U2 small nuclear RNA (U2 snRNA); and histones H1, H3, and H4. Sequence analyses revealed that U2 snRNA contains a major portion corresponding to the Tx1-type non-LTR retrotransposon Keno, the preferential insertion sites of which are U2 snRNA sequences. All histone sequences were found to be associated with TEs. In situ localization revealed that these DNA sequences are dispersed throughout the autosomes of the species, but they are not involved in differentiation of the specific region of the W sex chromosome in C. gomesi. We discuss mechanisms of TE invasion into multigene families that lead to microstructural variation in Characidium genomes.

Fish species exhibit substantial variation in the degree of genetic differentiation between sex chromosome pairs, and therefore offer the opportunity to study the full range of sex chromosome evolution. We used restriction-site associated DNA sequencing (RAD-seq) to study the sex chromosomes of Characidium gomesi, a species with conspicuous heteromorphic ZW/ZZ sex chromosomes. We screened 9863 single-nucleotide polymorphisms (SNPs), corresponding to ~1 marker/100 kb distributed across the genome for sex-linked variation. With this data set, we identified 26 female-specific RAD loci, putatively located on the W chromosome, as well as 148 sex-associated SNPs showing significant differentiation (average FST=0.144) between males and females, and therefore in regions of more recent divergence between the Z and W chromosomes. In addition, we detected 25 RAD loci showing extreme heterozygote deficiency in females but which were in Hardy–Weinberg equilibrium in males, consistent with degeneration of the W chromosome and therefore female hemizygosity. We validated seven female-specific and two sex-associated markers in a larger sample of C. gomesi, of which three localised to the W chromosome, thereby providing useful markers for sexing wild samples. Validated markers were evaluated in other populations and species of the genus Characidium, this exploration suggesting a rapid turnover of W-specific repetitive elements. Together, our analyses point to a complex origin for the sex chromosome of C. gomesi and highlight the utility of RAD-seq for studying the composition and evolution of sex chromosomes systems in wild populations.

The high diversity of freshwater fish species reflects a great morphological plasticity. Understanding the relationship between swimming capacity, morphology and habitat use may be important to predict the chances of finding a species at an anthropized environment. The swimming capacity and morphological aspects of two sympatric species of Characidium, and for which spatial segregation in different hydraulic habitats is known, were compared in this study. Twenty-one individuals of Characidium fasciatum Reinhardt, 1867 and 23 individuals of Characidium cf. zebra Eigenmann, 1909 were captured and used for the evaluation of the swimming capacity and ecomorphological attributes. The swimming capacity of each species was obtained by measuring critical and relative velocities. A total of 12 ecomorphological attributes correlated with habitat use and swimming characteristics were also compared. The Mann-Whitney mean test showed that the swimming capacity of C. fasciatum was greater than that of C. cf. zebra, and the standard length of the individuals explained 12.42% of the variation in their capacity to withstand water flow. Both species were morphologically distinct in the relative length of the caudal peduncle, ventral flattening index and the relative area of the pectoral fin. The relative area of the pectoral fin alone accounted for 16.71% of the differences in the ability to resist the water flow and which were not explained by body length. Our results showed that two species differed in the ecomorphological space and in their swimming capacity, supporting the hypothesis that the greater the hydrodynamism, the better a fish is able to withstand the water flow, and that this capacity is correlated with the morphological characteristics linked to the swimming activity of the fish.

Characidium nambiquara, a new species from the upper rio Guapore, rio Madeira basin, Brazil, is described. The new species differs from most congeners by having isthmus and area between contralateral pectoral-fin bases completely naked. From congeners with some degree of scaleless ventral surface of the body C. nambiquara differs by having 10 circumpeduncular scales. The new species is also distinguished from congeners by the spotted colour pattern on body of the large-sized specimens and by having black dashes on all fins and conspicuous midlateral longitudinal dark stripe or conspicuous vertical bars absent. Characidium nambiquara further differs from most congeners by having 34-36 pored scales on the lateral line, 3 horizontal scale rows above the lateral line and 3 horizontal scale rows from the lateral line to the midventral scale series. Remarks on intraspecific colour variation within the genus, not related with sexual dimorphism, are also given. This article is protected by copyright. All rights reserved.

