Exostoma sentiyonoae, Shangningam, 2024

Shangningam, Bungdon & Limatemjen, 2024, Exostoma sentiyonoae, a new catfish (Teleostei: Sisoridae) from Nagaland, Northeastern, India, Zootaxa 5447 (3), pp. 424-432 : 425-428

Exostoma sentiyonoae , new species

urn:lsid:zoobank.org:act:8F62926A-848E-43D0-A926-7525BEEC9AE1

( Fig. 1 )

Type material. Holotype. ZSI FF 9871, 75.8 mm SL, India: Nagaland: Kohima District: Dzuleke River, a tributary of the Barak River (Barak-Surma-Meghna drainage) near Dzuleke village , 25.62 º N 93.95 º E, 1765m asl. Limatemjen, 18 October 2022.

Paratypes. ZSI FF 9872, 6 ex., 36.5–75.8 mm SL, data as for holotype .

Common name: Khokhwü (in Angami Naga local dialect)

Diagnosis.

Exostoma sentiyonoae is distinguished from congeners in having a combination of the following characters: presence of tubercles on dorsal-fin spine, anterolateral surfaces of lip with parallel and rounded striae, adipose fin confluent with upper procurrent caudal-fin rays, slender head 7.7–13.1% SL, long maxillary barbel 56.6–70.1 % HL, long dorsal-adipose distance 16.8–24.6% SL, small eye 5.1–8.8 % HL, 10 branched pectoral-fin rays, and 41 vertebrae.

Description. Morphometric data as in Table 1 . Head and body broad, very strongly depressed, with paired fins greatly enlarged to form elongate ovoid adhesive disc. Dorsal profile rising gently from internarial region to base of dorsal fin, thereafter elevating gently towards adipose fin, and sloping ventrally to base of caudal fin. Rostral margin rounded in dorsal view, moderately curved in lateral view. Ventral profile flat to anal-fin base, then rising gently to end of caudal fin. Anus and urogenital openings located closer to anal-fin origin than posterior end of pelvic fin.

Eyes subcutaneous, dorsolaterally situated. Gill openings narrow, extending from base of first pectoral-fin ray to above dorsal much higher than level of last pectoral-fin base. Barbels in four pairs. Nasal barbel long, reaching to posterior margin of orbit. Maxillary barbel flattened, with flap of skin fringing posterior margin; its tip pointed; ventral surface with numerous striae; extending to base of first pectoral-fin ray. Inner mandibular barbel slightly flattened, very short; originating from notch on posterior margin of lower lip. Outer mandibular barbel situated lateral to inner mandibular barbel; slightly flattened, reaching almost first pectoral-fin ray.

Mouth inferior with broad, fleshy, papillate lips ( Fig. 2 ). Tooth patches on both jaws separated in midline. In closed mouth, most of premaxillary tooth patches exposed. Teeth in jaws distally flattened, oar-shaped and in two rounded triangular patches narrowly separated at midline on upper jaw. Lower lip with prominent labial fold, uneven at insertions of inner mandibular barbels. Teeth on lower jaw situated in two well-separated, unevenly triangular patches. Palate edentulous. Anterolateral surfaces of lip with numerous fine, parallel, rounded striae. Dorsal surface of head with small scattered conical tubercles.

Dorsal fin without spine, with i,6 (7) rays; surfaces of fin covered with small conical tubercles. Adipose-fin base long, anterior extremity at vertical through middle of posterior end of pelvic fin and anal-fin origin, posterior extremity confluent with upper procurrent caudal-fin rays. Pectoral fin greatly enlarged, without spine and with i,10 (7) rays; first ray greatly flattened, with numerous parallel striae on ventral surface. Pelvic fin enlarged, with convex distal margin and i,5 (7) rays, first ray greatly flattened, with numerous parallel striae on ventral surface. Anal fin with i,5 (7) rays. Caudal fin with i,6,7,i (3) or i,7,8,i (4) rays, its posterior margin slightly lunate, lower lobe slightly longer than upper. Vertebrae 41.

Coloration. In 70 % ethanol, dorsolateral surfaces of head and body brown, with yellow on the ventral surfaces of head, and anterior body to genital opening. Distal margin of dorsal, pectoral, pelvic and anal fins hyaline, brownish black basally. Adipose fin dark brown, distally lighter. Caudal fin hyaline medially, brown basally and distally. Maxillary and nasal barbels brownish and creamish-grey ventrally. Mandibular barbels cream white.

Distribution. Exostoma sentiyonoae is currently known only from its type locality, Dzuleke River, a tributary of the Tepuiki River (Barak drainage) near Dzuleke village, Kohima District, Nagaland, India ( Fig. 3 ).

Habitat. The type locality in Dzuleke River ( Fig. 4 ) is a gently-flowing, clear-water stream with rocks and boulders as substrate. However, during the monsoon season, it becomes torrential and muddy. The river features substrates such as rocks and boulders, microhabitats such as rapids, and pools, and riparian vegetation comprising trees, shrubs, and other plant species adapted to local climatic conditions.

Etymology. Exostoma sentiyonoae is dedicated to Miss Sentiyono, the lovely daughter of the second author. The specific name is a noun in the genitive case.

Figures

FIGURE 1. Exostoma sentiyonoae, holotype, ZSI FF 9871, 75.8 mm SL. Dorsal, lateral, and ventral views.

FIGURE 2. Exostoma sentiyonoae, holotype, ZSI FF 9871, 75.8 mm SL. Dorsal and ventral views of head.

FIGURE 3. Map showing the type locality of Exostoma sentiyonoae in Dzuleke River in Nagaland.

FIGURE 4. Dzuleke River in Nagaland, a tributary of the Barak River, type locality of Exostoma sentiyonoae.