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Petersius conserialis Hilgendorf, 1894 Figures 1–4, table 1 Petersius conserialis Hilgendorf, 1894: 173 [original type locality: “ Kinganiflusse in Deutsch-Ostafrika ” (= Kingani River in German East Africa), Tanzania]. Pfeffer, 1896: 44 [short description]. Boulenger, 1909: 233–234 [morphometrics; meristic, data from types]. Myers, 1929: 5 [key to genera; notes; restriction of genus Petersius]. Hoedeman, 1951: 5 [key to genera and species]. Poll, 1967: 28 [description; morphometrics; meristic data; distribution; figures of specimen and dentition]. Matthes, 1975: 171 [key to freshwater fishes; Tanzania]. Géry, 1977: 50 [remarks]. Paugy, 1984: 140–183 [synonym list, genus, species] Ibarra and Stewart, 1987: 64 [catalog of types, FMNH]. Géry, 1995: 40 [key, comments on cranial fontanel]. Murray and Stewart, 2002: 1892 [osteology; phylogeny]. Zanata and Vari, 2005: 100, 117 [character description; morphological phylogeny]. Zarske, 2011: 64 [catalog of types; description of ZMB types of Petersius]. Dueck, 2020: 55–99 [ontogeny; osteology]. DIAGNOSIS: As for Petersius. DESCRIPTION: Morphometric data summarized in table 1. Medium-sized species (maximum observed size 137.0 mm SL), with general appearance as in figure 1. Body moderately elongate, dorsal head profile concave from snout to supraoccipital, convex to dorsal-fin origin, slightly convex along dorsal-fin base to adipose fin, and slightly concave from adipose fin to origin of caudal fin. Ventral body profile convex from anterior tip of lower jaw to end of anal-fin base, slightly concave to caudal fin. Caudal peduncle longer than deep. Adipose eyelid weakly developed, restricted to thin band immediately anterior to orbit. Snout shorter than orbital diameter. Nostrils closely aligned, anterior nostril circular, posterior nostril semi lunate. Lower jaw slightly prognathous, mouth superior, horizontally aligned with dorsal margin of pupil. Teeth in both jaws pluricuspid and incisiform with reduced buccal shelves. Dentary with 4* (21) outer row teeth, median tooth frequently with five cusps, second and third teeth with seven cusps, fourth tooth markedly smaller than adjacent tooth. Inner row of conical teeth proximate to dentary symphysis absent in all specimens (fig. 2E). Contralateral premaxillae separated by anteromedial process of mesethmoid and without interdigitations connecting medial surfaces (fig. 3C). Premaxilla with two rows of pluricuspid teeth. Outer premaxillary row usually with 2* (13) tricuspid teeth, but number variable 0 (2), 1 (3), or 3 (3), even variable contralaterally in a few specimens. Regardless of number, outer row premaxillary teeth always implanted above and between inner row teeth (i.e., alternating). Inner premaxillary row with 4* (21) teeth, each with 7 cusps. Series of cutting-edge cusps of inner row premaxillary teeth located along buccal (vs. lingual) face of each tooth (fig. 3C, see also Discussion). Four replacement teeth in both premaxillary and dentary replacement trenches. Maxilla edentulous, ascending process elongate and pointed, without terminal bifurcation (fig. 2F). Distal margin of dorsal fin straight, second unbranched and first branched fin rays longest. Dorsal-fin rays ii,8* (21), first unbranched ray very short. Distal margin of pectoral fin straight or slightly rounded. Adpressed pectoral fin reaching or surpassing pelvic-fin origin. Pectoralfin rays ii,13 (10), ii,14 (8), or ii,15* (3). Pelvic fin pointed, adpressed pelvic fin reaching two to four scales short of anal-fin origin. Pelvic-fin rays ii,7 (1), ii,8 (6), ii,9* (13), or ii,10 (1). Caudal fin forked. Adipose fin present, tall with narrow base. Anal fin emarginate, anteriormost branched rays more than twice length of ultimate ray. Anal-fin rays iii,18* (9), iii,19 (11), or iii,20 (1), first unbranched ray very short. Lateral line scales from supracleithrum to hypural joint 30 (3), 31* (6), 32 (5), or 33 (7). Anteriormost 6 scales of lateral line descending steeply to below midlateral line. Last 3–4 pored scales slightly ascending to midlateral body plane. Scales posterior to hypural joint 2 (10) or 3* (11). Scales in transverse series from lateral line to dorsal-fin origin 6.5 (9) or 7.5* (12). Scales in transverse series from lateral line to pelvic-fin origin 2* (10) or 2.5 (11). Middorsal series from supraoccipital tip to dorsal-fin origin 13 (1), 14 (8), 15* (8), 16 (2), or 17 (1). Circumpeduncular scales 10* (20) or 11 (1). Axial scale present, extending over basal third of pelvic fin. First gill arch with 11* (20) or 12 (1) epibranchial rakers and 18 (1), 19 (1), 20* (6), 21 (12), or 23 (1) rakers on ceratobranchial and hypobranchial arches. Total vertebrae 36 (1) or 37 (21). Supraneurals 8 (12), first supraneural associated with fourth vertebra. ADDITIONAL OSTEOLOGICAL FEATURES: Supraoccipital distinctively shaped with steep anterodorsal convexity at junction of parietals and supraoccipital followed by dorsomedial concavity on surface of the crest (fig. 2A). Three pairs of posttemporal fossae present (fig. 2 A, B). Median posttemporal fossae located entirely within epioccipital. Dorsal posttemporal fossae (bounded by the supraoccipital, parietals, and epioccipitals) somewhat smaller than ventral posttemporal fossae (bounded by the epioccipitals and pterotics). Exoccipital foramen well developed. Dorsomedial cranial fontanel present, size correlated with developmental stage. In juveniles smaller than 60 mm SL, fontanel extends anteriorly from posterior region of frontal to anterior margin of supraoccipital. In larger specimens, fontanel is restricted to a small, ovoid opening extending just in front of frontoparietal ridge to anterior margin of supraoccipital (fig. 2C, G). Circumorbital series complete, in adults forming an uninterrupted ring around orbit, in juveniles (ca. 40–60 mm SL) supraorbital separated from 6th infraorbital by wide gap (fig. 2D, H). Supraorbital elongate, slightly sigmoid, and without ventral process. Syntype FMNH 54287 with supraorbital segmented into two elements (fig. 2D). Anterior element in contact with antorbital, posterior element contacts 6th infraorbital. All other examined specimens with a single ossification of supraorbital. Whether a bipartite supraorbital represents an autapomorphy of an isolated lineage from Ruvu River or is an individual anomaly cannot be determined without detailed examination of remaining syntypes. Second infraorbital with a pronounced, sigmoid-shaped process on the dorsal margin (fig. 2D, H see also Discussion). COLORATION: In preservation, overall body coloration brownish yellow, darker dorsally than ventrally, often with overlay of silver iridescence (fig. 1). Small, vertically elongated humeral blotch of pigmentation around fourth and fifth scale of midlateral surface of body, faint in most specimens but more evident in larger individuals. Faint deep-lying longitudinal stripe along midlateral surface from supracleithrum to anterior margin of caudal peduncle. Posterior region of caudal peduncle with blotch of dark pigmentation, circular to ovoid in shape extending to proximal margin of middle caudal-fin rays. Distal caudal-fin lobes with dark margins. Adipose fin outlined by small dark chromatophores, more so on dorsal margin. In life overall body coloration iridescent silver, darker dorsally (fig. 4). Humeral and caudal blotch visible but overlain by silver iridescence. Dorsal, caudal, and anal fins yellowish to dark orange, distal margin of caudal fin darker. Adipose fin yellowish. Pectoral and pelvic fins hyaline; first unbranched pectoral-fin ray slightly darker. SEXUAL DIMORPHISM: Specimen FMNH 54287 was the single male analyzed, clearly identified by the pronounced sexual dimorphism typical of many alestids. The specimen has the fifth through ninth rays of the anal fin expanded and forming a distinct median anal-fin lobe (fig. 1A). Females have straight-edged anal fin with no median lobe (figs. 1B, 4). ECOLOGY: Petersius conserialis has been collected in sandy river courses and floodplain lakes with bushy shorelines with forested or grassy margins. The species was found recently (2018) in a seasonally flooded area of the Rufiji River in shallow water with submerged vegetation (Fraser Gear, personal commun.). Petersius conserialis appears to be endemic to lowland regions, with the highest elevation point at Mkalinzu sands of the Rufiji River at approximately 95–100 m asl (CMN-FI 1981-0174.4). The lowest altitudinal record (5 m asl) is at the type locality of Mtoni Fort approximately 10 km from the Ruvu River mouth in the Indian Ocean. The alestids Alestes stuhlmannii, Brycinus affinis, B. imberi, B. lateralis, Hemigrammopetersius barnardi, and Hydrocynus vittatus were collected in sympatry in the Rufiji River basin (CMNFI records; www.fishnet2.net). DISTRIBUTION AND CONSERVATION: Hilgendorf (1894) described Petersius conserialis based on five specimens collected in eastern Tanzania. The original description mentioned “Kinganiflusse in Deutsch-Ostrafrika,” and subsequent authors indicated the type locality as the Kingani River at Dunda (Boulenger, 1909; Poll, 1967; Zarske, 2011). The Kingani River is an alternative name for the southern Ruvu River, with annotations of Stuhmann’s 1890 expedition indicating Dunda near the current Mtoni Fort, west of Bagamoyo, eastern Tanzania (Turner et al., 2021). Thus, we herein consider the type locality of Petersius conserialis as the Ruvu River near Mtoni Fort, approximately 06° 28′ 04.8″S 38° 50′ 31.2″E, Magomeni, Tanzania. Petersius conserialis is seemingly endemic to lowland regions of the Rufiji and Ruvu rivers in the Pwani Region of eastern Tanzania (fig. 5). Within the Rufiji basin the species has been reported from lakes Lugongwe, Chemchem, Siwandu, Ruwe, Tagalala, and Nzerakera. Although the Ruvu River is apparently in good condition, the Rufiji basin has been affected by loss of hydrological connectivity, sediment trapping, and construction of hydropower dams (Hamerlynck et al., 2011; Duvail et al., 2014), which are likely to impact some populations of P. conserialis. TAXONOMIC REMARKS: Following the ICZN Recommendation 74G, lectotypes should not be designated for curatorial convenience. Therefore, we do not designate lectotype and paralectotypes keeping the syntype series unaltered. Noteworthy, one of the syntypes from ZMB 13535 was sent to Carnegie Museum in 1910, and posteriorly to FMNH 54287. MATERIALS EXAMINED: Petersius conserialis, all from Pwani Region, Tanzania: FMNH 54287, syntype of Petersius conserialis, 99.0 mm SL, Kingani at Dunda, Stuhlmann (approximate locality: Ruvu River, Magomeni, 06° 28′ 04.8″S 38° 50′ 31.2″E), 1µCT scan. – CMN-FI 1981-0177.4, 9, 37.0–49.4 mm SL, Lake Siwandu (Nzerakera), northwest corner, internal delta region of upper Rufiji River floodplain, Mwaseni, 7° 40′ 00″S 38° 07′ 00″E, 17 Jul 1979, Hopson et al., 1µCT scan. – CMN-FI 1981-0194.4, 1, 55.0 mm SL, Rufiji River, north shore, at Ndundu ferry landing, Ikwiriri, 08° 02′ 00″S 39° 02′ 00″E, 31 Jul 1979, Hopson et al. – CMN-FI 1981-0196.7, 6, 51.1–70.0 mm SL, Rufiji River, south bank near Utete, muddy creek below Rubada camp and courthouse, Utete, 07° 58′ 00″S 38° 47′ 00″E, 01 Aug 1979, Hopson et al., 1µCT scan. – CMN-FI 1981-0201.1, 4, 106.0–137.0 mm SL, Lake Ruwe, 2 km southeast of Mkongo, south shore, northern Rufiji River floodplain, Mkongo, 07° 53′ 00″S 38° 46′ 00″E, 28 Jul 1979, Bernacsek et al. COMPARATIVE MATERIALS EXAMINED: Alestes macrophthalmus: AMNH 217360, Malagarazi River, Tanzania. – AMNH 245441, 1µCT scan, Sangha River at Senga Bato, Republic of Congo. – Alestopeterius dentex: AMNH 226449, 1C&S, Niger River, Benin. – Alestopetersius caudalis: AMNH 263304, Congo River, Boma, Democratic Republic of Congo. – Alestopetersius hilgendorfi: AMNH 244114, 1µCT scan, Yenge River at Boyenga, Democratic Republic of Congo. – Arnoldichthys spilopterus: AMNH 233398, Lower Niger River, Nigeria. – AMNH 216017, 1µCT scan, New Calabar River, Nigeria. – Bathyaethiops atercrinis: AMNH 253502, 2C&S, 1µCT scan, Lekoumou River, Republic of Congo. – Bathyaethiops greeni: AMNH 252261, Salonga National Park, Democratic Republic of Congo. – Bathyaethiops breuseghemi: AMNH 269023, 1µCT scan, Lulua River, Democratic Republic of Congo. – Brachypetersius altus: AMNH 252504, Kwilu River, Democratic Republic of Congo. – AMNH 259243, 2µCT scan, Mai Ndombe River, Democratic Republic of Congo. – Brachypetersius notospilus: AMNH 253967, 1µCT scan, Lebayi River, Republic of Congo. – Brycinus macrolepidotus: AMNH 239507, 1C&S, Congo River, Brazzaville, Republic of Congo. – AMNH 270775, 1µCT scan, Niger River at Mafou, Guinea. – Brycinus nurse: AMNH 227279, Gambella, Ethiopia. – AMNH 230623, Ouandja River, Central African Republic. – AMNH 215629, 1µCT scan, Bahr El Ghazal, Sudan. – Brycinus taeniurus: AMNH 262981, 2µCT scan Gniabale River, Gabon. – Bryconaethiops microstoma: AMNH 238290, 2C&S, Malebo Pool, Brazzaville, Republic of Congo. – AMNH 263324, Boma, Congo River, Democratic Republic of Congo. – AMNH 253823, 1µCT scan, Kwilu River, Democratic Republic of Congo. – Bryconaethiops boulengeri: AMNH 240415, 1µCT scan, Odzala National Forest, Republic of Congo. – Bryconalestes longipinnis: AMNH 258383, Noumbi River, Republic of Congo. – AMNH 59626, 1µCT scan, Gola north forest reserve, Sierra Leone. – Bryconalestes. tholloni: AMNH 253925, 1 µCT scan, Kouilou-Niari at Loudima, Republic of Congo. – Clupeocharax schoutedeni: AMNH, 242487, 1µCT scan, Lac Ndekengelo, Bandudu, Democratic Republic of Congo. – AMNH 242485, 1µCT scan, Lac Ikenge, Democratic Republic of Congo. – Hemigrammopetersius barnardi: AMNH 50825, Tanzania. – Hydrocynus forskahlii: AMNH 238308, Kasai River, Bandundu, Democratic Republic of Congo. – AMNH 238305, 1µCT scan, Kasai River, Democratic Republic of Congo. – Hydrocynus vittatus: AMNH 238297, 1C&S, Fimi River, Bandundu, Democratic Republic of Congo. – Ladigesia roloffi: AMNH 50886, Sierra Leone. – AMNH 233394, 2µCT scan, Aquarium material. – Lepidarchus adonis: AMNH 261317, 2µCT scan, Guinea. – Micralestes humilis: AMNH 245464, Lengoue River, Sangha, Republic of the Congo. – AMNH 240814, 1µCT scan, Luilaka River, Democratic Republic of Congo,. – M. holargyreus: AMNH 263359, 1µCT scan, Congo River at Boma, Democratic Republic of Congo. – M. pabrensis: AMNH 57427, 2C&S, Volta River, Ghana. – AMNH 50831, 2µCT scan, no locality data. – Nannopetersius ansorgii: AMNH 258095, Kouilou, Republic of the Congo. – AMNH 263093, 2µCT scan, Lake Tchibanji, Republic of Congo. – Nannopetersius lamberti: AMNH 238370, 1µCT scan, Foulakari River, Republic of Congo. – Phenacogrammus aurantiacus: AMNH 274780, 2µCT scan, Ndzaa River, Democratic Republic of Congo. – Phenocogrammus concolor: AMNH 276321, 2µCT scan, Ndzaa River, Democratic Republic of Congo. – Phenacogrammus deheyni: AMNH 252208, 1µCT scan, Bionga Bionga, Democratic Republic of Congo. – Phenacogrammus flexus: AMNH 276320, 2µCT scan, Ndzaa River, Democratic Republic of Congo. – Phenacogrammus interruptus: AMNH 239467, 2C&S, Congo River, Brazzaville, Republic of the Congo. – AMNH 256217, Kwilu River, Democratic Republic of Congo. – AMNH 274784, 2µCT scan, Lomomo River, Democratic Republic of Congo. – Phenacogrammus major: AMNH 236514, 1µCT scan, Pont So’o, Cameroon. – Phenacogrammus polli: AMNH 240818, 1C&S, Salonga National Park, Democratic Republic of Congo. – AMNH 240816, 1µCT scan, Luilaka River, Democratic Republic of Congo. – Phenacogrammus urotaenia: AMNH 253971, 2µCT scan, Lebayi River, Republic of Congo. – Rhabdalestes aeratis: AMNH 242479, 2µCT scan, Lac Besako, Democratic Republic of Congo. – Rhabdalestes septentrionalis: AMNH 275205, Kodiwol, Gaoual, Guinea. – AMNH 254042, 1µCT scan, Liberia. – Rhabdalestes yokai: AMNH 274862, 2µCT scan, Kouyou River, Republic of Congo. – Tricuspidalestes caeruleus: AMNH 252193, 1µCT scan, Ta’Simon a Bouagui, Democratic Republic of Congo., Published as part of Melo, Bruno F. & Stiassny, Melanie L. J., 2022, Systematic review and cranial osteology of Petersius with redescription of P. conserialis (Teleostei: Alestidae) from the Rufiji and Ruvu rivers of Tanzania, pp. 1-16 in American Museum Novitates 2022 (3992) on pages 4-11, DOI: 10.1206/3992.1, http://zenodo.org/record/7399556, {"references":["Hilgendorf, F. M. 1894. Eine neue Characinidengattung, Petersius, aus dem Kinganiflusse in DeutschOstafrika, und sprach uber die sonstigen von Dr. Stuhlmann dort gesammelten Fische. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1894: 172 - 173.","Pfeffer, G. 1896. Die Thierwelt Ost-Afrikas und der Nachbargebiete. Lieferung V. Die Fische Ost-Afrikas 3: 1 - 72.","Boulenger, G. A. 1909. Catalogue of the fresh-water fishes of Africa in the British Museum (Natural History). London: Taylor and Francis.","Myers, G. S. 1929. Cranial differences in the African characin fishes of the genera Alestes and Brycinus, with notes on the arrangement of related genera. American Museum Novitates 342: 1 - 7.","Hoedeman, J. 1951. Studies on African characid fishes I. The tribe Alestidi (I). Beaufortia 1: 1 - 8.","Poll, M. 1967. Revision des Characidae nains Africans. Annales, Musee Royal de l'Afrique Centrale 162: 1 - 158.","Matthes, H. 1975. A key to the families and genera of freshwater fishes of Tanzania. African Journal of Tropical Hydrobiology and Fisheries 4: 166 - 183.","Gery, J. 1977. Characoids of the world. Neptune City, FL: TFH Publications.","Paugy, D. 1984. Characidae. In J. Daget, J. - P. Gosse, and D. F. E. Thys van den Audenaerde (coordinators), Check-list of the freshwater fishes of Africa (CLOFFA): vol. 1: 140 - 183. Paris: ORSTOM.","Ibarra, M. and D. J. Stewart. 1987. Catalogue of type specimens of recent fishes in Field Museum of Natural History. Fieldiana Zoology 35: 1 - 112.","Gery, J. 1995. Description of new or poorly known Alestinae (Teleostei: Characiformes: Alestidae) from Africa, with a note on the generic concept in the Alestinae. Aqua Journal of Ichthyology and Aquatic Biology 1: 37 - 63.","Murray, A. M., and K. M. Stewart. 2002. Phylogenetic relationships of the African genera Alestes and Brycinus (Teleostei, Characiformes, Alestidae). Canadian Journal of Zoology 80: 1887 - 1899.","Zanata, A. M., and R. P. Vari. 2005. The family Alestidae (Ostariophysi, Characiformes): a phylogenetic analysis of a trans-Atlantic clade. Zoological Journal of the Linnean Society 145: 1 - 144.","Zarske, A. 2011. The type of material of Characiformes of the Museum of Natural History to Berlin. Part 1 (3), introduction and African taxa (Teleostei: Ostariophysi: Characiformes: Hepsetidae, Alestidae, Citharinidae, Distichodontidae). Vertebrate Zoology 61 (1): 47 - 89.","Dueck, M. 2020. Miniaturization in Alestidae (Ostariophysi: Characiformes). University of Alberta, Department of Biological Sciences, Master's thesis.","Turner, G., B. P. Ngatunga and M. J. Genner. 2021. Astatotilapia species (Teleostei, Cichlidae) from Malawi, Mozambique and Tanzania, excluding the basin of Lake Victoria. EcoEvoRxiv preprints [10.32942 / osf. io / eu 6 rx].","Hamerlynck, O., et al. 2011. To connect or not to connect? Floods, fisheries and livelihoods in the Lower Rufiji floodplain lakes, Tanzania. Hydrological Sciences Journal 56: 1436 - 1451.","Duvail, S., et al. 2014. Jointly thinking the post-dam future: exchange of local and scientific knowledge on the lakes of the Lower Rufiji, Tanzania. Hydrological Sciences Journal 59: 713 - 730."]}

