Badis pancharatnaensis , a new percoid fish species from Brahmaputra River drainage , Assam , India ( Teleostei : Badidae )

Badis pancharatnaensis, a new percomorph, is described from the Brahmaputra River drainage of Assam, India. It is distinguished from its congeners by having the following combination of characters: a conspicuous black blotch on the superficial part of cleithrum; pointed soft dorsal, anal, and pelvic fins, the 2nd soft ray of pelvic-fin reaching slightly beyond the vent; 13 ‒ 14 pectoral-fin rays; circumpeduncular scales 14 ‒ 17; body depth 28.2 ‒ 33.8% of SL; interorbital distance 7.1 ‒ 9.4% of SL; and 28 number of vertebrae.


Introduction
Bleeker (1853) erected the genus Badis for Labrus badis Hamilton, 1822 by absolute tautonymy under the family Nandidae.After a comparative study on the osteology, behavior and ontogeny of the two genera, Badis and Nan dus, Barlow et al. (1968) erected the family Badidae for Badis.However, a thorough revision by kullander & Britz (2002) led to the description of a new genus Dario, and as such, the family Badidae comprises of two valid genera till date.Badis has currently 21 species and Dar io, six species (escHemeyer, 2015;Valdesalici & Van der Voort, 2015a& 2015b).
The diversity of badids lies in the southern and northeastern India, Nepal, Bangladesh, China, Myanmar, Thailand and Laos (kullander & Britz, 2002;scHindler & linke, 2010;Britz & kullander, 2013;daHanukar et al., 2015;escHemeyer & Fricke, 2015).Of the 21 species of Badis, the Brahmaputra basin alone harbours seven species, viz., Badis assamensis aHl, 1937;B. badis &kadu, 2011 andB. tuivaiei VisHwanatH &sHanta, 2004.During field surveys to a floodplain wetland -Hasila Beel, at the vicinity of the River Brahmaputra in the Goalpara District of Assam, India, the second author was able to collect specimens of an unknown species of Badis which differs from its congeners in respect to morphology and osteology.The species is herein described as Badis pancharatnaensis, new species.(2002).Morphometric measurements were made point to point on the left side of the specimens (as far as possible) with an electronic digital caliper to the nearest 0.1 mm.Meristic counts were made under a PC-based binocular stereo zoom microscope (Leica S8APO) with transmitted light.Body proportions are expressed as percentages with respect to standard length (SL).Snout length and orbital diameter are further expressed as percentages of head length (HL).

Counts and measurements follow kullander & Britz
Nomenclature of laterosensory pores follow kul lander & Britz (2002).Osteological protocols follow Hollister (1934).For identification and nomenclature of bones as well as vertebrae counts, the method of Green wood (1976) was followed.The analysis of water parameters was done by using digital water analyzing kit (Systronics 371).Photographs were taken with a Canon EOS 550D camera.
The specimens were fixed in 10% formaldehyde for morphometric study, and then transferred to 70% ethanol.The holotype and nine paratypes were deposited to Gauhati University Museum of Fishes (GUMF), Assam, India.Two paratypes were deposited to the Zoological Survey of India (ZSI), Kolkata, India.

