Indian Journal of Geo Marine Sciences Vol.46 (03), March 2017, pp. 624-628

New records of adenensis, melvill, 1898 (: : ) from India

Srinivasa Rao M, C. Annapurna* & Ch. Vijaya Bhanu

Department of Zoology, Andhra University, Visakhapatnam 530003, Andhra Pradesh, India.

* [E-mail: [email protected]]

Received 22 September 2014 ; revised 11 November 2016

Thracia adenensis (Melvill, 1898), a bivalve formerly known only from Gulf of Aden and Arab east was recorded for the first time from India during October 2006. While dredging the epifauna, four living adults of T. adenensis species were discovered in Nizampatnam Bay, Bay of Bengal, East coast of India. Re-description of the species along with its geographical distribution were presented in this paper. This record will contribute to the molluscan checklist of Indian seas.

[Key Words: Thracia adenensis, New record, Re-description, Distribution.]

Introduction Thracia adenensis (Bivalvia: Thraciidae), a fragile, its habitat ecology and geographic distribution may semi-trapezoid bivalve was first described by be considered as important and were presented in Melvill1 from Red sea, Gulf of Aden. While this study. This paper will also provide the reviewed sampling the epifauna of Nizampatnam Bay, Bay of morphological descriptions for this poorly known Bengal, during October 2006 four live specimens of species. family Thraciidae were discovered. Morphological characteristics of this bivalve were in agreement Materials and Methods with those described by Melvill (1898) for Thracia The study was carried out over two subsequent post adenensis reported from the Red sea, Gulf of Aden. monsoons (October-November 2006 and 2007) and In the Indian sub-continent, a number of isolated pre monsoons (March 2007 and April 2008) investigations on macrobenthos of shelf, slope, spanning an area 1825 Sq.km. along 20 GPS fixed intertidal regions, estuaries, backwater areas, stations in Nizampatnam Bay (15 º 28’ N to 15 º 48’ lagoons and such other near shore habitats from N and 80 º 17’ E to 80 º 47’ E), Bay of Bengal, east both west and east coasts were conducted from the coast of India (Fig.1). A naturalist’s dredge made of first contribution by Ganapathi & Lakshmana Rao2 a metal frame (30 cm x 45 cm) fitted with a nylon to a recent study by Srinivasa Rao et al.3. But, this mesh (1 sq. cm) net was used upto 50 m depth for species has never been recorded in Indian waters collecting benthos. Altogether, 40 dredge hauls and elsewhere from any division of the world were made from the 20 stations. At each location, expect from the Gulf waters. Lack of any record of twin dredges were operated for 10-15 minutes at 1.5 T. adenensis from previous bivalve collectors in nm.h-1 speed. Only live specimens were picked, India suggests a comparatively fresh introduction. labeled and preserved in 7% formalin. Later, they As, the distribution of T. adenensis represents an were thoroughly washed and transferred into 70% extreme diverse of locality from its native region, alcohol in the laboratory.

INDIAN J. MAR. SCI., VOL. 46, NO. 03, MARCH 2017 625

According to salinity data presented by Ramanadhan et al.6 and Sreenivasa Rao et al.7, Nizampatnam Bay is a hyposaline-normal marine environment similar to Galveston Bay, Texas8 and Coos Bay9. The salinity distributions in different sections of this bay indicate different types of diffusion and mixing. While dredging the Nizampatnam bay for the study of epifaunal diversity, a single specimen of the bivalve, Thracia adenensis was collected 15.5 from station 10 (15 º 36’000” N; 80 º 27’000” E) of Nizampatnam Bay the sampling site (Fig.1). Environmental parameters 15.45 and sediment characteristics of sampled location were presented in Table 1. This species was collected at depth of 15m where the bottom water 15.4 St.10 Bay of Bengal

15.35 Table 1. Environmental and Sediment characteristics of Thracia adenensis’s habitat from sampling site of Nizampatnam Bay, Bay of Bengal. 80.15 80.2 80.25 80.3 80.35 80.4 80.45 80.5

0 15 30km DO (ml.l- St. No. 10 3.92 Figure.1. Study area of Nizampatnam Bay, Bay of Bengal, 1) India with sampling location of Thracia adenensis

