A new catfish , Hara koladynensis from northeastern India ( Siluriformes : Erethistidae )

Author Details: N. ANGANTHOIBI is a Project Fellow under a project funded by the National Bureau of Fish Genetic resources, Lucknow. She is working on the inventory of the catfishes of North East India and their phylogenetic analysis. She is undergoing PhD on a relevant topic in the Department of Life Sciences, Manipur University. W. VISHWANATH is a Professor in the Department of Life Sciences, Manipur University. His field of specialization is fish and fisheries. He is presently engaged in taxonomy and systematics of freshwater fishes of northeastern India.


INTRODUCTION
Fishes of the genus Hara Blyth of the family Erethistidae are characteristic in having a stumpy body, unidirectional denticles along the outer margin of pectoral fin, externally smooth and internally serrated dorsal fin and a thorax with no adhesive apparatus (Hora 1950).It is also characterized in having coracoid with ventral anterior process, pectoral spine with serrated anterior margin, antero-ventral flange on the ventral surface of the complex centrum and the parapophysis of the fifth vertebra with a vertical lamina (de Pinna 1996).The genus includes small to medium sized catfishes having brown cryptic colouration and heavily tuberculate skin inhabiting hill streams in the subhimalayan region and western Indochina (Ng & Kottelat 2007).Hamilton (1822) described Pimelodus hara from Hooghly River, India.Hora (1950) considered the species as a representative of the genus Hara.Hara buchanani Blyth (1860) and Pimelodus asperus McClelland ( 1844) are now considered junior synonyms of H. hara (Ng & Kottelat 2005;Ferraris 2007).Day (1870) described Hara jerdoni from Sylhet district, Bangladesh.Misra (1976) described H. horai from Terai and Duars, West Bengal.Ng & Kottelat (2007) described H. longissima, H. minuscula and H. spinulus from Myanmar and H. mesembrina, H. filamentosa from Thailand.They also treated H. saharsai Munshi & Srivastava (1988) and H. serrata Vishwanath & Kosygin (2000) as junior synonyms of H. hara.Thus eight species of Hara are known so far.
A recent collection of fishes from Koladyne River, Mizoram, India included a new Hara species which is herein described as H. koladynensis.

MATERIAL AND METHODS
Measurements were made on the left side of specimens with dial calipers to the nearest 0.1mm following Ng & Kottelat (2007).Head length (HL) and measurements of body parts are presented as proportions of standard length (SL) and subunits of head as of head length (HL).Numbers in parentheses following meristic data denote number of specimens examined with that count.Osteological structures were observed in cleared and alizarin stained specimens.Vertebral counts followed Roberts (1989).Two paratypes of H. koladynensis (SL = 56.4& 58.0 mm) were dissected for osteology.Fin rays were counted under a stereo-zoom light microscope.Type specimens are deposited in the Manipur University Museum of Fishes (MUMF).

Description
Morphometric data are shown in Table 1.Body robust, moderately compressed laterally.Dorsal profile gently curved from tip of snout to level of nares, then sloping steeply to the origin of dorsal fin and evenly sloping ventrally to the end of caudal peduncle.Ventral profile roughly straight and flat upto origin of pelvic fin, then gently sloping dorsally to the end of caudal peduncle.Head ventrally compressed and longer than width.Supraoccipital process long reaching anterior tip of nuchal plate.Eyes moderate, superior in position.
Snout narrow, profile dorsally curved and rounded when viewed laterally and acutely triangular when viewed from above.Snout with pronounced steepening of curvature anteriorly at level of posterior nares when viewed laterally.Anterior and posterior opening of nares large and separated by flap of skin comprising base of nasal barbel.Gill opening narrow, extending ventrally upto the level of base of coracoid process.Bony elements of dorsal surface of head very prominent and covered with thin tuberculate skin.
Barbels in four pairs.Maxillary barbel when adpressed extend beyond the base of the pectoral spine.Nasal barbel short, subtending by a flap of skin at base and extending to midway between posterior edge of posterior nares and anterior margin of orbit.Anterior mandibular barbel when adpressed reaching the anterior base of pectoral spine; posterior mandibular, when adpressed reaching the gill opening.
Mouth inferior, premaxillary tooth band not exposed when mouth is closed.Upper lip with indistinct plicae.Oral teeth small and villiform, in irregular rows on all tooth-bearing surfaces.Premaxillary teeth in single crescentic band across midline.Palate edentulous.Dentary teeth in two narrow crescentic bands separated at midline.Anus and urogenital openings located straight through posterior three quarters of adpressed pelvic fin.Skin tuberculated, distributed evenly throughout head and body.Lateral line complete and mid lateral.Vertebrae 15+17=32(2).Dorsal fin located above anterior third of body, with I,5,i (6) rays.Dorsal spine moderately long and gently curved backward with rough anterior margin, posterior margin with 5-6 serrae.Adipose fin with anterior margin straight and posterior margin angular.Caudal fin with i,7,7,i (5) or i,6,7,i (1) principal rays.Lower lobe of caudal fin slightly longer than the upper lobe.Analfin base approximately in line with adipose-fin base.Anal fin with iii,7 (6) rays.Pelvic fin with i,4,i (1) or i,5 (5) rays.Pectoral fin with I,6,i rays; anterior margin with 15-25 small distally directed serrations, posterior margin with 7-12 large medially directed serrations.Coracoid with well developed posterior processes, extending to two thirds distance between base of posteriormost pectoral-fin ray and pelvic-fin origin.
Coloration: Head and body dark chestnut to dark chocolate brown.Belly and ventral surface of head light brown, that of head lighter and creamish.Two thin irregular light brown bars on body; first chevron-shaped and located between dorsal and adipose-fin bases, second thicker than first located on caudal peduncle.Dorsal fin dark brown except for thin hyaline distal margin.Pectoral fin brown with thin hyaline distal margin and either a small ovoid hyaline spot or a crescentic median hyaline band on middle third of fin.Pelvic and anal fins hyaline, with dark brown bases and subdistal stripes.Adipose fin brown as in body, with lighter coloured distal margin.Caudal fin hyaline, with irregular W-shaped band subdistally and with small dark brown flecks randomly distributed throughout fin.Maxillary and mandibular barbel light brown, with dark brown annuli.

Etymology
The species is named after Koladyne River, Mizoram, India, its type locality.

DISCUSSION
Hara koladynensis is easily distinguished from its congeners by the combination of characters mentioned in diagnosis.The new species also differs from H. jerdoni in having longer caudal peduncle ) and shorter pectoral spine (28.9-31.0%SL vs. 42.2-51.7);from H. horai in having wider eye diameter (11.5-17.5% HL vs. 8.0-9.0) and from both the species in having longer caudal fin  Most of the highly specialized rheophilic fish species in Southeast Asia have restricted distribution ranges (Kottelat 2001).Hara koladynensis is found in the Koladyne River (also known as Kaladan or Chimtuipui) which originates from the western face of Chin Hills in Myanmar bordering Mizoram and Manipur states of India.At Kolchaw, the river bottom is rocky and the water current is very fast.The river is not connected with Ganga-Brahmaputra and Chindwin-Irrawaddy drainages as it is respectively separated by the Chittagong hill tract and the Arakan Yoma hill range.The isolated habitat is expected to support many endemic species including the new species.

Figure 1 .
Figure 1.Map of Mizoram showing type locality (star) of Hara koladynensis sp.nov.