Nemachilichthys rueppelli (Sykes, 1839)

Cobitis rupelli Sykes, 1839: Sykes (1839, p. 162), Sykes (1841, p. 366, Pl. 64, fig. 1)

Nemachilichthys ruppelli: Day (1878, p. 611, Pl. 155, fig. 7), Bănărescu & Nalbant (1995, fig. 19A, B) Kottelat (2012, p. 93, fig. 10.22.1)

Nemacheilus ruppelli: Talwar and Jhingran (1991, p. 499)

Noemacheilus ruppelli: Bănărescu & Nalbant (1968, p. 329)

Noemacheilus (Noemacheilichthys) ruppelli: Menon (1987, p. 158, Pl. 12, fig. 1)

Nemachilichthys rueppelli: Eschmeyer & Fricke (2015)

Nemachilichthys shimogensis Narayan Rao, 1920: Narayan Rao (1920, p. 62, Pl. 2, fig.5, 5a, 5b)

Material examined. Krishna River System: 3 ex., BNHS FWF 178–180, 74.2–79.0mm SL, Mula-Mutha River, Yerawada (18.540°N, 73.880°E, 553m ASL), coll. N. Dahanukar and M. Paingankar, 6 October 2012 (topotypes of N. rueppelli); 3 ex., WILD-15-PIS-225–227, 73.8–77.5mm SL, Mula-Mutha River, Yerawada (18.540°N, 73.880°E, 553m ASL), coll. N. Dahanukar and M. Paingankar, 6 October 2012 (topotypes of N. rueppelli); 4 ex., ZSI-WRC P/4495, 69.5–77.1mm SL, Mula-Mutha River, Yerawada (18.540°N, 73.880°E, 553m ASL), coll. N. Dahanukar, M. Paingankar, 6 October 2012 (topotypes of N. rueppelli); 1 ex., AMS B.7528, Poonah (18° 34' N, 73° 58' E), coll. F. Day, 1865; 2 ex., BNHS FWF 168–169, 53.8–66.9mm SL, Krishna River, Wai (17.955°N, 73.880°E, 707m ASL), coll. N. Dahanukar and M. Paingankar, 6 October 2012; 4 ex., BNHS FWF 170–173, 84.7- 93.5mm SL, Koyna River, Patan (17.368°N, 73.903°E, 571m ASL), coll. P. Kumkar and S. Gosavi, 11 October 2013; 1ex., BNHS FWF 174, 74.2 mm SL, Hiranyakeshi River, Ajara (16.130°N, 74.210°E, 647m ASL), coll. P. Kumkar, 22 December 2013; 3 ex., BNHS FWF 175–177, 67.9–70.5mm SL, Nira River, Bhor (18.154°N, 73.840°E, 598m ASL), coll. A. Keskar and P. Kumkar, 31 October 2013; 2ex., WILD-15-PIS-215–216, 50.0– 57.4mm SL, Krishna River, Wai (17.955°N, 73.880°E, 707m ASL), coll. N. Dahanukar and M. Paingankar, 6 October 2012; 6 ex., WILD-14-PIS-120–121 and WILD-15-PIS-217–220, 51.0–65.0mm SL, Koyna River, Patan (17.368°N, 73.903°E, 571m ASL), coll. P. Kumkar and S. Gosavi, 11 October 2013; 2 ex., WILD-14-PIS-119 and WILD-15-PIS-221, 72.1–77.8mm SL, Hiranyakeshi River, Ajara (16.130°N, 74.210°E, 647m ASL), coll. P. Kumkar, 22 December 2013; 5 ex., WILD-14-PIS-122–123 and WILD-15-PIS-222–224, 56.0– 68.9mm SL, Nira River, Bhor (18.154°N, 73.840°E, 598m ASL), coll. A. Keskar and P. Kumkar, 31 October 2013; 1 ex., ZSI-WRC P/4491, 52.6mm SL, Krishna River, Wai (17.955°N, 73.880°E, 707m ASL), coll. N. Dahanukar and M. Paingankar, 6 October 2012; 3 ex., ZSI-WRC P/4492, 65.1–67.6mm SL, Koyna River, Patan (17.368°N, 73.903°E, 571m ASL), coll. P. Kumkar and S. Gosavi, 11 October 2013; 1ex., ZSI-WRC P/4493, 69.1 mm SL, Hiranyakeshi River, Ajara (16.130°N, 74.210°E, 647m ASL), coll. P. Kumkar, 22 December 2013; 4 ex., ZSI-WRC P/4494, 49.8–58.6mm SL, Nira River, Bhor (18.154°N, 73.840°E, 598m ASL), coll. A. Keskar, P. Kumkar, 31 October 2013; 3 ex., CRG-SAC.2014.03.190.1–3, 43.6–89.2mm SL, Tunga River, Shimoga (13.901°N, 75.564°E, 569m ASL), coll. A. Ali, R. Britz and N. Sood, 1 March 2014 (topotypes of N. shimogensis); 1 ex., WILD-14-PIS-118, 47.3mm SL, Tunga River, Shimoga (13.901°N, 75.564°E, 569m ASL), coll. A. Ali, R. Britz and N. Sood, 1 March 2014 (topotype of N. shimogensis); 2 ex., BMNH 1919.11.19.13 and BMNH 1919.11.19.15, Tunga River, Shimoga, coll. Narayan Rao (syntypes of N. shimogensis), 1919.