Characidium cricarense, new species u r n:l s i d:z o o b a n k.o rg:a c t: C2D B8 3 2 9-F8 9 A -4A2 5 -9 6 8E - C6 F52896 E386 Fig. 1, Tabs. 1-2 Holotype. MNRJ 51282, 49.0 mm SL, Brazil, Espírito Santo, São Mateus municipality, São Mateus basin, rio Cricaré at Cachoeira do Inferno rapids, 18°42’24.5”S 40°16’7.2”W, 18 m above sea level, 15 Aug 2017, P.A. Buckup, D.F. Moraes Junior, E. Malanski & V. de Britto. Paratypes. All from Brazil, Espírito Santo. Rio Itaúnas basin: MNRJ 50962, 46 (2 for DNA, 2 CS), 41.3-47.7 mm SL (13, 41.3-47.7 mm SL), Pedro Canário municipality, rio Itaúnas at Cachoeira da Mata waterfall, north of Floresta do Sul, 18°12’11.6”S 40°4’36.3”W, 17 m above sea level, 15 Aug 2017, P.A. Buckup, D.F. Moraes Junior, E. Malanski & V. de Britto. Rio São Mateus basin: MNRJ 50973, 16 (2 for DNA, 2 CS), 39.2-48.0 mm SL (4, 39.2-48.0 mm SL), MBML 13549, 5, 42.0- 48.8 mm SL, collected with holotype. Rio Doce basin: MNRJ 41832, 33 (10 for DNA), 40.7-55.9 mm SL (9, 40.7-55.9 mm SL), Santa Teresa municipality, rio Santa Maria do Rio Doce at Cachoeira do Rúdio waterfall, 19°50’5”S 40°41’12”W, 159 m above sea level, 5 Oct 2013, J. R. Gomes, E. Neuhaus & C.C.D. Quijada. Non-types. Locality data has been abbreviated to include only the municipality, state abbreviation, and name of main river. All from Brazil, grouped according to hydrographic basins from north to south. Rio Jucuruçu basin: MBML 7501 (3 for DNA), 12, 22.2-31.2 mm SL, Palmópolis, MG, rio do Prado; MBML 7508 (1 for DNA), 2, 39.3- 39.7 mm SL, Palmópolis, MG, córrego Paulino Laranjeira; MBML 12879, 1, 30.3 mm SL, Itamaraju, BA, tributary of rio Jucuruçu. Rio Itanhém-Alcobaça basin: MBML 3846, 5, 33.7-36.7 mm SL, Medeiros Neto, BA, córrego do Medeiros Neto. Rio Mucuri basin: MNRJ 38334, 8, 29.2-50.2 mm SL, Teófilo Otoni, MG, rio Todos os Santos; MNRJ 38335, 32, 23.3-39.3 mm SL, Teófilo Otoni, MG, rio Todos os Santos; MNRJ 38336, 11, 33.4-40.5 mm SL, Teófilo Otoni, MG, rio Todos os Santos; MZUSP 54818, 25, 18.4-34.4 mm SL, Teófilo Otoni, MG, riacho São Pedro; MZUSP 54821, 8, 25.0- 38.6 mm SL, Teófilo Otoni, MG, rio Todos os Santos. Rio Itaúnas basin: CZNC 874 (2 for DNA), 41, 38.8-44.0 mm SL, Montanha, ES, rio Itaúnas; CZNC 1376, 57, 28.4-40.7 mm SL, Pedro Canário, ES, rio Itaúnas; MBML 4782, 1, 31.4 mm SL, Conceição da Barra, ES, córrego Grande; MBML 4807, 4, 22.7-25.2 mm SL, Conceição da Barra, ES, córrego Grande; MBML 4808, 6 (1 for DNA), 22.2-23.1 mm SL, Pedro Canário, ES, córrego Douradão; MBML 4830, 2, 29.6 mm SL, Conceição da Barra, ES, córrego Grande; MBML 7217, 4, 34.7 mm SL, Pinheiros, ES, córrego Santo Antônio; MBML 7223, 19, 22.8-31.9 mm SL, Pinheiros, ES, tributary of córrego Santo Antônio; MBML 7227, 1 (1 for DNA), 25.8 mm SL, Pinheiros, ES, córrego Santo Antônio; MBML 7235, 2, 31.0- 32.1 mm SL, Pinheiros, ES, córrego do Veado; MBML 7248, 2, 32.8-38.5 mm SL, Pinheiros, ES, córrego São Roque; MBML 7261, 1, 22.1 mm SL, Pinheiros, ES, córrego do Veado; MNRJ 37635, 41 (4 for DNA), 21.3- 40.8 mm SL, Barra de São Francisco, ES, rio Itaúnas; MZUSP 54817, 80, 18.5-39.6 mm SL, Pinheiros, ES, rio do Sul. Rio São Mateus basin: CZNC 167, 6, 32.4-34.4 mm SL, São Mateus, ES, rio Cricaré; CZNC 1047, 6, 39.1- 41.2 mm SL, São Mateus, ES, rio Cricaré; CZNC 1389, 8, 39.6-39.8 mm SL, Ecoporanga, ES, rio Dois de Setembro; CZNC 1443, 45 (1 for DNA), 37.4-40.0 mm SL, Vila Pavão, ES, córrego da Rapadura; CZNC 1467, 9, 45.4 mm SL, Vila Pavão, ES, córrego Alecrim; CZNC 1477 (2 for DNA), 17, 36.4-48.7 mm SL, Barra de São Francisco, ES, rio Cricaré; CZNC 1506 (1 for