ACTA ICHTHYOLOGICA ET PISCATORIA (2017) 47 (2): 145–161 DOI: 10.3750/AIEP/02108 NEW RECORDS OF MARINE FISHES FROM THE CORAL REEFS AND DEEP WATERS OF GULF OF MANNAR, INDIA Vinay P. PADATE1, Chandrashekher U. RIVONKER1*, A. Chandrashekar ANIL2, Subhash S. SAWANT2, and VENKAT Krishnamurthy2 1Department of Marine Sciences, Goa University, Taleigao Plateau, Goa, India 2CSIR—National Institute of Oceanography, Dona Paula, Goa, India Padate V.P., Rivonker C.U., Anil A.C., Sawant S.S., Venkat K. 2017. New records of marine fishes from the coral reefs and deep waters of Gulf of Mannar, India. Acta Ichthyol. Piscat. 47 (2): 145–161. Background. The coral reefs and deep water ecosystems of Gulf of Mannar support diverse assemblages of marine fishes vulnerable to indiscriminate mechanized fishing. However, lack of comprehensive information on the fish diversity of these ecosystems is aggravated by the habitat complexity of the fishing grounds, inadequate faunistic surveys and insufficient taxonomic expertise. In view of this, the present paper aims to document rare fishes and supplement the existing species inventory from this region. Materials and methods. Sampling surveys included 23 hauls on-board commercial single-day otter trawlers operating bottom trawls at 15–100 m depths, and mid-water trawls at 100–153 m depths in the Gulf of Mannar. In addition, by-catch landings of commercial trawlers were surveyed at Tuticorin fishing harbour. Specimens were subjected to morphometric and meristic examination and deposited at the Central Marine Fisheries Research Institute, Kochi. Results. The presently reported survey of rare fishes revealed one elasmobranch,Hypogaleus hyugaensis (Miyosi, 1939). In addition, 12 species of teleosts belonging to four orders, 10 families, and 11 genera were identified as Uropterygius micropterus (Bleeker, 1852); Dendrochirus bellus (Jordan et Hubbs, 1925); Snyderina guentheri (Boulenger, 1889); Acropoma japonicum Günther, 1859; Gymnocranius elongatus Senta, 1973; Pomacentrus similis Allen, 1991; Pristotis cyanostigma Rüppell, 1838; Leptojulis cyanopleura (Bleeker, 1853); Naso annulatus (Quoy et Gaimard, 1825); Naso thynnoides (Cuvier, 1829); Pseudalutarius nasicornis (Temminck et Schlegel, 1850); and Lagocephalus suezensis Clark et Gohar, 1953. The present paper provides descriptions of each species supplemented with meristic counts and morphometric measurements. An identification key to these species is provided. Conclusion. Hypogaleus hyugaensis, U. micropterus, D. bellus, P. cyanostigma, N. thynnoides, P. nasicornis, and L. suezensis represent the first records in Indian waters. Additionally, G. elongatus, P. similis, and N. annulatus represent the first records off the Indian mainland, and S. guentheri, A. japonicum, and L. cyanopleura represent the first records off the East coast of India. Among these,D. bellus, S. guentheri, and P. cyanostigma represent the first records outside their known zoogeographical ranges. Patchy zoogeographical distribution and extension of known geographical ranges are attributed to recurrence of vicariance events in the geological past. Keywords: rare fishes, bottom trawl, new records, taxonomy, morphometry INTRODUCTION associated finfish species, which are being gradually The Gulf of Mannar with an area of 10 500 km2 is removed by large scale mechanized fishing (Yogesh situated off the southeast coast of India and comprises Kumar et al. 2013). This region is also prone to tremendous 21 small islands surrounded by fringing coral reefs anthropogenic pressure owing to large scale industrial and (Venkataraman et al. 2004). The sub-tidal habitats shipping activities, which are potentially hazardous to the comprise live coral cover, coral boulders with encrusting fragile coral reefs and sea-grass habitats (Kathal 2005). algal beds at 10–50 m depths (Prakash and Kumar 2016). Therefore, in order to assess the diversity of demersal Thomas (1970) described new sponges associated with fishes in the Gulf of Mannar, trawling surveys on- deep water corals of the genus Pachyseris up to 180 m board commercial trawlers were undertaken off the depth indicating the existence of deep water reefs in this V.O. Chidambaranar Port, Tuticorin. These surveys region. This ecosystem reportedly supports > 900 reef- revealed thirteen new records of rare fishes in the Indian * Correspondence: Prof. Chandrashekher U. Rivonker, Department of Marine Sciences, Goa University, Taleigao Plateau, Goa 403206, India, phone: +91-832-6519352, e-mail: (CUR) [email protected], (VPP) [email protected], (ACA) [email protected], (SSS) [email protected], (VK) [email protected]. 