The Gobiidae constitute one of the largest families of percomorph fishes. The family has a total of over 1, 640 species belonging to six subfamilies (Pezold 1993, Hoese and Larson 1994, Nelson 2006). These subfamilies are distributed in reef environments of the Indian and Pacific oceans, which are home to the greatest diversity of gobiid fishes. Recent re-evalutaion of gobioid systematic using molecular methods resulted in six family clade-based classification for the family Gobiidae that includes all the genera of the former subfamilies (Thacker 2003, 2009, 2011, Ruber and Agorreta 2011). The gobiine genus Valenciennea has 15 recognised species, including Valenciennea helsdingenii that is one of larger sized species with the documented maximal total length of 25 cm (Kuiter 1993). Prior to the discovery of the material reported on in this paper, the known range of Valenciennea helsdingenii included the Marquesas Islands, Japan, the Philippines, Indonesia, New Britain, the Solomon Islands, the Great Barrier Reef and New South Wales, Australia, Saudi Arabia, Maldives, Seychelles, and southern Africa (Hoese and Larson 1994, Lieske and Myers 1994, Clark et al. 2000, Randall et al. 1990, Randall et al. 1997). In India, about 150 species of gobiids have been reported (Day 1876, Jones and Kumaran 1980, Murty 2002) but the finding of Valenciennea helsdingenii represents the first occurrence of the species from the southeast coast of India and an extension of its range within the Indian Ocean.

Two specimens of Valenciennea helsdingenii (Bleeker, 1858) (Fig. 1) were collected from the Punnakayal fish landing centre located about 15 km south of major port town of Tuticorin on 16 November 2012. The capture location was in the Gulf of Mannar (8°38'127"N, 78°12'612"E), 20 km southeast of Tuticorin (Fig. 2) at a depth of 30 to 50 m by a drift gill net operated from traditional fishing craft. The specimens were preserved in 5% formalin and brought to the laboratory for a detailed examination. Morphometric measurements were taken to the nearest millimeter using digital calipers according to Hubbs and Lagler (1958). The specimens are deposited in the National Marine Biodiversity Referral Museum at the Central Marine Fisheries Research Institute, Cochin.

Hoese and Larson (1994) revised Indo-Pacific gobiid fishes and described seven new species from this area. Among these species, Valenciennea helsdingenii shows wide distribution from Southern Red sea, east Africa to Indonesia and Japan to the Great Barrier Reef (Clark et al. 2000, Lieske and Myers 1994, Randall et al. 1990). Valenciennea sexguttata (Valenciennes, 1837) was distributed along the Red sea, Persian Gulf, East Africa and Australia (Hoese and Larson 1994). The species like Valenciennea longipinnis (Lay & Bennett, 1839) and Valenciennea muralis (Valenciennes, 1837) were widely distributed in the eastern Indian Ocean. Valenciennea parva (Hoese & Larson, 1994), Valenciennea strigata (Broussonet, 1782) and Valenciennea puellaris (Tomiyama, 1956) were distributed in the Indo-Pacific from Red Sea to the Great Barrier Reef. The species Valenciennea wardii (Playfair, 1867) is rare and distributed in widely scattered localities in the Indian Ocean (Hoese and Larson 1994). Other species of this genus show narrow ranges. Distribution of Valenciennea alleni (Hoese & Larson, 1994) is restricted to the Australian coast whereas Valenciennea bella (Hoese & Larson, 1994) occurs along the coast of Japan and Philippines (Hoese and Larson 1994). Valenciennea immaculata (Ni, 1981) is distributed along the coast of Taiwan, Hongkong, the Philippines and Australia (Randall et al. 2004) and Valenciennea limicola (Hoese & Larson, 1994) occurs along the coast of Thailand and Fiji (Allen and Adrim 2003).

The nearest known record of Valenciennea helsdingenii is from the Maldives. The present report adds to our knowledge of species diversity of Gobiidae from the Bay of Bengal, and it assumes that the Bay of Bengal contains as many species as the entire western Indian Ocean. The long stretch of coral islands along the Gulf of Mannar and Andaman Nicobar Islands increases the chance of species abundance and richness in the Bay of Bengal. During recent years, great numbers of new fish species have been described and recorded from the east coast of India (Kannan et al. 2012, Joshi et al. 2012, Zacharia and Kannan 2012).