Description
Biometric data and frequency distribution of meristic counts are provided in Table 1 and 2 respectively.Body elongate, moderately compressed laterally.Pre-dorsal contour strongly sloping till nape, running at some angle till dorsal-fin origin, giving a convex profile; along with presence of a slight depression just above orbit in larger specimens.Pre-pelvic profile less sloping, running almost horizontal from opercle to pelvic-fin base.Snout obtusely pointed with terminal oblique mouth; lower jaw slightly projecting.Both jaws bear tiny caniniform rows of teeth; with 2 rows laterally, expanding to 4 rows anteriorly.Gape of mouth reaching about ⅓ of eye diameter.Orbit situated in anterior half of the head and at about mid axis of body.Opercular spine slender ending with a sharp tip.Laterosensory pores on head (Fig. 3): 3 dentary, 2 anguloarticular, 5 preopercular, 2 nasal, 4 frontal, 1 coronalis, 3 lachrymal, 3 infraorbital, 3 pterotic, 2 posttemporal, 5 extrascapular (internally).
Pectoral-fin rounded, reaching about ½ to ⅔ of distance to anal-fin origin.Dorsal-fin starting a little ahead of pectoral-fin.Soft dorsal-fin pointed; its 23 rd fin ray reaching about half of caudal-fin.Pelvic-fin bluntly pointed with the second soft ray reaching just beyond the vent in both male and female.Caudal-fin rounded.Analfin pointed reaching about ⅓ of caudal-fin length.Colouration in life (Fig. 2): body dark brown with five distinct black bars on sides (colour variation -Bars often distinct to almost absent according to the mood of the fish).Dorso lateral half of head grayish-brown with a distinct blackish preorbital stripe continuing across chin, a black postorbital stripe formed by two successive blotches, indistinct supraorbital stripe and a black suborbital stripe faintly continuing across posterior part of lower jaw.A series of prominent blackish blotches on interra-  Sexual dimorphism.No visible differences could be seen in external morphology among male and female as dissection of freshly killed specimens for gonadal identity showed no relation of external colouration pattern or morphometric data with sexual differences.

Distribution and habitat.
Presently the species is known from Hasila Beel -a riverine wetland of Brahma putra drainage at Goalpara district, Assam, India (Fig. 4).The type locality is a low lying wetland having dense macrophytic vegetation well connected with the River Brahmaputra and often flooded by the river water; that shows high degree of rise and fall of water level depending on seasonal climatic variations (Fig. 5).The associated fish fauna caught along with the species were Amblyphar yngodon mola, Anabas testudineus, Channa gachua, Lepidocephalichthys guntea, Mastacembelus ar matus, Macrognathus pancalus, Puntius sophore and Tri cho gaster fasciata which commonly occur in the region.Water quality analysis carried out during the month of May 2015 estimated as temperature -24.8°C, pH -8.2, do -7.8mgl -1 , conductivity -194 mgl -1 and hardness -81 mgl -1 .Pelvic to anal distance 27.9 23.9 -28.1 25.9 ± 1.5 In percent of head length (HL)   Etymology.The species is named after the historical place called 'Pancharatna' in Goalpara district of Assam, India.
Fig. 1): dark cocoa brown colour body to almost black on sides within indistinct bars.Bars on sides form black blotches on scaly part of dorsal-fin base.Black blotch on cleithrum above pectoral-fin base prominent.Overall fin colouration blackish brown; pectoral-fin hyaline; caudal, soft dorsal and analfin dusky gray with darker interradial membranes.Bases of fins with dark gray to brown interradial membranes.A continuous series of black blotches starting behind the 3 rd spine along dorsal-fin base.Dorsal lappets white distally, bordered by sub marginal black stripes.Presence of prominent elongate black blotch with posterior bar surrounding the caudal-fin base (in some specimens, black bar surrounding the entire caudal-fin base without any visible blotch).
(kullander & Britz, 2002).Based on diagnostics, they have been classified under seven groups(kullander & Britz, 2002; Valdesalici & Van der Voort, 2015a, b), of which, the hitherto species described belongs to the Badis badis group, all sharing a cleithral blotch.Badis pancharatnaensis has the basic bar pattern similar to its congeners but the bars become almost indistinct to absent with respect to behavioral response of the fish towards prevailing stimulus.The new species can immediately be distinguished from B. assamensis and B. blosyrus in the absence of a blotch on opercle (vs.presence).It is also distinct from the recently described species viz., B. andrewraoi, B. autumnum and B. kyanos by the presence (vs.absence) of a cleithral blotch.The new species is distinct from B. singenensis and B. laspiophilus in the absence (vs.presence) of blotches on the dorsal-fin and anal-fin and in the presence (vs.absence) of a cleithral blotch.

Table 3 .
Comparative measurements in percentage of standard length and meristic counts of Badis pancharatnaensis sp.nov.with related species Badis pancharatnaensis is distinguished from B. di bruensis in having a deeper body