146 Padate et al. waters, and supplement the existing information pertaining morphometric and meristic studies of each species were to the finfish diversity in this region. carried out following the specifications provided by published literature relevant to each taxon. Morphometric MATERIALS AND METHODS measurements of Hypogaleus hyugaensis (Miyosi, The area of the presently reported study encompasses 1939) and Uropterygius micropterus (Bleeker, 1852) are the trawling grounds in the Gulf of Mannar, located off expressed as percentages of Total Length, whereas those the south-eastern coast of India (Fig. 1) from 15 through of the other eleven species are expressed as percentages of 153 m depth. The bathymetry of the study area (between Standard Length. latitudes 8°27′54′′N and 8°52′43′′N and longitudes Reference voucher samples were deposited in 78°12′33′′E and 78°32′38′′E) is characterized by gentle the Marine Biodiversity Museum of Central Marine gradient from the shoreline to 20 m depth, followed by Fisheries Research Institute, Kochi (a designated national slightly steep gradient between 20 m and 50 m depth repository), and accession numbers to specimens are contours, and very steep gradient between 50 m and 500 provided in the Results section. m depth contours (Anonymous 2010). The following abbreviations are used in the text: A = anal fin, BD = body depth, BW = body width, C = caudal A fin, CPD = caudal peduncle depth, CPL = caudal peduncle 10°N Palk length, CPW = caudal peduncle width, D = dorsal fin, D1 = Bay N India first dorsal fin,2 D = second dorsal fin, ED = eye diameter, GR, number of gill rakers, HH = head height, HL = head 9°N Arabian Tuticorin Sea length, HW= head width, INS = inter-nasal space, IOW = Gulf of Mannar Sri Lanka inter-orbital width, LJL = lower jaw length, LS = lateral line scales, ML = mouth length, P = pectoral fin, PAL = 8°N 76°E 77°E 78°E 79°E 80°E pre-anal length, PDL = pre-dorsal length, POL = pre-oral B length, POS = pre-orbital snout length, PPL = pre-pectoral 8°50’ length, PVL = pre-pelvic fin, SL = standard length, SnL = 2 snout length, TL = total length, UJL = upper jaw length, 5 20 8°50’ 10 V = pelvic fin. 2 10 20 The presently reported study was carried out on board 30 TUTICORIN 8°45’ commercial trawlers in accordance with the Indian national 2 5 50 5 100 regulations and did not require any special permit. 200 8°40’ 500 RESULTS The presently reported survey of rare fishes for the 50 100 8°35’ 200 Gulf of Mannar revealed one elasmobranch, Hypogaleus 500 hyugaensis (Miyosi, 1939). In addition, 12 species of 5 10 8°30’ teleosts belonging to four orders, 10 families, and 11 genera were identified as Uropterygius micropterus 20 (Bleeker, 1852); Dendrochirus bellus (Jordan et Hubbs, 8°25’ 78° 78°05’ 78°10’ 78°15’ 78°20’ 78°25’ 78°30’ 78°35’ 1925); Snyderina guentheri (Boulenger, 1889); Acropoma Trawling grounds japonicum Günther, 1859; Gymnocranius elongatus Senta, 1973; Pomacentrus similis Allen, 1991; Pristotis Fig. 1. Geographical location of study area (A), Detailed cyanostigma Rüppell, 1838; Leptojulis cyanopleura map of the study area indicating the sampling site (B) (Bleeker, 1853); Naso annulatus (Quoy et Gaimard, 1825); Naso thynnoides (Cuvier, 1829); Pseudalutarius Sampling surveys were carried on-board commercial nasicornis (Temminck et Schlegel, 1850); and single-day otter trawlers operating bottom trawls at 15– Lagocephalus suezensis Clark et Gohar, 1953. 100 m depths, and mid-water trawls at 100–153 m depths in the Gulf of Mannar during July 2012 to March 2013 with Order Carcharhiniformes Compagno, 1977 a total effort of 35 man hours. Altogether, 23 bottom trawl Family Triakidae Gray, 1851 hauls were examined. Rare fishes hauled up by trawl nets Genus Hypogaleus Smith, 1957 were collected, photographed, temporarily preserved on Hypogaleus Smith, 1957: 589 (type species: ice, and taken to the laboratory for detailed examination. Galeorhinus (Hypogaleus) zanzibarensis Smith, 1957 by Additionally, rare fishes were also collected from by-catch original designation; monotypic). of commercial trawlers at Tuticorin fisheries harbour. Remarks. It is a monotypic genus distributed off South At the laboratory, taxonomic identification was Africa, Tanzania, Kenya, Arabian Gulf, Taiwan, Japan, carried out following FAO Species Identification Sheets and south-western Australia (Compagno and Niem 1998). (Carpenter and Allen 1989, Compagno and Niem 1998, The presently reported observation constitutes the first Böhlke et al. 1999, Poss 1999, Allen 2001, Hutchins 2001, record from Indian waters. Matsuura 2001, Randall 2001a, Westneat 2001). Detailed New fish records from Gulf of Mannar, India 147 Hypogaleus hyugaensis (Miyosi, 1939) According to the second step, this specimen possesses Fig. 2A rudimentary anterior nasal flap, a prominent ventral Eugaleus hyugaensis Miyosi, 1939: 91, fig. 1 (type locality: caudal