Puntius rohani ( Teleostei : Cyprinidae ) , a new species of barb in the Puntius filamentosus group from the southern Western Ghats of India

The cyprinid fishes of the Puntius filamentosus group presently comprise seven species, five of which are endemic to India: Puntius arulius (Jerdon), P. assimilis (Jerdon), P. exclamatio Pethiyagoda & Kottelat, P. filamentosus (Valenciennes) and P. tambraparniei (Silas), and two to Sri Lanka: P. singhala (Duncker) and P. srilankensis (Senanayake). These barbs are characterized by adult males developing filamentous extensions to the dorsal-fin branched rays and a juvenile colour pattern consisting of three black bars on the side of the body (Pethiyagoda & Kottelat 2005a). This group of fishes was last reviewed by Pethiyagoda & Kottelat (2005a), who in addition to describing a new species from southern India, revalidated several nominal species until then buried in the synonymy. These authors also drew attention to a fish illustrated as a “colour variety” of Puntius filamentosus from Periyakulam reservoir, Kanyakumari District, Tamil Nadu by Indra (1992), and suggested that it could represent an undescribed species. Recent surveys of Kanyakumari Wildlife Sanctuary resulted in fresh collections of this fish, which is described here as Puntius rohani, a new species.

posterior margin of the maxilla.Subunits of the head are expressed in proportions of both head length (HL) and standard length (SL).Numbers in parenthesis after a count denote the frequency of that count.The 4 th lateral row scale from behind opercle, above the 4 th lateral-line pored scale and 7 th lateral-line pored scale, was removed and compared with the corresponding scales of similarsized P. filamentosus from Chembarampakkam Lake.Photographs of scales were taken with an Olympus SP570 UZ digital camera using super-macro mode.

Diagnosis
Adults of Puntius rohani are distinguished from all members of the Puntius filamentosus Group sensu Pethiyagoda & Kottelat (2005a) by their unique colour pattern of a black club-shaped blotch 1.5 scales high extending from the 12-13 th lateral-line scales to the caudal-fin base, the absence of any other body colour pattern anterior to it (vs.presence in P. arulius (Image 3K), P. tambraparniei (Images 3F,G), P. srilankensis and P. exclamatio (Image 3H)), and the absence of a transverse black band near the tip of each caudal-fin lobe (vs.presence in P. assimilis (Image 4J) and P. filamentosus (Image 3E)).

Description
Morphometric data of holotype and 14 paratypes  are provided in Table 1.General body shape and appearance as in Images 1 and 3A.Body elongate, laterally compressed; dorsal contour ascending, with a low indentation at nape, slightly convex anterior to dorsalfin origin, tapering gradually ventrad posterior to dorsal-fin inserion; ventral profile equally convex anterior to pelvic-fin origin, curving gently up to anal-fin origin, thence sloping dorsad towards caudal peduncle; caudal peduncle deep, its depth a little less than its length, concave in both dorsal and ventral profiles.Head length 27.9-31.4% SL; eyes large, their diameter 25.7-32.1 % HL, positioned nearer to snout than to opercular margin; interorbital wide, a little less than eye diameter; snout length almost equal to eye diameter; males with well-developed tubercles on snout (Image 2).Mouth small, subterminal; lips thick, maxilla extending almost to anterior border of eye.A pair of maxillary barbels present, 8.2-16 % HL.Dorsal fin inserted nearer to tip of snout than to caudal-fin base, with three simple and 8½ branched rays (some branched rays extending as filaments in adults), its distal margin slightly concave.Anal fin with three simple and 5½ branched rays.Pelvic fin with one simple and eight branched rays, its origin slightly posterior to dorsal-fin origin.Pectoral fin with one simple and 13(5) or 14(10) branched rays.Pectoral and pelvic fins short, not reaching pelvic and anal-fin origins, respectively.Caudal fin with 1+9+8+1 principal rays, deeply forked, with pointed lobes.Lateral line complete, with 21(6), 22(8) or 23(1) scales on body including one scale on the caudal-fin base.Transverse scales from dorsal-fin origin to mid-ventral scale row ½4+1+3(13)-3½(2), scales between lateral line and pelvic-fin origin 2(13)-2½(2).An axillary pelvic scale present.Eighteen circumferential scales (counted as the number of scales around the greatest depth of body beginning from the first scale anterior to dorsal-fin origin), 11(14) or 12(1) circumpeduncular scales.2(9)-3(6)+6(1), 7(8), 8(5) or 9(1) gill rakers on first gill arch.
Colouration: In life, adult specimens greenish above, cream-white underside.Dorsal fin dusky, with traces of red.Pectoral and pelvic fins hyaline.Anal fin bordered with a bright red margin.Caudal fin bright red, lacking markings except for darker colour of principal rays.A dark bluish to black club-shaped marking present on tail, continuing on to principal rays of caudal fin.Formalin-fixed and alcohol-preserved specimens brownish above with a pale yellowish underside.Dorsal fin with branched rays more pigmented than other rays.All other fins creamish.Preserved juveniles express characteristic colouration of P. filamentosus group: pale yellow with three black bars on body (Image 3B).

