Hepsetus akawo, Decru & Vreven & Snoeks, 2011

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: 13-19

publication ID

http://doi.org/ 10.1080/00222933.2011.622055

persistent identifier

http://treatment.plazi.org/id/87098107-1145-FF9A-8759-22BF261341CD

treatment provided by

Felipe

scientific name

Hepsetus akawo
status

sp. nov.

Hepsetus akawo   sp. nov.

Type material

Holotype. MRAC 73-5 View Materials -P-465; 211.5 mm; Anecho, lagune (± 06 ◦ 14 ′ N, 01 ◦ 35 ′ E), Coll. D. Thys van den Audenaerde (10 September 1966). GoogleMaps  

Paratypes. MRAC 73-5 View Materials -P-457-459; n = 2; 194.5–221.5 mm; Dunkwa, riv. Ofin (05 ◦ 58 ′ N, 01 ◦ 47 ′ W) Coll. D. Thys van den Audenaerde (22 September 1966) GoogleMaps   .

MRAC 87-18 View Materials -P-762; 200.0 mm; Kosua, small tributary of the Wawa River near Dodi- Papase (07 ◦ 42 ′ N, 00 ◦ 29 ′ E); Coll. G. Teugels (17 February 1987) GoogleMaps   .

MRAC 73191 View Materials (ex. MRAC 73191-73192 View Materials ); n = 1; 167.5 mm; Abomey-Calavi (06 ◦ 27 ′ N, 02 ◦ 21 ′ E) Coll. Cadenat, J. GoogleMaps  

MRAC 73-1 View Materials -P-428; 189.5 mm; Porto Novo, lagune (06 ◦ 29 ′ N, 02 ◦ 37 ′ E); Coll. P. De Kimpe (15 November 1963) GoogleMaps   .

MRAC 80-16 View Materials -P-8; 221.0 mm; Asejura lake, Oshun riv., Dugbe market Ibadan (07 ◦ 20 ′ N, 04 ◦ 10 ′ E); Coll. G. Teugels & L. Risch (2 May 1980) GoogleMaps   .

Diagnosis

Hepsetus akawo   can be distinguished from all other Hepsetus species   by the following unique combination of characters: number of lateral line scales, low: 43–51; nostril-lower jaw distance, short: 36.6–42.1 (mean 39.6) % HL (Figure 3); number of gill rakers, high: 17–23; number of scales between dorsal fin and lateral line: 71 / 2 – 91 / 2 number of scales between adipose fin and lateral line: 41 / 2 – 61 / 2 head width, broad: 32.8–42.3 (mean 37.0) % HL; and internasal distance, high: 21.9–28.3 (mean 24.7) % HL.

Description

The holotype is illustrated in Figure 6 View Figure 6 . Maximum observed size: 277.5 mm SL. Meristic and morphometric data are given in respectively Table 5 and 6.

Head broad but shallow, with a relatively long but broad snout. Body elongated and broad, which gives it a plump appearance. Dorsal and anal fins, though in a posterior position in all Hepsetus species   , are more anteriorly positioned relatively to the other Hepsetus   . Small number of lateral line scales and a large number of quite small gill rakers on the epibranchiale of the first gill arch.

Differential diagnosis

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

Hepsetus akawo   can be distinguished from H. cuvieri   by a higher number of gill rakers (17–23 vs 8–13), a lower number of scales between dorsal fin and lateral line (71 / 2 – 91 / 2 vs 101 / 2 – 111 / 2); a lower number of scales between adipose fin and lateral line (41 / 2 – 61 / 2 vs 61 / 2 – 71 / 2); and by a broader head width: 32.8–42.3 (mean 37.0 % HL vs 27.8–40.4 (33.5) % HL; a larger interorbital distance 28.0–34.9 (mean 31.7) % HL vs 23.7–32.6 (28.2) % HL; and a larger internasal distance 21.9–28.3 (mean 24.7) % HL vs 18.0–26.8 (20.8) % HL. The latter three characters are positively allometric.

