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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

Two new Phenacogrammus are described from the Ndzaa River, a small left-bank tributary of the Mfimi-Lukenie River in the central Congo basin. They share with P. deheyni, a congener endemic to the Cuvette Centrale to the north, a prominent anterior expansion of the first pleural rib; a feature interpreted here as a synapomorphy diagnostic for this species assemblage. The two new species are readily differentiated from P. deheyni based on differences in pigmentation patterning, a lower number of scales in longitudinal series (26–28 vs. 29–33) and a longer head length (m. 24.9% SL vs. 21.7 and 23.2% SL). Phenacogrammus flexus, new species, is distinguished from all congeners in the possession of 6 (vs. 7) supraneural bones, and a characteristic zigzag pattern of black pigmentation along and below the midline extending from the posterior border of the opercle to the base of the caudal peduncle. While no unambiguous morphological autapomorphies have been located to diagnose P. concolor, new species, it is nonetheless readily distinguished from all congeners, except P. deheyni and P. flexus, in the possession of a prominent anterior expansion of the first pleural rib. It differs from both P. deheyni and P. flexus in the absence of a dominant pigmentation patterning over the flanks and caudal peduncle. Additionally, it differs from P. flexus in a shallower body depth (m. 24.9% vs. 27.0% SL) and in the possession of 7 (vs. 6) supraneurals. The three species exhibit extensive divergence in mt-COI sequence (P. flexus vs. P. concolor 10.2%–11%; P. flexus vs deheyni 12.9%–13.5%; P. concolor vs. deheyni 11.3%–12.9%). Furthermore, analysis of shape variation utilizing geometric morphometrics indicates that each species differs significantly in body shape.

The present study aimed to investigate the karyotype and molecular sex differences in Brycinus nurse. Analysis of 430 metaphases spreads from 12 specimens revealed that the diploid chromosome number is 44 chromosomes and the proposed karyotype formula is n = 3 M + 3 SM + 16 A, FN = 56. No morphologically differentiated heteromorphic sex chromosomes were observed. On the other hand, 29 primers of three molecular markers (RAPD, SCoT and ISSR) were tested to differentiate between males and females of B. nurse. From all tested primers only two primers (OPI-18 and SCoT-18) successfully generated female specific bands in the bulked DNA samples which further confirmed using individual DNA samples. According to molecular analysis result in this study it seems that females of B. nurse are the heterogametic gender (ZW) and males of B. nurse are the homogametic gender (ZZ). In the future, SCoT marker can be used as suitable and powerful marker in genetic analysis studies in fish.

To investigate the presence of cryptic diversity in the African longfin-tetra Bryconalestes longipinnis, we employed DNA barcoding in a phylogeographic context, as well as geometric morphometrics, documenting for the first time genetic and body shape variation in the species. Analysis of cytochrome oxidase I gene (coI) sequence variation exposed extremely high levels of genetic differentiation among samples from across the geographic range of the species (up to 18%), certainly much greater than the traditionally employed c. 3% sequence divergence heuristic threshold for conspecifics. Phylogeographic analyses of coI data revealed eight clusters/clades that diverge by >4% and up to 18% (p-distance), potentially representing cryptic members of a species complex. A clear biogeographic pattern was also uncovered, in which the two main coI lineages corresponded geographically with the upper Guinea (UG) and lower Guinea (LG) ichthyofaunal provinces of continental Africa, respectively. Within each of these main lineages, however, no apparent phylogeographic structuring was found. Despite strong genetic differentiation, there is considerable overlap in body shape variation between UG and LG populations. For the most part, morphological variation does not match the strength of the molecular phylogeographic signal. Therefore, the ability to reliably utilise external body shape for regional delimitation remains elusive. Further anatomical investigation appears necessary to establish whether compelling diagnostic morphological features do exist between the divergent lineages of the B. longipinnis complex uncovered in this study.

In tropical Africa, and particularly in Benin, running waters dwell a high and valuable fish fauna that are almost unknown, but under severe degradation. The current study inventoried the fish biodiversity of the Okpara stream, the main tributary of the Oueme River (the largest in Benin), in order to fill the gap of ichthyological data and to improve habitat protection, species conservation and valorization. During 18 months, fish samplings were made monthly with various fishing gears on five (5) locations. A total of 53 fish species belonging to 30 genera, 14 families and 7 orders were recorded among a total of 9552 individual fish collected. The most representative families were Mormyridae with 9 species and Cichlidae with 8 species, then follow Mockokidae, Clariidae, Cyprinidae and Alestidae with 6, 6, 6, 4 species, respectively. Families such as Anabantidae, Bagridae, Claroteidae, Malapteruridae, Polypteridae and Schilbeidae were less represented and individually included 2 species. The Hepsetidae and Aplocheilidae were represented by one (1) species, respectively the African pike, Hepsetus odoe and Epiplatys bifasciatus. A holistic scheme of ecosystem management and species conservation requires a complete knowledge on the fish community structure, eco-toxicology and species ecological status.Read Complete Article at ijSciences: V82019042052 AND DOI: http://dx.doi.org/10.18483/ijSci.2052

Diet of 300 specimens of Bryconaethiops boulengeri from Djiri River (Congo Brazzaville) caught with cash nets was studied according to the size of fish, sampling stations and hydrological season. Sampling focused on twelve annual withdrawals made during three years. The relative importance index combining numerical and weight percentages of occurrence was calculated and also the sex ratio was evaluated. Bryconaethiops boulengeri consumes terrestrial and aquatic insects and everything that falls into the water (birds feathers, plant debris, fruits, etc.). The percentage of emptiness is 9.66% of the three sampling stations selected; no significant difference in diet was observed whatever the season.