etymology
The species is named after Rohan Pethiyagoda, in appreciation of his extensive work on the freshwater fishes of India and Sri Lanka.The species name is formed as a noun in the masculine genitive singular.

Distribution
Puntius rohani sp.nov. is at present known only from the hill streams of Kanyakumari District, Tamil Nadu, India, draining into the Arabian Sea (Fig. 1).

DIsCussIon
Fishes of the genus Puntius (Hamilton, 1822), commonly called barbs, are prolific and known to occupy a broad variety of freshwater niches in tropical Asia (Jayaram 1999).Despite a revision of the genus by Jayaram (1991), several taxonomic problems persisted in the P. filamentosus Group until the work of Pethiyagoda & Kottelat (2005a,b).One such was the identity of P. mahecola, long misidentified or considered a junior synonym of P. filamentosus.This resulted in some authors confusing the two species (e.g., Jayaram 1991;Menon 1991;Talwar & Jhingran 1991).Raj (1916) sought to differentiate the two species by the presence or absence of barbels, and a few other authors too, tried unsuccessfully to resolve this confusion (e.g., Selvaraj & Abraham 1987), but none referred to the type specimens of the two species and freshly-collected topotypes until Pethiyagoda & Kottelat (2005b), who showed P. mahecola to be distinct from P. filamentosus, and indeed not even closely related.Members of the P. filamentosus Group have a characteristic juvenile coloration of three black bars on the body, with adult males having filamentous extensions of their branched dorsal-fin rays.
Until now, the P. filamentosus Group has included seven species, two of which (P. singhala and P. srilankensis) are endemic to Sri Lanka.We have not in the present study examined Sri Lankan material but have relied on data provided in Pethiyagoda & Kottelat (2005a).The 4 th lateral row scale above the 4 th lateral-line scale and 7 th lateral-line scale of P. rohani sp.nov.was compared with those of P. filamentosus collected from Chembarampakkam Lake (Image 4) and found to be very different.The scales of P. rohani sp.nov.(3 ex.) have longer and fewer radii meeting at the focus, which is not reticulate, while the scales of P. filamentosus (5 ex.) from Chembarampakkam had numerous short radii meeting at a largely reticulated focus.Indra (1992) published a colour photograph of a barb which she identified as a colour variation of P. filamentosus from the Periyakulam Reservoir in Kanyakumari.The same species also featured in the work of Johnson et al. (2007), which compared the genetic variation in different populations of P. filamentosus from southern India using restriction fragment length polymorphism (RFLP) analysis.This study showed that the population of P. filamentosus in Alancholai, Kanyakumari District, possessed a distinct genetic identity and did not cluster with the other populations studied.The present work shows that the species from Alancholai identified as P. filamentosus by Johnson et al. (2007) is in fact a distinct (new) species and not an instance of intraspecific polychromaticism of P. filamentosus as it has a shorter interorbital width and a longer maxillary barbel length when compared to P. filamentosus.This species is now described as P. rohani sp.nov.It has a single pair of well developed maxillary barbels of length 2.5-4.6 % SL (vs.0.8-2.2% SL in P. filamentosus, 0.0-1.3% SL in P. singhala, and 7.0-10.2% SL