Colouration (in alcohol)

Dorsal side of head and body brownish, with a gradual change from darker to lighter tones on the flanks. Entirely yellowish ventrally. Some specimens darker brownish and 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, resulting from the scales having a darker upper and lower border, whereas the remaining part of the scales remains paler. These lines cover the flanks from approximately three scale rows above lateral line down to two scale rows below the lateral line. Sometimes series of 10 to 16 greyish vertical bands are 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 head and just above 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. Rounded dorsoventrally elongated blackish spot behind the head, above the lateral line.

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, dark-brown spots. Spots on fins more prominent on larger specimens (±> 150 mm SL). Adipose fin base yellowish to darker brownish, black distally.

Distribution

Within West Africa, H. akawo   is restricted to the easternmost part of the region, i.e. from the Sassandra River ( Ivory Coast) in the west to the Shari River ( Central African Republic) in the east and the Cross River ( Cameroon / Nigeria) in the southeast

( Figure 5 View Figure 5 ). Elsewhere it also occurs in Lower Guinea, from the Cross ( Cameroon) to the Kribi River ( Cameroon) (see additional specimens examined).

Etymology

The specific name refers to the local names in the Adangme language of Hepsetus   specimens in Ghana: “ Akawo nyagbe ”, which means “dog-like teeth” and “ akawo   ” which means “attacker” or “predator” ( Dankwa 2003).

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

Sassandra: MRAC 73-5 View Materials -P-466; 184.5 mm; Guiglo, riv. Nzo (06 ◦ 33 ′ N, 07 ◦ 29 ′ W) GoogleMaps   . MRAC 73-10 View Materials -P-961; 160.5 mm; Guiglo, riv. Nzo (06 ◦ 33 ′ N, 07 ◦ 29 ′ W) GoogleMaps   . MRAC 85- 55 View Materials -P-128; 108.0 mm; riv. N’Zo, tribut. Du Sassandra à Guiglo (06 ◦ 33 ′ N, 07 ◦ 29 ′ W) GoogleMaps   . MRAC 86-13 View Materials -P-21; 234.5 mm; riv. Méné, sur la route entre San Pedro et Sassandra (05 ◦ 02 ′ N, 06 ◦ 31 ′ W) GoogleMaps   .

Bandama: MRAC 74-14 View Materials -P-2765; 277.5 mm; lac Kossou (07 ◦ 10 ′ N, 05 ◦ 20 ′ W) GoogleMaps   .

Bia: MRAC 80-19 View Materials -P-41; 178.0 mm; lagune Ebrié à Layo (05 ◦ 19 ′ N, 04 ◦ 19 ′ W) GoogleMaps   . MRAC 95-014 View Materials -P-0235-0238; 202.0–222.0 mm; Ayamé, lac d’Ayamé (05 ◦ 36 ′ N, 03 ◦ 09 ′ W) GoogleMaps   . MRAC 74-14 View Materials -P-2581; 149.0 mm; lac Kossou (07 ◦ 10 ′ N, 05 ◦ 20 ′ W) GoogleMaps   . MRAC 95- 014 View Materials -P-0240-0242., 194.0–219.0 mm; Bianouan, riv. Bia (06 ◦ 01 ′ N, 03 ◦ 12 ′ W) GoogleMaps   .

Volta Noire : MRAC 143762-763 View Materials ; 196.5–217.5 mm   ; Volta Noire (11 ◦ 34 ′ N, 02 ◦ 50 ′ W // 12 ◦ 45 ′ N, 04 ◦ 18 ′ W). MRAC 141116 View Materials ; 134.5 mm; riv. Bougouriba, afflt. De la GoogleMaps   Volta Noire (10 ◦ 56 ′ N, 03 ◦ 39 ′ W) GoogleMaps   .

Volta Rouge : MRAC 143761 View Materials ; 226.0 mm; petite afflt. de la   Volta Rouge, près Kokologho, route Ouagadougou-Koudougou (12 ◦ 10 ′ N, 01 ◦ 51 ′ W) GoogleMaps   .

Pra: MRAC 73-5 View Materials -P-460; 125.5 mm; Dunkwa, riv. Ofin (05 ◦ 58 ′ N, 01 ◦ 47 ′ W). MRAC 73-5 View Materials -P-461; 92.5 mm; Dunkwa, riv. Ofin (05 ◦ 58 ′ N, 01 ◦ 47 ′ W) GoogleMaps   .

