Indian Journal of Geo Marine Sciences Vol. 47 (03), March 2018, pp. 660-664 New distributional record of the endemic estuarine sand whiting, Sillago vincenti McKay, 1980 from the Pichavaram mangrove ecosystem, southeast coast of India Mahesh. R1δ, Murugan. A2, Saravanakumar. A1*, Feroz Khan. K1 & Shanker. S1 1CAS in Marine Biology, Faculty of Marine Sciences, Annamalai University, Porto Novo, Tamil Nadu, India - 608 502. 2Department of Value Added Aquaculture (B.Voc.), Vivekananda College, Agasteeswaram, India - 629 701. δ Present Address: National Centre for Sustainable Coastal Management, MoEF & CC, Chennai, India - 600 025. *[E-mail: [email protected]] Received 27 December 2013 ; revised 17 November 2016 The Sillaginids, commonly known as sand whiting are one among the common fishes caught by the traditional fishers in estuarine ecosystems all along the Tamil Nadu coast. The present study records the new distributional range extension for Sillago vincenti from the waters of Pichavaram mangrove, whereas earlier reports were restricted to only the Palk Bay and Gulf of Mannar regions of the Tamil Nadu coast, whereas it enjoys a wide range of distribution both in the east and west coast of India. This study marks the additional extension of the distributional record for S. vincenti in the east coast of India. Biological information on these fishes will have ecological applications particularly on account on their extreme abundance in the mangrove waters. The present study is based on the collection of specimens from handline fishing practices undertaken in the shallow waters of Pichavaram mangroves, on the southeast coast of India. [Keywords: Sillagnids, Sillago vincenti, Pichavaram, India] Introduction Sillaginopodys and Sillaginops)8. In Indian Estuarine sand whiting, Sillago vincenti waters they are distributed both along the east McKay, 1980 belongs to the order Perciformes and west coast9,10,11,12 in various ecosystems representing the family Sillaginidae, locally which suggest the stenohaline adaptation of called as “Keelaikan” in Tamil. These fishes these fishes. As per the available literature usually inhabitant the shallow waters of around 13 valid species (Sillaginopodys brackish water ecosystems with a preference for chondropus, Sillaginopsis panijus, Sillago sandy substrata1,2. Globally, most of the species aeolus, S.argentifasciata, S.ingenuua, belonging to the family Sillaginidae are S.intermedius, S.indica, S.lutea, S.maculata, distributed in tropical and subtropical S.sihama, S.soringa, S.vincenti and S.vittata) regions1,2,3,4,5 while some species are distributed have been reported from Indian in temperate waters6,7. Around 34 species of waters11,13,14,15,16,17,18,19,20,21. Sillaginid species fishes belonging to the family Sillaginidae have have been considered as a candidate species for been recorded worldwide, which comprised of 5 brackish water aquaculture in Asia and India genus (Sillago; Sillaginopsis; Sillaginodes, MAHESH et al.: ENDEMIC ESTUARINE SAND WHITING, SILLAGO VINCENTI MCKAY, 1980 661 making them an economically important and a the head has a golden tinge and each eye has a 22 preferred food species . silver iris with a golden outer surface (Fig. 2 (a)). The snout has a dusky tinge and the Materials and Methods operculum is dark yellow to golden colour. The Fishes were caught by handlines operated by fins are hyaline, with two discontinuous dorsal fishermen in the shallow waters of Pichavaram fins, where first dorsal fin consists of 11 spines o o mangroves (Lat: 11 26.04'N; Long: 79 47.82'E) and the second dorsal fin consists of 1 spine, (Fig. 1) during July, 2012. The freshly captured followed by 23 soft rays and they bear distinct fishes (n=2), from the shallow waters, dark spots, running parallel, closer to each spine approximately 2m depth on a sandy bottom and ray shown in Fig. 2(b) and (c). The anal fin (near the estuarine mouth region) were collected is milky white with white tips which consist of 2 for the present study. spines and 24 soft rays. The pectoral fin base is golden yellow and the pelvic fin is white with a yellowish tip. There are minute discrete black spots present on the flanks of the lateral line shown in Fig. 2(c). In the case of the swim bladder outer morphology, a short bulbous projection was present anteriorly with three anterolateral lobate or recurved projections and no anterior extensions from the swim bladder but, a post coelomic extension present posteriorly with a duct like process on the ventral surface that continues to the vent shown in Fig. 2(d) and (e). They have 34 vertebrae and 74 scales on the lateral line. Five rows of scales are present between the base of the first dorsal- Fig. 1 - Map showing sampling area, Pichavaram, fin spine and lateral