Summary The monogenean, Afrogyrodactylus ardae sp. n., is described from the African tetra, Rhadbalestes septentrionalis (Characiformes: Alestidae), collected from the Niokolo Koba and Gambie Rivers in the Niokolo-Koba National Park, Senegal during 2008. The newly described species can be differentiated from three known species of the genus based on the dimensions of its opisthaptoral hard parts, having the smallest ones, and based on the shape of the marginal hooks sickle. The present finding represents a new host record for the genus Afrogyrodactylus.

Ichthyofaunal distribution was studied in the Musolo River system, a small affluent tributary of the Congo River flowing into Pool Malebo (Democratic Republic of the Congo). Twelve ecological stations were sampled, of which eight were located in the Musolo main-channel and four in the Fushi River, a principal tributary of the Musolo. Each station was sampled four times over a two-year period, with fishing techniques following standardized methods utilizing dip and cast nets, and nine environment variables were measured at each station. Fifty-three fish species belonging to 36 genera and 16 families were collected with the Alestidae, Distichodontidae, Cichlidae, Cyprinidae, Mormyridae, and Mochokidae being the most diversified. Redundancy Analysis with forward selection coupled with Monte Carlo permutation tests (499 permutations) identified total dissolved solid (25.8%) and altitude (24.4%) as accounting for 50.2% of total variance (p < 0.05). The contribution of the two first axes was significant (F = 3.41; p = 0.004). Species richness increases from upstream to downstream. In general, the high value of Shannon’s diversity (1.07-2.67) and Equitability (0.62-0.96) indices at all sites, indicates that the examined stretch of the Musolo River system is in good ecological health, despite its location adjacent to the megacity of Kinshasa.

The Kahuzi-Biega National Park (KBNP), situated mainly in the Eastern Highlands Ecoregion of the Upper Congo basin, is drained by the Lowa and Ulindi rivers, and some western affluents of Lake Kivu. In this study, the first list of the fish diversity of these systems is provided based on museum collections and complemented, for the Lowa River system and the western Lake Kivu affluents, with recently collected specimens (2013-2017). A total of 118 species are reported from the Lowa basin, 22 from the Ulindi basin and seven from these Lake Kivu affluents. Within the Lowa and Ulindi, respectively, five and one species, all cichlids, have been introduced. Currently, 51 species are reported from within the park, only two of which have been reported from the highlands, i.e., Amphilius kivuensis from the Luha, the source of the Luka River, and Clarias liocephalus from the headwaters of the Lake Kivu' affluents. With a total of 30 species, Cyprinidae is by far the largest family, representing 25% of the total species diversity of the Lowa basin. It is followed by Mormyridae with 13 species (11%), Alestidae and Mochokidae with 10 species each (8%), Clariidae and Amphiliidae with eight species (7%), and Distichodontidae with six species (5%). Seven new species for science were discovered and 11 species were found to be endemic to the Lowa system. Although further exploration is needed, this underscores the importance of the KBNP in protecting the fish fauna of the Lowa basin but also highlights the park's limited coverage of the fish fauna of the Lowa basin.

Lake Kariba is a tropical lake with slight variations in seasonal temperature. Temperature is an important physical variable in the biology of both fish and their parasites. Currently, there is no information on the seasonal occurrence of fish parasites in Lake Kariba. The objective of this study was to investigate the seasonal occurrence of metazoan parasites in Hydrocynus vittatus in Lake Kariba, Zimbabwe. Twenty fish specimens were collected by seine netting per season between October 2014 and July 2015 in the Sanyati Basin, Lake Kariba, and examined for metazoan parasites. Mean water temperatures ranged from 24.1 °C to 31.2 °C with slight variations between the seasons. Metazoan parasites consisting of Monogenea ( Annulotrema pikei, Annulotrema pseudonili, Annulotrema bracteatum ), Nematoda ( Contracaecum larvae), Copepoda ( Lamproglena hemprichii ), Cestoda (larval cestodes, Ichthybothrium sp.) and Pentastomida (pentastomid larvae) were recorded. Larval cestodes were recorded in autumn and spring, while pentastome larvae were recorded in summer and spring. The Ichthybothrium sp. was recorded once in winter. Annulotrema pikei and A. pseudonili were observed on the gills and A. bracteatum on both the gills and the skin. Contracaecum larvae, L. hemprichii and A. bracteatum (from the skin) were recorded in all the seasons, with slight variations in prevalence, mean abundance and mean intensity. However, these variations were not statistically significant (analysis of variance or ANOVA, p > 0.05). The slight variations in occurrence of the parasites were probably because of the thermal stability of the lake where variation in temperature was small between seasons. Both A. bracteatum and Contracaecum larvae were aggregated on the fish host, whereas L. hemprichii exhibited a random distribution. Parasite diversity was at its highest during winter.

