And Dougaloplus Echinatus (Family: Amphiuridae) from Andaman and Nicobar Islands, India

World Journal of Zoology 6 (4): 334-338, 2011 ISSN 1817-3098 © IDOSI Publications, 2011

First Report of Two Brittle Star Ophiothela venusta (Family: Ophiotrichidae) and Dougaloplus echinatus (Family: Amphiuridae) from Andaman and Nicobar Islands, India

Koushik Sadhukhan and C. Raghunathan

Zoological Survey of India andaman and Nicobar Regional Centre, National Coral Reef Research Institute, Port Blair - 744102 Andaman and Nicobar Islands

Abstract: Andaman and Nicobar group of islands being a part of India shows a great deal of ecological diversity in marine ecosystem. The Ophiuroids species represent major concentration of benthic biomass and play important role in functioning of their local ecosystem. Specimens were collected in subtidal sampling followed by preserving in 70% alcohol and carefully examined the specimens under light microscope Leica M 205A.Two species of Brittle star (Class: Ophiuroidea) Ophiothela venusta and Dougaloplus echinatus are firstly reported from Andaman and Nicobar Islands. The present study describes the taxonomical features of the identified echinoderms based on their morphological characters. The species Ophiothela venusta belongs to family Ophiotrichidae are distinguished by the spinelets on their disks, thorny arm spines and an oral armament consists of dental papillae. Another species Dougaloplus echinatus belongs to family Amphiuridae are characterized by their radial shields, finely scaled disc and attached oral plates with adoral shields.

Key words: Ophiuroids Subtidal Radial shields Dental papillae Morphological characters

INTRODUCTION Ophiothela venusta and Dougaloplus echinatus are firstly reported from Andaman and Nicobar Islands and The coastline of Andaman and Nicobar islands described them with morphological and taxonomic provides varied habitats such as rocks, sand, mud, characters. mangroves etc. All these factors have encouraged a rich settlement of echinoderms in the coastal and MATERIALS AND METHODS offshore habitats of these islands. The echinoderm fauna of these islands is around 53.1% of the entire The survey was conducted in Pongibalu Indian Coast, though the coastline of these islands is (Lat: 11°30.956’N and Long: 92°39.201’E) Rutland island only 28% and the exclusive economic zone only 30% (Lat: 11°23.737’N and Long: 92°40.838’E) of South of the Indian subcontinent [1]. The Ophiuroidea Andaman in November, 2010 by using self-contained survives in all types of marine habitats, such as soft underwater breathing apparatus (SCUBA) diving. During bottoms in shallow water and tide pools. This class scuba diving, we collected the specimens by hand and represents 103 species from the reef habitats of Andaman then transferred the animal to fresh water for killing. The and Nicobar islands that constitutes higher percentage specimens were then carefully lifted and immersed into (62%) of their diversity in the islands [2]. At first Bell [3] their respective sea-water-filled containers to which 95% is the first who published the list of echinoderm species ethanol (3 parts sea water: 1 part 95% ethanol) was added, from Andaman islands. Several species of Ophiuroidea oral side down with arms spread out [14]. In laboratory, collected as reference collection for Indian museum were specimens were examined under Leica M205 A light identified by Koehler [4, 5, 6, 7]. In addition, some microscope. Specimens were collected to study their monographic and revisionary accounts on Ophiuroidea morphological and taxonomic characters. All specimens have also been performed by Doderlein [8], Clark, [9, 10], were registered and deposited in the National Zoological Fell [11], Madsen [12]. At earlier, James [13] reported Collection of Z.S.I, Port Blair. Identification was done by Dougaloplus echinatus from gulf of Manner in India. in situ observation and photographs in conjunction with During our survey these two species named as Clark and Rowe [15], Koehler [7].

Corresponding Author: Koushik Sadhukhan, Zoological Survey of India, Andaman & Nicobar Regional Centre, National Coral Reef Research Institute, Port Blair- 744102, Andaman & Nicobar Islands. 334 World J. Zool., 6 (4): 334-338, 2011

Fig. 1: Ophiothela venusta (de Loriol, 1900): a. Dorsal view; b. Ventral view; c. Oral Shields with the arrangement of tooth papillae; d. Dorsal arm plate with arm spines; e. Arrangement of ventral arm plate; f. Tentacles and tentacle scale.

