Notoglanidium akiri (Risch 1987)

(Figs. 2A, 2 B & 10A)

Auchenoglanis akiri Risch 1987

Holotype. MRAC 84-15-P-9: Imo river at Umuayara Mba, Etche Rivers State, Nigeria; 4°52’N 7°02’E; 91 mm SL.

Paratypes. MRAC 84-15-P-3–4: same locality; 2 spec., 88–92 mm SL.

Other specimens examined. MRAC 87-24-P-124–125: New Calabar river at Eveku, Nigeria; 4°55’N, 6°49’E; 2 spec., 59–85 mm SL. MRAC 87-24-P-126–131: New Calabar River at Rumuji, Nigeria; 4°56’N, 6°47’E; 6 spec., 32–74 mm SL. MRAC 88-43-P-307–308: New Calabar, Isiokpo River 3 km south of Isiokpo town, Nigeria; 4°53’N, 6°53’E; 2 spec., 61–69 mm SL. MRAC 93-39-P-73–74: Etim Ekpo, Kwa Ibo River, Nigeria; 5°09’N, 7°40’E; 2 spec., 97–107 mm SL.

Diagnosis. Notoglanidium akiri differs from other species in the genus in having: an average interorbital distance (24.1–32.8% HL) [vs. smaller in N. boutchangai (17.2–23.4% HL), N. depierrei (18.2–23.7% HL), N. pallidum (20.0–23.3% HL) and N. pembetadi (17.4–24.0% HL), and larger in N. maculatum (35.3–36.8% HL) and N. thomasi (41.0–46.7% HL)]; a large eye diameter (6.6–10.5% HL) [vs. smaller in N. maculatum (3.3–5.3% HL) and N. pallidum (3.8–7.0% HL)]; a deep adipose fin (4.7–7.3% SL) [vs. less deep in other species except N. macrostoma and N. walkeri (see Table 4)]; an average combined premaxillary tooth plate width, (22.0–26.1% HL) [vs. broader in N. boutchangai (30.1–35.3% HL) and N. macrostoma (33.5–41.7% HL) and smaller (18.2% HL) or less, in all other species except N. depierrei and N. pembetadi]; only seven soft (branched) dorsal-fin rays [vs. more than eight in N. depierrei (9–10), N. maculatum (16–22), N. pallidum (10–13), N. pembetadi (10–13), N. thomasi (12–16) and N. walkeri (11–15)]; a high dorsal-fin spine length (9.8–12.8% SL) [vs. shorter (<7.5% SL) (see Table 4), in all other species except N. macrostoma].

Description. Snout only moderately depressed, body not depressed (predorsal body depth 19.5–24.4% SL, minimal caudal peduncle depth 13.0–15.9% SL, head depth 58.0–75.9% HL). Branchiostegal membranes completely fused. Adipose fin rather high, at 4.7–7.3% SL. See also Table 4.

Colouration in alcohol. Brown to greyish; in juveniles the flanks and the adipose fin have a reticulate pattern which may vaguely persist or disappear in adults. Dorsal and caudal fins sometimes spotted; other fins always uniformly greyish.

Maximum size recorded. 107 mm SL.

Etymology. Named in honour of P.J. Akiri, collector of the type specimens (Risch 1987).

Distribution. Known from the Imo and New Calabar River basins, southern Nigeria (Fig. 13).