We here report the oldest remains (teeth) of the African tigerfish (Hydrocynus) from the Oued Méridja and Garet Dermchane sections, Hamada of Méridja deposits, in southwestern Algeria. The tigerfish, a large carnivorous fish today represented by several species in the freshwaters of Africa, was previously found in upper middle to upper Eocene deposits in Egypt and Libya. The remains described here are several million years older, being early to middle Eocene in age, and are associated with other fish elements including lungfish, polypterid, amiiform, possible cichlid, and Alestes and Brycinus material, along with several fish elements that cannot be associated with a specific taxon and some fragmentary amphibian bones. This represents the first detailed description of a freshwater fish assemblage from the Eocene of Algeria, although a short list of fish taxa from Eocene Algerian deposits was previously reported. Furthermore, these new Algerian fossils allow us to assess the hypothesized existence of an east–west or west–east hydrological connection between eastern and western parts of northern Africa. We suggest that the shared presence of tigerfish in the Eocene deposits of Algeria, Libya, and Egypt does not necessarily indicate a permanent (i.e., nonseasonal) connection east–west or west–east among these areas. Rather, the observed faunal similarities could have been the result of seasonal flooding that caused the dispersal of Hydrocynus and associated taxa across coastal flood plains.

Changes made to the scientific names of southern African freshwater fishes since 2001 are explained and discussed. Adjustments to the phylogeny and classification of the fauna are outlined. Recent systematic studies on cyprinines are discussed and changes to the genera Labeobarbus (expanded concept), Pseudobarbus (expanded concept), and Enteromius are supported. The introduction of the family names Alestidae and Nothobranchiidae is discussed. Adjustments made to the genera Nannocharax, Micropanchax, Tilapia, Coptodon and Mastacembelus are explained. Species name changes for Hepsetus and Zaireichthys are detailed. New species described from the region, or resurrected from synonymy, since 2001 are listed.

This study aimed to determine the growth patterns, mortality, and exploitation status of two species of Alestidae in the New Calabar River, Nigeria. For this purpose, fish samples were collected monthly from three landing sites from the local fishermen using gill nets (mesh sizes: 15-25mm), beach seine (mesh sizes: 2.3-10mm), and cast nets (mesh sizes: 15 -25mm). The length-weight relationship revealed exponent “b” value for Brycinus nurse was 3.54 and 3.21 for Brycinus macrolepidotus while the condition factors were 1.08 and 1.02 for Brycinus nurse and Brycinus macrolepidotus respectively. The growth parameters of Brycinus nurse asymptotic length (L) and growth coefficient (K) were 24.46 cm and 0.52 yr-1, respectively, while those for Brycinus macrolepidotus L was 28.88 cm and K was 0.22 yr-1. The reproductive load (L50/L) ratio was found to be 0.59 and 0.61 for B. nurse and B. macrolepidotus, respectively. Exploitation rate (E) for B. nurse was 0.26 and 0.11 for B. macrolepidotus while length-at-first capture (Lc) was 14.49 cm for B. nurse and 17.64 cm for B. macrolepidotus. The natural mortality was greater than the fishing mortality for both species and Logistic regression of the probability of capture routine values recorded for B. nurse were higher than that of B. macrolepidotus. Maximum exploitation rate (Emax) was less than 0.5 for both B. nurse (0.41) and B. macrolepidotus (0.42). These values were close to the maximum allowable limit; therefore, the species may be unsustainable when fishery intensifies in the future. To ensure sustainable exploitation of the two Alestid species in the area, fishing effort should be regulated.

The aim of this study was to analyze fish species caught by gill nets and fish diversity of the New Calabar River. Three sampling stations were set based on the coverage situation of the river and ichthyofauna associated with gill nets were sampled twice monthly from February to July 2018. A total of 3,251 fish specimens, representing 11 orders, 15 families, and 28 species, were captured. The order Perciformes was identified as the most abundant representing five families while the remaining had one family each. The fish family Cichlidae was the most represented with seven species, and other notable families were Alestidae, Clupeidae, and Mugilidae, representing three species each. Prominent among the fish caught monthly included Liza falcipinnis, Mugil cephalus, Sarotherodon melanotheron, Sarotherodon galilaeus, Coptodon guineensis, and Sardinella maderensis. The mean catch per unit effort (CpUE) ranged from 3.15±0.2 to 4.85±0.2 kg unit-1 day11. Results of diversity indices revealed that Shannon-Wiener index values varied between 2.64 and 2.82, Simpson diversity ranged from 0.07 to 0.10, and Pielou’s evenness index values ranged from 0.85 to 0.95. The values obtained in this study showed that the status of fish diversity in New Calabar River was stable.