DNA), 20, 36.8-47.0 mm SL, Água Doce do Norte, ES, rio Preto; CZNC 1531, 11, 34.3 mm SL, Ecoporanga, ES, rio Cotaxé; CZNC 1535, 6, 34.3- 36.8 mm SL, Ataléia, ES, rio do Norte; CZNC 1545, 10, 26.4-47.7 mm SL, Ecoporanga, ES, rio Dois de Setembro; CZNC 1556, 50, 32.1-34.1 mm SL, Ataléia, ES, rio Paraju; CZNC 1576, 1, 37.4 mm SL, Ecoporanga, ES, ribeirão Santa Rita; CZNC 1593 (1 for DNA), 37, 33.6-34.5 mm SL, Ecoporanga, ES, córrego Lajeado; MBML 3480, 1, 40.9 mm SL, Água Doce do Norte, ES, córrego Água Doce; MBML 3484, 15, 28.0- 43.2 mm SL, Água Doce do Norte, ES, rio Preto; MNRJ 50845, 1, 34.8 mm SL, Boa Esperança, ES, rio Cotaxé; MZUSP 54820, 5, 36.0- 37.2 mm SL, Boa Esperança, ES, rio Braço Norte. Rio Doce basin: MBML 4369, 6, 31.4-43.7 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MBML 4371, 15, 29.1-40.1 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MBML 4381, 2, 32.4-46.6 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MBML 4388, 6, 38.7-53.0 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MBML 4403, 1, 34.2 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MBML 4422, 3, 33.5- 33.9 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MBML 4456, 1, 44.5 mm SL, Santa Teresa, ES, tributary of rio Santa Maria do Rio Doce; MBML 7636, 10, 44.6-52.7 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MNRJ 22420, 11, 38.7-55.6 mm SL, Santa Teresa, ES, rio Santa Maria; MNRJ 36190, 10, 23.9-42.6 mm SL, Laranja da Terra, ES, ribeirão Lagoa; MNRJ 37625, 5, 30.0- 39.2 mm SL, Baixo Guandu, ES, rio Mutum; MNRJ 37730, 8, 27.7-34.3 mm SL, Águia Branca, ES, rio Braço Sul; MNRJ 37737, 6, 32.6-50.5 mm SL, Águia Branca, ES, córrego Água Calma; MNRJ 41879, 7 (5 for DNA), 34.9-49.2 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce; MNRJ 50842, 55, 36.1-46.7 mm SL, Santa Teresa, ES, rio Santa Maria do Rio Doce at cachoeira do Rúdio. Diagnosis. The new species is included in a group of species of Characidium with an unscaled area in the isthmus (vs. isthmus scaled in C. bahiense, C. bimaculatum Fowler, 1941, C. boehlkei Géry, 1972, C. borellii (Boulenger, 1895), C. caucanum Eigenmann, 1912, C. chupa Schultz, 1944, C. clistenesi, C. deludens, C. etheostoma Cope, 1872, C. etzeli Zarske, Géry, 2001, C. geryi (Zarske, 1997), C. heinianum Zarske, Géry, 2001, C. heirmostigmata Graça, Pavanelli, 2008, C. interruptum Pellegrin, 1909, C. lagosantense Travassos, 1947, C. lanei Travassos, 1967, C. laterale (Boulenger, 1895), C. litorale Leitão, Buckup, 2014, C. longum Taphorn, Montaña, Buckup, 2006, C. marshi Breder, 1925, C. mirim Netto-Ferreira, Birindelli, Buckup, 2013, C. nana Mendonça, Netto-Ferreira, 2015, C. nupelia Graça, Pavanelli, Buckup, 2008, C. occidentale Buckup, Reis, 1997, C. orientale Buckup, Reis, 1997, C. papachibe Peixoto, Wosiacki, 2013, C. pellucidum Eigenmann, 1909, C. phoxocephalum Eigenmann, 1912, C. pteroides Eigenmann, 1909, C. rachovii Regan, 1913, C. roesseli Géry, 1965, C. samurai, C. sanctjohanni Dahl, 1960, C. satoi Melo, Oyakawa, 2015, C. schindleri Zarske, Géry, 2001, C. serrano Buckup, Reis, 1997, C. steindachneri Cope, 1878, C. stigmosum Melo, Buckup, 2002, C. tapuia Zanata, Ramos, Oliveira-Silva, 2018, C. tenue (Cope, 1894), C. vestigipinne Buckup, Hahn, 2000, C. xanthopterum Silveira, Langeani, da Graça, Pavanelli, Buckup, 2008, C. xavante Graça, Pavanelli, Buckup, 2008, and C. zebra Eigenmann, 1909). Within this group of species, Characidium cricarense is distinguished from other species, except C. alipioi Travassos, 1955, C. fasciatum, C. hasemani Steindachner, 1915, and C. kamakan, by