Hepsetus cuvieri ( Castelnau, 1861 )

Zengeya, T. A., Decru, E. & Vreven, E., 2011, Revalidation of Hepsetus cuvieri (Castelnau, 1861) (Characiformes: Hepsetidae) from the Quanza, Zambezi and southern part of the Congo ichthyofaunal provinces, Journal of Natural History 45 (27 - 28), pp. 1723-1744 : 1732-1737

Hepsetus cuvieri ( Castelnau, 1861)

( Tables 5, 6; Figure 7 )

Neotype

BMNH 1910.5 .31.21, 160.0 mm SL, Lake Ngami (± 20 ◦ 30 ′ S 22 ◦ 40 ′ E) ( Botswana) Coll. Esq. R. Woosman.

Note on the neotype designation

The specimen herein designated as the neotype of H. cuvieri , although missing a few scales, was selected because it is topotypical with H. cuvieri .

Other specimens examined

Angola. BMNH 1965.3.15.351–352, 132– 175.5 mm SL, Cubangamua River, at Cuima, tributary of the Cunene River (Cuima ± 13 ◦ 13 ′ S, 15 ◦ 42 ′ E) . MRAC 158582 , 245.0 mm SL, Muita Luembe (± 7 ◦ 50 ′ S, 21 ◦ 22 ′ E) . MRAC 158583, 224.5 mm, SL, Lac Calundo (± 11 ◦ 48 ′ S, 20 ◦ 52 ′ E) . MRAC 158584, 311.5 mm SL, Maludi, River Luembe (± 8 ◦ 02 ′ S, 21 ◦ 20 ′ E) . MRAC 78-006 -P-0465, 197.5 mm SL, Lumboma, River Luembe, Basin River Kasai (± 07 ◦ 51 ′ S, 21 ◦ 27 ′ E) . MRAC 78-006 -P-0466, 171.5 mm SL, Quimbango, Moyenne River, Cuanza (± 10 ◦ 58 ′ S, 17 ◦ 35 ′ E) .

Botswana. BMNH 1976.3.18:2357-2359, 135.5–158.0 mm SL, Thalamakane River , upstream of Maun (Maun ± 19 ◦ 59 ′ S, 23 ◦ 25 ′ E) . BMNH 1976.3.18:2360-2362, 210.0– 249.5 mm SL, Shorobe lagoon, Thamalakane River, upstream of Maun (Maun ± 19 ◦ 59 ′ S, 23 ◦ 25 ′ E) . MRAC 89-012 -P-0568-570, 139.5–162.0 mm SL, Okavango delta, Tokatsebee, Boro River (± 19 ◦ 55 ′ S, 23 ◦ 30 ′ E) .

Zambia. BMNH 1969.9.25: 34, 206.5 mm SL, Voissia edge, Chiansi lagoon, Kafue ( Chiansi lagoon ± 15 ◦ 42 ′ S, 28 ◦ 00 ′ E) . MRAC 94-019 -P-0641-0643, 111.0– 138.5 mm SL, Kashilu , 5 km upstream from mouth, Luapula River (Luapula ± 9 ◦ 26 ′ S, 28 ◦ 33 ′ E) .

Democratic Republic of Congo. MRAC 14209 , 242.0 mm SL, rivière. Luapula à Kasenga (± 10 ◦ 22 ′ S, 28 ◦ 38 ′ E) . MRAC 14230 , 333.0 mm SL, Luapula à Kasenga (± 10 ◦ 22 ′ S, 28 ◦ 38 ′ E) . MRAC 81285 , 260.0 mm SL, Kasenga , fleuve Luapula (± 10 ◦ 22 ′ S, 28 ◦ 38 ′ E) . MRAC 177040-042 , 91.5 –106.0 mm SL, Kisenge , River Luashi , affluent de la rivière. Luala, Terr. De Dilolo (± 10 ◦ 41 ′ S, 23 ◦ 10 ′ E) .

Diagnosis

Hepsetus cuvieri can be distinguished from H. odoe based on a lower total number of gill rakers on the first gill arch (8–13 versus 14–21); a generally higher number of scales between the dorsal fin and the lateral line (101 / 2 – 111 / 2 versus 71 / 2 – 101 / 2); a typically higher number of scales between the adipose fin and the lateral line (61 / 2 – 71 / 2 versus 41 / 2 – 61 / 2); and a unique colour pattern characterized by a mottled appearance of the dark

brown blotches on the lateral surface of the body versus the presence of vertical brown stripes/bars in that region in H. odoe .

Description

Meristic and morphometric data are given in Tables 5 and 6 respectively. Maximum size: 350 mm SL. Head narrow and deep. Snout pointed, narrow and short. Body form elongate with dorsal and anal fins set well back. Laterally compressed, body torpedo-shaped.

Colouration of preserved specimens

Overall body colour marbled light to darker brown dorsal surface. Dark or lightbrown dorsal surface with mottled dark brown blotches (not always very obvious in preserved specimens) on flanks and cream coloured ventrally. Fins grey or blackish; generally translucent distally and sometimes transparent. Caudal fin translucent, sometimes transparent in mid-centre and central part of upper and lower lobes. Dorsal, anal and caudal fin with some small, rounded, dark-brown spots on membranes in-between rays and on rays themselves. Spots more obvious in larger individuals (±> 145 mm SL). Adipose fin cream basally, distally black. Three, well-marked, dark-brownish bands radiate behind eye on infra-orbitals and terminate on opercle. Small black dorsoventrally elongated spot present behind head above lateral line. Series of 10 to 16 small greyish elongated vertical bands, first situated just behind opercle and last situated just anterior to the caudal-fin base sometimes present. These bands tentatively identified as stress bands.

Colouration in life or in freshly caught specimens: body colour marbled brassy olive to darker brown. Dorsal surface dark brassy olive with mottled dark brown blotches on flanks and cream coloured ventrum. Adipose fin orange basally, remain- der part black ( Skelton et al. 1985; Skelton 2001).

Distribution

Hepsetus cuvieri was described from lac N’gami in Botswana by Castelnau (1861). Based on the specimens examined in this study, the distribution of H. cuvieri includes the Quanza, Cunene, Okavango, upper Zambezi and Kafue River systems. Within the Congo River Basin H. cuvieri has been found in the middle Congo Basin, i.e. the southernmost part of the Kasai Basin, and the upper Congo Basin, i.e. the Luapula River (Figure 8).

Figures

Figure 7. Lateral view of H. cuvieri, neotype, BMNH 1910.5.31.21, 160.0 mm SL, Lake Ngami (Botswana).