Chalceus guaporensis is an endemic fish to the upper Madeira River whereas C. epakros is widespread in many rivers of the central and lower portions of the Amazon Basin, middle and upper Orinoco River Basin, the Essequibo River in Guyana and in the Nanay River in northern Peru. According to literature, both species do not occur in syntopy. We carried out ichthyological surveys along the Madeira River Basin and its rapids, and data on abundance, diet and habitat use were obtained for both species. Chalceus guaporensis and C. epakros are morphologically similar, occupying floodplain habitats and exploiting similar food resources. The former predominated upstream from the Jirau Fall, whereas the latter had most of its abundance bellow the last fall of the Madeira River; both species co-occurred along part of the rapids stretch and in the Machado River, but with strongly uneven abundances. This pattern may have developed in the past by speciation regarding the presence of the falls, while co-occurrence of the two species seems to be regulated by competitive interactions or maintained by slight differences in environmental requirements nowadays. The recent disruption of the Madeira River by two run-of-river dams built in cascade submerged a large portion of the rapids stretch and substituted it by semi-lenthic habitats created by the dam reservoirs, together with the construction of a fish passage. These environmental changes may allow the invasion of the upper reaches of the Madeira River by C. epakros, and disturb the population of endemic C. guaporensis. RESUMO Chalceus guaporensis é descrita como uma espécie endêmica do alto rio Madeira, enquanto C. epakros está amplamente distribuída em rios das porções central e inferior da bacia Amazônica, no médio e alto rio Orinoco, e nos rios Essequibo, na Guiana, e Nanay, no norte do Peru. A literatura não registra essas espécies como sintópicas. Expedições ictiológicas realizadas ao longo do rio Madeira e suas corredeiras nos deram a oportunidade de registrar a presença, abundância, habitat e dieta utilizadas por essas espécies. Chalceus guaporensis e C. epakros são muito similares morfologicamente, ocupam habitats inundáveis e apresentam espectro alimentar semelhante. A primeira espécie predominou a montante da cachoeira Jirau, enquanto que a segunda teve a maior parte de sua abundância registrada à jusante das cachoeiras do rio Madeira. Ambas espécies coocorreram ao longo de parte do trecho de corredeiras e no rio Machado, mas com abundâncias muito desiguais. Esse padrão pode ter se desenvolvido no passado, por especiação, em função da presença das corredeiras, enquanto a coocorrência das duas espécies parece ser regulada por interações competitivas ou mantida por diferenças sutis em requisitos ecológicos no tempo atual. O recente barramento do rio Madeira por duas hidrelétricas construídas em cascata submergiu uma grande porção do trecho de corredeiras e o substituiu por habitats semilênticos, criados pelos reservatórios das hidrelétricas a fio d’água, juntamente com a construção de uma passagem para peixes. Essas alterações ambientais podem permitir que C. epakros invada o trecho superior da bacia do rio Madeira, com possíveis impactos negativos sobre a população da espécie endêmica C. guaporensis.

Made available in DSpace on 2018-11-26T17:42:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-12 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Hepsetidae is a small fish family with only the genus Hepsetus, with six described species distributed throughout the South, Central and Western regions of Africa, showing a close relationship with the Alestidae and some Neotropical fish families. However, no cytogenetic information is available for both Hepsetidae and Alestidae species, thus preventing any evolutionary comparative studies at the chromosomal level. In the present study, we are providing new cytogenetic data for Hepsetus odoe, including the standard karyotype, C-banding, repetitive DNAs mapping, comparative genomic hybridization (CGH) and whole chromosome painting (WCP), providing chromosomal patterns and subsidies for comparative cytogenetics with other characiform families. Both males and females H. odoe have 2n = 58 chromosomes (10m + 28sm + 20st/a), with most of the C-band positive heterochromatin localized in the centromeric and subtelomeric regions. Only one pair of chromosomes bears proximal 5S rDNA sites in the short arms, contrasting with the 18S rDNA sequences which are located in the terminal regions of four chromosome pairs. Clear interstitial hybridization signals are evidenced for the U1 and U2 snDNA probes, but in only one and two chromosome pairs, respectively. Microsatellite motifs are widely distributed in the karyotype, with exception for the (CGG)(10), (GAA)(10) and (GAG)(10) probes, which highlight conspicuous interstitial signals on an unique pair of chromosomes. Comparative data from conventional and molecular cytogenetics, including CGH and WCP experiments, indicate that H. odoe and some Erythrinidae species, particularly Erythrinus erythrinus, share similar chromosomal sequences suggesting some relatedness among them, although bearing genomic specificities in view of their divergent evolutionary histories. Univ Fed Sao Carlos, Dept Genet & Evolucao, Sao Carlos, SP, Brazil Estado Educ Mato Grosso Seduc MT, Cuiaba, Brazil Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Botucatu, SP, Brazil Royal Museum Cent Africa, Sect Vertebrates Ichthyol, Tervuren, Belgium Adamawa State Univ, Dept Fisheries & Aquaculture, Mubi, Nigeria Univ Hosp Jena, Inst Human Genet, Jena, Germany Univ Estadual Paulista, Inst Biociencias, Dept Morfol, Botucatu, SP, Brazil CNPq: 304992/2015-1 CNPq: 401575/2016-0 FAPESP: 2016/21411-7 FAPESP: 2016/17556-0 FAPESP: 2017/08471-3 FAPESP: FAPESP 2014/26508-3 FAPESP: CNPq 306054/2006-0

Two new and one known species of Annulotrema Paperna & Thurston, 1969 are reported from the gills of the tigerfish Hydrocynus vittatus Castelnau, 1861, collected in Lake Kariba, Zimbabwe. The new species, Annulotrema pseudonili n. sp. and A. bracteatum n. sp., are described and distinguished mainly on the basis of features of the male copulatory organ (MCO). Annulotrema pseudonili n. sp. most closely resembles A. nili Paperna, 1973, but differs from it by possessing a more delicate MCO with a thin-walled base without a fibrous distal part. Annulotrema bracteatum n. sp. is most similar to Annulotrema ruahae Paperna, 1973, from which it differs by having an MCO composed of a longer copulatory tube and a leaf-shaped accessory piece enveloping the distal part of the tube. The presence of Annulotrema pikoides Guégan, Lambert & Birgi, 1988 on H. vittatus in Zimbabwe represents a new locality record for this parasite.

