Garra arupi, a new cyprinid fish species (Cypriniformes: Cyprinidae) from upper Brahmaputra basin in Arunachal Pradesh, India

Author contribution: W. VISHWANATH The study: Supervision of taxonomy and phylogeny of freshwater fishes of northeastern India. Current paper: Supervised the work and helped in identifying the species. K. NEBESHWAR The study: Morphometric study and identification of fish species. Current paper: Detailed examination of specimens and comparison with closely related species to establish the new species. D.N. DAS The study: Exploration fish species in the region. Current paper: Supervision of fish collection and assisted in comparative study.


MATERIALS AND METHODS
The descriptions are based on formalin preserved specimens.Counts, measurements and terminology follow Kullander & Fang (2004).Measurements were taken point to point with digital calipers to the nearest 0.1mm.The number in parentheses after a specific count indicates number of specimens examined.Fin rays and number of scales were counted under a zoom stereoscopic microscope.Terminology used for description of disc follows Zhang et al. (2002).Other measurement techniques adopted are as follows: disc width, the widest portion of the lower lip; disc length, length from anterior mid-point of the anterior papillated skin fold to the posterior mid-point of the posterior margin of mental disc; head height, distance from the midline at occiput vertically downward to ventral contour of the breast; lateral line scales, counted from the anteriormost scale in contact with the shoulder girdle to the last scale on the caudal fin; lateral transverse scales above the lateral line, counted from the dorsal fin origin to the lateral line obliquely ventral and caudal and scales below lateral line are counted from the ventral fin origin obliquely dorsal and rostral to lateral line and also from the anal fin origin to the lateral line.Measurements of the head parts are also given in percentages of head length for comparison with data of literature.For vertebral count, eight 198 specimens were dissected and stained with alizarin S. Vertebral count includes the first four vertebrae of Weberian apparatus.Abdominal vertebrae were counted from the first four vertebrae of the apparatus to the last vertebra bearing pleural rib and caudal vertebrae, from the vertebra immediately posterior to the anal fin pterygiophore.Types of the comparative materials were physically examined for the study.

