Badis dibruensis, a new species (Teleostei: Badidae) from northeastern India

Author Details: KH. GEETAKUMARI is a research scholar in the Department of Life Sciences, Manipur University. She is pursuing research in Phylogenetic studies of fishes belonging to the order Perciformes found in northeastern India under the supervision of W. Vishwanath. W. VISHWANATH is a professor in the Department of Life Sciences, Manipur University. His field of specialization is Fish and Fisheries. He is at present engaged in taxonomy and systematics of freshwater fishes of northeastern India


INTRODUCTION
described Labrus badis and L. dario from Gangetic provinces. Bleeker (1854) established genus Badis for L. badis under family Nandidae. Barlow et al. (1963) erected a new family, Badidae, in which Badis has been incorporated based on osteological characters. The genus is separated from the nandid genus Nandus in having a smooth (versus serrated) preopercular margin and edentulous (versus toothed) tongue. As per Kullander & Britz (2002) the genus is characterized by a combination of the following features: opercle with a single sharp spine at its posterodorsal corner; spinous and soft dorsal fins contiguous, the base of the soft part longer than that of the spinous part; anal fin with three spines; lateral line pores tubed and interrupted; jaws, vomer and palatines with villiform teeth; scales both ctenoid and cycloid; 2-4 dentary foramina; hypobranchial 3-toothed; males with short pelvic fin, not reaching the first dorsal spine; short dorsal fin lappets; rounded caudal fin. Ahl (1937) described Badis badis assamensis from Assam, while Talwar & Jhingran (1991) did not recognize any subspecies of B. badis. Kullander & Britz (2002)

MATERIALS AND METHODS
Measurements were made point to point with dial calipers to the nearest 0.1mm and expressed as percentages of standard length (SL). Counts and measurements were made on the left side of specimens under a PC-based binocular stereo zoom microscope (Olympus SZ40) with transmitted light. Counts and measurements followed Kullander & Britz (2002). The method of clearing and staining of specimens for osteology follows Hollister (1934). Identification and nomenclature of bones and vertebral counts follows Greenwood (1976). For branchial toothplate count, the first gill arch on the left side of the specimens was taken, and plates starting from hypobranchial to epibranchial of the outer side were counted. Type specimens are deposited in the Manipur University Museum of fishes (MUMF).

Description
Morphometric data and counts are in Tables 1 & 2, respectively. Frequency distributions of meristic characters are provided in Table 3 and comparison with related species in Table 4. Body elongate, moderately compressed laterally. Predorsal profile in small specimens straight, sloping at some angle as of prepelvic profile in larger specimens and more strongly as the size increases. Orbit situated in anterior half of head, at about mid-lateral axis of body. Jaws almost equal anteriorly, lower jaw slightly projecting, maxilla reaching to 1/ 3 of orbit. Opercular spine slender, with a sharp tip. Palatine, vomer and parasphenoid toothed.
Soft dorsal and anal fins with rounded tips reaching to almost about 1/3 or 1/4 of caudal fin. Caudal fin rounded. Pectoral fin rounded, extending about 2/3 distance to anal-fin origin. Pelvic fin pointed, inner branch of second soft ray longest, not reaching up to vent. Orbital diameter, interorbital width and upper jaw length respectively (7.69.4), (9.9-15.0) and (7.1-8.3) % SL.

Colouration
In 10% formaline, overall dark brownish to yellowish. Preorbital stripe dark grey, continued across chin; postorbital stripe blackish, formed by a single blotch close to orbit; dark pigment also on one scale posterior to that blotch. No supraorbital stripe. A conspicuous black blotch covering the superficial part of the cleithrum above pectoral-fin base. Dorsal fin dusky. Dorsal lappets white along distal margin, bordered by blackish submarginal stripe in male. Caudal fin with a small oval black blotch at middle of base, also covering last lateral scale on body. Anal fin dusky basally, soft part hyaline throughout in large specimens. Pelvic fin dusky in small specimens, dark brown in large specimens. Vertical dark black or brown bars are completely absent across the side and caudal peduncle.

Sexual dimorphism
Males have uniform dark brown fins with white dorsal fin lappets along distal margin, bordered by blackish submarginal stripe. Extension of the posteriormost tip of the dorsal fin extends upto 1/2 of the caudal fin.
In females, body pale yellow with dark grey spots, fins with uniform light brown coloration. Extension of the posteriormost tip of dorsal fin extends upto 1/3 of the caudal fin.

Etymology
Named after the Dibru River, the type locality.

DISCUSSION
Badis dibruensis is similar to B. badis, B. kanabos and B. tuivaiei in having a conspicuous dark blotch covering the superficial part of cleithrum above pectoral-fin base. However, the species differs from them in morphometric characters as in diagnosis above.   B. chittagongis of Matamohuri River drainage, Bangladesh, in absence (vs. presence) of the vertical bars across side and caudal peduncle. Kullander & Britz (2002) classified the species of Badis into five groups viz., B. ruber group, B. assamensis group, B. corycaeus group, B. kyar group and B. badis group. The species of B. badis group share a cleithral blotch. They expected more number of species in B. badis group from the view i.e. the limited material from India, variable characters and scattered locality record of the species. The present species under diagnosis belongs to B. badis group.
Out of the known 13 valid species of Badis, six is reported from northeast India. In addition to this the present species under study is also from the Brahmaputra basin. General inventory and phylogenetic study of the diverse species of Badis in northeast India and adjoining areas would be of great interest.