Objectifs: Ce travail vise a faire le premier inventaire qualitatif et quantitatif du peuplement ichtyologique du lac de barrage d’Ayame 2. Methodologie et resultats: L’ichtyofaune a ete echantillonnee mensuellement entre Juin 2015 et Mai 2016 au moyen des filets maillants. Les donnees des peches experimentales ont ete completees par celles des peches commerciales. Au total, 40 especes de poissons incluant un Tilapia hybride ( T. zillii x T. guineensis ) et deux especes introduites ( Oreochromis niloticus et Heterotis niloticus ) ont ete recoltees. Ces especes sont reparties en 26 genres et 15 familles. Le peuplement ichtyologique est domine par les Cichlidae (35,04%), Claroteidae (28,89%) et Alestidae (24,91%). Les especes majoritaires sont Oreochromis niloticus (30,99%), Chrysichthys nigrodigitatus (17,9%) et Brycinus nurse (11,74%). Les valeurs des indices de diversite traduisent que le peuplement du milieu est diversifie. Conclusion et application des resultats: Cette etude a permis de faire le premier inventaire qualitatif et quantitatif de l’ichtyofaune du lac de barrage d’Ayame 2. Ces resultats serviront de references pour les investigations ulterieures de suivi de la faune ichtyologique et a l’elaboration de mesures adequates pour assurer une meilleure protection et une exploitation durable des ressources aquatiques de ce lac. Mots cles: Poisson, inventaire, diversite, lac de barrage d’Ayame 2, Cote d’Ivoire English Title: Preliminary data on the ichtyofauna of a west African Lake situated between two hydroelectric dams: man-made Lake Ayame 2 (Cote d’Ivoire) English Abstract Objectives: The objective of this work is to study for the first time the composition of fishes in the man-made Lake Ayame 2 situated between two hydroelectric dams. Methodology and Results: The ichthyofauna of man-made Lake Ayame 2 (South eastern of Cote d’Ivoire) was collected between June 2015 and May 2016. Fish samples were collected using gill-nets and commercial fish landings and held workshop with the local fishermen. Forty (40) species were identified in this study. The family of Cichlidae (35.04%), Claroteidae (28.89%) and Alestidae (24.91%) were dominated the fish community of man-made Lake Ayame 2. The most abundant species were Oreochromis niloticus (30.99%), Chrysichthys nigrodigitatus (17.9%) and Brycinus nurse (11.74%). The values of diversity index show that the population of environment is diversified. Conclusion and application of findings: This study allowed to make an inventory of the ichthyofauna of manmade Lake Ayame 2 for the first time and to characterize the population. These results will be references to follow through ichthyofauna and to take appropriate steps to avoid losses in aquatic biodiversity. Keywords: Fish, inventory, diversity, man-made Lake Ayame 2, Cote d’Ivoire

This study revises the originally monotypic genus Afrogyrodactylus Paperna, 1968 (Monogenea), the species of which infect alestid fish (Characiformes) in Africa, and includes new records of these parasites from three geographically distant countries, Senegal, Sudan and South Africa. Morphology of opisthaptoral hooks and bars and nuclear ribosomal DNA data revealed three Afrogyrodactylus species. Afrogyrodactylus girgifae sp. n. is described from the fins of the Sudanese nurse tetra, Brycinus nurse (Ruppell), and A. kingi sp. n. presents from the gill arches of the South African sharptooth tetra, Micralestes acutidens (Peters), whereas a previously undescribed Afrogyrodactylus sp. occurred on the fins of B. nurse from Senegal. All three species differ conspicuously from the only one known species of this genus, A. characinis Paperna, 1968, by the dimensions of their haptoral hard parts. Detailed morphological and molecular descriptions and comparisons are presented.

Human pressures and loss of natural fish habitats led to a decline in fish populations in terms of abundances, biodiversity, and average size in sub-Sahelian Burkina Faso. Little knowledge exists about fish assemblages regarding their composition, their habitat preferences, or their sensitivity to or tolerance of human pressures. This research provides the first data-driven basis for sustainably managing fish and associated aquatic and terrestrial habitats. Surveys in four different regions sampled 18,000 specimens from 69 species during the dry season. Fish communities, available abiotic habitat conditions, habitat use, and human pressures were assessed and analyzed. Fish communities cluster into four distinct types, each dominated by either Cichlidae, Clariidae, Cyprinidae, or Alestidae and accompanied by specific other families and genera of fish. Habitat preferences of four key species (Labeo coubie, Bagrus bajad, Chelaethiops bibie, and Lates niloticus) were linked to ecological habitat conditions. Results show that physical parameters influence fish community composition and abundances and, when indexed according to pressure type, are linked to responses in fish metrics. Relative abundance either dropped (Mormyridae) or increased (Cichlidae, Cyprinidae) with rising pressure intensity, and some sentinel taxa (Auchenoglanis, Hydrocynus) were only found in low-pressure sites. The outcomes of this study provide basic knowledge of habitat availability, habitat use by fish, species associations, and human pressures and therefore provide the basis for effective conservation and management of fish populations.

Nematodes of the genus Rhabdochona Railliet, 1916, identified as R. paski Baylis, 1928, were collected from the intestine of Hydrocynus forskahlii (Cuvier) (Characiformes: Alestidae), Oreochromis niloticus (Linnaeus) and Tilapia zillii (Gervais) (both Perciformes: Cichlidae) from Lake Turkana, Kenya during 2007–2009. Their morphology was studied in detail using light and scanning electron microscopy. Paratypes of R. paski and museum specimens of R. congolensis Campana-Rouget, 1961 from six other host species were examined for comparison. Based on these studies and the available literature data, Rhabdochona congolensis, R. aegyptiaca El-Nafar & Saoud, 1974 (emend.) and R. vesterae Boomker & Petter, 1993 are considered to be junior synonyms of R. paski. The occurrence of this widely distributed African nematode in many fish species belonging to different families and orders suggests that most of them are probably not definitive hosts of this parasite, but only serve as paratenic, paradefinitive or postcyclic hosts (sensu Odening, 1976). True definitive hosts of R. paski appear to be characiform species belonging to some genera (e.g., Alestes, Brycinus, Hydrocynus) of the family Alestidae.