line. The maximum length Southeast coast of India. of the fish species from the present study was 9 The fishes were photographed and identified 17.1 cm. However, it can grow up to 30 cm . based on their morphometric, meristic and swim The present results are similar to earlier results 24 bladder characteristics22,,23,24. which recorded a length of 158 to 308mm . Results and Discussions Present study is based on detail study of two specimens of Sillago vincenti from the Pichavaram mangrove ecosystem, in the southeast coast of India. Though this species is closely related to other species like Sillago sihama; S. soringa; S. boutani of the same genus, it can be distinguished by the following characters such as, minute black dots on flanks below the lateral line, pigmentation on dorsal fins, number of rows of scales between the base of the first dorsal-fin spine and the lateral line, Fig. 2 - Sillago vincenti (McKay 1980) with dark black number of vertebrae, and importantly, its swim spots in first and second dorsal fin and its swim bladder bladder structure which consists of one post- structure 25 coelomic extension . The morphometric measurements and meristic From the present observation, the body and head values of the study specimens are presented in colour of the S. vincenti are sandy to light olive; 662 INDIAN J. MAR. SCI., VOL. 47, NO. 03, MARCH 2018 Table 1. Around three fish species belonging to Kakinada and Visakhapatnam waters10. the family Sillaginidae viz., Sillago domina, S. Recently two more species viz., S. aeolus and S. sihama and S. maculate where reported for the ingenuua was based on collections made from first time from Indian waters12. Later S. vincenti Mallipattinam waters17. was reported for the first time in India waters from its observation from Kavand, near The distributional range extension of S. vincenti Neendakara, north of Quilon, Kerala State, India in Indian waters has been reported from the 26 27 20. Afterwards seven species of Sillaginidae coast of Kerala , Karnataka , former Andhra 28 5 29,30 family (S. paryisouamis, S. macrolepis, Pradesh , Goa and Tamil Nadu . In the case S. maculata, S. argentifasciata, Sillaginopodys of the Pichavaram mangrove waters, which are 31 chandropus and Sillaginopis panijus) were rich in ichthyofauna diversity , where S. sihama 32 accounted from the Indian coast13. Subsequently is already reported and the observation of two more species namely S. soringa and S.vincenti adds to existing sand whiting S. intermedius were recorded from Chennai, diversity here. Table 1 Morphometric measurements and meristic characteristics of S.vincenti (McKay, 1980) from present study Morphometric characters value Specimen I Specimen II (mm) (mm) Total length 171 117 Standard length 149 113 Head length 48 31 Body depth 22 17 Pre orbital length 18 13 Post orbital length 17 10 1st dorsal fin base length 34 21 2nd dorsal fin base length 57 38 Pectoral fin length 22 15 Pelvic fin length 19 18 Anal fin length 46 37 Caudal fin length 22 19 1st dorsal fin spine length 31 19 2nd dorsal fin spine length 30 18 3rd dorsal fin spine length 28 17 4th dorsal fin spine length 24 16 11th dorsal fin spine length 4 4 Pectoral base length 6 5 Pelvic base length 5 3 Anal base length 52 37 Caudal peduncle length 27 18 Caudal peduncle depth 8 4 Eye diameter 7 5 Inter nasal width 5 4 Head depth 28 19 Upper jaw length 6 5 Lower jaw length 5 4 Meristic characters Number of branchiostegal rays 3 3 Number of 1st dorsal spines 11 11 Number of 2nd dorsal spine 1 1 Number of 2nd dorsal soft rays 23 23 Number of pectoral soft rays 15 15 MAHESH et al.: ENDEMIC ESTUARINE SAND WHITING, SILLAGO VINCENTI MCKAY, 1980 663 Number of pelvic soft rays 6 6 Number of anal spine rays 2 2 Number of anal soft rays 24 24 Number of rows of scales between base of first dorsal-fin 5 5 spine and lateral line Number of scales on lateral line 74 74 Number of vertebrae column 34 34 Number of post-coelomic extension in 1 1 swim bladder Some research studies claims that S.vincenti is 6. Celand K. W., Studies on the Economic Biology 33 of the Sand whiting (Sillago ciliate, C. & V). endemic to Indian waters , whereas the Proceedings of the Linnaeus Society of New observation of its occurrence has been reported South Wales. 72 (1947) 215 - 228. from Sri Lankan waters25, which suggest its 7. Hayward C. J., Distribution of External Parasites Indicates Boundaries to Dispersal of Sillaginid occurrence in the Sri Lankan part of the Gulf of Fishes in the Indo-West Pacific. Mar. Mannar or that is shared by waters of both Freshwater Res., 48 (1997) 391 - 400. 8. Froese, R. & Pauly, D. 2017. Fish Base (version nations. Although there are several reports on 10/2017). Available at www.fishbase.org the fish diversity31,32, the present record of S.