Description. General appearance as in Fig. 6. Mouth structure as in Fig. 7. Variation in body form and coloration as in Fig. 3. Morphometric data, separately for the various populations and pooled, provided in Table 2. Body elongate, sub-cylindrical, slightly compressed laterally; dorsal profile convex; ventral profile straight to slightly convex. Body deepest at dorsal-fin origin. Head large, about a quarter of SL. Eyes large, positioned dorsolaterally, in posterior half of head, closer to opercular margin than to tip of snout. Interorbital width slightly greater than eye diameter. Nares positioned dorsolaterally, slightly closer to anterior border of eye than to tip of snout, with large nasal flap. Barbels in three pairs, long, inner rostral shorter than outer rostral, outer rostral not reaching anterior border of eye, maxillary shorter than or equal to outer rostral, extending to perpendicular from anterior border of eye. Lips fleshy, separated by a deep groove, joined at isthmus (Fig. 7). Upper lip with a median groove, with 2 to 4 large papillae on either side of groove. Lower lip with deep median groove, 2 to 4 large papillae on either side of groove. Body with minute scales throughout, except on head and ventral surface from belly to anal fin base. Lateral line complete. Caudal peduncle long, its length 1.3 to 1.8 times its depth.

Dorsal fin origin almost midway between tip of snout and caudal-fin base, with 3 (38) or 4 (10) unbranched rays and 10 (48) branched rays. Pectoral fin with 1 (48) unbranched and 10 (2), 11 (17) or 12 (29) branched rays, not reaching pelvic-fin origin. Pelvic fin originating slightly posterior to the vertical from dorsal-fin origin, with 1 (48) unbranched and 7 (48) branched rays, extending beyond anus, not reaching anal fin. Anal fin with 3 (48) unbranched and 5 (48) branched rays. Anus closer to ventral-fin base than to anal-fin origin. Caudal fin forked, with 10 (48) dorsal and 9 (48) ventral principle rays.

Vertebral column with 22 abdominal vertebrae (including 4 vertebrae in the Weberian apparatus); 12 caudal vertebrae (including compound centrum); total vertebrae 34 (c&s specimen BNHS FWF 189).

Coloration. In life, body beige to pale yellow, with brown bars covering dorsal surface, extending ventrolaterally below the lateral line, not reaching ventral surface; brown bars irregular, 12–20 in number. A rosette of large, brown spots on dorsal surface of head. Cheeks uniform pale brown, turning pale yellow to beige ventrolaterally. Ventral surface uniform beige to pale yellow throughout. Dorsal fin with three or four rows of brown spots, present only on fin rays; dorsal fin membrane hyaline. Caudal fin with 4–6 posteriorly-directed 'V'- shaped brown bands; a distinct black spot on the middle of the caudal-fin base. Pectoral, pelvic and anal fins hyaline, often with two rows of brown bands, sometimes faint or absent. Barbels beige, turning orange to red during breeding season from June to September. Body suffused faint-orange during breeding season, along with pectoral and pelvic fins; anal and caudal fins yellow. Rarely, snout becoming red during breeding season. In alcohol preservation, coloration similar to that in life, but more faded. Banding pattern varying with age and size (see examples in Fig. 3).

Distribution. Nemachilichthys rueppelli is currently known only from the upper reaches of the east-flowing Krishna River system in the Western Ghats. In particular, the species is reported from seven rivers, Indrayani (Dahanukar et al. 2012), Mula-Mutha, Nira, Krishna, Koyna, Hiranyakeshi and Tunga (Fig. 1). Bhat (2004) reported the species from the west-flowing Aghanashini River in the central region of the Western Ghats; this record is not supported by voucher specimens and has been omitted from Fig.1. Similarly, reports of the species from three other west-flowing rivers, viz. Amba, Kundalika and Savitri (Katwate et al. 2012), are disregarded here as those were clearly based on misidentifications of Schistura species.

Habitat. Nemachilichthys rueppelli inhabits moderate to fast-flowing streams and rivers. It is often found associated with aquatic vegetation and the submerged roots of riparian vegetation. The species is usually found on the stream or river bed. Preferred substrates include mud, silt, pebbles, small rocks and boulders. Syntopic species include Cyprinidae: Garra mullya (Sykes), Devario aequipinnatus (McClelland), Rasbora daniconius (Hamilton) and Pethia sp.; Nemacheilidae: Nemacheilus anguilla Annandale, Paracanthocobitis mooreh (Sykes); Cobitidae: Lepidocephalichthys thermalis (Valenciennes), Gobiidae: Glossogobius giuris (Hamilton) and Mastacembelidae: Mastacembelus armatus (Lacepède).

Ecology. Gut content revealed insect parts with higher frequency, followed by ostracods, with relatively low frequency of plant matter and diatoms (based on 12 unregistered unsexed specimens from Mula-Mutha River at Yerawada, Koyna River at Patan and Nira River at Bhor).