Human induced habitat destruction and modifications cause losses of aquatic and terrestrial biodiversity. The Congo and its islands constitute special ecosystems and have been used by humans for many purposes over centuries. However, little is known about the effects of these human activities on the fish species richness and distribution. This study is a preliminary assessment of island habitat types, fish species richness and effects of human activities on fish distribution. Islands were randomly selected to describe island habitats, to collect fish specimens using nets and to record human activities, including agriculture. Terra firma island habitats were mostly mixed mature forest with clay and muddy substrates. We captured 29 fish morphotypes (13 families). Clariidae and Cyprinidae were widely distributed whereas Alestidae, Chanidae, Malapteridae and Polypteridae were restricted in their distribution. Humans permanently settled 76 % of the islands and 70 % were cultivated. Permanent human settlements and agriculture were related to erosion on ~50 % of islands. For reasons that are difficult to explain at this stage, fish morphotype richness decreased with increasing field sizes, warranting further investigations.

Renewed research at the early Miocene fossil site of Bukwa in northeastern Uganda has resulted in new fossil finds, including fish, with representatives of two families, Cichlidae and Alestidae. Although the two families were previously briefly reported from Bukwa, we here give a more detailed account of the fishes based on newly collected material. The cichlid material, mainly composed of vertebrae, can be tentatively assigned to one or more species of Pseudocrenilabrinae. The alestid material, comprising a diversity of teeth, likely represents several different species of Alestes, Brycinus, and/or Bryconaethiops. Although the ichthyofaunal diversity of Bukwa is low, the fishes are important for indicating the paleoenvironment and hydrographic connections of Bukwa. The early Miocene was a critical time for African faunas, because it was during this time that the Afro-Arabian and Eurasian plates came into contact with one another, ending the long isolation of Africa, which, along with rifting in E...

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

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�� Boen&dstrok;e 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

A new species of Bathyaethiops is described from the Lekoumou River in the Kouilou–Nairi basin of the Republic of Congo. Bathyaethiops atercrinis, new species, is distinguished from its three central African congeners in the possession of 21–24 scales in longitudinal series vs. 28–42 scales, and from Brachypetersius altus by the possession of a short, abridged lateral line consisting of only six or seven pored scales vs. a complete lateral line of 20–28 pored scales. The species is unique among congeners and related taxa in displaying marked sexual dichromatism and dimorphism of the supporting skeleton of the anal fin. The presence of B. atercrinis in the Lekoumou represents the first record of the genus in the Lower Guinean ichthyofaunal province and the first occurrence outside of the Congo basin.

Micralestes eburneensis Daget 1965, an endemic characin fish of Ivory Coast / Liberia is assessed as Near Threatened due to its restricted range. In addition, there is strong fishing pressure, habitat loss and aquatic pollution from clandestine gold mining in the Cavally River bed.Moreover, given the development and intensification of mining activities in the study area, it is to be expected that the population of the endemic species will continue to decline. The strong anthropogenic pressure in this region on the Cavally hydrosystem and its environment must be taken into account for a future update of M. eburneensis conservation status.There is an immediate need for developing protection and management actions for this fish species.

A collection of fossil fish teeth and other elements from Eocene deposits on the northshore of Birket Qarun, Fayum Depression, Egypt, is reported. This collection adds significantly to our knowledge, as it consists of material that was screened from the sediments, allowing collection of small teeth that represent taxa not previously reported from the Fayum. Previous collections from these sediments have concentrated on larger remains that generally represent elasmobranchs, which are marine species from deposits lower in the section. Most of this material, collected by screening at the Birket Qarun 2 (BQ-2) locality, represents fully freshwater fishes. It includes the first record of the mormyrid Gymnarchus in the Fayum Depression, which represents the oldest record for this group, known previously only from the late Miocene or younger deposits. Similarly, Mochokidae (Siluriformes) and Hydrocynus (Alestidae) remains from the site are the oldest record of these taxa. Other taxa recovered are the os...

To ensure the utilisation of optimal tigerfish gene pools for artificial propagation, the hypothesis that tigerfish from the Okavango system should have greater heterozygosity than those from smaller river systems was tested. This electrophoretic analysis provides the first report of the quantity and pattern of genetic variation for tigerfish of the Okavango Delta to be considered for artificial propagation and as candidates for an evolutionary significant unit. Mean heterozygosity was 1% in the Okavango, as compared to 1.9% in the Upper Zambezi and 5.6% in the Olifants River systems. Possible reasons for this anomaly, in terms of the Hardy-Weinberg principle, include the founder effect caused when the Okavango and Zambezi rivers became separated, and/or that the Okavango is a more stable system and therefore that a large variation might not be required in its individuals for survival. Significant differences of genotypes were found among all populations previously studied. The selection of potential cand...

