Notoglanidium akiri (Risch 1987)

Geerinckx, Tom, Vreven, Emmanuel, Dierick, Manuel, Hoorebeke, Luc Van & Adriaens, Dominique, 2013, Revision of Notoglanidium and related genera (Siluriformes: Claroteidae) based on morphology and osteology, Zootaxa 3691 (1), pp. 165-191 : 176

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 ).

Figures

FIGURE 13. Distribution of all * documented specimens of Notoglanidium species known by the authors (* not exhaustive for N. macrostoma).

FIGURE 2. A, Dorsal and B, lateral view of the skull region of Notoglanidium akiri (paratype, MRAC 84 - 15 - P- 3 – 4, 92 mm SL, lower jaw damaged). C, Dorsal and D, lateral view of the skull region of N. boutchangai (MRAC 80 - 51 - P- 10 – 11, 76 mm SL). CT scan reconstructions. Only selected structures indicated (see text for details). Scale bars = 5 mm.