Notoglanidium pallidum Roberts & Stewart 1976

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 : 182

Notoglanidium pallidum Roberts & Stewart 1976

( Figs. 4 C, 4D & 10F)

Holotype. MCZ 50236: Congo River near Bulu, west of Luozi, Democratic Republic of the Congo (Congo- Kinshasa); 5° 01’ S, 14° 01’ E; 53 mm SL (only images of specimen examined).

Paratypes. MCZ 50294: Congo River at Tadi, near Kibunzi, Democratic Republic of the Congo (Congo- Kinshasa); 5° 14’ S, 13° 56’ E; 5 out of 16 spec. examined, 19–83 mm SL. BMNH 1976.5.21.24–25: same locality; 2 spec., 40–63 mm SL. MRAC 76-17-P-5–6: same locality; 2 spec., 36–76 mm SL. MCZ 50237: same locality as holotype; 20 mm SL (not examined). MCZ 76321: same locality; two out of four cleared and stained spec. examined, 41–58 mm SL. MCZ 50379: Zaire River main stream a few km northeast of Kinganga; 73 mm SL (not examined).

Diagnosis. Notoglanidium pallidum differs from other species in the genus in having: a small eye diameter (3.8–7.0% HL) [vs. larger in N. boutchangai (7.5–10.4% HL), N. walkeri (7.8–10.6% HL), N. thomasi (9.1–12.5% HL) and N. macrostoma (9.1–13.3% HL)]; a small interorbital distance (20.0–23.3% HL) [vs. larger in N. akiri (24.1–32.8% HL), N. macrostoma (28.0–40.4% HL), N. maculatum (35.3–36.8% HL), N. thomasi (41.0–46.7% HL) and N. walkeri (27.8–33.3% HL)]; a small combined premaxillary tooth plate width (11.1–15.3% HL) [vs. larger (>18.2% HL) in N. akiri , N. boutchangai , N. depierrei , N. macrostoma and N. pembetadi ]; an average number of soft dorsal-fin rays (8–10) [vs. seven rays in N. akiri , N. boutchangai and N. macrostoma , and>10 rays in N. maculatum (16–22), N. thomasi (12–16) and N. walkeri (11–15)].

Description. Both head and body dorsoventrally flattened, with depth almost constant from head to body (predorsal body depth 10.6–14.3% SL, minimal caudal peduncle depth 9.1–10.4% SL, head depth 9.8–13.8% SL). Branchiostegal membranes fused along anterior half only, with a slit separating the posterior halves (they may overlap). Adipose fin low (2.3–3.3% SL). See also Table 4.

Colouration in life. Pallid pink, without any markings (pale brownish when preserved).

Maximum size recorded. 81 mm SL.

Etymology. The species name indicates the pale (pallidus, Latin) skin of the species.

Distribution. Congo River west of Luozi, and more downriver at Tadi (Kibunzi; Fig. 13 ).

Figures

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

FIGURE 4. A, Dorsal and B, lateral view of the skull region of Notoglanidium maculatum (syntype, BMNH 1915.5. 19.9, 49 mm SL, lower jaw damaged). C, Dorsal and D, lateral view of the skull region of N. pallidum (paratype, MRAC 76 - 17 - P- 5 – 6, 76 mm SL). CT scan reconstructions. Only selected structures indicated (see text for details). Scale bars = 5 mm.