Lake Volta / Rivers: MRAC 73-7 View Materials -P-27; 165.5 mm; Anpem , lac Volta (06 ◦ 40 ′ N, 00 ◦ 25 ′ W) GoogleMaps   . MRAC 73-11 View Materials -P-54; 222.0 mm; Fazao alt: 500 m (08 ◦ 42 ′ N, 00 ◦ 46 ′ E) GoogleMaps   . MRAC 73-11 View Materials -P-55; 193.0 mm; Fazao alt: 500 m (08 ◦ 42 ′ N, 00 ◦ 46 ′ E) GoogleMaps   .

Mono: MRAC 73-14 View Materials -P-50-51; 126.5–138.0 mm; Dotékopé, riv. Mono (woodland + galerijwoud) alt: 150 m (07 ◦ 49 ′ N, 01 ◦ 18 ′ E) GoogleMaps   . MRAC 73-14 View Materials -P-52; 134.5 mm; Ogbone (07 ◦ 46 ′ N, 01 ◦ 19 ′ E) GoogleMaps   . MRAC 73-5 View Materials -P-462-464; n = 4 (instead of 3); 97.5–109.5 mm; Corrékopé, riv. Mono (07 ◦ 48 ′ N, 01 ◦ 16 ′ W) GoogleMaps   . MRAC 73192 View Materials (ex. MRAC 73191-73192 View Materials ); n = 1; 125.0 mm; Abomey-Calavi (06 ◦ 27 ′ N, 02 ◦ 21 ′ E) GoogleMaps   . MRAC 90-13 View Materials -P-1; 139.0 mm; lac Nokoue, station de Ganvie (06 ◦ 28 ′ N, 02 ◦ 25 ′ E) GoogleMaps   . MRAC 73-1 View Materials -P-425; 125.0 mm; Awansouri, lac Nokoué (06 ◦ 23 ′ N, 02 ◦ 26 ′ E) GoogleMaps   .

Lower Niger: MRAC 91-10 View Materials -P-301-302; 137.5–142.0 mm; Akpor , New Calabar River (04 ◦ 52 ′ N, 06 ◦ 54 ′ E) GoogleMaps   . MRAC 90-19 View Materials -P-72; 126.0 mm; Elele-Alimini , New Calabar River (05 ◦ 03 ′ N, 06 ◦ 44 ′ E) GoogleMaps   . MRAC 91-01 View Materials -P-80; 118.5 mm; Odieke , Orashi River (05 ◦ 01 ′ N, 06 ◦ 27 ′ E) GoogleMaps   . - MRAC 91-055 View Materials -P-0236; 142.0 mm; Forcados River , about 1 km west of Oboro and 7 km northwest of Bomadi (05 ◦ 11 ′ N, 05 ◦ 52 ′ E) GoogleMaps   .

Cross: MRAC 86-39 View Materials -P-2; 217.0 mm; Itu bridge   , Cross River (05 ◦ 11 ′ N, 08 ◦ 03 ′ E). MRAC 88-03 View Materials -P-12-13; 100.0–164.0 mm; site 2: Calabar GoogleMaps   , Cross River (04 ◦ 58 ′ N, 08 ◦ 19 ′ E) GoogleMaps   .

Shari: MRAC 73-26 View Materials -P-46; 266.5 mm; région au sud de Hollom (11 ◦ 10 ′ 20 ′′ N, 15 ◦ 03 ′ 10 ′′ E) GoogleMaps   . MRAC 82-13 View Materials -P-1015; 201.5 mm; campement de Gounda, riv. Gounda (09 ◦ 13 ′ N, 21 ◦ 00 ′ E) GoogleMaps   . MRAC 82-13 View Materials -P-1014; 265.0 mm; riv. Gounda, pont route Ndele- Birao (08 ◦ 33 ′ N, 21 ◦ 30 ′ E) GoogleMaps   .

