Indoreonectes rajeevi, Kumkar & Pise & Gorule & Verma & Kalous, 2021

Kumkar, Pradeep, Pise, Manoj, Gorule, Pankaj A., Verma, Chandani R. & Kalous, Lukas, 2021, Two new species of the hillstream loach genus Indoreonectes from the northern Western Ghats of India (Teleostei: Nemacheilidae), Vertebrate Zoology 71, pp. 517-533 : 517

Indoreonectes rajeevi sp. nov.

Figs 4 , 5 , 6 , 8 Common name: Rajeev’s hill stream loach

Holotype.

BNHS FWF 1081, 45.76 mm SL, India: Maharashtra, Hiranyakeshi River, Krishna river system, Amboli (15°58.02'N; 74°0.66'E, ca 692 m a.s.l.), coll. P. Gorule and A. Gorule 23 Oct. 2017.

Paratypes.

BNHS FWF 1082-1092, 11 ex., 26.4-36.3 mm SL, same data as holotype. Paratypes BNHS FWF 1090 (35.1 mm SL), 1091 (33.0 mm SL) and 1092 (35.2 mm SL) used for clearing and staining.

Diagnosis.

Indoreonectes rajeevi can be distinguished from all congeners by having maxillary barbel reaching the posterior border of operculum (vs. not reaching); presence of conspicuous black marking on the lower lip of mouth (vs. absence).

Indoreonectes rajeevi is further distinguished from I. keralensis by having long nasal barbel reaching middle of eye (vs. short nasal barbel barely reaching anterior margin of eye); dorsal-fin origin vertical from pelvic-fin base (vs. posterior to vertical at pelvic-fin base); dorsal-fin insertion between neural spines of 12th and 13th abdominal vertebrae (vs. between 13th and 14th); presence of a dark brown to black spot on base of first dorsal-fin ray and distinct spots on dorsal side of head (vs. absence); spots on cheek below eye absent (vs. present); total vertebrae 36 (vs. 35).

Indoreonectes rajeevi is distinguished from I. evezardi by having inner rostral barbel reaching anterior margin of eye (vs. reaching middle of nostril); absence of dorsal hump behind nape (vs. presence); dorsal fin origin at vertical from pelvic-fin base (vs. posterior to vertical at pelvic-fin base); caudal peduncle slightly longer than deep (vs. deeper than long); caudal peduncle bar not divided into two spots (vs. divided); total vertebrae 36 (vs. 35).

Indoreonectes rajeevi distinguished from I. telanganaensis by lacking spots on cheek below eye (vs. spots present); absence of dorsal hump behind nape (vs. presence); caudal peduncle slightly longer than deep (vs. as long as deep).

Indoreonectes rajeevi distinguished from I. neeleshi by having inner rostral barbel reaching anterior margin of eye (vs. reaching middle of nostril); absence of dorsal hump behind nape (vs. presence); dorsal-fin insertion between neural spines of 12th and 13th abdominal vertebrae (vs. between 13th and 14th); caudal peduncle slightly longer than deep (vs. as long as deep); lateral bars narrower than inter-bar spaces (vs. wider); total vertebrae 36 (vs. 35).

Description.

General morphology is shown in Figure 8 ; morphometric data are provided in Table 1 .

Body sub-cylindrical, elongate; head and anterior part of body almost cylindrical; body laterally compressed posteriorly; pre-dorsal outline slightly convex, gradually rising up to dorsal-fin origin, no hump behind nape; post dorsal outline straight up to base of caudal fin; ventral profile almost straight. Caudal peduncle as deep as long or slightly longer. Lateral line present, incomplete, short, ending above middle of adpressed pectoral fin. Scales minute.

Head small, about one fifth of SL. Snout round, its length more than one-third of head length. Eye dorsolaterally positioned, closer to tip of snout than to posterior margin of operculum, its diameter about 14-20% HL. Mouth semi-circular, with thick fleshy lips, lower lip interrupted medially by a deep groove with conspicuous black markings on the either side of the groove (Fig. 4C ). Barbels four pairs. Two pairs of rostral barbels, inner rostral barbel extending to anterior margin of eye, outer rostral barbel reaching posterior margin of eye; Maxillary barbel longest, originating at vertical from nostril, reaching posterior border of operculum. Nasal barbel well developed, reaching middle of eye.