Description
Measurements and counts of specimens (35.5-72.4mmSL) are given in Table 1.A comparison of the species with its closest congeners is in Table 2.The general appearance of the body is in Image 1, the ventral appearance of body in Image 2, and the morphology of dorsum of head in Image 3. Body elongate, slightly compressed laterally, more on caudal peduncle region.Dorsal profile of body slightly convex from tip of the supraoccipital process to dorsal fin origin.Dorsal fin base almost straight, slightly sloped posteroventrally.Profile from posterior end of dorsal fin base to caudal fin base straight.Ventral profile of body convex from pectoral to pelvic fin origin and straight from pelvic to anal fin origin.Anal fin base nearly straight, posterodorsally inclined.Profile between posterior end of the anal fin base to caudal fin base straight.Head moderately large, depressed with a convex interorbital space; height less than length; width greater than height.Snout broadly rounded with a mere groove across its tip to form a transverse lobe, which contains a band of 6-9 small or large pointed tubercles; 3-5 small lateral tubercles anteroventral to nostrils; 4-12 minute tubercles anteromedially to nostrils, of which 2-4 on each side on the anterosuperior region of nostrils; lateral from the base of rostral barbel having a slightly posteroventrally sloping shallow groove continuous to the lateral groove of rostral cap; rostral lobe absent.Eyes placed dorsolaterally in the posterior half of head.
Two pairs of barbels; rostral ones anterolaterally located, similar to eye diameter; maxillary ones at corner of mouth, shorter than rostral ones.Rostral cap well developed, moderately crenulated, and with a narrow papillated margin; separated from upper jaw by a deep groove and laterally continuous with a distinct antero-lateral lobe of lower lip.No lip in the form of papilliferous tissue along the upper jaw and no papilliferous fold in the corner of mouth.Upper jaw entirely covered by rostral cap.Lower lip modified into a mental adhesive disc.Disc elliptical, shorter than wide and narrower than head width through roots of maxillary barbels; anterior margin modified to form a transverse, fleshy, and crescentic skin fold covered by numerous tiny papillae; anteriorly separated from lower jaw by a groove running along lower jaw and posteriorly bordered in a deep groove with central callous pad; lateral and posterior margin surrounding central callous pad, papillated and free; posteriormost margin extending a little beyond vertical from posterior margin of eye.
Dorsal fin with three (15) simple and seven (15) branched rays; last simple ray shorter than HL; distal margin slightly concave; origin a little nearer to snout tip than caudal fin base, inserted anterior to pelvic fin; first branched ray longest, last branched ray not extending to vertical from anal fin origin.Pectoral fin with one simple and 10 (2), or 11 (13) branched rays, reaching beyond midway to pelvic fin origin; its length shorter than HL; subacuminate margin; fourth branched ray longest, not extending to base of pelvic fin.Pelvic fin with one simple and seven (4) or eight (11) branched rays reaching beyond midway to anal fin origin, surpassing the vent; second branched ray longest, not extending to base of anal fin; origin closer to anal fin origin than to pectoral-fin origin, situated vertically at base of third branched dorsal fin ray; its distal margin almost convex.Anal fin short with three (15) simple and five (15) branched rays; first branched ray longest, straight posterior margin; its tip not reaching base of caudal fin; origin of anal fin closer to caudal-fin base than to pelvic fin origin.Vent slightly closer to pelvic fin origin than to anal fin origin.Caudal fin emarginated; lobe tips slightly pointed; tenth ray shortest; lobes equal in length.Lateral line complete with 35 (6) or 36 (9) scales.Scales in transverse row above lateral line 3½ (8), 4 (4), or 4½ (3) and below lateral line from ventral fin origin 2½ (15) and from anal fin origin 3½ (10), 4 (1), or 4½ (4).Circumpeduncular scales 15 (3) or 16 (12).Predorsal scales 11 (10) or 12 (5); scales arranged regularly, same size as flank scales.Chest and belly scaled, embedded under thin skin.An axillary scale at base of pelvic fin nearly reaching its base.Scales between vent and anal-fin base six (1), seven (10), or eight (4) scales.A row of small elongated scales at the base of dorsal fin five (15) and a row of two (5) or three ( 10  whitish or yellowish.All the last six branched dorsal fin rays excluding its distal rim highly spotted with black.These black spots extend anteriorly from its corresponding rays to its distal 1 /3 -½ interradial membranes.Whole length of interradial membrane between last simple and 1 st branched ray and proximal 2 /3, ½ and 1 /3 length of those between 1 st and 2 nd branched, 2 nd and 3 rd branched and 3 rd and 4 th branched rays covered with elongated membranous flaps, which are gradually tapered distally and originate from their corresponding anterior rays.
Seven or eight thin lateral stripes, more in the caudal peduncle region.All the full length of the 9 th to 13 th rays of caudal fin and outer rays of the dorsal and ventral lobe dark grayish, more on the median.A small rounded black spot at the upper angle of gill opening.

Etymology
Named in honour of Prof. Arup Kumar Das, Coordinator, UGC sponsored Centre of Excellence in Biodiversity, Rajiv Gandhi University, Itanagar.