The following four species (only females available) of the Philometridae (Nematoda: Dracunculoidea) were recorded from freshwater fishes of Lake Turkana, northwestern Kenya in 2007-2008: Philometra bagri (Khalil, 1965) from the subcutaneous tissue around the mouth, on gill covers and the fin base of the bayad Bagrus bajad (Forsskål) (Bagridae: Siluriformes), Philometra lati sp. n. from the abdominal cavity of the Nile perch Lates niloticus (Linnaeus) (Latidae: Perciformes), Philometra spiriformis sp. n. from capsules on the inner surface of gill covers of L. niloticus and Afrophilometra hydrocyoni (Fahmy, Mandour et El-Nafar, 1976) comb. n. from the fins of Hydrocynus forskahlii (Cuvier) (Alestidae: Characiformes). The new species P. lati is characterized mainly by the presence of distinct oesophageal teeth, absence of large cephalic lobes and caudal projections, and by a combination of other features. Philometra spiriformis differs from all congeners principally in the spirally coiled body and from individual species by a combination of other morphological features. The already known species P. bagri and A. hydrocyoni are redescribed based on light and scanning electron microscopy; findings of both these species in Kenya represent new geographical records.

A new species of Alestes from the Mpozo River in the Bas Congo Province of the Democratic Republic of Congo is described and diagnostic characters for the genus are presented. Alestes inferus, new species, is differentiated from all other members of the genus by its lower and non-overlapping lateral-line scale count (31–33 versus 36–51) and its reduced and non-overlapping vertebral count (39–40 versus 41–49). Within Alestes, the new species appears to be most closely related to A. macrophthalmus and A. liebrechtsii, based on the shared possession by these three species of a tubular, bony extension enclosing the olfactory nerve on the lateral ethmoid, and bifurcated lateral-line canals terminating in two pores. Alestes liebrechtsii and A. inferus are the only species of the genus known from the lower Congo River.

Ultrastructural studies of spermiogenesis in Phenacogrammus interruptus using transmission electron microscopy revealed that the process is characterized by flagellum development, formation of a cytoplasmic canal, nuclear rotation, and nuclear fossa formation. Chromatin compaction proceeds during spermatid transformation within the spermatocysts as well as after spermiation within the lumen of the efferent ducts. The spermatozoon is of primitive type and exhibits characters typical for Type I aquasperm. The head consists of a spherical nucleus with highly condensed chromatin and a centrally located electron lucent area connected to a moderate-sized nuclear fossa. The nuclear fossa contain centrioles in perpendicular arrangement, surrounded by osmiophilic fibrous material. In the short midpiece, several mitochondria and vesicles are unevenly distributed in the cytoplasm forming the cytoplasmic collar at the base of the nucleus. The cytoplasmic collar surrounds the initial part of the flagellum, running in the cytoplasmic canal. The flagellar axoneme has a typical pattern (9 x 2 + 2) and the flagellum contains membranous compartments in the portion immediately posterior to the termination of the cytoplasmic canal.

