Parambassis serrata, Dishma, Mayanglambam & Vishwanath, Waikhom, 2015

Dishma, Mayanglambam & Vishwanath, Waikhom, 2015, Parambassis serrata, a new species of glassperch (Teleostei: Ambassidae) from the Kaladan drainage, India, Zootaxa 4040 (5), pp. 583-588 : 584-585

Parambassis serrata , new species

( Figs. 1−2 )

Holotype. MUMF 27381, 51.9 mm SL; India: Mizoram: Lawngtlai District: Kolo River, Kaladan drainage, 22°22′42″ N 92°59′ 56″E, 325m asl, Dishma et al., 3 May 2014.

Paratypes. MUMF 27382−27392, 37.4–60.2 mm SL; same collection data as holotype; one paratype ( MUMF 27390, 37.4 mm SL) dissected and stained for osteology.

Diagnosis. Parambassis serrata is distinguished from its closest congeners by the combination of the following characters: a faint vertically-elongated brown humeral blotch; posterior margin of most spines of first dorsal fin proximally black in colour; absence of predorsal scales; 51−56 scales in lateral series; 14−16 dorsal- and anal-fin branched rays; a black longitudinal stripe on ventral surface of caudal peduncle; 17−18 gill rakers on first gill arch; 4−9 large serrae on preopercular ridge; and 11 pectoral-fin rays.

Description. Morphometric data and counts are presented in Table 1 . Body laterally compressed. Dorsal profile slightly arched from tip of snout to occiput, rising steeply up to first dorsal-fin origin, sloping ventrad towards caudal-fin base. Ventral profile convex up to posterior end of anal-fin base, then sloping dorsad towards caudal-fin base. Eye large, its margin free. Gill membranes free from isthmus; 6 branchiostegal rays. First branchial arch with 17−18 gill rakers.

Nasal spine present. Preorbital ridge with 3−4 (12) retrose spine-like serrae, partly hidden beneath skin; preorbital edge with 4−8 (12) distinct, exposed serrae projecting ventrally; suborbital ridge not serrated. Supraorbital ridge with 3−6 (12) retrorse serrae, partly subdermal; preopercular ridge with 4–9 (12) large serrae. Lower edge of preoperculum with 7–14 (12) serrae, posteriormost ones largest; hind margin of preopercular with 10–18 (12) minute denticulations. Interoperculum smooth or with 2−7 weakly developed serrae ( Fig. 3 ).

Body covered by scales, except in predorsal region. Head naked, except 3−4 (12) scale rows on cheek. Lateralline scales 49−53 + 2−3 (12); 6 (12) rows of scales between lateral line and base of last dorsal-fin spine; ½4/1/4½ (12) scale rows across caudal peduncle. First dorsal fin with seven spines, second one longest; second dorsal fin continuous with first, with one spine and 14−16 (12) branched rays. Anal fin with three spines, third one longest, and 14−16 (12) branched rays. Pelvic fin with one spine and 5 (12) branched rays. Pectoral fin with 11 (12) rays. Caudal fin with 1 simple, 8+7 (12) branched rays and 1 simple rays. Gill rakers 17−18 (1). Total vertebrae 25 (1).

Coloration. In 10% formalin, head and body background creamish. A faint blackish axial streak on body, darker posteriorly. A small brown dot on each scale on dorsolateral surface of body. A vertically-elongate brown humeral blotch, more or less continuing immediately anterior to first dorsal-fin origin. Proximal posterior margin of most spines of the first dorsal fin blackish. Second dorsal fin with scattered melanophores on interradial membrane and bases. Pectoral and pelvic fins hyaline. Anal fin with scattered melanophores on interradial membrane. Ventral surface of caudal peduncle with a black longitudinal stripe. Caudal fin with scattered melanophores on rays and base.

Distribution. Parambassis serrata is known only from the type locality, the Kolo River, Kawlchaw, Lawngtlai District, Mizoram, India ( Fig. 4 ).

Etymology. The species name alludes to the serrated preopercular ridge. An adjective.

Habitat. The type locality, Kolo River ( Fig. 5 ) has clear, shallow water with a depth of about 0.05 m to 1.0 m (during the month of April-May). It flows from southeast to northwest and the water is fast-running, with numerous riffles among the boulders and smaller rocks. The Kolo drains into the Kaladan River. Other species occurring with Parambassis serrata include: Barilius profundus Dishma & Vishwanath , Devario sp., Garra sp., Gyptothorax ater Anganthoibi & Vishwanath, G. churamanii Rameshori & Vishwanath , G. jayarami Rameshori & Vishwanath , Olyra sp., Pethia expletiforis Dishma & Vishwanath and Semiplotus modestus (Day) .

Figures

FIGURE 1. Parambassis serrata, holotype, lateral view, MUMF 27381, 51.9 mm SL.

FIGURE 2. Parambassis serrata, holotype, MUMF 27381, 51.9 mm SL, ventral view showing a black longitudinal stripe on caudal peduncle.

FIGURE 3. Cephalic serration of Parambassis serrata, MUMF 27381, 51.9 mm SL. Abbreviation: Pe, Preorbital edge; Ns, nasal spine; Pr, preorbital ridge; Sr, supraorbital ridge; PoR, preoperculum ridge; LPo, lower edge of preoperculum; HPo, hind margin of preoperculum; IO, interoperculum.

FIGURE 4. Map showing collection locality of Parambassis serrata (Kolo River).

FIGURE 5. Kolo River, type locality and habitat of Parambassis serrata.

Tables

TABLE 1. Morphometric data of holotype and 11 paratypes of Parambassis serrata.

	Holotype MUMF 27381	Range MUMF 27381−27392	Mean	S.D.
Standard length (mm)	51.9	37.4−60.2
In % of standard length
Head length	32.7	30.7−33.5	32.6	1.2
Predorsal length	46.2	44.3–46.2	45.1	0.6
Preanal length	61.1	54.0–62.3	58.3	2.6
Body depth	49.7	44.2–50.5	47.2	1.9
Depth of caudal peduncle	12.1	10.7–12.3	11.5	0.5
Length of caudal peduncle	15.4	12.2–16.4	14.8	1.0
Body width	14.6	12.6–16.3	14.6	1.2
Snout length Eye diameter	9.6 10.4	7.7–9.6 10.1–10.7	8.6 10.5	0.5 0.2
Interorbital width	9.4	8.0–9.6	9.0	0.5
Length of dorsal-fin base	48.5	46.5–54.0	49.5	2.1
Length of anal-fin base	37.6	34.4–39.4	37.0	1.2
Length of pelvic-fin spine Length of pectoral fin Length of upper caudal-fin lobe Length of median caudal-fin rays Length of lower caudal-fin lobe	18.5 25.6 30.0 15.8 30.2	16.7–20.9 23.8–26.9 27.8–32.2 13.0–17.3 29.1–32.0	18.4 25.3 30.0 15.7 30.4	1.3 0.9 1.3 0.9 0.9