Hepsetus odoe ( Bloch, 1794 )

Decru, E., Vreven, E. & Snoeks, J., 2011, A revision of the West African Hepsetus (Characiformes: Hepsetidae) with a description of Hepsetus akawo sp. nov. and a redescription of Hepsetus odoe (Bloch, 1794), Journal of Natural History 46 (1 - 2), pp. 1-23 : 8-13

Hepsetus odoe ( Bloch, 1794)

Type material

Holotype: ZMB 3615, 149.4 mm SL, Coast of Guinea, provided by Dr Isert ( Paepke 1999).

Diagnosis

Hepsetus odoe can be distinguished from all other Hepsetus species by the following unique combination of characters; number of lateral line scales, high: 50–60 (exceptionally 49); nostril-lower jaw distance, high: 40.4–47.6 (42.6) % HL (Figure 3); number of gill rakers on first arch, low: 14–22; number of scales between dorsal fin and lateral line: 71 / 2 – 91 / 2; and number of scales between adipose fin and lateral line: 41 / 2 – 61 / 2.

Description

A representative specimen is illustrated in Figure 4 . Maximum observed size: 350.0 mm SL. Meristic and morphometric data are given in respectively Tables 3 and 4.

Head intermediately broad, but relatively deep. Intermediate snout width and snout length compared with congeners. Body rather broad, more or less as broad as the head. Body form elongate, with dorsal and anal fins, though in a posterior position in all Hepsetus species , more forward-positioned relative to the other Hepsetus . High number of scales and an intermediate to high number of quite small gill rakers on the first gill arch.

Differential diagnosis

Hepsetus odoe can be distinguished from H. akawo by a higher total number of lateral line scales [50–60 (exceptionally 49) vs 43–51], and by a longer nostril-lower jaw distance [40.4–47.6 (42.6) % HL vs 36.6–42.1 (39.6) % HL].

Notes: SL, standard length; HL, head length.

Hepsetus odoe can be distinguished from H. cuvieri by a higher number of gill rakers (14–22 vs 8–13), a lower number of scales between dorsal fin and lateral line (71 / 2 – 91 / 2 vs 101 / 2 – 111 / 2); and a lower number of scales between adipose fin and lateral line (41 / 2 – 61 / 2 vs 61 / 2 – 71 / 2).

Colouration (in alcohol)

General colour pattern quite variable from light brownish with a yellow belly to a dark brownish colour all over the body. Dorsal surface of head and body darker than ventrally with a gradual change from darker to lighter tones on the flanks. Some specimens more uniformly coloured. A vague horizontal line pattern on the flanks, from anterior border of adipose fin (occasionally from posterior border of dorsal fin) to caudal fin base is sometimes present, resulting from the scales having a darker upper and lower border, while the remaining part of the scales remains paler. These lines cover the flanks from approximately three scale rows above down to two scale rows below the lateral line. Higher on the flanks, there is sometimes a mosaic pattern in the overall colour of the scales (darker and brighter scales alternating) from approximately three scales above the lateral line to eight lines above the lateral line. Sometimes series of 10 to 16 greyish vertical bands present on the dorsolateral body parts. The presence of these bands appears to be linked to stress (personal observation). Rounded dorsoventrally elongated blackish spot behind the head and just above the lateral line.

Posterior part of head with three, well-marked, dark brownish bands running from posterior border of the eye to anterior edge of preopercle. Bands sometimes faded and poorly visible. Lower half of postopercle brownish, sometimes blackish. All fins but the adipose fin yellowish to dark brownish (more or less the same as body colour); distally translucent. Caudal fin translucent, in mid-centre and proximally on upper and lower lobes. Dorsal, anal and caudal fins with prominent small, roundish, darkbrown spots. Spots on fins more prominent on larger specimens (±> 150 mm SL). Some large specimens (±> 290 mm SL) with spots also on pelvic fins. Adipose fin base yellowish to darker brownish, black distally.

Distribution

The distribution of H. odoe covers the westernmost part of the distribution area of the genus ( Figure 5 ). The species is known from the region between the Senegal River ( Senegal) in the west to the Cavally River ( Ivory Coast) in the east.

Etymology

The specific name is possibly derived from the Greek ‘ odon ’ which means tooth ( Brown 1954).