Petersius Hilgendorf, 1894 TYPE SPECIES: Petersius conserialis Hilgendorf, 1894. Type by monotypy. DIAGNOSIS: Petersius is diagnosed by a unique cuspidation pattern of the inner row premaxillary dentition with the cusps of the cutting-edge oriented buccally (vs. lingually oriented in all other alestids), and the possession of a distinctively shaped margin of the supraoccipital with a steep anterodorsal convexity at the junction of the parietals followed by a dorsomedial concavity on the surface of the supraoccipital. DESCRIPTION. Corresponds to the description of the type species Petersius conserialis Hilgendorf, 1894. ETYMOLOGY. In naming Petersius Hilgendorf (1894) honored the naturalist and curator Wilhelm C.H. Peters of the Museum für Naturkunde, Berlin., Published as part of Melo, Bruno F. & Stiassny, Melanie L. J., 2022, Systematic review and cranial osteology of Petersius with redescription of P. conserialis (Teleostei: Alestidae) from the Rufiji and Ruvu rivers of Tanzania, pp. 1-16 in American Museum Novitates 2022 (3992) on page 3, DOI: 10.1206/3992.1, http://zenodo.org/record/7399556, {"references":["Hilgendorf, F. M. 1894. Eine neue Characinidengattung, Petersius, aus dem Kinganiflusse in DeutschOstafrika, und sprach uber die sonstigen von Dr. Stuhlmann dort gesammelten Fische. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1894: 172 - 173."]}