Benoué: MRAC 73-15 View Materials -P-21; 198.0 mm; Garoua (gekocht) (09 ◦ 18 ′ N, 13 ◦ 24 ′ E). MRAC 73-15 View Materials -P-215; 276.5 mm; Garoua, riv GoogleMaps   . Benoué (09 ◦ 18 ′ N, 13 ◦ 24 ′ E) GoogleMaps   .

Cross: MRAC 88-53 View Materials -P-113-114; 53.5–120.5 mm   ; Cross basin, small stream on Bamenda-Mamfé road, 98 km southwest of Bamenda, 24 km north of Mamfé (05 ◦ 43 ′ N, 09 ◦ 27 ′ E) GoogleMaps   . MRAC 73-40 View Materials -P-22; 274.0 mm; Nguti, Ohumbe   River on the Mamfe road (05 ◦ 18 ′ N, 09 ◦ 26 ′ E) GoogleMaps   . MRAC 73-40 View Materials -P-21; 257.5 mm; Nguti, under the bridge, Ohumbe   River (05 ◦ 18 ′ N, 09 ◦ 26 ′ E) GoogleMaps   .

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

Sassandra : MRAC 86-13 View Materials -P-22-30; 22.0– 30.1 mm; riv. Méné, sur la route entre San Pedro et Sassandra (05 ◦ 02 ′ N, 06 ◦ 31 ′ W). MRAC 86-13 View Materials -P-31; 219.2 mm; Grand Gallo, riv. Nieri (04 ◦ 47 ′ N, 06 ◦ 56 ′ W) GoogleMaps   .

Bandama: MRAC 87-18 View Materials -P-756-758; 28.3–32.0 mm; riv. N’Zi , sur la piste entre Katiola et Dabakala (08 ◦ 14 ′ N, 04 ◦ 51 ′ W). MRAC 87-18 View Materials -P-759; 25.2 mm; riv. Maraoué, à env. 15 km de Mankono sur la piste entre Mankono et Séguéla (08 ◦ 07 ′ N, 06 ◦ 42 ′ W) GoogleMaps   .

Bia: MRAC 86-18 View Materials -P-335; 126.2 mm; Koui (= Koun) près de Yaou, riv. La Bia (07 ◦ 30 ′ N, 07 ◦ 16 ′ W) GoogleMaps   . MRAC 173384-385 View Materials ; 111.5–129.5 mm; lagune Ebrié (05 ◦ 09 ′ N, 04 ◦ 00 ′ W // 05 ◦ 19 ′ N, 04 ◦ 52 ′ W) GoogleMaps   . MRAC A0-046-P-0004; 208.5 mm; riv. Niouniourou (± 5 ◦ 06 ′ N, 5 ◦ 29 ′ E) GoogleMaps   . MRAC 74-17 View Materials -P-292-297; 260.5–294.5 mm; lac Kossou (07 ◦ 10 ′ N, 05 ◦ 20 ′ W // 07 ◦ 00 ′ N, 05 ◦ 30 ′ W) GoogleMaps   . MRAC 95-014 View Materials -P-239; 251.5 mm; riv. Agneby , pont autoroute (05 ◦ 29 ′ N, 04 ◦ 14 ′ W) GoogleMaps   .

Tano: MRAC 85-29 View Materials -P-243-244; 145.2–167.3 mm; Noe, riv. Tano (05 ◦ 18 ′ N, 02 ◦ 47 ′ W) GoogleMaps   .

Comoe: MRAC A0-044-P-0049; 31.0 mm; affl. sec. Mamou, ont près d’Annepé, bassin Mé (05 ◦ 54 ′ N, 03 ◦ 46 ′ W) GoogleMaps   . MRAC 86-18 View Materials -P-1296; 36.0 mm; Yakassé-Attobrou, riv. La Mé (05 ◦ 49 ′ N, 03 ◦ 57 ′ W) GoogleMaps   . MRAC A0-046-P-0050; 110.5 mm; riv. Mé, 3km E. d’Annepé (05 ◦ 54 ′ N, 03 ◦ 45 ′ W) GoogleMaps   . MRAC 97-27 View Materials -P-1; 18.0 mm; Wiawso (06 ◦ 12 ′ N, 02 ◦ 29 ′ W) GoogleMaps   .

