Glyptothorax gopii, Kosygin & Das & Singh & Chowdhury, 2019

Kosygin, Laishram, Das, Ujjal, Singh, Pratima & Chowdhury, Basudhara Roy, 2019, Glyptothorax gopii, a new species of catfish (Teleostei: Sisoridae) from Mizoram, north-eastern India, Zootaxa 4652 (3), pp. 568-578 : 569-570

Glyptothorax gopii , new species

( Fig. 1 )

Type material. Holotype. ZSI FF 5007, 63.5 mm SL; India: Mizoram: Champhai district: Tuipui River near Champhai ( Kaladan River drainage), 23°27’N 93°15’E; Santanu Mitra & party, September 24, 2013.

Paratypes. ZSI FF 5008, 1, 61.6 mm SL; same data as holotype. ZSI FF 5009, 1, 57.0 mm SL; same data as holotype .

Diagnosis. Glyptothorax gopii is distinguished from congeners in the Indian subcontinent by the combination of the following characters: an axe-shaped anterior nuchal plate element with extensive contact with the posterior nuchal plate ( Fig. 2a ); the presence of plicae on the ventral surface of the pectoral-fin spine and outer rays of pelvicfin rays ( Figs. 3a, b ); skin sparsely tuberculated; dorsal-fin spine length 16.3–17.8% SL; thoracic adhesive apparatus elliptical, with lanceolate median depression ( Fig. 3c ), its length 16.2–20.7 % SL; predorsal length 36.2–38.1 % SL; adipose-fin base length 16.5–18.1% SL; postadipose distance 16.2–17.4% SL; caudal peduncle depth 7.9–9.1 % SL; nasal barbel not reaching the anterior margin of the eye; the first branchial arch with 2–3 + 4–5 rakers; and body with two longitudinal pale-cream stripes, one each along mid-dorsal line and lateral line.

Description. Morphometric data are presented in Table 1 . Body elongate. Head depressed with almost truncate snout when viewed dorsally and ventrally. Dorsal profile rising evenly from tip of snout to origin of dorsal-fin, then sloping gently from there to end of caudal peduncle. Occipital process not in contact with anterior nuchal plate element. Anterior nuchal plate element visible as a saddle with axe-shaped extensions, extensively in contact with posterior nuchal plate element. Ventral profile flat up to posterior end of pectoral-fin base, then slightly convex to anterior margin of pelvic-fin base, thereafter rising gently to end of caudal-fin base. Caudal peduncle deep. Mouth inferior, lips papillate, teeth on upper jaw as one continuous band, its anterior margin almost truncate; teeth on lower jaw in two patches, separated by a wide partition. Eyes small, round, located on dorsal surface of head. Thoracic adhesive apparatus elliptical, longer than broad, extending from isthmus to posterior end of pectoral-fin base with lanceolate median depression, almost enclosed posteriorly by loosely packed dermal ridges ( Fig. 3c ). Anus and urogenital opening located at vertical through posterior half of adpressed pelvic-fin. Skin on head and body sparsely tuberculate. Lateral line complete, mid-lateral. First branchial arch bearing 2+4 (2) or 3+5 (1) rakers. Total vertebrae 35 comprised of 18 abdominal and 17 post-abdominal vertebrae.

Barbels in four pairs. Maxillary barbel long, slender, reaching middle of pectoral-fin base. Outer mandibular barbel longer than inner, not reaching gill opening. Nasal barbel short, not reaching anterior margin of orbit when adpressed, extending halfway to orbital margin.

Dorsal fin located halfway between snout tip and adipose-fin origin, with i,6 (3) rays. Dorsal-fin spine strong, gently curved, with slightly rough surface posteriorly, shorter than depth of body at dorsal-fin origin. Adipose-fin short, anterior margin straight, posterior margin slightly convex. Pectoral-fin longer than head, with i,8 (2) or i,9,i (1) rays; posterior margin slightly concave. Pectoral-fin spine broad, anterior margin smooth, posterior margin with 13–14 serrae. Pelvic fin with i,5 (3) rays, not reaching the origin of anal-fin when adpressed. Ventral surface of pectoral-fin spine and simple and adjacent branched ray of pelvic-fin pleated ( Figs. 3a, b ). Anal fin long, with ii,8,i (2) or ii,9 (1) rays, its origin slightly posterior to adipose-fin origin. Caudal fin forked, with i,9,8,i (3) rays.

Coloration. In 70 % alcohol: Dorsal surface of head and body dark brown, lateral surface yellowish-light brown fading to yellowish cream ventrally. Nuchal plate elements visible as a distinct pale axe-shaped saddle overlying plate elements ( Fig. 2a ). Two prominent pale creamish longitudinal stripes: one mid-dorsal, originating from occiput, and another mid-lateral originating from eye, extending to caudal-fin base ( Fig. 1 ). Dorsal fin proximally blackish brown at base, distally hyaline. Adipose fin creamish yellow, with a broad dark-brown band at middle. Caudal-fin dusky with two black blotches at base, margins hyaline. Pectoral-fin spine dorsally dusky, pelvic and anal fins uniformly cream.

Distribution. The species is presently known only from the type locality, the Tuipui River near Champhai, Champhai District, Mizoram (Kaladan River drainage), India.

Etymology. The species is named after K.C. Gopi (retired scientist) of the Zoological Survey of India, Kolkata, honouring his contribution to the Indian Ichthyology.

Figures

FIGURE 1. Glyptothorax gopii, ZSI FF 5007, holotype, 63.5 mm SL; dorsal, lateral and ventral views.

FIGURE 2. Dorsal view of nuchal plate elements of: (a) Glyptothorax gopii, holotype, ZSI FF 5007, 63.5 mm SL; (b) G. ater, paratype, ZSI FF 4618, 48.5 mm SL; (c) G. chimtuipuiensis, paratype, ZSI FF 4617, 40.0 mm SL; (d) G. churamanii, paratype, ZSI FF 5271, 60.0 mm SL; (e) G. jayarami, paratypes, ZSI FF 4620, 84.5 mm SL; (f) G. caudimaculatus, paratype, ZSI FF 4619, 39.4.0 mm SL; and (g) G. verrucosus, paratype, ZSI 5272, 60.0 mm SL, from Kaladan River drainage. Illustrations not to scale.

FIGURE 3. Glyptothorax gopii, ZSI FF 5007, holotype, 63.5 mm SL; a. Ventral surface of pectoral-fin showing plicae; b. Ventral surface of pelvic-fin showing plicae and c. Thoracic adhesive apparatus.