Melo, Bruno F., Stiassny, Melanie L.J. (2022): Systematic review and cranial osteology of Petersius with redescription of P. conserialis (Teleostei: Alestidae) from the Rufiji and Ruvu rivers of Tanzania. American Museum Novitates 2022 (3992): 1-16, DOI: 10.1206/3992.1, URL: https://bioone.org/journals/american-museum-novitates/volume-2022/issue-3992/3992.1/Systematic-Review-and-Cranial-Osteology-of-Petersius-with-Redescription-of/10.1206/3992.1.full

Bathyaethiops baka, new species Dwarf Moon Tetra (Figs. 1���2; Tables 1���2) Type material. Holotype: ZSM 43939, 24.1 mm SL, male; Cameroon, Moloundou province: Ngoko River between Ch��te de Cholet and Ch��te de Nki (N 02�� 19 ��� 10 ������, E 14 �� 28 ��� 15 ������); coll: J. Schwarzer & T. Moritz, 10.02. 2008. Paratypes (n= 15): DMM IE/9789, 2 specimens, 20.5���23.2 mm SL, same data as holotype; ZSM 38450, 1 specimen, 23.0 mm SL, same data as holotype; AMNH 265019, 3 specimens, 19.8���21.2 mm SL, Cameroon, Moloundou province: Ngoko River below Ch��te de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; ZSM 43940, 3 specimens, 20.3���21.6 mm SL, Cameroon, Moloundou province: Ngoko River below Ch��te de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; ZSM 38454, 1 specimen, 22.1 mm SL, Cameroon, Moloundou province: Ngoko River at Ndongo (N 02��06��� 40 ������, E 14 �� 52 ��� 42 ������); coll. J. Schwarzer & T. Moritz, 04.02.2008; MRAC B 5 -023- P-0004-0006, 3 specimens, 21.5���23.7 mm SL Cameroon, Moloundou province: Ngoko River at Ndongo (N 02��06��� 40 ������, E 14 �� 52 ��� 42 ������); coll. J. Schwarzer & T. Moritz, 05.02.2008; ZSM 43941, 2 specimens, 23.3���24.4 mm SL, Cameroon, Moloundou province: Ngoko River at Ndongo (N 02��06��� 40 ������, E 14 �� 52 ��� 42 ������); coll. J. Schwarzer & T. Moritz, 0 5.02. 2008. Additional material. ZSM 38453, 6 specimens, same data as holotype; ZSM 38456, 3 specimens, Cameroon, Moloundou province: Ngoko River at Ndongo; coll. J. Schwarzer & T. Moritz, 0 3.02. 2008 ZSM 43942, 6 specimens, Cameroon, Moloundou province: Ngoko River at Ndongo; coll. J. Schwarzer & T. Moritz, 05.02.2008; ZSM 43943, 15 specimens, Cameroon, Moloundou province: Ngoko River at Ndongo; coll. J. Schwarzer & T. Moritz, 08.02.2008; ZSM 43944, 8 specimens, Cameroon, Moloundou province: Ngoko River below Ch��te de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; DMM IE/9792, 1 c&s, Cameroon, Moloundou province: Ngoko River below Ch��te de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; Differential diagnosis. Distinguished from all congeners by an incomplete squamation with the scale cover variably reduced to no pre-dorsal scales, usually no scales on caudal peduncle, and usually a scale-free patch on middle flank at about level of pelvic-fin origin. Furthermore distinguished by a unique color pattern, i.e., a combination of a humeral spot of about pupil-size and the absence of dark vertical bars along midlateral flanks. Difficult to distinguish from juvenile B. caudomaculatus, from which the new species differs by the (usually) absence of unicuspid teeth in the second row of lower jaws (vs. presence), and (usually) the absent or rudimentary supraneural between two neural spines directly in front of the first dorsal fin pterygiophore (vs. well developed). Description. Based on holotype and 15 paratypes. For general appearance refer to Figs. 1 and 2. Measurements and meristics summarized in Tables 1 and 2. A comparatively small species, maximum size 24.4 mm SL. Body laterally compressed, slightly elevated. Dorsal fin originating midway along body; pelvic fins originating slightly in front of dorsal fin; anal fin originating approximately at level of end of dorsal-fin base; adipose fin originating at level of caudal end of anal-fin base, positioned closer to caudal than to dorsal fin. Scale cover variably reduced: no pre-dorsal scales; usually no scales on caudal peduncle; usually a scale free patch on middle of flank at level of pelvic-fin origin. Number of pored scales in lateral line variable (0���9); lateral line never complete. Premaxilla with two teeth in outer row, each with three major and two minor cusps and four teeth in inner row with four cusps in the first, six cusps in the second and third, and seven cusps in the last tooth (Fig. 3). Dentary with four teeth in outer row, each with six cusps, except the last with only five cusps (Fig. 3); an inner single monocuspid tooth usually absent (where it was possible to check this character without damaging the specimen only 2 out of 12 had inner monocuspid teeth). Anal fin convex in males (Figs 1, 2), but almost straight in females and juveniles. Pectoral fin with 12 rays with dorsalmost and ventralmost rays unbranched. Pelvic fin with 8 rays, with first and last rays unbranched. 2 hypurals in lower lobe and 4 hypurals in upper lobe; 3 epurals; small cartilage present in front of anterior-most haemal spine. Other fin and vertebrae counts presented in Table 2. Supraneural directly in front of first pterygiophore of dorsal fin reduced in size or absent. This species seems to be a dwarf species within the genus Bathyaethiops. Juveniles of this species and juvenile sympatric B. caudomaculatus are difficult to differentiate. Coloration. In life (Fig. 2) body pale translucent; dorsal, adipose and caudal fin bright red; pelvic and anal fin light orange to yellow; pectoral fin yellowish; upper quarter of iris orange; caudal peduncle on its dorsal and ventral margin slightly red. A prominent humeral spot the size of the pupil or larger, and a slightly larger dark spot on the caudal peduncle; the latter is bisected by a dark line along the midlateral line starting slightly in front of dorsal-fin origin and terminating just distal to the caudal peduncle spot; never any vertical stripes or barring along the midlateral line. Few melanophores in mid-dorsal line along the back starting on lower jaw and reaching caudal peduncle; thin line of melanophores along anal-fin base; often an elevated line of melanophores proximal to the anal-fin base; a dark bar at the end of the caudal peduncle. Melanophores densely set on posterior dorsal half of head. In general, contrast and coloration more pronounced in mature males. In preservative (Fig. 1) pale whitish to light brown; red, orange and yellow coloration absent. Melanophore pattern as in preserved specimens, but spot on the caudal peduncle less pronounced and smaller, i.e. not reaching the anal fin base; humeral spot more intensively colored but of same size. Etymology. Named after the Baka people, the native hunter-gatherer tribe in Southeastern Cameroon, where the species was found. A noun in aposition. Distribution and habitat. The species is so far known from several localities along the Ngoko River, from below the Nki falls to the village of Ndongo (Fig. 4���5). The Ngoko, called Dja River above the Nki falls, is a tributary to the Sangha River, a major northern tributary of the Congo River. All specimens were caught in the main river channel, usually in or close to riparian vegetation over a substrate of fine particles and organic material. Water parameters from the Ngoko River at Ndongo taken on 0 4.02. 2008 were: pH 7.08; conductivity 23 ��S; temperature 27.5 ��C. Meristic character Holotype Paratypes (N= 15) Simple dorsal fin rays 3 2 (15) Branched dorsal fin rays 8 8 (15) Simple anal fin rays 3 3 (15) Branched anal fin rays 21 18 (1); 19 (5); 20 (7); 21 (1); - (1) Upper procurrent caudal fin rays 9 5 (1); 6 (5); 7 (5); 8 (4) Upper principal caudal fin rays 10 10 (13); 11 (2) Lower principal caudal fin rays 9 9 (14); 10 (1) Lower procurrent caudal fin rays 7 5 (4); 6 (10); 7 (1) Vertebrae 37 35 (1); 36 (11); 37 (3) Abdominal vertebrae 16 16 (4); 17 (10); 18 (1) Caudal vertebrae 21 19 (10); 20 (5) Dorsal fin inserting after vertebra 10 10 (10); 11 (5) Anal fin inserting after vertebra 17 17 (10); 18 (5) Supraneurals 6 6 (7); 7 (7); 8 (1); Pored scales in LL* 5 0 (1); 5 (6); 6 (5); 7 (2); 9 (1), Published as part of Moritz, Timo & Schliewen, Ulrich K., 2016, Description of two new Bathyaethiops species (Teleostei: Alestidae) from the Congo basin, pp. 476-490 in Zootaxa 4117 (4) on pages 477-481, DOI: 10.11646/zootaxa.4117.4.2, http://zenodo.org/record/257926