15 36’ Organic Latitude º 0.3 Simultaneously, observations on Physico-chemical 00” N matter (%) variables of water (temperature, dissolved oxygen Longitud 80 27’ and salinity) and sediment (organic matter, mean º Sand (%) 99.2 particle diameter and texture - sand, silt, and clay) e 00” E 4 were made according to standard protocols . The Depth T. adenensis 15 Silt (%) 0.8 specimen of was identified and kept in (m) display in the Museum of Zoology Department,

Andhra University and Visakhapatnam, India. Temperat 30.5 Clay (%) 0 ure (0c) Results and Discussion Nizampatnam bay, one of the sea port cities of India Salinity 33.3 MPD (µm) 288 was located in the southern vicinity of Andhra (PSU) Pradesh (15° 30' 000'' - 15° 47' 500'' N and 80° 17' 000'' - 80° 45' 000'' E) with a coast line of 122 km along east coast of India in Bay of Bengal. This was temperature was 30.5 º c, salinity 33.3 PSU and a shallow bay slopes gently from the shore with dissolved oxygen was 3.92 ml.l-1. The percentage depths rarely exceeding 30 m to a maximum of 50 contribution of sand, silt and clay in the sediment 5 meters . This place is affected by both the south were 99.2:0.8:0 respectively representing a sandy west and north east monsoons, the later yielding a substratum with a mean particle diameter of 288 µm major part of the annual rainfall. Mixing of fresh and accumulated 0.3 % organic matter. Ecology of water discharges, wastages of aquaculture ponds this species discovered by Melvill in 1898 from Red and salt pans along its northern and western sea was not described then. But, the present study margins and circulation pattern in the bay controls probably provides better understanding of T. the hydrographical parameters of this region. adenensis’s habitat of surveillance.

626 RAO et al.: NEW RECORDS OF THRACIA ADENENSIS, MELVILL, 1898 FROM INDIA

Systematics Phylum MOLLUSCA Linnaeus, 1758 study were in conformity with Thracia adenensis. Class BIVALVIA Linnaeus, 1758 Order Dall, 1889 Distribution: Family THRACIIDAE Stoliczka, 1870 Thracia adenensis was first discovered by Melvill Genus: Thracia Sowerby, 1823 (1898) in Red sea, gulf of Aden. Later, its Species adenensis Melvill, 1898 (Fig. 2) occurrence from Arab East (gulf of Oman and Muscat) was revealed by Bosch et al.10 and from Material examined: Bahrain was reported by Stephan Fuller11. From its Andhra Pradesh: Four specimens (st.10) were native range in the gulf waters, T. adenensis is now collected in October 2006 from Guntur district, been discovered from the Indian waters. The Nizampatnam Bay, Bay of Bengal, East coast of previous and present reports of this species were India. demonstrated in (Fig.3).

30mm 30mm

Figure.2. Shells of Thracia adenensis collected from Nizampatnam Bay, Bay of Bengal

Diagnosis: Melvill (1898) has given the morphological The shell has a measured length of 30mm, height illustration of the species in that paper. However, its 22mm and thickness 12mm. Shell Semi-trapezoid redescription along with habitat and distribution in shape, inaequivalve, thin, fragile, Creamish white were revealed in the present study. The in colour (Fig. 2). Umbo smooth behind midpoint. measurements of the shell collected from Anterior margin broadly rounded, posterior short Nizampatnam Bay suggested it to be an adult and broadly subquadrate. Ventral margin broadly (Approximately analogous to the species discovered rounded and smooth inside. Outer surface by Melvill, 1898). Hence, existence of an adult T. sculptured with fine concentric lines throughout the adenensis elsewhere from its resident locality will shell. A longitudinal narrow depression extends afford us a base for its survival and invasive nature. from umbo to postero-ventral margin. Right valve is As Nizampatnam was a sea port city, this alien, more convex than left. Shell internally smooth and invasive, non-indigenous or non-native species shiny. Anterior adductor muscle impression intentionally or accidentally was transported and narrowly elongate, whereas posterior impression released through shipping into a habitat outside its broadly oval. Pallial sinus broadly oval. No teeth resident geographical range. The narration of and hinge, both external and internal. The habitat ecology of T. adenensis provides us its morphological characters of the bivalve described preferred region of living. In the past, T. salsettensis Melvill (1898) has given the morphological was recorded from Bombay coast by Melvill12. The character of the bivalve described in the present numerous single valves of T. salsettensis collected

INDIAN J. MAR. SCI., VOL. 46, NO. 03, MARCH 2017 627 by Melvill were re-reported by Subramanyam et . al.13 from the same coast and he described them as the dead shells wafted along with scum to the shore by waves.

