Koima monilis ( Hora 1921 )

Anoop, V. K., Dahanukar, Neelesh & Raghavan, Rajeev, 2024, Koima, a new genus of nemacheilid loach from the Western Ghats, India (Cypriniformes: Nemacheilidae), Zootaxa 5538 (2), pp. 101-126 : 112-117

Koima monilis ( Hora 1921)

Figs.11–13

Nemacheilus monilis Hora,1921: 19 , Fig. 1 , v. 22 ( type locality: Bhavani River, 10 miles from Mettupalayam, Nilgiri Hills , Tamil Nadu, India. Holotype: ZSI F9981/1 . Paratypes: ZSI (1) . (Types examined.)

Additional material examined: KUFOS-AN-2019.2.1–10 , 29.8–67.8 mm SL, 10 ex.; India: Bhavani River , Mettupalayam (11.336° N & 76.882° E, 395 m ASL); V.K. Anoop; May 2019 . KUFOS-AN-2019.4.1–4 , 36.5–58.8 mm SL, 4 ex.; India: Chinnar, Pambar River (10.297° N & 77.187° E, 630 m ASL); V.K. Anoop; 18 August 2017 . KUFOS-AN-2019.3.1–4 , 30.0–55.0 mm SL, 4 ex.; India: Thengumarahada, Moyar River (11.571° N & 76.918° E, 370 m ASL); V.K. Anoop; March 2018. KUFOS-AN- 2019.3.1 –3, 25.2–50.5 mm SL , 3 ex.; India: Begur, Kabini River (11.890° N & 76.061° E, 765 m ASL); V.K. Anoop; January 2018. KUFOS-AN-2019.4.1–3 , 30.5–45.1 mm SL , 3 ex.; India, Thirunelli, Kabini River (11.908° N & 75.989° E, 805 m ASL); V.K. Anoop; January 2018. KUFOS-AN-2019.5.1–2 , 25.0– 40.6 mm SL ,, 2 ex.; India: Thavalam, Bhavani River (11.096° N & 76.593° E, 548 m ASL); V.K. Anoop; 11 December 2017 .

Diagnosis. Koima monilis is distinguished from Koima remadevii by its unique colour pattern comprising well-developed moniliform black band along lateral line, starting from snout to middle of caudal fin with 17–22 spots (vs. absence of black band (in adults), and 3–11 spots on lateral line), absence of bands on dorsal (vs. irregular bands or spots), and no bands or spots on head (vs. small spots on head). Koima monilis differs from its congener K. remadevii with a raw genetic distance of 5.2–6.0% in barcoding region of cox1 gene.

Description. Morphometric data in Table 2 . Body elongate, slightly compressed anteriorly, more compressed posteriorly. Snout elongate, head slightly pointed, its length about 1/4 th of SL. Pectoral fin not reaching pelvic-fin base; its length less than 1/5 th of SL. Pointed axillary pelvic lobe present. Pelvic-fin origin opposite to dorsal-fin origin. Pelvic fin length about 1/6 th of SL reaching halfway of anal-fin origin, but not reaching anal opening. Pre-anal fin length slightly more than 3/4 th of SL. Anal fin not reaching caudal-fin base; almost equal to pelvic-fin length. Distal margin of dorsal fin concave. Dorsal-fin base length about 1/7 th of SL, twice anal-fin base length. Body width at dorsal-fin origin lesser than body depth at dorsal-fin origin. Caudal peduncle depth and length almost equal. Caudal peduncle length about 1/8 th of SL. Caudal fin forked. Adipose crest supporting caudal fin, lower adipose crest reaching end of anal fin.

Dorsal fin composed of three supernumerary ray, one unbranched and seven to eight branched rays. Pectoral fin with one unbranched ray and 10 branched fin rays, pelvic fin with one unbranched and six branched rays, and anal fin with two supernumerary rays, one unbranched ray and five branched rays. Principal caudal-fin rays nineteen. Five to ten procurrent rays on upper caudal fin, and three to seven procurrent rays on lower.

Body including belly covered with scales. Lateral line almost complete, reaching beyond anal fin, with 77– 103 pores. Cephalic lateral line with 6 supraorbital pores, 4+12 infraorbital, 9 preoperculo-mandibular and 3 supratemporal pores. Total vertebrae 35 (2 ex.), with insertion of dorsal fin after 11 th vertebrae, and anal fin after 22 nd vertebrae.

