Istigobius ornatus (Rüppell, 1830)

Sreeraj, Chemmencheri Ramakrishnan, 2022, First report of two gobiid fishes from the coral reefs of Gulf of Mannar, Tamil Nadu, India, Records of the Zoological Survey of India 122 (1), pp. 51-55 : 52-53

Istigobius ornatus (Rüppell, 1830)

Common name - Ornate goby

Material examined: ZSI/SbRC/KN3090, 1ex, (TL 26.7mm, SL 22.5 mm, BD 4.6 mm, HL 6.5 mm), Pullivasal Island , Gulf of Mannar Marine National Park (9°14’55.01”N; 79°11’3.25”E), 24.01.2020, Coll: Sreeraj, C. R .

Diagnostic characters: Istigobius ornatus is diagnosed from congeners in having a combination of the following characters -First dorsal VI; Second dorsal I, 10; Anal I, 9; Pectoral rays 19. Upper 4 pectoral rays free. Predorsal scales 10, cycloid. Longitudinal scale series 31, ctenoid. No scales on cheek or opercle. Small fish with slender and compressed body. Dorso-laterally situated eyes. Mouth with overhanging snout, lips greatly thickened. Pale grey body colour with few (6-8) brownish dots forming a blotch like appearance on the operculum. First dorsal fin with yellow colour on top and brown in the middle region (colour prominent on the spines) and pale bottom. Scattered white speckles over the dorsal fins, numerous brownish-black streaks arranged in horizontal rows on side ( Figure 2 ).

Distribution: India: Andaman and Nicobar Islands, West Bengal, Andhra Pradesh, Kerala ( Rajan et al., 2013; Mishra et al., 2019; Koumans, 1941) and GoM (Current Study). Elsewhere: Indo-Pacific: Red Sea South to Northern Mozambique and east to Fiji, north to southern Taiwan, south to New Caledonia and Tonga ( Froese & Pauly, 2019).

Remarks: Found solitary in the shallow (less than 1m depth) silty coral reef area. As the species was found in this kind of area, live base colouration of body is light brownish and for that reason the pattern on the body is more prominent making this species well camouflaged in the environment.

Figures

Figure 2. Istigobius ornatus (Rüppell, 1830).