Previous Reports: Gulf of Aden and Arab east

Present Report: Nizampatnam Bay, Bay of Bengal, India

Figure.3. Map showing the previous and present distributions of Thracia adenensis

After a century, another species, T. adenensis of the References same genus was discovered from Indian waters. 1. Melvill, J. C. (1898). A brief bibliographical resume Hence, these two species, T. adenensis and T. of the Erythrean Molluscan Fauna, with Descriptions salsettensis of Sixteen Species from Aden. The Annals and of family Thraciidae were hereby added Magazine of Natural History, including Zoology, to the Indian marine molluscan biodiversity. Botany and Geology. 1: 194-206. 2. Ganapati, P. N. and M. V. Lakshmana Rao (1959). Conclusions Preliminary observations on the bottom fauna of the This is the first report of species Thracia adenensis continental shelf of the northeast coast of India. Proc of the First All-India Congress of Zoology. 3: 8-13. in Indian waters and contributes to the knowledge 3. Srinivasa Rao, M., Vijaya Bhanu, C. H., Annapurna, about the morphological and ecological features of C., Sastry, D. R. K. and D. Srinivasa Rao. (2009). this species. This record will contribute to the Echinoderms of Nizampatnam Bay, east coast of molluscan checklist of Indian seas. India. Journal of the Bombay Natural History Society. 106: 30-38. 4. Holme, N. A. and A. D. Mc Intyre. (1984). Methods Acknowledgements for the study of marine Benthos. Blackwell Scientific Authors are grateful to the Ministry of Earth Sciences, Publication, Oxford. 399 pp. Government of India, New Delhi, for funding the project 5. Subba Rao, M. (1964). Some aspects of Continental (F.No. DOD/ MOES /11-MRDF/1/31/P/05). The present shelf sediments off East coast of India. Marine Geology. 1: 59-87. work was carried out at the Marine Biology Laboratory, 6. Ramanadhan, R. and R. Varadarajulu. (1973). Department of Zoology, Andhra University, Hydrology and Hydrography of the Krishna estuary. Visakhapatnam. Authors wish to acknowledge Dr. N. V. Recent researches in Estuarine Biology. 151-164.

Subba Rao, a retired taxonomist from Zoological Survey 7. Sreenivasa Rao, P., Krishna Rao, G., Durgaprasada Rao, N. V. N. and A. S. R. Swamy. (1990). of India for sharing his knowledge in the identification of Sedimentation and sea level variations in specimen. Nizamapatnam bay, east coast of India. Indian Journal of Marine Science. 19: 261–264.

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8. Phleger, F. B. (1965) Patterns of Marsh Foraminifera, Prepared for the General Directorate of Environment Galveston Bay, Texas. Limnology and and Wildlife Protection, Kingdom of Bahrain and Oceanography. 10: 169-184. United Nations Development Program Bahrain 9. Phleger, F. B. (1967). Marsh Foraminiferan patterns, Country Office. Pacific coast of North America. An Institute 12. Melvill, J. C. (1893). Description of twenty-five new Biological Unics National Autonomy. 38: 11-38. species of marine shells from Bombay, collected by 10. Bosch, D. T., Peter Dance, S., Moolenbeck, R. G. and Mr. Alexander Abercrombie. Journal of the Bombay P. G. Oliver. (1995). Seashells of eastern Arabia. Natural History Society. 8: 234-245. Motivate Publishing, Dubai, UAE, 300 pp. 13. Subramanyam, T. V., Karandikar K. R., and N. N. 11. Stephan Fuller. (2005). Towards a Bahrain national Murti. (1949) The marine Pelecypoda of Bombay. report to the convention on biological diversity. Journal of the University of Bombay. 1949, 17, 50-81