Additional specimens examined (ordered by river system; all sizes as SL)

Senegal: MRAC 73-5 -P-449; 226.0 mm; Dakar Bango, riv. Djeuss, près de St-Louis (16 ◦ 03 ′ N, 16 ◦ 29 ′ W) .

Casamance: MRAC 73-5 -P-451-452; 198.5–202.5 mm; Guérina, marigot, bassin fl. Casamance (12 ◦ 46 ′ N, 16 ◦ 15 ′ W) .

Gambia: MRAC 73-5 -P-450., 289.5 mm; Georgetown, fl . Gambie (13 ◦ 31 ′ N, 14 ◦ 45 ′ W) . MRAC 81-03 -P-282; 120.0 mm; Ba-Foula-Bé, riv . Gambia (13 ◦ 01 ′ N, 13 ◦ 14 ′ W) . MRAC 79-2 -P-165-169; n = 3; 147.0–192.0 mm; Ba-Foula-Bé, riv . Gambia (13 ◦ 01 ′ N, 13 ◦ 14 ′ W) . MRAC 80-01 -P-81-82; 195.5– 125.5 mm; Ba-Foula-Bé, riv . Gambia (13 ◦ 01 ′ N, 13 ◦ 14 ′ W) .

Waanje: MRAC 73-10 -P-966; 314.0 mm; Kalu, pêche dans le lac Mabesi et la riv. Malen (07 ◦ 14 ′ N, 11 ◦ 45 ′ W) . Moa: MRAC 73-10 -P-967; n = 2 (instead of one); 169.5–180.5 mm; near Moa River, north east of Kenema , marigots près de la Moa River, à 4–5 km du nord du pont (07 ◦ 52 ′ N, 11 ◦ 08 ′ W) . MRAC 73-10 -P-971-974; n = 2; 125.5–174.5 mm; Pendehun, riv. Moa, à ± 3 km en amont du pont (07 ◦ 51 ′ N, 11 ◦ 09 ′ W) .

Kogon: MRAC 92-059 -P-0648; 203.0 mm; Kamouri, riv. Batapon, affl. rio Nuñez (11 ◦ 00 ′ N, 14 ◦ 19 ′ W) . MRAC 92-059 -P-00657; 149.5 mm; Ndyarendi, riv. Kogon (± 11 ◦ 21 ′ N, 14 ◦ 30 ′ W) . MRAC 92-059 -P-0649; 177.0 mm; Ndyarendi, riv. Kogon (± 11 ◦ 21 ′ N, 14 ◦ 30 ′ W) . MRAC 92-059 -P-0650-0655; n = 5; 169.0–230.0 mm; Dabiss, riv. Aboulapon , affl. Kogon (11 ◦ 11 ′ N, 14 ◦ 32 ′ W) .

Kapatchez: MRAC 92-059 -P-0636-0647; n = 11; 144.0–180.0 mm; rio Kapatchez , pont près de Songolon (Kakala) (10 ◦ 43 ′ N, 14 ◦ 22 ′ W) .

Loffa: MRAC 73-10 -P-975; 276.0 mm; Bombo-junction, marais et marigots à ± 16 km à l’est de Mano, route Mano-Bomi Hills (07 ◦ 22 ′ N, 10 ◦ 53 ′ W). MRAC 73-10 -P- 976; 303.0 mm; bombo-junction, marais et marigots à ± 16 km à l’est de Mano, route Mano-Bomi Hills (07 ◦ 22 ′ N, 10 ◦ 53 ′ W) .

St Paul: MRAC 73-10 -P-977; 343.0 mm; Mount Coffee , St. Paul riv., lac de barrage (06 ◦ 32 ′ N, 10 ◦ 35 ′ W) .

St. John: MRAC 80-36 -P-814; 178.0 mm; Jusohn , Sangwin bekken (06 ◦ 04 ′ N, 08 ◦ 37 ′ W) . MRAC 73-10 -P-978; 287.0 mm; Hartford , riv. St. John, en aval du pont et des premiers rapides (05 ◦ 59 ′ N, 09 ◦ 59 ′ W) . MRAC 80-36 -P-815; 199.5 mm; Chesla , Sangwin bekken (06 ◦ 07 ′ N, 08 ◦ 34 ′ W) . MRAC 80-36 -P-813; 131.5 mm; Jusohn , Sangwin bekken (06 ◦ 04 ′ N, 08 ◦ 37 ′ W) .