the presence of 5-7 scales and distance between the anus and the anal-fin greater than 10% SL (vs. 2-4 scales and distance shorter than 10% SL in C. boavistae Steindachner, 1915, C. grajahuense Travassos, 1944, C. helmeri, C. japuhybense Travassos, 1949, C. lauroi Travassos, 1949, C. oiticicai Travassos, 1967, C. pterostictum Gomes, 1947, C. schubarti Travassos, 1955, C. summum Zanata, Ohara, 2015, C. timbuiense, C. travassosi Melo, Buckup, Oyakawa, 2016, and C. vidali Travassos, 1967), and 14 series of scales around the caudal peduncle (vs. 12 or less series of scales around caudal peduncle in C. amaila Lujan, Agudelo-Zamora, Taphorn, Booth, López-Fernández, 2013, C. brevirostre Pellegrin, 1909, C. crandellii Steindachner, 1915, C. declivirostre Steindachner, 1915, C. gomesi Travassos, 1956, C. macrolepidotum (Peters, 1868), C. purpuratum Steindachner, 1882 and C. sterbai (Zarske, 1997)). Characidium cricarense is distinguished from C. alipioi by having 4 series of scales above the lateral line (vs. 5 series) and a greater distance between the anus and the anal fin (11.4-15.5 vs. 10.1-11.1% SL); from C. fasciatum and C. kamakan by the smaller body depth at the dorsalfin origin (16.3-20.0 vs. 20.1-23.1 and 20.6-21.8% SL, respectively), at the anal fin origin (13.0-15.5 vs. 16.1-17.2 and 16.6-17.8% SL, respectively), and at the caudal peduncle (8.8-10.5 vs. 11.6-12.5 and 12.0-12.9% SL, respectively); from C. hasemani by the short distances between the tip of the snout and the pelvic fin (46.1-50.2 vs. 53.2-55.6% SL), the tip of the snout and the anal fin (72.1-76.4 vs. 76.4-79.9% SL), and the tip of the snout and the tip of anal fin (87.5-92.2 vs. 94.4-100.6% SL). Description. In Tab. 2, morphometric data is summarized for holotype and paratypes. Characidium cricarense has elongate, fusiform body (Fig. 1). Greatest body depth at dorsal-fin origin. Dorsal profile in lateral view convex from snout to origin of dorsal fin; convex, posteriorly slanted at base of dorsal fin, almost straight between base of dorsal fin and adipose fin; posteriorly slanted at base of adipose fin, almost straight between adipose fin and caudal fin. Ventral profile in lateral view slightly concave between lower lip and base of pectoral fin, slightly straight from pectoral base to anal-fin origin, straight and slightly slanted at base of anal fin, straight below caudal peduncle. Pelvic-fin origin at vertical line about two scales posterior to dorsal-fin origin. Adipose fin at vertical line about two and a half scales posterior to anal-fin origin. Snout directed downwards, dorsally convex in lateral view (Fig. 1a). Mouth subterminal, aligned with or lower to ventral margin of orbit. Posterior tip of maxilla not reaching level of anterior margin of orbit. Orbit oval, slightly elongate along axis from tip of snout to parietal bone; margin of eye free. Nares widely separated; distance between nares larger than distance between posterior naris and eye. Margin of anterior naris expanded, forming circular rim; posterior naris with expanded margin on its anterior-most portion. Parietal branch of supraorbital laterosensory canal present, reaching parietal bone in larger specimens; frontal branch of supraorbital laterosensory canal present. Fontanel reduced, limited anteriorly by frontals, laterally by parietals and posteriorly by supraoccipital bones. Premaxillary teeth 6(3) in single series; teeth decreasing gradually in size posteriorly, unicuspid or tricuspid. An anomalous specimen with premaxillae fused, with 13 teeth in total. Dentary teeth in