Key to the species presently recognized in the genus Bathyaethiops 1 4.5 scale rows between lateral line and dorsal fin; 2.5 scale rows between lateral line and ventral fins; squamation always complete................................................................................... B. atercrinis - 6.5 or more scales between lateral line and dorsal fin; 3.5 scale rows or more between lateral line and ventral fins; or squamation incomplete................................................................................. 2 2 A spot free of any melanophores (red in life, white in preserved specimens) directly in front of dorsal fin........ B. flammeus - No such spot......................................................................................... 3 3 Humeral spot only slightly smaller as the dark spot on the caudal peduncle; squamation on flanks incomplete; lateral line incomplete...................................................................................... B. baka - Humeral spot significantly smaller than the dark spot on the caudal peduncle; squamation on flanks complete; lateral line complete or incomplete................................................................................. 4 4 Dark spot on the caudal peduncle more or less rectangular and horizontally elongated hardly extending above midlateral level.......................................................................................... B. breuseghemi - Dark spot on the caudal peduncle round or irregular with one third or more positioned above midlateral level............. 5 5 6.5 scales between lateral line and dorsal fin; humeral spot smaller than ½ of the pupil (or even absent); caudal peduncle spot horizontally elongated with a more or less irregular outline....................................... B. caudomaculatus - (7.5) 8.5 scales between lateral line and dorsal fin; humeral spot ¾ of the pupil or more; caudal peduncle spot about as high as wide and more or less rounded..................................................................... B. greeni

Moritz, Timo, Schliewen, Ulrich K. (2016): Description of two new Bathyaethiops species (Teleostei: Alestidae) from the Congo basin. Zootaxa 4117 (4): 476-490, DOI: http://doi.org/10.11646/zootaxa.4117.4.2

Key to the species presently recognized in the genus Bathyaethiops 1 4.5 scale rows between lateral line and dorsal fin; 2.5 scale rows between lateral line and ventral fins; squamation always complete................................................................................... B. atercrinis - 6.5 or more scales between lateral line and dorsal fin; 3.5 scale rows or more between lateral line and ventral fins; or squamation incomplete................................................................................. 2 2 A spot free of any melanophores (red in life, white in preserved specimens) directly in front of dorsal fin........ B. flammeus - No such spot......................................................................................... 3 3 Humeral spot only slightly smaller as the dark spot on the caudal peduncle; squamation on flanks incomplete; lateral line incomplete...................................................................................... B. baka - Humeral spot significantly smaller than the dark spot on the caudal peduncle; squamation on flanks complete; lateral line complete or incomplete................................................................................. 4 4 Dark spot on the caudal peduncle more or less rectangular and horizontally elongated hardly extending above midlateral level.......................................................................................... B. breuseghemi - Dark spot on the caudal peduncle round or irregular with one third or more positioned above midlateral level............. 5 5 6.5 scales between lateral line and dorsal fin; humeral spot smaller than �� of the pupil (or even absent); caudal peduncle spot horizontally elongated with a more or less irregular outline....................................... B. caudomaculatus - (7.5) 8.5 scales between lateral line and dorsal fin; humeral spot �� of the pupil or more; caudal peduncle spot about as high as wide and more or less rounded..................................................................... B. greeni, Published as part of Moritz, Timo & Schliewen, Ulrich K., 2016, Description of two new Bathyaethiops species (Teleostei: Alestidae) from the Congo basin, pp. 476-490 in Zootaxa 4117 (4) on pages 488-489, DOI: 10.11646/zootaxa.4117.4.2, http://zenodo.org/record/257926

Bathyaethiops flammeus, new species Red-back Moon Tetra (Figs. 6���8, Tables 3���4) Type material. Holotype: ZSM 43945, 39.1 mm SL, female; Democratic Republic of Congo, Province Orientale: Bak��r�� river at Yambula-Bakere (N 01�� 42 ��� 41 ������, E 23 �� 43 ��� 24 ������); coll: U. Schliewen, J. Schwarzer & P.B. Mongindo, 19.07. 2009. Paratypes (n= 22): ZSM 39295, 13 specimens, 24.5���39.9 mm SL, same data as holotype; AMNH 265018, 3 specimens, 29.4���32.3 mm SL, same data as holotype; DMM IE/9790, 2 specimens, 29.9���31.8 mm SL, same data as holotype; DMM IE/9791, 1 c&s, 34.1 mm SL, same data as holotype; MRAC B 5 -023-P-0001-0003, 3 specimens, 30.5���36.3 mm SL, same data as holotype. Additional material. MRAC 177882 ���889, 8 specimens, 26.7-42.3 mm SL; Democratic Republic of Congo, Boende (S 0�� 14 ���, E 20 �� 50 ���); coll. P. Brichard, 1969; ZSM A- 0649, 3 specimens, 25.2���27.8 mm SL; Democratic Republic of Congo, Ruki River (= lower Tshuapa River), Eala (close to Mbandaka); coll. Dr. Kiss, 17.11. 1981. Differential diagnosis. Distinguished from all congeners by the presence of a spot lacking melanophores (red in life, white in preservation), located in front of the dorsal fin. Description. Based on holotype and 22 paratypes augmented with data from 11 non-type specimens. For general appearance refer to Figs. 5���7. Measurements are summarized in Tables 3���4 for type and non-type specimens. Body laterally compressed, moderately elevated, maximum size 42 mm SL. Dorsal fin originating at midbody; pelvic fins originating slightly in front of dorsal fin; anal fin originating at level of, or slightly caudal to, end of dorsal-fin base. Scale cover complete; lateral line usually incomplete, but complete in a few specimens; when incomplete, number of pored scales in anterior section variable, 5���16 (5���14 on type locality); sometimes pored scales also present posteriorly after an interruption of varying extent. 7���10 pre-dorsal scales, but without scales immediately in front of dorsal-fin origin. Premaxilla with two teeth in outer row, first with tree and second with five cusps, and four teeth in inner row with four to five cusps on first, seven cusps on second and third and five cusps on last tooth (Fig. 9). Dentary with four teeth in outer row with seven cusps on second, six cusps on first and third, and four cusps on last tooth; an inner single monocuspid tooth close to symphysis present (Fig. 9). Anal fin enlarged and convex in mature males, more or less straight in females and juveniles. Pectoral fin with 11���12 rays; pelvic fin with 9 rays. 2 hypurals in lower lobe and 4 hypurals in upper lobe; 3 epurals; small cartilage present in front of anterior-most haemal spine. Other fin and vertebrae counts presented in Table 4. Supraneural directly in front of the first dorsal pterygiophore well developed or sometimes completely absent (well developed in all specimens from Boende and Eala). Coloration. In life (Fig. 7) body silvery, slightly translucent; anterior half of dorsal fin and the melanophorefree area in front of dorsal fin bright red; rest of dorsal fin, adipose fin and caudal fin grey; pectoral, pelvic and anal fin transparent; anterior distal part of anal fin black marked in males; upper half of adipose fin black in most specimens. A prominent dark humeral spot smaller than pupil and an extensive black blotch on the caudal peduncle; the latter is bisected by a dark line along the horizontal septum starting slightly behind humeral spot and continuing to the end of the caudal peduncle (this line is faint on the caudal peduncle of specimens from Boende); about 9 (7���9 in Boende, 10 in Eala) more or less regular vertical bars along the horizontal line with most bars located dorsally from the level of midbody. A dark line from the lower jaw over along the mid-dorsal line on the back to the end of caudal peduncle dark, with a prominent spot free of any melanophores in front of dorsal-fin base; base of anal fin darkly pigmented, more prominent anteriorly; a prominent dark bar on the end of the caudal peduncle broadened medially (less expressed in specimens from Boende and Eala); distal edge of adipose fin often black or dark grey, rest of fin slightly grey or colourless (black edge in all specimens from Boende; colourless in all specimens from Eala). Melanophores densely set on upper half of skull. Data on life coloration of specimens from Boende and Eala unavailable. Yambula-Bak��r�� Boenđe Eala Merisitic character Holotype Paratypes (N= 22) (N= 8) (N= 3) In preservative (Fig. 6, 8) pale yellow to brownish, all prominent red coloration vanished; the melanophore free spot in front of the dorsal fin appears clear white; upper half of flank darker. Melanophore pattern less pronounced, but better visible as in life specimens; black mid-dorsal line less prominent; black mark along anal-fin base well visible in anterior part as in posterior part, where it is sometimes missing; this line (in contrast to life) not confluent with blotch on caudal peduncle. Etymology. From the Latin flammeus for bright red or burning, referring to the bright red spot on nape in front of dorsal fin. An adjective. Distribution and habitat. Type locality: Bak��r�� River at Yambula-Bak��r��, Province Orientale, Democratic Republic of Congo (Fig. 4), a large blackwater rainforest stream with no aquatic vegetation and sandy soil northwest of Kisangani directly entering the Congo River. Additional specimens were collected in 1969 in the Tshuapa River at Boende, and 1981 from the Ruki River (the name of the lower Tshuapa River after it has united with the Momboyo River) at Eala, both in the Democratic Republic of Congo. For these collections no additional data is available. Remark. The specimens collected at Boende are clearly distinguishable from the type series, e.g., by scale counts. However, because the three specimens from Eala appear somewhat intermediate, e.g. in having 33���34 scales in supposed lateral line (vs. 33���36 in Yambula-Bak��r�� and 36���41 in Boende) 7.5 scales between lateral line and dorsal fin (vs. 6.5 in Yambula-Bak��r�� and 7.5���8.5 in Boende) and 14���16 scales around caudal peduncle (vs. 12 in Yambula-Bak��r�� and 13���18 in Bak��r��), we conservatively interpret these differences as geographical variation and consider these geographically disparate populations as conspecifics rather than being separate species., Published as part of Moritz, Timo & Schliewen, Ulrich K., 2016, Description of two new Bathyaethiops species (Teleostei: Alestidae) from the Congo basin, pp. 476-490 in Zootaxa 4117 (4) on pages 482-487, DOI: 10.11646/zootaxa.4117.4.2, http://zenodo.org/record/257926