in P. assimilis).It is also distinguished by having the mouth subterminal (vs.inferior in P. srilankensis and P. assimilis) and a greater postorbital head length of 11.2-15.2% SL (vs.8.2-10.4% SL in P. assimilis), a shorter caudal-peduncle length of 14.5-17.8% SL (vs.17.9-19.9% SL in P. singhala and 18.5-21.4% SL in P. srilankensis but longer than P. arulius, which is 13.1-14.3% SL).It further differs from P. srilankensis by its longer head of 27.9-31.4% SL (vs.24.8-26.7 % SL), and greater body depth of 32.2-39.1 % SL (vs.28-31.9% SL).Puntius rohani sp.nov.also has a narrower interorbital width of 9.0-11.1% SL (vs.11.2-12.2% SL in P. filamentosus).It further differs in meristic characters such as lateral line scale count of 21-23 + 1 (vs.18-20 + 1-3 in P. filamentosus and 19-20 in P. assimilis ), and pectoral fin with 1 simple and 13-14 branched rays (vs.15 in P. arulius, P. tambraparniei and P. srilankensis).It is likely that the locality name 'Periyakulam' mentioned by Indra (1992) is in fact Palkulam (8.371 0 N & 77.407 0 E ), which is in the same west-flowing drainage, close to the type locality, while Periyakulam (10.050 0 N & 77.593 0 E) is on the Vaigai River, which is an east-flowing drainage in Theni District, more than 200km distant from the type locality.
According to Pethiyagoda & Kottelat (2005a), though P. exclamatio belongs to the P. filamentosus Group, adult males were not known to have filamentous extensions to their dorsal-fin branched rays.Specimens of P. exclamatio (see Image 3H) collected from the Kallada River, however, exhibit such filamentous extensions and we speculate that the males examined by Pethiyagoda & Kottelat (2005a) may have had the extensions absorbed during the season in which they were collected (March-April, the end of the dry season in Kerala).Interestingly, during the present study we also encountered a few female specimens of P. filamentosus collected from Chembarampakkam Lake (13.000 0 N & 80.082 0 E) in the outskirts of Chennai, and Vaigai Dam in Theni District, Tamil Nadu, with filamentous extensions of the dorsal-fin branched rays (Image 5), which suggests that this character is not always sexually dimorphic.Moreover, we also observed that male P. filamentosus maintained in aquaria by the third author shed their dorsal-fin filaments, which grow back after some time (Image 6).We also examined specimens (Image 4I) from the Cauvery River near Bhavani Town, (ZSI/SRS F.79), which resembled P. assimilis but had a deeper body, the black band near the caudal fin tips very small and faint, and the shape of the caudal blotch more rounded than elongate (Image 3I).We propose to elucidate the identity of this fish in a subsequent work.Jerdon (1848) described P. maderaspatensis, which has been considered a synonym of P. filamentosus (Pethiyagoda & Kottelat 2005a).We collected specimens from the lakes around Sriperambathur (12.970 0 N & 80.031 0 E), the type locality of P. maderaspatensis.As mentioned by Jerdon (1848), some males from this locality possess bright red caudal fins (Image 7), apart from which they resemble P. filamentosus: we too, tentatively treat P. maderaspatensis as a synonym of P. filamentosus pending further investigation.As stated by Pethiyagoda & Kottelat (2005a) the waters of Tamil Nadu and Kerala have been inadequately explored.Systematic surveys are likely to add more species to this interesting group of fishes.