Journal of Fish Biology (2007) 70, 310–312 doi:10.1111/j.1095-8649.2006.01278.x, available online at http://www.blackwell-synergy.com
Occurrence of the Japanese seahorse Hippocampus mohnikei Bleeker 1854 from the Palk Bay coast of south-eastern India M. T HANGARAJ
AND
A. P. L IPTON *
Marine Biotechnology Laboratory, Vizhinjam Research Centre of CMFRI, Vizhinjam, Thiruvananthapuram 695521, India (Received 17 April 2005, Accepted 1 August 2006) The occurrence of the Japanese seahorse, Hippocampus mohnikei is reported for the first time # 2007 The Authors from the Palk Bay coast of south-eastern India. Journal compilation # 2007 The Fisheries Society of the British Isles
Key words: Hippocampus mohnikei; Palk Bay.
A female Hippocampus mohnikei Bleeker, with a size of 70 mm overall length (trunk length þ tail length þ head length) was collected as a by-catch on 3 April 2005 off Mullimunai in Palk Bay coast, South India (09°459 N; 79°019 E). The specimen was found at a depth of 6 m, among Halophila and Thalasia species of sea grasses. The specimen is preserved in the museum collections at Vizhinjam Research Centre of the Central Marine Fisheries Research Institute (CMFRI), Vizhinjam (Cat. No. 146). The Palk Bay specimen (Fig. 1) has the following morphometric and meristic features: trunk length (TrL) 22 mm; tail length (TaL) 38 mm; coronet height (CH) 5 mm; head length (HL) 10 mm; snout length (SnL) 3 mm; snout depth (SD) 25 mm; head depth (HD) 7 mm; trunk depth between 4th and 5th trunk rings (TD4) 55 mm; trunk depth between 9th and 10th trunk rings (TD9) 8 mm; trunk width (TW) 6 mm; distance between the tips of the lateral trunk ridge spines of the 9th trunk ring (SPW) 6 mm; pectoral fin length (PL) 3 mm; dorsal fin length (DL) 6 mm; trunk ring (TrR) 11; tail ring (TR) 38 and keel depth (KD) 4 mm. All the above morphometric measurements were taken using dial callipers to the nearest 05 mm, on the right side of the fish and are based on the methods of Lourie et al. (1999). Fin rays were counted under a binocular microscope. The specimen has two cheek spines and a prominent eye spine. The coronet is slightly elevated with five tiny projections. The body has low
*Author to whom correspondence should be addressed. Tel.: þ91 4712480324; fax: þ91 4712480324; email:
[email protected]
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FIG. 1. Hippocampus mohnikei, CMFRI number 146, from the Palk Bay coast of India.
spines. The dorsal spines on trunk rings 1, 4, 7 and tail rings 4, 8, 11 and 14 are slightly enlarged. The pectoral fin rays (12) and dorsal fin rays (14) cover 2 þ 1 trunk rings. The freshly collected specimen was yellowish deep green in colour. The morphometric and meristic characters of the Palk Bay specimen, in particular the short snout (33 times in HL), double check spines and prominent eye spine, agree with the diagnostic features of H. mohnikei noted by Lourie et al. (1999). Three other species of Hippocampus are reported from Palk Bay, Hippocampus trimaculatus Leach 1814, Hippocampus fuscus Ruppell 1838 and Hippocampus kuda Bleeker 1852, and Lipton & Thangaraj (2002) provided descriptions which allow H. mohnikei to be distinguished from them. Hippocampus trimaculatus has three prominent black spots on the dorso-lateral surface of the first, fourth and seventh trunk rings (spots absent in H. mohnikei), and has a longer snout (19–24 of the HL). Hippocampus fuscus and H. kuda have longer snouts compared to H. mohnikei (24–30 of the HL in H. fuscus; 20–26 of the HL in H. kuda). Hippocampus kuda also has a single cheek spine (v. two in H. mohnikei). According to Froese & Pauly (2005), Hippocampus histrix Kaup 1856 and Hippocampus kelloggi Jordan & Snyder 1902 have an Indo-Pacific distribution # 2007 The Authors Journal compilation # 2007 The Fisheries Society of the British Isles, Journal of Fish Biology 2007, 70, 310–312
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and both are listed as possibly from Indian marine waters. The specimen of H. mohnikei from Palk Bay, however, can be easily distinguished from both species. Hippocampus histrix is characterized by the presence of very long sharp spines over the entire body, a single check spine, and a long snout (17–20 of the HL). Hippocampus kelloggi can be distinguished by its thick and long snout (20–23 of the HL) and larger body size (28 v. 8 cm overall length; Froese & Pauly, 2005). The specimen of H. mohnikei from Palk Bay represents a significant range extension for this species, which is otherwise known only from coastal marine waters of Japan and Vietnam (Masuda et al., 1984; Lourie et al., 1999). The morphometric and meristic features of the Palk Bay specimen agree with those of Vietnamese specimens, given by Lourie et al. (1999). Nevertheless, further genetic analyses would be very useful to confirm the apparent conspecificity of Palk Bay specimens with H. mohnikei from Japan and Vietnam. Hippocampus mohnikei is included as ‘Data Deficient’ in the IUCN Red List of Threatened Species (Morgan, 2005). Hence the occurrence of this species in Palk Bay of south-eastern India is of conservation and biogeographic importance. The authors are thankful to the Ministry of Environment and Forests, Government of India, for financial assistance in the form of a sponsored project.
References Lipton, A. P. & Thangaraj, M. (2002). Present status of seahorse fishing along the Palk Bay coast of Tamilnadu. Marine Fisheries Information Service. Technical & Extension Series 174, 5–8. Lourie, S. A., Vincent, A. C. J. & Hall, H. J. (1999). Seahorses: an Identification Guide to the World’s Species and their Conservation. London: Project Seahorse. Masuda, H., Amaoka, K., Araga, C., Uyeno, T. & Yoshino, T. (1984). The Fishes of the Japanese Archipelago. Tokyo: Tokai University Press.
Electronic References Froese, R. & Pauly, D. (Eds) (2005). FishBase. Available at http://www.fishbase.org (version November 2005). Morgan, S. (2005). Hippocampus mohnikei. In 2006 IUCN Red List of Threatened Species. Available at http://www.iucnredlist.org (downloaded on 8 May 2006).
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# 2007 The Authors 2007 The Fisheries Society of the British Isles, Journal of Fish Biology 2007, 70, 310–312