Bathyaethiops baka, new species Dwarf Moon Tetra (Figs. 1–2; Tables 1–2) Type material. Holotype: ZSM 43939, 24.1 mm SL, male; Cameroon, Moloundou province: Ngoko River between Chûte de Cholet and Chûte de Nki (N 02° 19 ’ 10 ’’, E 14 ° 28 ’ 15 ’’); coll: J. Schwarzer & T. Moritz, 10.02. 2008. Paratypes (n= 15): DMM IE/9789, 2 specimens, 20.5–23.2 mm SL, same data as holotype; ZSM 38450, 1 specimen, 23.0 mm SL, same data as holotype; AMNH 265019, 3 specimens, 19.8–21.2 mm SL, Cameroon, Moloundou province: Ngoko River below Chûte de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; ZSM 43940, 3 specimens, 20.3–21.6 mm SL, Cameroon, Moloundou province: Ngoko River below Chûte de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; ZSM 38454, 1 specimen, 22.1 mm SL, Cameroon, Moloundou province: Ngoko River at Ndongo (N 02°06’ 40 ’’, E 14 ° 52 ’ 42 ’’); coll. J. Schwarzer & T. Moritz, 04.02.2008; MRAC B 5 -023- P-0004-0006, 3 specimens, 21.5–23.7 mm SL Cameroon, Moloundou province: Ngoko River at Ndongo (N 02°06’ 40 ’’, E 14 ° 52 ’ 42 ’’); coll. J. Schwarzer & T. Moritz, 05.02.2008; ZSM 43941, 2 specimens, 23.3–24.4 mm SL, Cameroon, Moloundou province: Ngoko River at Ndongo (N 02°06’ 40 ’’, E 14 ° 52 ’ 42 ’’); coll. J. Schwarzer & T. Moritz, 0 5.02. 2008. Additional material. ZSM 38453, 6 specimens, same data as holotype; ZSM 38456, 3 specimens, Cameroon, Moloundou province: Ngoko River at Ndongo; coll. J. Schwarzer & T. Moritz, 0 3.02. 2008 ZSM 43942, 6 specimens, Cameroon, Moloundou province: Ngoko River at Ndongo; coll. J. Schwarzer & T. Moritz, 05.02.2008; ZSM 43943, 15 specimens, Cameroon, Moloundou province: Ngoko River at Ndongo; coll. J. Schwarzer & T. Moritz, 08.02.2008; ZSM 43944, 8 specimens, Cameroon, Moloundou province: Ngoko River below Chûte de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; DMM IE/9792, 1 c&s, Cameroon, Moloundou province: Ngoko River below Chûte de Nki; coll. J. Schwarzer & T. Moritz, 09.02.2008; Differential diagnosis. Distinguished from all congeners by an incomplete squamation with the scale cover variably reduced to no pre-dorsal scales, usually no scales on caudal peduncle, and usually a scale-free patch on middle flank at about level of pelvic-fin origin. Furthermore distinguished by a unique color pattern, i.e., a combination of a humeral spot of about pupil-size and the absence of dark vertical bars along midlateral flanks. Difficult to distinguish from juvenile B. caudomaculatus, from which the new species differs by the (usually) absence of unicuspid teeth in the second row of lower jaws (vs. presence), and (usually) the absent or rudimentary supraneural between two neural spines directly in front of the first dorsal fin pterygiophore (vs. well developed). Description. Based on holotype and 15 paratypes. For general appearance refer to Figs. 1 and 2. Measurements and meristics summarized in Tables 1 and 2. A comparatively small species, maximum size 24.4 mm SL. Body laterally compressed, slightly elevated. Dorsal fin originating midway along body; pelvic fins originating slightly in front of dorsal fin; anal fin originating approximately at level of end of dorsal-fin base; adipose fin originating at level of caudal end of anal-fin base, positioned closer to caudal than to dorsal fin. Scale cover variably reduced: no pre-dorsal scales; usually no scales on caudal peduncle; usually a scale free patch on middle of flank at level of pelvic-fin origin. Number of pored scales in lateral line variable (0–9); lateral line never complete. Premaxilla with two teeth in outer row, each with three major and two minor cusps and four teeth in inner row with four cusps in the first, six cusps in the second and third, and seven cusps in the last tooth (Fig. 3). Dentary with four teeth in outer row, each with six cusps, except the last with only five cusps (Fig. 3); an inner single monocuspid tooth usually absent (where it was possible to check this character without damaging the specimen only 2 out of 12 had inner monocuspid teeth). Anal fin convex in males (Figs 1, 2), but almost straight in females and juveniles. Pectoral fin with 12 rays with dorsalmost and ventralmost rays unbranched. Pelvic fin with 8 rays, with first and last rays unbranched. 2 hypurals in lower lobe and 4 hypurals in upper lobe; 3 epurals; small cartilage present in front of anterior-most haemal spine. Other fin and vertebrae counts presented in Table 2. Supraneural directly in front of first pterygiophore of dorsal fin reduced in size or absent. This species seems to be a dwarf species within the genus Bathyaethiops. Juveniles of this species and juvenile sympatric B. caudomaculatus are difficult to differentiate. Coloration. In life (Fig. 2) body pale translucent; dorsal, adipose and caudal fin bright red; pelvic and anal fin light orange to yellow; pectoral fin yellowish; upper quarter of iris orange; caudal peduncle on its dorsal and ventral margin slightly red. A prominent humeral spot the size of the pupil or larger, and a slightly larger dark spot on the caudal peduncle; the latter is bisected by a dark line along the midlateral line starting slightly in front of dorsal-fin origin and terminating just distal to the caudal peduncle spot; never any vertical stripes or barring along the midlateral line. Few melanophores in mid-dorsal line along the back starting on lower jaw and reaching caudal peduncle; thin line of melanophores along anal-fin base; often an elevated line of melanophores proximal to the anal-fin base; a dark bar at the end of the caudal peduncle. Melanophores densely set on posterior dorsal half of head. In general, contrast and coloration more pronounced in mature males. In preservative (Fig. 1) pale whitish to light brown; red, orange and yellow coloration absent. Melanophore pattern as in preserved specimens, but spot on the caudal peduncle less pronounced and smaller, i.e. not reaching the anal fin base; humeral spot more intensively colored but of same size. Etymology. Named after the Baka people, the native hunter-gatherer tribe in Southeastern Cameroon, where the species was found. A noun in aposition. Distribution and habitat. The species is so far known from several localities along the Ngoko River, from below the Nki falls to the village of Ndongo (Fig. 4–5). The Ngoko, called Dja River above the Nki falls, is a tributary to the Sangha River, a major northern tributary of the Congo River. All specimens were caught in the main river channel, usually in or close to riparian vegetation over a substrate of fine particles and organic material. Water parameters from the Ngoko River at Ndongo taken on 0 4.02. 2008 were: pH 7.08; conductivity 23 µS; temperature 27.5 °C. Meristic character Holotype Paratypes (N= 15) Simple dorsal fin rays 3 2 (15) Branched dorsal fin rays 8 8 (15) Simple anal fin rays 3 3 (15) Branched anal fin rays 21 18 (1); 19 (5); 20 (7); 21 (1); - (1) Upper procurrent caudal fin rays 9 5 (1); 6 (5); 7 (5); 8 (4) Upper principal caudal fin rays 10 10 (13); 11 (2) Lower principal caudal fin rays 9 9 (14); 10 (1) Lower procurrent caudal fin rays 7 5 (4); 6 (10); 7 (1) Vertebrae 37 35 (1); 36 (11); 37 (3) Abdominal vertebrae 16 16 (4); 17 (10); 18 (1) Caudal vertebrae 21 19 (10); 20 (5) Dorsal fin inserting after vertebra 10 10 (10); 11 (5) Anal fin inserting after vertebra 17 17 (10); 18 (5) Supraneurals 6 6 (7); 7 (7); 8 (1); Pored scales in LL* 5 0 (1); 5 (6); 6 (5); 7 (2); 9 (1)

A new dwarf alestid from the vicinity of Inga on the lower Congo River, Bas Congo Province, Democratic Republic of Congo is described. Assignment of the new taxon to the poorly defined genus, Micralestes, is discussed and justified on the basis of available morphological character data. With the recognition of Micralestes schelly sp. nov., a total of six Micralestes are now known to inhabit the 350 km stretch of the Congo River from Pool Malebo to Boma near the river’s estuary. These are Micralestes acutidens (Peters, 1852), Micralestes humilis Boulenger, 1899, Micralestes lualabae Poll, 1967, Micralestes holargyreus (Günther, 1873), Micralestes stormsi Boulenger, 1902, and the new species Micralestes schelly. Of these Micralestes schelly and Micralestes holargyreus are considered herein as restricted-range endemics of the lower Congo River. An illustrated key to Micralestes of the lower Congo River is provided.