Pra: MRAC 87-18 View Materials -P-760-761; 22.0– 57.5 mm; Ofin River near Ahenkro , between Kumasi and Ofinso (06 ◦ 53 ′ N, 01 ◦ 38 ′ W) GoogleMaps   .

Lake Volta / Rivers: MRAC 94-011 View Materials -P-0014; Densu River at Koforidua (06 ◦ 05 ′ N, 00 ◦ 22 ′ W) GoogleMaps   .

Ouéme: MRAC 73-01 View Materials -P-426-467; 108.6–144.5 mm; Porto Novo, lagune (06 ◦ 29 ′ N, 02 ◦ 37 ′ E) GoogleMaps   .

Lower Niger: MRAC 91-10 View Materials -P-295-300; 104.7–153.7 mm; Akpor, New Calabar River (04 ◦ 52 ′ N, 06 ◦ 54 ′ E) GoogleMaps   .

Niger: MRAC 76-32 View Materials -P-1228; 29.2 mm; ro 69/1 mellem Lafia og Akwanga (08 ◦ 29 ′ N, 08 ◦ 31 ′ E) GoogleMaps   . MRAC 76-32 View Materials -P-1937; 14.0 mm; bro 63/3 v. for Bida   pa Jebba vejen (09 ◦ 05 ′ N, 06 ◦ 01 ′ E) GoogleMaps   .

Bénoué: MRAC 73-15 View Materials -P-217; 212.2 mm; Garoua, riv   . Benoué (09 ◦ 18 ′ N, 13 ◦ 24 ′ E). MRAC 76-14 View Materials -P-227; 153.0 mm; Touroua, riv. Faro (09 ◦ 05 ′ N, 12 ◦ 58 ′ E) GoogleMaps   .

Wouri: MRAC 73-29 View Materials -P-702; 147.5 mm; Tondé, riv. Sandjé, Wouri bekken (04 ◦ 13 ′ N, 09 ◦ 50 ′ E) GoogleMaps   . MRAC 73-2 View Materials -P-984-987; 115.0–138.0 mm; Deido, riv. Wouri, 4 km en amont du pont à Douala (04 ◦ 04 ′ N, 09 ◦ 43 ′ E) GoogleMaps   . MRAC 73-29 View Materials -P-707; 142.0 mm; Yabassi, riv. Wouri (04 ◦ 27 ′ N, 09 ◦ 58 ′ E) GoogleMaps   . MRAC 73-29 View Materials -P-702; 147.5 mm; Tondé, riv. Sandjé, Wouri bekken (04 ◦ 13 ′ N, 09 ◦ 50 ′ E) GoogleMaps   . MRAC 73-2 View Materials -P-984-987; 115.0–138.0 mm; Deido, riv. Wouri, 4 km en amont du pont à Douala (04 ◦ 04 ′ N, 09 ◦ 43 ′ E) GoogleMaps   . MRAC 73-29 View Materials -P-707; 142.0 mm; Yabassi, riv. Wouri (04 ◦ 27 ′ N, 09 ◦ 58 ′ E) GoogleMaps   .

Sanaga: MRAC 73-08 View Materials - 85-86 View Materials ; 186.5–189.0 mm; Edea, riv. Sanaga (03 ◦ 48 ′ N, 10 ◦ 08 ′ E) GoogleMaps   . MRAC 95-089 View Materials -P-1546 (ex. MRAC 95-089 View Materials -P1545-1546); 79.5 mm; riv. Djin à Djin, sur la route de Yoko, Sanaga Moyen (05 ◦ 26 ′ N, 12 ◦ 19 ′ E) GoogleMaps   . MRAC 73- 2 View Materials -P-976-977; 208.0– 218.5 mm; Edéa, riv. Sanaga, en aval du pont (03 ◦ 48 ′ N, 10 ◦ 08 ′ E) GoogleMaps   .

Kribi: MRAC 77-17 View Materials -P-3; 139.0 mm; 16 km south east of Kribi (02 ◦ 57 ′ N, 09 ◦ 54 ′ E) GoogleMaps   .

MRAC

Musée Royal de l’Afrique Centrale