Distribution
Garra arupi sp.nov. is known from the upper Brahmaputra basin in the Lower Divang Valley and the Lohit District of Arunachal Pradesh (Fig. 1).
Garra arupi sp.nov. is characteristic in having a shallow groove transversely on its snout tip with a band of 6-9 small or large pointed tubercles.In the specimens having smaller tubercles on the snout tip, there is no such transverse groove.The new species is similar to G. lamta and G. mullya by the presence of a groove on the snout tip.However, G. lamta and G. mullya have a distinct lateral broad stripe and a black blotch on caudal base which G. arupi does not have.G. arupi differs from G. lamta in having 35-36 (vs. 31-34) perforated lateral line scales, 11-12 (vs.8-10) predorsal scales, and vent to anal distance 1.67-1.90(vs.4.00-6.67) in pelvic to anal fin distance.G. arupi further differs from G. mullya in 35-36 (vs. 32-34) perforated lateral line scales, 11-12 (vs.9-11) predorsal scales, vent to anal distance 1. 67-1.90 (vs. 2.67-3.80) in pelvic to anal fin distance, and 2½ (vs.3½) transverse scales between the pelvic fin and lateral line.
In addition to Garra kempi and G. lissorynchus, there are five species of Garra from the Brahmaputra basin in India, namely G. annandalei, G. naganensis, G. gotyla, G. nasuta, and G. rupecula (Menon 1964;Talwar & Jhingran 1991;Jayaram 1999).G. arupi sp.nov. is separated from them by having a distinct transverse submarginal band on the dorsal fin and an anterior position of the vent.G. arupi has a vent to anal distance 52.6-60.0% pelvic to anal distance (vs. 40.6-44.2 in G. naganensis, 30-33.8 in G. annandalei).G. arupi further differs from Menons (1964) G. gotyla in having 9-10 (vs.11-12) predorsal scales, a snout without a proboscis and with a mere transverse groove on snout tip (vs. a snout with a prominent proboscis and a prominent transverse groove on the snout tip), presence (vs.absence) of a black band on branched dorsal fin rays, and an absence (vs.presence) of black spots at the base of branched dorsal fin rays.G. arupi differs from Menons (1964) G. nasuta in having an absence (vs.presence) of a trilobed proboscis with a distinct transverse groove on the snout tip, anterior position of the vent (vent to anal distance 1. 67-1.90 vs. 3.71-5.25 in pelvic to anal distance), and an absence (vs.presence) of black spots at the base of branched dorsal fin rays.
Garra rupecula McClelland, 1839 was described from the Mishmi Mountains, Assam (now in Arunachal Pradesh) in Brahmaputra basin having the following characteristics: a W-shaped band on the caudal fin and naked scales in the predorsal region (Talwar & Jhingran 1991), which differentiate it from G. arupi sp.nov.While describing G. abhoyai as a new species from the specimens collected from the area of the Ukhrul district in Manipur, Hora (1921) reviewed the description of G. rupecula based on fresh specimens collected from the hill streams of Manipur valley, an altogether different river basin.He did not mention significant differentiating characteristics between the two species except for the small body size and presence of pores on the snout in G. rupecula.After decades, Menon (1964) also reviewed the characteristics of G. rupecula based on Manipur valley specimens and put G. abhoyai as its junior synonym.All the streams and rivers draining in the Manipur valley and Ukhrul district belong to Chindwin drainage.Ten specimens (45.0-54.9mmSL) having pores on their snout presently collected from the Iril and Nambul rivers (Chindwin basin) have close similarity with those of Hora (1921) and Menon (1964) mentioned above.The distribution pattern clearly suggests the validity of G. abhoyai and absence of G. rupecula in the basin.
Garra abhoyai characteristically has 16-27 small scales embedded in a thin skin on the predorsal region arranged irregularly, with the size of these scales much smaller than those on the flank scales.It has also a narrow black band in the middle of the dorsal fin, a characteristic that G. arupi sp.nov.does not have.Vishwanath & Sarojnalini (1988) mentioned the type locality of Garra manipurensis in the Manipur River at Sherou in the Chindwin basin in Manipur.However, several subsequent collections from the type locality did not represent the species.Instead, it is represented in the collections from Tuivai River in the Brahmaputra River basin, Manipur.Thus type locality as given in the original description might be due to wrong labeling.The species has the following combination of characteristics: 4 branched anal fin rays, 13 branched pectoral fin rays, and a rostral lobe which easily differentiates it from G. arupi sp.nov.G. arupi further differs from G. manipurensis in having head height 21. .6%SL), callous pad width 35.0-40.0(vs.31.9-34.9%SL), callous pad length 25.7-30.0(vs.20.4-21.9%SL), and an anterior position of the vent (vent-anal distance 52.6-60.0 vs. 24.8-29.7%pelvic to anal distance).
There are seven species of Garra from the Irrawaddy River basin in Rakhine Yoma, Myanmar, namely Garra propulvinus, G. vittatula, G. spilota, G. rakhinica, G. flavatra, G. poecilura, and G. nigricollis (Kullander & Fang 2004).All the species (except G. spilota) share a common character, a rostral lobe on the snout, which can be utilized to separate them from G. arupi sp.nov.G. arupi differs from G. spilota in having the presence (vs.absence) of a submarginal black band on the dorsal fin, an absence (vs.presence) of blotches on the sides, and seven (vs. 8) branched dorsal fin rays.Kottelat (1990Kottelat ( , 2001) also remarked that most of the highly specialized rheophilic fish species in Southeast Asia have restricted distribution ranges.So, a thorough revision to present the precise differentiating characteristics and geographical distributions of G. nasuta, G. gotyla, G. rupecula, and Garra mullya would be essential.