two rows; outer series of dentary teeth 8(2) or 9(2) unicuspid or triscuspid with small medial and lateral cuspids; teeth decreasing gradually in size posteriorly; inner series of dentary teeth with several tiny conical teeth on edge of replacement tooth trench. Maxillary teeth absent. Ectopterygoid teeth present, in single row, conical, unicuspid. Mesopterygoid teeth absent. Branchiostegal rays 4(1), 5(2) or 6 including one as vestigial (1); 3(1), 4(2) or 4 including one as vestigial (1) attached to anterior ceratohyal. Gill rakers on first arch 11(3) or 12(1). Scales cycloid; parallel radii present on posterior field. Lateral series of scales 35(4), 36(25*), or 37(3), all perforated by lateral-line canal. Scales above lateral line 4(32*). Scales below lateral line 4(32*). Scales around caudal peduncle 14(32*). Pre-dorsal scale series arranged in single, regular row; scales in pre-dorsal series 8(1), 9(7), 10(17), 11(6*), or 12(1). Scales between anus and origin of anal fin 5(5), 6(23*), or 7(4). Isthmus without scales; chest scaled (Fig. 1d). Dorsal-fin rays i,9(1), ii,8(3), ii,9(27*), or ii,10(1). Adipose fin present (32*). Pectoral-fin rays iii,8,i(3), iii,9(4), iii,9,i(15*), iii,10(9), or iii,10,i(1). Pelvic-fin rays i,7,i(23*), or i,8(9). Anal-fin rays i,6(2), i,7(3), ii,6(5), or ii,7(21*); adnate rays on last pterygiophore of anal fin 1(21*), or 2(8). Principal caudal-fin rays i,9,7,i(1) or i,9,8,i(12*). Postcleithrum I absent; and postcleithrum II and postcleithrum III present in pectoral girdle; cleithrum with posteriorly directed process at region immediately below ventral tip of supracleithrum. Precaudal vertebrae 19(2) or 20(6); total vertebrae 33(1), 34(3), 36(3) or 37(1). Supraneurals 4(3), 5(3) or 6(1). Upper procurrent rays 7(1), 8(6) or 9(2); lower procurrent rays 6(7), 7(1) or 8(1). Epurals 3(3). Coloration in alcohol. Background color yellowish (Fig. 1). Black longitudinal stripe about half scale thick extending from tip of snout to base of caudal fin. Body with 8 to 13 triangular bars, wider dorsally, thinner ventrally; bars from opposite sides united across dorsal midline by a corresponding series of dorsal blotches; bars located posteriorly to pelvic fin extending to ventral surface of body. Humeral blotch partially merged into first bar. Dark spot present at base of middle caudal fin rays. All fins mostly hyaline, with scattered chromatophores along rays forming bands of variable intensity. Dorsal fin with three bands; main (intermediate) band dark, not reaching anterior-most margin of fin. In smaller specimens, caudal-fin pigmentation restricted to some scattered chromatophores at outer lobes, ontogenetically developing into conspicuous incomplete B-shaped pattern in larger specimens, formed by a posterior extension of the lateral stripe and diagonal bands across the dorsal and ventral portions of fin. Pectoral, pelvic and anal fins with dark, diffuse distal bands. Color in life. Slightly translucent body, with olive-greenish or light-brownish background color on head and dorsum. Silvery background below lateral stripe. Dark chromatophore patterns as described for specimens preserved in ethanol. Sexual dimorphism. No hooks on fins or other sexually dimorphic features were observed externally on the examined specimens. Molecular delimitation. DNA barcodes based on the amplified 656bp (base pairs) partial sequence of COI mitochondrial gene were generated for a total of 36 specimens of Characidium cricarense (Tab. 1), encompassing specimens from the Jucuruçu basin (4 individuals), Itaúnas basin (6 individuals), São Mateus basin (11 individual), and Doce basin (15 individuals). All samples exhibit less than 2% of genetic divergence, which is the usually accepted upper limit of conspecific similarity (Pereira et al., 2013). Characidium cricarence received the Barcode Index Number (BIN) BOLD:ACI3743 through the BoldSystems automated algorithm (Ratnasingham, Hebert, 2013). The genetic distance of Characidium cricarense from other congeneric species analyzed were 6% divergence from C. alipioi specimens from Macaé (MNLM 3004, MNLM 3007) and São João (MNLM 5462) basins; 11% divergence from C. timbuiense specimen from Reis Magos basin (MNLM 5403); 12% divergence from C. vidali specimen from Guanabara basin (MNLM 2043) (Fig. 2). The specimen used as outgroup, C. litorale from São João basin (MNLM 7660), is 23% divergent from the remaining species in the analysis. Geographical distribution. Characidium cricarense is known from the southern portion of Bahia State, northern portion of Espírito Santo State, and eastern portion of Minas Gerais State, where it is known from the rio Jucuruçu, rio Itanhém-Alcobaça, rio Mucuri, rio Itaúnas, and rio São Mateus drainages, extending to the rio Doce drainage in the central portion of the Espírito Santo State, Brazil (Fig. 3). The rivers from the northern portion of the distribution are within the coastal tablelands of the Barreiras sedimentary formation. These coastal tablelands correspond to a region of mild relief, with elevations usually not surpassing 150 m above sea level, formed by Cenozoic sediments, well-seen along the border between the States of Espírito Santo and Bahia (Sarmento-Soares, Martins-Pinheiro, 2013). On the right bank of the rio Doce, C. cricarense reaches the lower slopes of the Serra de Santa Teresa. According to a global biogeographic regionalization of freshwater systems, this geographic distribution belongs to the Northeastern Mata Atlântica ecoregion (Abell et al., 2008). Ecological notes. Characidium cricarense inhabits lowland stretches of rivers, usually below 200 m above sea level, except in the Mucuri drainage, where it has been found in the upper rio Todos os Santos, above the city of Teófilo Otoni at about 500 m above sea level (G. M. Mattox, pers. comm.), and in the Jucuruçu drainage, in tributaries around the city of Palmópolis at about 300 and 600 m above sea level. Based on our field observations, individuals of this species usually occupy the edge of turbulent, moderately fast flowing rivers and streams (Fig. 4). Specimens aggregate along stretches less than 1.5 m deep, with transparent waters, occupying the waterfalls in rocky areas, and unconsolidated bottom over sandy, pebbles or gravel areas at the edge of the waterfall. Etymology. The name refers to the rio Cricaré, where type locality of this fish is found, and is used as a Latinized geographic adjective. Conservation status. Characidium cricarense occurs in coastal basins from Northeastern Mata Atlântica ecoregion (sensu Abell et al., 2008) along three Brazilian states: Bahia, Espírito Santo and Minas Gerais. The species inhabits turbulent waters in rapids, occupying the rocky areas as well as the unconsolidated bottom near the rapids. Even though a mining disaster occurred in Doce basin, where Characidium cricarense might occur, no specific threats to the species is detected in the whole area of distribution. Consequently, the conservation status of Characidium cricarense may be classified as Least Concern (LC), according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN, 2017).