The overall most parsimonious hypothesis of relationships based on 200 characters indicates that the Alestidae is the closest relative of Chalceus, a genus previously assigned to the Neotropical Characidae. Chalceus is shifted into the Alestidae, which becomes the only trans-Atlantic family level group within the Characiformes. Various previously proposed suprageneric assemblages within the Alestidae (e.g. Petersiini) failed to delimit monophyletic groups under the intrafamilial phylogenetic analysis. The evaluation of fossil alestids within the context of the phylogeny indicates that the ancestors of Alestes, Arnoldichthys, Brycinus, Bryconaethiops and Hydrocynus evolved prior to the early Eocene (Cuisian of Upper Ypresian), 49–54.8 million years ago, with the fossil Alestoides most closely related to Alestes. The phylogenetic information further indicates a minimum age of 90–112 million years for the Alestidae. Contrary to previous hypotheses, the fossil African Sindacharax was found to be most similar to the clade including the alestid genus Bryconaethiops rather than most closely related to the South American subfamily Serrasalminae. Evaluation of the fossil Mahengecharax carrolli fails to support its hypothesized placement as the sister group to all Recent members of the Alestidae. Two separate episodes of miniaturization and one episode of gigantism occurred within the evolution of the Alestidae. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 1−144. No claim to original US government works.

Laan, Richard Van Der, Eschmeyer, William N., Fricke, Ronald (2014): Family-group names of Recent fishes. Zootaxa 3882 (2): 1-230, DOI: http://dx.doi.org/10.11646/zootaxa.3882.1.1, URL: http://dx.doi.org/10.11646/zootaxa.3882.1.1

Alestopetersius conspectus, new species Fig. 4 Holotype. AMNH 253473, 3, 52.9 mm SL, Democratic Republic of Congo, Bandundu Province, Kwilu River at Carrefour, 05.19160�� S, 18.94947 �� E, Coll. J.J. Mbimbi Mayi Munene, 24 February 2011. Paratypes. AMNH 253475, 9 specimens, 42.3���53.6 mm SL, 2 CS, same data as holotype.��� AMNH 253476, 10 specimens, 45.5���56.9 mm SL, 2 CS, Democratic Republic of Congo, Bandundu Province, Kwilu River at Kwilu beach, 05.04810��S, 18.83968 ��E, Coll. J.J. Mbimbi Mayi Munene, 19 February 2011.��� AMNH 253477, 5 specimens, 42.4���49.2 mm SL, Democratic Republic of Congo, Bandundu Province, Democratic Republic of Congo, Bandundu Province, Kwilu River at Mbuji, 05.07180��S, 18.86935 ��E, Coll. J.J. Mbimbi Mayi Munene, 22 February 2011.��� MRAC B 1-19 -P- 5 -6, 2 specimens, 44.8���44.9 mm SL, same data as holotype.��� ZSM 40759, 2 specimens, 45.4 ���53.0 mm SL, same data as AMNH 253476.���CU 96797, 2 specimens, 42.3���44.3 mm SL, same data as AMNH 253477. Diagnosis. Alestopetersius conspectus, new species, is distinguished from A. smykalai, A. leopoldianus, A. nigropterus, A. caudalis, and A. sp. ���mbuji��� in the possession of 12 (vs. 10) circumpeduncular scales. It is readily distinguished from A. brichardi, A. compressus, A. hilgendorfi, and A. tumbensis in the possession of a caudal-fin pigmentation consisting of a median black band extending to the caudal-fin margin and flanked by dense black bands in both upper and lower fin lobes. Alestopetersius bifasciatus, which shares similar caudal fin pigmentation, is distinguished from A. conspectus by the absence of a broad mid-lateral band on the body, and in tooth morphology. Description. Medium-sized species, maximum size 56.9 mm SL. See Figure 4 for general appearance and Table 1 for summary of morphometric and meristic data. Relatively gracile and shallow-bodied, body depth 26.4��� 34.5 % SL (mean 32.1), greatest depth at vertical through pelvic-fin insertion. Head length 20.4���29.7 (mean 27.5), eye large, bony orbit diameter 28.2���37.2 % HL (mean 34.9). Dorsal head profile straight from upper lip to nape, gently convex from that point to dorsal-fin origin. Dorsal body profile gently convex along dorsal-fin base to caudal-fin base, ventral body profile gently convex between isthmus and anal-fin base, caudal peduncle slightly longer than deep. Mouth terminal, lower jaw prominent and slightly prognathous. Premaxilla with two teeth in outer row, each bearing five cusps, positioned opposite interspaces between and alternating with, four inner row teeth, each bearing 6���8 cusps (Fig. 5). Outermost premaxillary tooth is markedly compressed and elongate with 7 or 8 small evenly sized cusps and a low median cusp. Dentary with four teeth in outer row, each bearing 6 or 7 cusps, outermost tooth smallest in jaw. No inner row teeth on dentary. Dorsal-fin rays, ii 8 anal-fin rays iii, 18-20 (mode 19). Origin of dorsal fin slightly in advance of vertical through pelvic-fin insertion. There is muted sexual dimorphism in fin shape; anal-fin margin convex in mature males, and concave in females and juveniles. The first 4 or 5 branched rays of dorsal fin of mature males somewhat elongated and filamentous. Body covered with small, regularly imbricate scales. Lateral line complete, with 31���34 pored scales to caudal flexion, 6.5���7 scale rows between lateral line and dorsal-fin insertion, 2.5 between lateral line and pelvic-fin insertion, 12 circumpeduncular scales. Twelve to 14 elongate gill rakers arrayed along lower limb of first arch. Total vertebral count 36 or 37 (mode 37). Miscellaneous osteological features. Seven supraneurals are situated above the first seven rib-bearing vertebrae anterior to first dorsal-fin pterygiophore (Fig. 6 A). This condition contrasts with that in most other species examined which possess only 6 supraneurals interdigitating with neural spines of six predorsal vertebrae (Fig. 6 B). We note that Alestoptersius leopoldianus also exhibits 7 rib-bearing vertebrae anterior to dorsal fin pterygiophore, but unlike A. conspectus has 6 rather than 7 supraneurals. Both Alestopetersius tumbensis and Alestopetersius bifasciatus share the modal Alestopetersius configuration with 6 supraneurals interdigitating with 6 vertebrae anterior to the dorsal fin pterygiophore. The condition in the single individual of A. sp. ���mbuji��� is not discernable in radiographs. Coloration. In alcohol (Fig. 4 A&C), base body coloration pale creamy brown with darker basal crescents at contact zones of contiguous scales on dorsum. In males faint humeral stripe present above pectoral fin, but no trace of humeral stripe present in preserved females (Fig. 4 C). In males (Fig. 4 A) a broad black band extends from behind opercle, thickening gradually to caudal peduncle base, then narrows and extends to posterior caudal-fin margin. Distinctive broad black band in each caudal-fin lobe flank central black band and are separated from it by white bands. Remaining fins dusky hyaline, leading edge of pectoral fin dark brown or black. In females coloration similar but mid-lateral band and caudal-fin bands somewhat muted (Fig. 4 C). In life (Fig. 4 B&D) all individuals are iridescent silver with greenish-copper reflections anterolaterally, becoming bluish on flanks and caudal peduncle. Mid-lateral band is obscured anteriorly on body but clearly marked on caudal peduncle. Markings on caudal fin as in preserved specimens but much of the white interspaces between black bands are bright orange. Distribution. Currently known from the Kwilu River in the vicinity of Kikwit (Fig. 1). Collections in the main channel of the Middle Congo River, the Kasai main channel in the region of Bandundu, and Lulua River (a neighboring tributary Kasai) did not recover any individuals of A. conspectus despite intensive sampling, suggesting that the species may be a Kwilu endemic. Ecology and habitat. Numerous specimens of Alestopetersius conspectus were collected at all sample sites along a 35 km stretch of the river (Fig. 1). Most were collected using seine nets at depths of between 1��� 2 m. Water temperature in the shallows where most specimens were collected was between 21���22.5 o C and pH ranged from 5.8���6.5. The Kwilu River at the sampling sites is between 15���40 meters wide and the banks are variously covered with dense, undisturbed riparian vegetation, heavily degraded urban areas, and cleared agricultural areas (Mbimbi & Stiassny 2011). Female specimens contain numerous, maturing eggs in the ovaries and males have enlarged testes suggesting that reproductive activity was approaching at time of capture (February). Short guts (ca. 60 % of SL when unraveled) and large stomachs with 6���8 fleshy pyloric caeca are suggestive of a carnivorous diet, and all specimens examined contained large numbers of insect head capsules and disarticulated body parts, most of terrestrial origin, with a preponderance of ants and small midges presumably taken at the water surface. Etymology. Conspectus, from the Latin, in reference to the conspicuous markings on the caudal fin and striking, bright coloration of the species in life., Published as part of Munene, Jos�� Justin Mbimbi Mayi & Stiassny, Melanie L. J., 2012, A new Alestopetersius (Characiformes: Alestidae) from the Kwilu River (Kasai basin) of central Africa; with a phylogeny for the genus and synonymy of Duboisialestes, pp. 59-68 in Zootaxa 3166 on pages 64-67, DOI: 10.5281/zenodo.213011, {"references":["Mbimbi, J. J. & Stiassny, M. L. J. (2011). Fishes of the Kwilu River (Kasai basin, central Africa); a list of species collected in the vicinity of Kikwit, Bandundu Province, Democratic Republic of Congo. Check List, 7 (5), 691 - 699."]}