Cavally: MRAC 80-36 -P-812; 215.5 mm; Zleh Town , Cavalla basin (06 ◦ 13 ′ N, 08 ◦ 25 ′ W) . MRAC 80-19 -P-42-43; 227.0–256.0 mm; riv. Cavally en face du village de Tai (05 ◦ 52 ′ N, 07 ◦ 27 ′ W) . MRAC 85-29 -P-241-242; 209.0– 228.5 mm; Binhouye , riv. Nipoué (06 ◦ 47 ′ N, 08 ◦ 19 ′ W) . MRAC 73-10 -P-963; 110.0 mm; Sahibli , riv. Cavally (06 ◦ 33 ′ N, 08 ◦ 20 ′ W) . MRAC 73-10 -P-965; 140.4 mm; village Zoguiné , marigots du bassin de la riv. Cavally (06 ◦ 32 ′ N, 08 ◦ 28 ′ W) . MRAC 73-10 -P-959-960; 107.0– 130.5 mm; Sahibli , riv. Cavally (06 ◦ 33 ′ N, 08 ◦ 20 ′ W) .

Additional specimens identified (ordered by river system; all sizes as SL)

Gambia: MRAC 73-5 -P-456; 183.0 mm; Kounkane , riv. Kanyanga, tributaire de la riv. Geba (12 ◦ 55 ′ N, 14 ◦ 06 ′ W). MRAC 81-03 -P-283-284; 114.0– 130.5 mm; Kayanga riv. (12 ◦ 49 ′ N, 14 ◦ 10 ′ W). MRAC B0-16-P-001-0010, 222.5–295.0 mm SL Rivière Gambie au village Kani Kunda , situe à l’est de la ville de Farafenni (± 13 ◦ 33 ′ N, 15 ◦ 24 ′ W) Khady Diouf Goudiaby and Mamadou N’diaye, 22 July 2010 .

Cassamance: MRAC 73-5 -P-453-455; 205.5–208.8 mm; Kolda, haut fl. Casamance (12 ◦ 53 ′ N, 14 ◦ 57 ′ W) .

Moa: MRAC 73-10 -P-968-969; 64.6–107.5 mm; Pendehun, riv. Moa, à ± 3 km en amont du pont (07 ◦ 51 ′ N, 11 ◦ 09 ′ W). MRAC 73-10 -P-970; 67.0 mm; Pendehun, riv. Moa, à ± 3 km en amont du pont (07 ◦ 51 ′ N, 11 ◦ 09 ′ W) .

Kogon: MRAC 92-059 -P-0656; 56.8 mm; Pabole, afflt. du Kogon (11 ◦ 21 ′ N, 14 ◦ 08 ′ W) .

St John: MRAC 80-36 -P-801; 310 mm; L . T.C. camp (06 ◦ 16 ′ N, 08 ◦ 40 ′ W) . MRAC 80-60 -P-803-809; 113.0– 245.2 mm; Cestos , south of L . T.C. (± 06 ◦ 16 ′ N, 08 ◦ 43 ′ W) . MRAC 80-36 -P-810-811; 42.0– 43.2 mm; Duo Town (05 ◦ 42 ′ N, 08 ◦ 06 ′ W) . MRAC 80- 36 -P-802; 106.0 mm; Duzei , Cestos bekken (06 ◦ 16 ′ N, 08 ◦ 42 ′ W) .

Nipoué: MRAC 73-10 -P-964; 112.5 mm; Toyebli, riv. Cess (06 ◦ 38 ′ N, 08 ◦ 29 ′ W). MRAC 86-18 -P-336-337; 113.0– 132.5 mm; Binhouye, riv. Nipoué (06 ◦ 47 ′ N, 08 ◦ 19 ′ W) .

Cavally: MRAC 73-10 -P-962; 293.3 mm; Sahibli, riv. Cavally (06 ◦ 33 ′ N, 08 ◦ 20 ′ W) .

Figures

Figure 4. Lateral view of Hepsetus odoe, representative specimen, 288.0 mm standard length, Gambia River (MRAC B0-16-P-1-10).

Figure 5. Distribution of Hepsetus odoe and Hepsetus akawo based on the examined specimens from West Africa. Localities of H. odoe indicated by open circles; and for H. akawo large filled triangle indicates type locality; smaller filled triangles indicate other localities.