A new species of Characidium from southeastern Brazil is described based on morphological and molecular evidence from specimens collected between the rio Jucuruçu and rio Doce basins. The new species belongs to a group of species within Characidium with an unscaled area in the isthmus and is distinguished from these species, except C. alipioi, C. fasciatum, C. hasemani, and C. kamakan, by the greater distance (greater than 10% SL) and presence of 5-7 scales between the anus and the anal fin, and presence of 14 series of scales around the caudal peduncle. The species is distinguished from C. alipioi by having 4 series of scales above the lateral line (vs. 5 series) and greater distance between the anus and the anal fin; from C. fasciatum and C. kamakan, by the smaller body depth at the dorsal-fin origin, at the anal-fin origin, and at the caudal peduncle; from C. hasemani, by the short distances between the tip of the snout and the pelvic fin, the tip of the snout and the anal fin, and the tip of the snout and the tip of anal fin. The new species forms a presumably monophyletic group with C. alipioi and C. kamakan. RESUMO Uma nova espécie de Characidium do sudeste do Brasil é descrita com base em evidências morfológicas e moleculares provenientes de exemplares coletados entre as bacias dos rios Jucuruçu e Doce. A nova espécie pertence a um grupo de espécies de Characidium com área desprovida de escamas no ístmo e difere dessas espécies, exceto C. alipioi, C. fasciatum, C. hasemani e C. kamakan, pela grande distância (maior que 10% do comprimento padrão, CP) e presença de 5-7 escamas entre o ânus e a nadadeira anal, e pela presença de 14 séries de escamas em torno do pedúnculo caudal. A espécie difere de C. alipioi pela presença de 4 séries de escamas acima da linha lateral (vs. 5 séries) e maior distância entre o ânus e a nadadeira anal; de C. fasciatum e C. kamakan, pela menor altura do corpo na origem da nadadeira dorsal, na origem da nadadeira anal, e no pedúnculo caudal; de C. hasemani, pela menor distância entre a ponta do focinho e a nadadeira pélvica, a ponta do focinho e a nadadeira anal, e a ponta do focinho e a ponta da nadadeira anal. A nova espécie forma um grupo presumidamente monofilético com C. alipioi e C. kamakan.