Dorsal-fin origin at vertical from ventral-fin origin; slightly closer to caudal-fin base than tip of snout, its posterior margin rounded, with 3 (12) simple and 7 (12) branched rays. Pectoral fin slightly shorter than head length; with 1 (12) simple and 9 (12) branched rays. Pelvic fin with 1 (12) simple and 7 (12) branched rays. Anal fin with 3 (12) simple and 5 (12) branched rays. Caudal fin rounded, 8+9 (1) or 9+9 (11) principal rays. Dorsal procurrent rays 12(8) or 14(4) and ventral procurrent rays 6(10) or 7(2).

Total vertebrae 36 (Fig. 5C ) with 17 (3) abdominal and 19 (3) caudal vertebrae. Dorsal fin insertion between 12th and 13th abdominal vertebrae. Fifth ceratobranchial (Fig. 6C ) with single row of 14 to 18 small curved teeth with pointed tips; anterior teeth longer than posterior.

Colouration.

In life (Fig. 8A ), background colour golden yellow; with umber-coloured irregular vertical bars on lateral and dorsal side of body, lateral and dorsal bars usually separated from each other or rarely continuous; lateral bars narrower than inter-bar spaces; lateral complete bars 14 (4), 15 (2), 16 (3) or 17 (3); lateral incomplete bars 5 (4), 6 (3), 7 (2), 8 (2) or 11 (1). Head dorsally studded with dark brown spots; no spots on cheeks below eye. Caudal peduncle bar continuous. Dark brown to black spot on base of first dorsal-fin ray; dorsal fin membrane hyaline with three rows of black spots on rays. Pectoral, ventral and anal fins hyaline, lacking spots; caudal fin membrane hyaline, with three to four rows of dark-brown spots on rays. Ventral surface without any markings. In preservative (Fig. 8B-D ), colouration similar to that in life, but faded.

Etymology.

The species name honours Rajeev Raghavan from Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, India, for his remarkable contributions to the understanding of the Systematics and Evolution of Indian freshwater fishes.

Habitat and Distribution.

Indoreonectes rajeevi was found in a slow-flowing clear stream with boulders, pebbles and mud as major substratum. Co-occurring fish species includes Parapsilorhynchus sp., Schistura sp., Balitora laticauda , Rasbora dandia and Garra mullya . Currently, Indoreonectes rajeevi is known only from its type locality in the Hiranyakeshi tributary of east flowing Krishna River at Amboli, Maharashtra, India (Fig. 1 ).

Figures

Figure 1. Type localities of species of the genus Indoreonectes in southern Peninsular India.

Figure 4. Mouth of Indoreonectes species, in ventral view. (A) Indoreonectes evezardi (BNHS FWF 1070, 33.5 mm SL), (B) I. neeleshi holotype (BNHS FWF 1071, 38.5 mm SL), (C) I. rajeevi holotype (BNHS FWF 1081, 45.8 mm SL) and (D) I. keralensis (KUFOS. 2017. 11.217, 36.1 mm SL). Scale bar 2 mm. Red arrows in C points to conspicuous black markings on lower lip in I. rajeevi.

Figure 5. Cleared and stained specimens of Indoreonectes showing vertebral column and insertion of dorsal fin, in lateral view. (A) Indoreonectes evezardi (BNHS FWF 1068, 43.8 mm SL), (B) I. neeleshi (BNHS FWF 1074, 36.2 mm SL), (C) I. rajeevi (BNHS FWF 1090, 35.1 mm SL) and (D) I. keralensis (KUFOS. 2017.11.217, 36.1 mm SL). Scale bar 5 mm. Note that vertebral column of I. neeleshi is malformed in caudal region.

Figure 6. Cleared and stained fifth ceratobranchials showing dentition pattern, in dorsal view. (A) Indoreonectes evezardi (BNHS FWF 1068, 43.8 mm SL), (B) I. neeleshi (BNHS FWF 1074, 36.2 mm SL), (C) I. rajeevi (BNHS FWF 1090, 35.1 mm SL) and (D) I. keralensis (KUFOS. 2017. 11.217, 36.1 mm SL). Scale bar 0.5 mm.

Figure 8. Indoreonectes rajeevi holotype (BNHS FWF 1081, 45.76 mm SL) (A) in life, in lateral view; preserved in lateral (B) dorsal (C) and ventral (D) views. Sides reversed in A and B.