A new Alestopetersius is described from the Kwilu River in the Kasai basin of the Democratic Republic of Congo. Alesto- petersius conspectus, new species, is readily distinguished from all congeners based on attributes of squamation and col-oration. It is distinguished from “Duboisialestes” tumbensis by tooth morphology and in the possession of a distinctivecaudal-fin pigmentation patterning consisting of a median black band extending to the caudal-fin margin and flanked bydense black bands in both upper and lower fin lobes. “Duboisialestes” bifasciatus, which shares similar caudal-fin pig-mentation patterning, is distinguished from A. conspectus by the absence of a broad mid-lateral band on the body, and bytooth morphology. Results from an analysis of the relationships and generic composition of the Alestidae provide supportfor the monophyly for Alestopetersius inclusive of the members of the genus Duboisialestes, which are placed into syn-onomy with the former.Une nouvelle espece de Alestopetersius est decrite de la riviere Kwilu dans le bassin du Kasai de la RepubliqueDemocratique du Congo. Alestopetersius conspectus, nouvelle espece, se distingue tres facilement de tout ses congeneressur les attributs de la squamation et coloration. Cette espece est distinguee de “Duboisialestes” tumbensis par la morphol-ogie des dents et par la possession d'un type de pigmentation de la nageoire caudale composee d’une bande noire medianes'etendant de la marge de la caudale et flanquee de denses bandes noires dans les deux lobes superieur et inferieur de lanageoire. “Duboisialestes” bifasciatus qui partage le meme type de pigmentation de la nageoire caudale, se distingue de A. conspectus par l'absence d'une large bande mi-laterale sur le corps, et par la morphologie des dents. Les resultats d'uneanalyse des relations et de la composition generique du Alestidae fournissent un soutien pour la monophylie des Alestopetersius incluant les membres du genre Duboisialestes, qui sont places en synonymie avec le genre precedent.

Bryconaethiops yseuxi Boulenger, 1899, originally described from “Haut Congo”, is rehabilitated. The species was synonymized, successively with B. microstoma (Gunther, 1873) and B. macrops Boulenger, 1920, subsequently rehabilitated, and then again considered as a junior synonym of B. microstoma. Bryconaethiops yseuxi is here considered as a valid species, easily distinguished from all other Bryconaethiops species by its small size (maximum: 72.2 mm SL), 7.5 rows of scales between the dorsal‐fin origin and the lateral line; 11–13/1/8–12 gill rakers on the first gill arch and long dorsal‐fin and anal‐fin bases, respectively, 15.7–17.6% of SL and 22.7–25.9% of SL.

Micralestes acutidens - BMNH 1861.3.10: 3-4, syntype, 1; AMNH 227634, 1; AMNH 239475, 5, 2 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Virilia pabrensis - AMNH 50858, 6, 1 C&S., Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Hemmigrammopetersius barnardi - AMNH 19861, 10, 3 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

[[Genus Micralestes]] Roberts & Stewart (1976) in their work on the fishes of the lower Congo River reported the presence of two Micralestes in their collections: M. acutidens (Fig. 1A) and M. humilis (Fig. 1C). Recent collections in the region also include specimens of M. lualabae (Fig. 1D), M. stormsi (Fig. 1E) and M. holargyreus (Fig. 1B). In addition to these, a collection made in the vicinity of Inga revealed the presence of a population of diminutive alestid that appears most closely to resemble Micralestes but that are not assignable to any described Micralestes or to any other species dwarf African alestid.

Rhabdalestes sp.- AMNH 227602, 18, 1 C&S

M. ambiguous - MRAC G.966 a -c, paratypes, 2, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Duboisialestes tumbensis - AMNH 238391, 5, 3 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

B. huloti - AMNH 238374, 2, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Rhabdalestes aeratus - AMNH 235768, paratypes, 10, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Alestopetersius brichardi - AMNH 240416, 5, 2 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Brycinus macrolepidotus - AMNH 240383, 6, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

R. maunensis - AMNH 217434, 5, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Bathyaethiops caudomaculatus - AMNH 238423, 5, 2 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Brachypetersius altus - AMNH 240420, 5; AMNH 240485, 2 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

[[Genus Micralestes]] Roberts & Stewart (1976) in their work on the fishes of the lower Congo River reported the presence of two Micralestes in their collections: M. acutidens (Fig. 1A) and M. humilis (Fig. 1C). Recent collections in the region also include specimens of M. lualabae (Fig. 1D), M. stormsi (Fig. 1E) and M. holargyreus (Fig. 1B). In addition to these, a collection made in the vicinity of Inga revealed the presence of a population of diminutive alestid that appears most closely to resemble Micralestes but that are not assignable to any described Micralestes or to any other species dwarf African alestid., Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 18

Nannopetersius ansorgii - BMNH 1910.11.28: 71-80, paralectotypes, 4, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. occidentalis - AMNH 215533, 1, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. holargyreus - BMNH 1873.7.28: 19, 1, syntype; AMNH 239257, 4 C&S; AMNH 239479, 10; AMNH 239480, 3, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Micralestes schelly, new species (Figs 1 F, 2 D, 3���6) Holotype (Fig. 5 B) AMNH 240662, male, 40.1 mm SL; Democratic Republic of Congo, Bas Congo Province, Congo River main channel near Inga at point 50 (5 �� 31.69 S 13 �� 36.47 E), R.C. Schelly et al., 26 Sept. 2002. Paratypes (Fig. 1 F, 5 B), with same data as holotype. AMNH 239518, 33.9 ��� 48.9 mm SL (24 alcoholic, 5 cleared and stained), MRAC 2007 - 26 -P- 1-2, 36.5 ��� 39.0 mm SL (2 alcoholic), MNHN 2007 - 1629, 35.3 ��� 40.1 mm SL (2 alcoholic), ZSM 33982, 39.0 ��� 44.2 mm SL (2 alcoholic), MCZ 166773, 34.6 ��� 36.5 mm SL (2 alcoholic), CU 93431, 36.9 ��� 40.0 mm SL (2 alcoholic). Diagnosis. A member of a clade of small alestid fishes characterized by the combination of the absence of a supraorbital bone, and the presence of a deep-lying midlateral stripe extending along the body onto the caudal peduncle, a band of chromatophores above the anal fin, and a small pair of inner row symphyseal teeth on the dentary. Micralestes schelly is distinguished from all putative congeners in having an elevated vertebral count of 38 ��� 40 (mean 39) versus 34 ��� 36 (mean 35) vertebrae. Additionally the species is characterized by the presence of 4���6 outer row premaxillary teeth with a majority of specimens (23 of 40) with only four outer row teeth implanted in an alternating pattern with respect to the anterior inner row premaxillary teeth. Mature males are further diagnosed by live coloration, which is dominated by a broad, blue-green iridescent midlateral band extending from behind the opercle to the base of the caudal fin, and by a marked expansion of the band of black chromatophores above the anal fin. Description. Based on the holotype and 39 paratypes. See Figs. 5 and 6 for general appearance, and Table 1 for summary of morphometric and meristic data. Diminutive species, maximum observed size 48.9 mm SL. Relatively deep bodied, somewhat laterally compressed with greatest body depth at, or a little in front of, dorsal-fin origin. Dorsal body profile more-or-less smoothly convex to caudal peduncle, less strongly so in mature males; ventral profile markedly convex to anal-fin insertion. Caudal peduncle slightly longer than deep. Mouth terminal, gape not reaching beyond level of anterior margin of eye. Eye moderately large, flanked by adipose membrane extending over snout to level of nostril and posterodorsally over postorbital region. Nostril large and prominent; nasal and antorbital bones greatly reduced in size (Fig. 2 D). Teeth. Stout tri- or quadri-cuspid teeth in outer row on premaxillae variable in number; majority of individual have two teeth on either premaxilla (23 of 40 specimens), 13 specimens have two teeth on one side and three teeth contralaterally, and four specimens have three teeth on both premaxillae. When only two teeth are present each is positioned opposite interspaces between and alternating with, anterior inner row teeth (Fig. 3 A). Four inner row teeth on each premaxilla, most with one large central cusp and two or three minor cusps on either side, symphyseal teeth often with single minor cusp on medial face. Four outer row teeth on contralateral dentaries, each with large central cusp and two or three minor cusps on either side. A single pair of small, conically recurved, symphyseal inner row teeth on lower jaw invariably present (Fig. 3 B). Fins. Dorsal-fin rays ii, 6���7 (total rays, 8���9), anal-fin rays iii, 16���17 (total rays 19���20). Origin of dorsal fin at, or slightly behind, vertical through pelvic-fin origin. Marked sexual dimorphism in morphology of anal fin (see Figs. 4, 5). However, unlike condition in Rhabdalestes, Hemigrammopetersius and Virilia (Stiassny and Schaefer, 2005; Zanata and Vari, 2005) there is no posterior curvature or hypertrophy of third unbranched anterior ray of mature males (Fig. 4 C). Squamation. Scales in longitudinal series 26���28 (mean 27) to caudal fin flexure, 1���3 smaller scales continuing over caudal fin base, 4.5 transverse scales between lateral line and dorsal-fin origin, 2.5 transverse scale rows between lateral line and pelvic-fin insertion. Lateral line complete, with 25���29 canal-bearing scales to point of hypural flexure, 2���4 smaller pored scales continuing over caudal-fin base. Total number of gill rakers on first gill arch 18���22 (mean 19). Total number of vertebrae 38���40 (mean 39). Color in alcohol. Base body coloration yellowish brown dorsally and laterally, yellow-orange ventrally. A darkly pigmented, deep-lying midlateral stripe extends from posterior margin of opercle to base of caudal fin. Well-marked band of dark melanophores present above anal fin. Pectoral and pelvic fins pale yellow. Adipose fin tipped in black. Dorsal and caudal fins somewhat dusky. Anal fin of females dusky proximally, in males pigmentation is somewhat expanded distally in posterior portion of fin. Color in life. Recently two male specimens have been collected from the type locality and live coloration recorded (Fig. 6). In life a broad, blue-green iridescent midlateral band covers the lateral flanks and tail from behind the opercle to the base of the caudal fin. This iridescent band overlies and obscures the deep lying midlateral stripe evident in preserved specimens (Fig. 5). Above and below the midlateral band the body is silvery white. Numerous melanophores are present on the head and opercle, and scattered over the body with a concentration around lateral scale margins. An expanded band of black melanophores reaching to the lateral line is present above anal fin. Dorsal fin and pectoral fins are dusky gray; adipose fin is pale gray with a dark distal margin. Caudal fin is dusky gray at its base with a median dark band extending to mid-fork, distally the fin is dusky gray and medially each fin fork is deep crimson red. Anterior and distal margins of the anal fin are white, while the remainder of the fin is jet black. Pelvic fins are white. Iris is silvery white with a small red patch dorsally. Unfortunately no female specimens were collected during a recent site visit and female life coloration remains unknown. Geographical distribution. Known only from the type locality in Bas Congo Province, at Point 50 on the Congo River main channel near Inga, Democratic Republic of Congo (5 �� 31.69 ���S 13 �� 36.47 E). Specimens were collected with cast nets in a complex, partially protected riffle habitat adjacent to rapids (Fig. 7). A smallunnamed stream enters the Congo River at this point and supports a patch of forest in the draw between two steep, mostly-bare hills. Micralestes schelly was collected over a sand and gravel substrate in the main channel amongst large rock slabs of up to 4 m high thrusting upward at angles of 60���70 degrees, in pools up to 2 m in depth. At this site water depth and flow is highly variable due to water surges every 5���10 minutes resulting in depth fluctuations in excess of half a meter. Etymology. Named for our colleague and the intrepid collector of the type series, Robert C. Schelly. Discussion. Recent collections in the region allow us to document the presence of six Micralestes in the stretch of the lower Congo River from Pool Malebo to Boma near the river���s mouth, and as an aid for field identification we provide here an illustrated key to those species. 1 A Teeth with numerous small cusps, first inner row premaxillary tooth with 10���12 cusps (Key Fig. 1 A). Inner row tooth pair on dentary usually multicuspid (Key Fig. 3 A). Dorsal fin with distinctive black apical patch (Key Fig. 2 A).................................................................................................................. M. acutidens 1 B Teeth with fewer cusps, first inner row premaxillary tooth with 6���8 cusps (Key Fig. 1 B). Inner row tooth pair on dentary invariably unicuspid (Key Fig. 3 B). Dorsal fin without black apical patch (Key Fig. 2 B)................................................................................................................................................................ 2 2 A 23���28 scales in longitudinal series from opercle to point of caudal flexure (Key Fig. 2 A)........................ 3, Published as part of Stiassny, Melanie L. J. & Mamonekene, Victor, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo, pp. 17-29 in Zootaxa 1614 on pages 21-25, DOI: 10.5281/zenodo.179053, {"references":["Stiassny, M. L. J. & Schaefer, S. A. (2005) Rhabdalestes aeratis, new species (Characiformes: Alestidae): first occurrence of the genus from the Middle Congo River basin. Ichthyological Exploration of Freshwaters, 16 (3), 271 - 278.","Zanata, A. M. & Vari, R. P. (2005) The family Alestidae (Ostariophysi, Characiformes): a phylogenetic analysis of a trans-Atlantic clade. Zoological Journal of the Linnean Society, 145, 1 - 144."]}