The order Characiformes (Teleostei: Otophysi) is one of the most diverse freshwater fish groups. It contains around 1400 living species in South and Central America and Africa. Their fossil record starts in the Cretaceous on both continents and also in Europe. Here, we describe and discuss the occurrences of new characiform fish teeth from Provence (Maastrichtian, S. France). Five morphological types are recognized. They belong to possibly three different taxa, and they are regarded as Characiformes indet. However, two of them have resemblances to alestin fishes and could be related to the African family Alestidae. The characiform fishes from Provence are among the oldest known in Europe, together with a freshwater characiform fish occurring in Romania, and the recently described marine fish Sorbinicharax from Italy. The biogeographical history of characiform fishes has been intensively discussed during the last three decades. The group is generally accepted to be Gondwanan and its diversification linked with the break-up of this continent, with two main scenarios depending on whether the group is archaeoor telolimnic. Some authors also propose a Pangaean origin. The recent discoveries of Sorbinicharax and of the fossils from Provence change our view on the Cretaceous characiform diversity and their early ecology, and they also enable us to re-evaluate the proposed biogeographical scenarios, reinforcing the hypothesis of the telolimny of the group. The order Characiformes (Teleostei: Otophysi) includes the well-known tetras and piranhas. It contains around 1400 living species. About 1200 are South and Central American, the rest are African. Research over the last decade has hardly improved our knowledge of their intrarelationships; but many nodes of their phylogenetic tree are still debated and the monophyly of the order Characiformes itself is contested by some authors. For example, Peng et al. (2006) suggest that the order Gymnotiformes nests within the order Characiformes on the basis of molecular data. However, most specialists now agree about the monophyly of several taxa within the order, notably the four African families, i.e. Distichodontidae and Citharinidae which are also considered to be sister-groups (Vari 1979; Fink & Fink 1981; Orti & Meyer 1997), Hepsetidae (monogeneric with Hepsetus), and Alestidae (Paugy 1986, 1990; Murray & Stewart 2002; Zanata & Vari 2005). The family Alestidae corresponds to the African members of the nonmonophyletic Characidae sensu Greenwood et al. (1966), the polyphyly of which is now widely accepted (e.g. Buckup 1998; Lucena & Menezes 1998; Toledo-Piza 2000; Zanata & Vari 2005). The family Characidae as currently defined includes only American fishes. Whether they are based on morphological (Vari 1979, 1995; Buckup 1998) or DNA studies (Orti & Meyer 1997; Calcagnotto et al. 2005), the various phylogenetic analyses agree about the sister relationship of African and South American taxa in three cases and also about the fact that, of the transatlantic groups they form, one sits at the stem of the tree of the order and the two others at its crown. (1) Distichodontidae þ Citharinidae (African) is the sister group of all the other characiform fishes (with basal South American members), except for Uj (1990) who proposed a sister relation with the family Alestidae, thus forming with Erythrinidae, Hepsetidae and Ctenoluciidae the sister group of all the other characiform fishes. (2) The families Hepsetidae (African) and Erythrinidae (South American) form a monophyletic group either alone (Uj 1990; Orti & Meyer 1997), or including other families, i.e. Ctenoluciidae (Vari 1979; Buckup 1998), Ctenoluciidae and Lebiasinidae (Calcagnotto et al. 2005). Roberts (1972) remarks that among characiforms, only hepsetids and erythrinids From: CAVIN, L., LONGBOTTOM, A. & RICHTER, M. (eds) Fishes and the Break-up of Pangaea. Geological Society, London, Special Publications, 295, 155–164. DOI: 10.1144/SP295.10 0305-8719/08/$15.00 # The Geological Society of London 2008. are ambush predators with the particular behaviour of nest building and parental care. (3) The family Alestidae (African) is the sister-group of Acestrorhynchus and forms a monophyletic group with Ctenoluciidae and Brycon þ Salminus according to Orti & Meyer (1997) and to Calcagnotto et al. (2005), whereas it is the sister group of Brycon þ Chalceus according to Lucena (1993), and of Brycon and many others including Acestrorhynchus, Hepsetidae and Erythrinidae according to Buckup (1998). Uj (1990) only proposed a sister relation with the African monophyletic group Distichodontidae þ Citharinidae. Because of the Afro-South American distribution of living characiform fishes and the age of the fossils, a Gondwanan origin of the order is usually accepted (see also discussion). Depending on the ability of early members to stand salty waters, two different palaeobiogeographical scenarios have been proposed. That living characiform fishes are strictly freshwater fishes can be interpreted as reflecting the archaeolimny of the group (the archaeoand telolimny were defined by Patterson in 1975, according to primarily or secondarily fresh water habitat). This implies a vicariant scenario for the characiform fish historical biogeography. This hypothesis was first proposed by Lundberg (1993), who stressed two main points: (1) the diversification of the main taxa in the order Characiformes might have taken place on Gondwana before its break-up; and (2) early African characiform fishes would have to have suffered great extinctions in order to explain the lack of the many sister-groups of the South American families on this continent. A vicariant interpretation could also involve a primary break-up of Gondwana with possible temporary secondary connections between the lands formed, rather than just a unique break-up event. This would allow a better explanation of the differences between the American and African diversity and also the existence of three trans-Atlantic groups, due to three vicariant events (Patterson 1984; Fink et al. 1984; Maisey 1993, 2000; Lundberg et al. 1998). However, a second interpretative scenario takes shape if the order is telolimnic. The hypothesis of the telolimny of the group is supported by the brackish or marine habitat of several basal otophysan fishes and a few extinct characiform fishes: Lusitanichthys and Salminops (Cenomanian, Portugal), which are considered to be basal characiform fishes (Gayet 1981, 1985) or basal ostariophysan fishes possibly at the stem of the Otophysi (e.g. Fink & Fink 1981; Fink et al. 1984; Patterson 1993); Chanoides (Campano-Maastrichtian and Eocene, Italy), which is a primitive otophysan fish (Patterson 1984; Taverne 2005); Santanichthys (Aptian, Brazil), which is the earliest otophysan fish known yet, and should possibly be placed at the stem of the order Characiformes (Filleul & Maisey 2004); Sorbinicharax (CampanoMaastrichtian, Italy), which is a characiform fish recently described from marine Tethyan waters (Taverne 2003); and some Eocene and Oligocene characiform fossils from France that are described from brackish environments (Cappetta et al. 1972; Gaudant 1980). Moreover, many gonorynchiform fishes and the representatives of two siluriform families inhabit coastal marine waters or brackish waters: the Plotosidae and the Ariidae to which are related some of the oldest catfish fossils. In the opinion of some authors (e.g. Chardon 1967; Gayet 1982, 1986), this reflects the telolimny of the order Characiformes (among others), and supports the hypothesis of marine dispersal between the newly separated continents of the fragmented Gondwana. Based on the same evidence, Calcagnotto et al. (2005) also call on a probable early ability of characiform fishes to withstand salty waters, to build an alternate palaeobiogeographical scenario to the vicariance with possible migration from one plate to another. They note that this scenario could appear to be relatively more parsimonious, contra Patterson (1984), Fink et al. (1984), and Filleul & Maisey (2004), among others. Here, we describe and discuss the attribution of new characiform fishes from Provence (Maastrichtian, Southern France). They are among the oldest known, notably in Europe, together with the Campano-Maastrichtian marine fish Sorbinicharax from Italy (Taverne 2003), and a freshwater Maastrichtian characiform fish reported from Romania (Grigorescu et al. 1985). For a long time, the Romanian occurrence was the only one known north of the Tethys Sea for the Cretaceous, and it was logically interpreted as resulting from the trans-Tethyan dispersal(s) that affected vertebrate continental faunas during the Late Cretaceous (e.g. Gheerbrant & Rage 2006). Geological context and age The characiform teeth were collected by one of us (X.V.) from two new localities of the Provence Basin: Verane and Les Pennes-Mirabeau (Fig. 1). The fossiliferous deposits are composed of marly horizons with carbonate rich palaeosols (nodules and root traces). They are located just above the Rognac Limestone (dated as Maastrichtian by Garcia & Vianey-Liaud 2001). The material has been obtained by screen-washing the deposits. O. OTERO ET AL. 156