Parambassis bistigmata, Geetakumari, Khangjrakpam, 2012

Geetakumari, Khangjrakpam, 2012, Parambassis bistigmata, a new species of glassperch from north-eastern India (Teleostei: Ambassidae), Zootaxa 3317, pp. 59-64 : 60-61

Parambassis bistigmata , new species

( Figs. 1–2 )

Holotype. MUMF /Per–105, 39.3 mm SL; India: Arunachal Pradesh state: Ranga River, Kimin station, Brahmaputra drainage, 27°21'01'' N 93°57'11'' E; Kenjum Bagra., 6 May 2011.

Paratypes. MUMF /Per–106 – 108, 3, 33.1– 41.2 mm SL; same collection data as holotype. MUMF /Per–108, 1, dissected, cleared and stained for osteology; MUMF /Per–109– Per–111, 3, 35.2– 40.1 mm SL; India: Meghalaya state: Umtrao River, Brahmaputra drainage, I. Dhanabir Singh, 3 Mar 2005.

Diagnosis. Parambassis bistigmata is distinguished from all its congeners by presence of two distinct black spots on either side of the anal-fin origin, connected by a narrow black curved line; a well developed pre-orbital edge with prominent, acute spines, partially obscuring the maxilla; dorsal and ventral side of caudal peduncle each with a black longitudinal stripe; and the presence of a vague, faint, vertically-elongate humeral spot.

Description. Biometric data are presented in Table 1. Body laterally compressed, dorsal and abdominal profiles convex, rising steeply from the occiput to base of first dorsal fin, then gently sloping posteriorly becoming almost level at caudal peduncle. Eye large, its margin free. Gill membranes free from isthmus; 6 branchiostegal rays. First branchial arch with 2–3 + 12 gill rakers.

Holotype Paratypes (N=6)

mean range s.d.

Standard length (mm) 39.3 33.13–41.16

In % SL

Head length 33.8 31.2 27.9–34.4 3.6 Predorsal length 40.3 42.1 40.3–43.8 3.0 Preanal length 59.6 66.3 59.5–73.1 7.2 Body depth 36.4 36.2 34.4–37.9 1.7 Depth of caudal peduncle 11.9 11.6 10.7–12.4 2.3 Length of caudal peduncle 15.2 15.7 15.1–16.3 2.6 Body width 15.0 12.9 10.7–15.1 2.1 Snout length 9.8 8.1 6.3–9.9 1.6 Eye diameter 10.2 10.3 9.9–10.7 3.1 Interorbital width 9.5 10.5 9.4–10.7 2.5 Length of dorsal-fin base 49.2 49.7 49.0–50.3 1.6 Length of anal-fin base 32.4 32.1 31.4–32.8 0.8 Length of pelvic-fin spine 15.1 15.7 15.1–16.3 2.6 Length of pectoral fin 21.0 20.3 18.7–21.8 6.7 Length of upper caudal-fin lobe 27.7 27.1 22.8–31.4 3.6 Length of median caudal-fin rays 10.5 10.5 9.4–10.7 1.2 Length of lower caudal-fin lobe 27.7 27.1 22.8–31.4 3.6 Nasal spine present. Preorbital ridge with 5–6 (5) retrorse spine-like serrae; preorbital edge with 6–7 (6) distinct, exposed serrae projecting ventrally; serrae prominent, with sharp, pointed edges, partially obscuring maxilla. Suborbital ridge not serrated. Supraorbital ridge with 4–5 (4) retrorse serrae, partly subdermal. Preopercular ridge absent. Lower edge of preoperculum with 15–17 (15) serrae, posteriormost ones largest; hind margin of preoperculum subderminal, interoperculum smooth ( Fig. 3 ).

Body covered by scales, except in predorsal area. Head naked, except for 3–4 (4) scale rows on cheek. Lateralline scales 63–65 + 2–4 (63+2); 10 rows of scales between lateral line and base of last dorsal spine; ½9/1/9½ scale rows in transverse line on caudal peduncle. First dorsal fin with 7 spines, second one longest; second dorsal fin continuous with first, with 1 spine and 11–12 (11) branched rays (last two rays articulate on same pterygiophore, counted as one). Anal fin with three spines, third one longest with 11–12 (11) branched rays. Pelvic fin with one spine and five rays. Pectoral fin with 10 rays. Caudal fin with 1+8+7+1 principal rays, vertebrae 25 (2).

Coloration. In 10% formalin (the type series was subsequently transferred to 70% ethanol). Head and body background creamish. Occipital region with a few patches of melanophores. A faint blackish axial streak on body, darker posteriorly. Scale margins outlined by indistinct melanophores. A faint vertically elongate humeral blotch present. Two distinct black spots on either side of the anal fin origin, connected by a narrow black curved line ( Fig. 2 ). Dorsal and ventral side of caudal peduncle each with a black longitudinal stripe. The interradial membrane between the second and fourth spines of first dorsal with a distinct blackish outer margin, second dorsal hyaline. Pectoral, pelvic and anal fins hyaline. Caudal fin with scattered melanophores on interradial membrane.

Etymology. The species name alludes to the two distinct black spots at either side of the anal fin origin; it is formed as a noun.

Distribution. Parambassis bistigmata is known from the type locality, in the Ranga River, Arunachal Pradesh, Brahmaputra drainage and in Umtrao River, Brahmaputra drainage, Meghalaya State, northeast India (Fig. 4).

Figures

FIGURE 1. Lateral view of Parambassis bistigmata, holotype, MUMF / Per – 105, 39.3 mm SL.

FIGURE 2. Ventral view of Parambassis bistigmata, holotype, MUMF / Per – 105, 39.3 mm SL.

FIGURE 3. Cephalic serration of Parambassis bistigmata, MUMF / Per – 106, 33.1 mm SL.