Characidium zebra Eigenmann, 1909 (Fig. 6) FIRST RECORD FOR THE MITARAKA. ��� This study. OCCURENCES. ��� S3, S8, S9, S11. SPECIMEN IN COLLECTION. ��� None. DISTRIBUTION IN FRENCH GUIANA. ��� Widespread. ECOLOGY. ��� Observed on sandy bottoms and moderate to high current velocities in both Alama mainstream and tributaries. Lies immobile head directed upstream, waiting for drifting food. Captured using rotenone and observed in underwater inventories., Published as part of S��bastien Brosse, Fr��deric Melki & R��gis Vigouroux, 2019, Fishes of the Mitaraka Mountains (French Guiana), pp. 131-151 in Zoosystema 41 (8) on page 136, DOI: 10.5252/zoosystema2019v41a8, http://zenodo.org/record/2639414

Characidium zebra Eigenmann, 1909 (Fig. 6) FIRST RECORD FOR THE MITARAKA. — This study. OCCURENCES. — S3, S8, S9, S11. SPECIMEN IN COLLECTION. — None. DISTRIBUTION IN FRENCH GUIANA. — Widespread. ECOLOGY. — Observed on sandy bottoms and moderate to high current velocities in both Alama mainstream and tributaries. Lies immobile head directed upstream, waiting for drifting food. Captured using rotenone and observed in underwater inventories.

Genus Characidium Reinhardt, 1867 REMARK An undetermined morphospecies (Characidium sp., [Fig. 5]) is known from the Maroni drainage basin. It is referred as Characidium sp. 2 in Le Bail et al. (2012), but the particular colour pattern of the individuals collected in the Mitaraka might indicate another undetermined species, only known from Mitaraka, which was referred as Characidium sp. 3 by Melki (2016). FIRST RECORD FOR THE MITARAKA. ��� Keith et al. 2006. OCCURENCES. ��� S8, S9. SPECIMENS IN COLLECTION. ��� 1 MNHN (MNHN-IC-2018-0424); 1 Hydreco. ECOLOGY. ��� Observed in median sized streams with sandy bottoms and moderate current velocities. Captured using rotenone and observed in underwater inventories., Published as part of S��bastien Brosse, Fr��deric Melki & R��gis Vigouroux, 2019, Fishes of the Mitaraka Mountains (French Guiana), pp. 131-151 in Zoosystema 41 (8) on page 136, DOI: 10.5252/zoosystema2019v41a8, http://zenodo.org/record/2639414, {"references":["MELKI F. 2016. - Poissons d'eau douce de Guyane: plongee dans les eaux de l'Amazonie francaise. Biotope editions, Meze, 348 p."]}

Genus Characidium Reinhardt, 1867 REMARK An undetermined morphospecies (Characidium sp., [Fig. 5]) is known from the Maroni drainage basin. It is referred as Characidium sp. 2 in Le Bail et al. (2012), but the particular colour pattern of the individuals collected in the Mitaraka might indicate another undetermined species, only known from Mitaraka, which was referred as Characidium sp. 3 by Melki (2016). FIRST RECORD FOR THE MITARAKA. — Keith et al. 2006. OCCURENCES. — S8, S9. SPECIMENS IN COLLECTION. — 1 MNHN (MNHN-IC-2018-0424); 1 Hydreco. ECOLOGY. — Observed in median sized streams with sandy bottoms and moderate current velocities. Captured using rotenone and observed in underwater inventories.

Made available in DSpace on 2022-04-29T08:00:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) B chromosomes are apparently dispensable components found in the genomes of many species that are mainly composed of repetitive DNA sequences. Among the numerous questions concerning B chromosomes, the origin of these elements has been widely studied. To date, supernumerary chromosomes have been identified in approximately 60 species of fish, including species of the genus Characidium Reinhardt, 1867 in which these elements appear to have independently originated. In this study, we used molecular cytogenetic techniques to investigate the origin of B chromosomes in a population of Characidium alipioi Travassos, 1955 and determine their relationship with the extra chromosomes of other species of the genus. The results showed that the B chromosomes of C. alipioi had an intraspecific origin, apparently originated independently in relation to the B chromosomes of C. gomesi Travassos, 1956 C. pterostictum Gomes, 1947 and C. oiticicai Travassos, 1967, since they do not share specific DNA sequences, as well as their possible ancestral chromosomes and belong to different phylogenetic clades. The shared sequences between the supernumerary chromosomes and the autosommal sm pair indicate the origin of these chromosomes. Departamento de Morfologia Instituto de Biociências Universidade Estadual Paulista, Distrito de Rubião Junior, s/n Departamento de Morfologia Instituto de Biociências Universidade Estadual Paulista, Distrito de Rubião Junior, s/n