Anterior nostril on front side of a flaplike tube, with slightly pointed tip, not reaching eye. Semi-circular mouth, width about 1/4 th of HL. Mouth gape width lesser than interorbital width. Upper lip with small deep incision and lower lip with wide interruption. Well-developed barbels, outer rostral barbel reaching middle of eye, maxillary barbel reaching beyond posterior margin of eye. Thinner and wider suborbital flap, larger than nostril. Head depth at eye 36.8–41.8% HL. Maximum head width at posterior end of head. Interorbital width slightly more than 1/4 th of HL, greater than mouth gape width. Intestine with a loop at some distance behind stomach.

Sexual dimorphism. Males can be easily identified by the possession of an orbital flap ( Fig. 13A ), and a layer of tubercles on pectoral-fin rays.

Coloration. Yellowish-brown ground colour, with pale yellow on belly. Moniliform band on lateral line, starting from snout and ending at middle of caudal fin. Black spots on band varies between 17–22. Both side-bands joining tip of anterior snout. No bands or spots on dorsal side of body. All fins hyaline, but some individuals having fins with scattered black pigmentation. No bands or spots on head, but several melanophores dispersed throughout the body. In juveniles, a band on lateral line, without any spots.

Habitat. Koima monilis typically inhabits swift-flowing streams with substrates mostly comprising rocks, boulders, gravel, and sand ( Fig. 14 ). The species occurs at localities spread across an altitude range between 350 m to 800 m, in microhabitats ranging from large tributaries to several smaller, swift-flowing streams. The range of width and depth in the distribution range varies between 3 to 40 m, and 40 cm to 1.2 m. Co-occurring species include Mesonoemacheilus pambarensis , M. guentheri , Schistura denisoni , Bhavania australis , Devario malabaricus, Garra mullya, Haludaria fasciata, Mastacembelus sp., Rasbora dandia and Opsarius bendelisis .

Distribution. Koima monilis is known from various tributaries of the Cauvery River including the Kabini (at Thirunelli, Begur and Vythiri in Wayanad, Kerala), Pambar (inside the Chinnar Wildlife Sanctuary, Kerala), Bhavani (at Thavalam in Kerala, and Kallar in Tamil Nadu), and Moyar (at Masinagudi, and Thengumarhada in Tamil Nadu) ( Fig. 10 ).

Figures

FIGURE 1. Maximum likelihood phylogenetic tree of family Nemacheilidae showing the position of Koima. The tree is based on best partition scheme for concatenated mitochondrial cytochrome oxidase subunit 1 (cox1) and cytochrome b (cytb) and nuclear recombination activation gene 1 (RAG1) genes. Members of family Balitoridae (Balitora kwangsiensis and Bhavania australis) are used as outgroups. Values along the nodes are percentage bootstraps based on 1000 iterations. Species in blue are endemic to the Western Ghats. Asterisk indicates that at least one sequence for these species was generated in the current study.

FIGURE 10. Distribution range of Koima remadevii and K. monilis in the Southern part of the Western Ghats, India

FIGURE 11. Koima monilis (in life), from its type locality in Kallar (a tributary of the Bhavani River) at Mettupalayam, Tamil Nadu, India (KUFOS-AN-2019.2.2; 62.57 mm SL).

FIGURE 12. Koima monilis from its type locality in Kallar (a tributary of the Bhavani River), Mettupalayam, Tamil Nadu, India, in preservative. A. lateral, B. dorsal and C. ventral views (KUFOS-AN-2019.2.4; 67.07 mm SL).

FIGURE 13. Koima monilis from its type locality in Kallar (a tributary of the Bhavani River), Mettupalayam, Tamil Nadu, India, in preservative. (A-H) head lateral, head dorsal, head ventral, dorsal fin, pectoral fin, pelvic fin, caudal fin, and coloration below the dorsal fin respectively (KUFOS-AN-2019.2.4; 67.07 mm SL).

FIGURE 14. Habitat of Koima monilis in the Moyar River near Thengumarhada, Tamil Nadu, India.