M. fodori - MRAC 140901, 1, holotype, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. stormsi - BMNH 1902.4.14: 28-31, syntypes, 3; AMNH 239197, 5; AMNH 238440, 5; AMNH 238437, 4 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

Rhabdalestes sp.- AMNH 227602, 18, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

B. poptae - AMNH 240385, 5, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

R. rhodesiensis - AMNH 50894, 2, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. elongatus - AMNH 215347, 8, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

R. septentrionalis - AMNH 230605, 10, 5 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

A. hilgendorfi - AMNH 240421, 3, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. lualabae - MNHN 1967-0668, paratypes, 2; AMNH 5805, 10, 2 C&S; AMNH 238386, 3, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. eburneensis - AMNH 32763, 5, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

M. comoensis - AMNH 097605, 4, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

[[Genus Micralestes]] Discussion. Recent collections in the region allow us to document the presence of six Micralestes in the stretch of the lower Congo River from Pool Malebo to Boma near the river’s mouth, and as an aid for field identification we provide here an illustrated key to those species. 1A Teeth with numerous small cusps, first inner row premaxillary tooth with 10-12 cusps (Key Fig. 1A). Inner row tooth pair on dentary usually multicuspid (Key Fig. 3A). Dorsal fin with distinctive black apical patch (Key Fig. 2A).................................................................................................................. M. acutidens 1B Teeth with fewer cusps, first inner row premaxillary tooth with 6-8 cusps (Key Fig. 1B). Inner row tooth pair on dentary invariably unicuspid (Key Fig. 3B). Dorsal fin without black apical patch (Key Fig. 2B)................................................................................................................................................................ 2 2A 23-28 scales in longitudinal series from opercle to point of caudal flexure (Key Fig. 2A)........................ 3 2B 29-33 scales in longitudinal series (Key Fig. 2B).................................................................... M. lualabae 3A Outer row premaxillary teeth small and tricuspid or quadricuspid (Key Fig. 1A).....................................4 3B Outer row premaxillary teeth prominent, conical, or weakly shouldered, unicuspids (Key Fig. 1B)......................................................................................................................................................... M. holargyreus 4A Median cusp of symphyseal teeth on dentary less than twice the height of adjacent cusps (Key Fig. 3A). 24-28 scales in longitudinal series from opercle to point of caudal flexure. Adipose fin black distally, pale proximally (Key Fig. 2A)............................................................................................................................ 5 4B Median cusp of symphyseal teeth on dentary elongate and more than twice the height of adjacent cusps (Key Fig. 3B). 23-24 scales in longitudinal series from opercle to point of caudal flexure. Adipose fin black (Key Fig. 2B)...................................................................................................................... M. stormsi 5A Relatively gracile, body depth 3.8-4.2 times into standard length. Adipose eyelid restricted posteriorly to orbital margin (Key Fig. 2A)...................................................................................................... M. humilis 5B Relatively deep-bodied, body depth 3.0-3.8 times into standard length. Adipose eyelid extending posterodorsally over postorbital region (Key Fig. 2B).............................................................................. M. schelly Most of these species have widespread distributions encompassing most of the Congo basin and often also much of the rest of Central Africa (Poll, 1967). While we have not undertaken a revision of this genus and related taxa, a task that is ongoing, it is worthy of note that despite intensive collection and surveys in the region Micralestes holargyreus remains known only from the short stretch of the lower Congo River from Boma to Matadi, and M. schelly is only known from a single site in the vicinity of Inga. These two taxa are considered here to be lower Congo River endemics.

M. humilis - MRAC 805, 1, holotype; AMNH 238406, 1; AMNH 238427, 1; AMNH 240417, 4, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

[[Genus Micralestes]] Discussion. Recent collections in the region allow us to document the presence of six Micralestes in the stretch of the lower Congo River from Pool Malebo to Boma near the river���s mouth, and as an aid for field identification we provide here an illustrated key to those species. 1A Teeth with numerous small cusps, first inner row premaxillary tooth with 10-12 cusps (Key Fig. 1A). Inner row tooth pair on dentary usually multicuspid (Key Fig. 3A). Dorsal fin with distinctive black apical patch (Key Fig. 2A).................................................................................................................. M. acutidens 1B Teeth with fewer cusps, first inner row premaxillary tooth with 6-8 cusps (Key Fig. 1B). Inner row tooth pair on dentary invariably unicuspid (Key Fig. 3B). Dorsal fin without black apical patch (Key Fig. 2B)................................................................................................................................................................ 2 2A 23-28 scales in longitudinal series from opercle to point of caudal flexure (Key Fig. 2A)........................ 3 2B 29-33 scales in longitudinal series (Key Fig. 2B).................................................................... M. lualabae 3A Outer row premaxillary teeth small and tricuspid or quadricuspid (Key Fig. 1A).....................................4 3B Outer row premaxillary teeth prominent, conical, or weakly shouldered, unicuspids (Key Fig. 1B)......................................................................................................................................................... M. holargyreus 4A Median cusp of symphyseal teeth on dentary less than twice the height of adjacent cusps (Key Fig. 3A). 24-28 scales in longitudinal series from opercle to point of caudal flexure. Adipose fin black distally, pale proximally (Key Fig. 2A)............................................................................................................................ 5 4B Median cusp of symphyseal teeth on dentary elongate and more than twice the height of adjacent cusps (Key Fig. 3B). 23-24 scales in longitudinal series from opercle to point of caudal flexure. Adipose fin black (Key Fig. 2B)...................................................................................................................... M. stormsi 5A Relatively gracile, body depth 3.8-4.2 times into standard length. Adipose eyelid restricted posteriorly to orbital margin (Key Fig. 2A)...................................................................................................... M. humilis 5B Relatively deep-bodied, body depth 3.0-3.8 times into standard length. Adipose eyelid extending posterodorsally over postorbital region (Key Fig. 2B).............................................................................. M. schelly Most of these species have widespread distributions encompassing most of the Congo basin and often also much of the rest of Central Africa (Poll, 1967). While we have not undertaken a revision of this genus and related taxa, a task that is ongoing, it is worthy of note that despite intensive collection and surveys in the region Micralestes holargyreus remains known only from the short stretch of the lower Congo River from Boma to Matadi, and M. schelly is only known from a single site in the vicinity of Inga. These two taxa are considered here to be lower Congo River endemics., Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on pages 24-27

M. congicus - MRAC 96582, 1, holotype; AMNH 238430, 5, 1 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19

N. lamberti - AMNH 238370, 3, 2 C&S, Published as part of Melanie L. J. Stiassny & Victor Mamonekene, 2007, Micralestes (Characiformes, Alestidae) of the lower Congo River, with a description of a new species endemic to the lower Congo River rapids in the Democratic Republic of Congo., pp. 17-29 in Zootaxa 1614 on page 19