RESULTS Description: The dorsal side of the disc are covered with coarse granules often also with conical spines or rounded Ophiothela Venusta (de Loriol, 1900) tubercles. There are five oral shield attached at the point Systematic Position: of each arm. The oral shields are large; four sided with distal margin wider than the proximal (Fig. 1c). At the tip Phylum: Echinodermata of the jaw there are 11-14 tooth papillae. The dorsal arm Class: Ophiuroidea plates are fan-shaped and bear four tapering spines Order: Ophiurida throughout the arm (Fig. 1d). The first ventral arm plate is Family: Ophiotrichidae about half the size of the following one. Both are longer than wider. The proximal edge is almost rounded and the Morphometrics: Specimen: ZSI/NZC/ANRC/ 6206; distal edge is almost straight (Fig. 1e). The lateral edges of disc diameter: 1.5 cm; arm length: 9 cm (Fig. 1a); the plates are concave. Each tentacle pored are covered Length of arm spines: 1.990 mm; dorsal arm plate- with oval shaped tentacle scale (Fig. 1f). vertical line length: 1.035 mm (32X), horizontal line length: 1.718mm (32X); ventral arm plate- vertical Habitat: This species occupies a much extended zone in line length: 1.880mm (32X), horizontal line length: the intertidal region from almost the supra-littoral region 1.926mm (32X). to the low water mark. It is somewhat gregarious and its

335 World J. Zool., 6 (4): 334-338, 2011 rock pools with fissures. This species are also collected Dougaloplus Echinatus (Ljungman, 1867 ) from muddy button at a depth of 3-15 meters off Systematic Position: Pongibalu, South Andaman. At the slightest touch all the arms spread out and the brittle stars ties to get away. It is Phylum: Echinodermata always found either under a dead coral or seen through Class: Ophiuroidea the crevices of the rock. Order: Ophiurida Family: Amphiuridae DISTRIBUTION Morphometrics: Specimen: ZSI/NZC/ANRC/ 6207; East Africa, Madagascar, South East Asia, East disc diameter: 6.197mm (7.9X); arm length: 7.8-8.2 cm Indies and Islands of West Indian Ocean. (Fig. 2a and 2b); length of arm spines: 2.533mm (32X); dorsal arm plate- vertical line length: 1.218mm (32X), Remarks: This species is firstly reported from Andaman horizontal line length: 1.628mm (32X); ventral arm and Nicobar islands as well as from India also. The plate- vertical line length: 1.919 mm (32X), horizontal line synonymous species of Ophiothela venusta is length: 1.737mm (32X). Ophiothela beauforti which differs by extraordinarily variable armament ranging from complete absence of the Description: The dorsal surface of the disc is very finely disc dorsally, only marginal spines being present, to a scaled and no central rosette of primary plates is apparent continous covering of coarse granules with conical (Fig.2c). The radial shields are banana-shaped, three tubercles or spines near the centre of the disc. times as long as broad and equal to half the disc radius.

Fig. 2: Dougaloplus echinatus (Ljungman, 1867): a. Dorsal view; b. Ventral view; c. Details of the disc portion; d.; Detailed structure of oral plates e. Arrangement of ventral arm plate; f. Dorsal arm plate with arm spines.

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The oral plates are conspicuously sunken midway along from Gulf of Manner of Indian subcontinent by James their length; rising up to meet the adoral shields distally [19]. The similar species Dougaloplus acanthinus is and for the insertion of the infradental papillae proximally characteristically distinguished by their few scattered disc (Fig. 2d). The ventral arm plates are longer than broad for spines and distinct scaling on the disc. Arms of the greater part of the arm length. There is one moderate Dougaloplus ehinatus also characterized with black sized tentacle scale (Fig.2e). The dorsal arm plates are strips on yellow lines whereas Dougaloplus acanthinus rounded pentagonal and the lateral and distal margins has uniformly black arms. 427 species of echinoderms form a continuous fan shape; there is some overlap of which 105 Ophiuroids species have been reported between succeeding plates (Fig.2f). Proximally, there are from Andaman and Nicobar islands [2]. Finding of six arm spines, which reduce in number to five and then new records will be helpful for the preparation of four about halfway along the arm length. The spines are biodiversity conservation and management action plan cylindrical with bluntly pointed rugose tips; the for the echinoderms in Andaman and Nicobar islands. lowermost in each series is the longest and approaches Further study on echinoderm taxonomy are necessary one arm segment in length. should be done in terms of monographic works and marine scientist should be encouraged to study the other Distribution: Ceylon area, East Indies, North Australia aspects on this animal [20]. More surveys are also and Philippines. required in near future to get more apprehensive data on different types of Ophiuroids species from Andaman and Habitat: This species appears to live beyond 5m depth. It Nicobar Islands. appears to be associated with live corals and under the crevices of dead corals. ACKNOWLEDGEMENT

Remarks: Dougaloplus echinatus is newly recorded from The authors express their gratitude to the Director, Andaman and Nicobar islands and it is reported from Zoological Survey of India for facilities and Ministry of Pongibalu and Rutland island of South Andaman. In Environment and Forests, Govt. of India for providing India, the genus Dougaloplus represents only this financial support. species which were reported from gulf of Manner, Tamilnadu at earlier. REFERENCES

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