Ophichthus chilkensis Chaudhuri 1916

Mishra, Subhrendu Sekhar, Mohapatra, Anil, Ray, Dipanjan, Mohanty, Swarup Ranjan & Tudu, Prasad C., 2019, Ophichthus chilkensis Chaudhuri, 1916 (Anguilliformes: Ophichthidae) - resurrection as a valid species from India, with re-description, Zootaxa 4586 (1), pp. 194-200 : 195-197

Ophichthus chilkensis Chaudhuri 1916

( Table 1 , Figs. 1–2 , 3A, 3B )

Ophichthus chilkensis Chaudhuri 1916: 445 , Figs. 12–13 (Type locality: Rambha Bay, Chilka Lake, Orissa [Odisha], India).

Diagnosis. An extremely elongate snake eel, with head 18.1–20.4 times in TL, about 6.6–7.0 times in preanal length; anterior tubular nostrils on the upper lip; upper lip with a small flap-like barbel between anterior and posterior nostril; eye very small; maxillary and mandibular teeth biserial (inner row discontinuous); vomerine teeth two or three rows; pectoral fin base restricted to the dorsal half of the border of the gill opening; pectoral fin with 13 or 14 branching rays, dorsal fin origin just above pectoral fin tip or slightly behind, total vertebra 206–214 (10– 11/68–69 /206–214).

Description. Body rounded and elongate, slightly tapering towards tail ( Fig. 1 ); tail tip hard and pointed, projects beyond the dorsal and anal fins. Head slightly depressed, 35–43 times in TL and 6.6– 6.8 times in pre-anal length; upper jaw much longer than lower jaw (nearly 25% greater than the lower jaw); anterior nostril tubular, placed on upper lip and directed downwards; posterior nostril at upper lip edge and covered by a flap; single short flap-like barbel present between anterior and posterior nostril on edge of upper lip; eyes very small 12.5-16.8 times in head length and interorbital width 7.6–9.5 times in head length.

Supra orbital pores 1 + 4, infraorbital pores 6, preoperculo-mandibular pores 5 + 2. Lateral line pores distinct along entire length of body. Lateral line pores to pectoral fin 9–10 and to anus 69–71.

Vomerine teeth triangular with broad base and pointed teeth arranged in two rows, pre vomerine teeth 3 in rosette (holotype) and 5 in some recently collected specimens and arrangement is as shown in Fig. 3B , prevomerine and vomerine teeth slightly separated from each other; maxillary teeth conical and pointed, biserial (outer row continuous and inner row discontinuous); mandibular teeth conical and biserial anteriorly with 3 teeth each side with single continuous outer row throughout, only 3 teeth in inner in holotype ( Fig. 3A ), while in two other specimens irregularly biserial (inner row discontinuous) ( Fig. 3B ). Two specimens have three rows of vomerine teeth ( Fig. 3B ).

Dorsal fin low, originating above tip of pectoral fin (holotype and some recent collections) or slightly behind; pectoral fin fan shaped not elongated, with 13–14 branching rays; pectoral fin base restricted to the dorsal half of the gill opening; anal fin low. Predorsal vertebrae 10–11, preanal vertebrae 68–69 and total vertebra 206–214 (holotype—11/68/206) based on radiograph of 7 specimens including holotype (MVF 11/69/210).

Coloration: The colouration is dark olive brown and slightly faded to the abdomen in fresh condition. The portion of gill opening is slightly faded brown colour in comparison to the dorsal portion of the body. Pectoral and dorsal fins dull white, first two third of anal fin is dull white last one third is dark. After long preservation the colour is uniformly faded brown.

Distribution. It was described from the Chilika Lagoon, Odisha, India ( Chaudhuri, 1916). It’s subsequent collection from Talsari (Balasore district, Odisha), Digha, (West Bengal) along north-western bank of the Bay of Bengal and recently from Visakhapatnam (Andhra Pradesh) suggests a broader distribution of the species along the coasts of West Bengal, Odisha and Andhra Pradesh (north-eastern coast of India) with high influence of estuarine water.

Figures

FIGURE 1. Ophichthus chilkensis Chaudhury 1916, from Digha, West Bengal coast (MARC/ZSI F 4675, 690 mm)

FIGURE 2. Head pores of Ophichthus chilkensis Chaudhuri.

FIGURE 3. Dentition in A. Ophichthus chilkensis Chaudhuri (Holotype), B. Ophichthus chilkensis Chaudhuri (one of recent collection) C. Ophichthus microcephlus Day (Holotype).