New Record of a Primitive Brachiopod Benthic Fauna from the North- East Coast of India

ISSN: 2347-3215 Volume 2 Number 3 (March-2014) pp. 70-73 www.ijcrar.com

New record of a primitive brachiopod benthic fauna from the North- East coast of India

S.Samanta1*, A.Choudhury2 and S.K.Chakraborty3

1Department of Zoology,Vidyasagar University Midnapore-721102, West Bengal, India 2S.D.Marine Biological Research Institute, Sagar Island, Sundarban, 24 Parganas(S)- 743373.West Bengal, India 3Faculty of Science, Department of Zoology, Vidyasagar University, Midnapore-721102, West Bengal, India *Corresponding author

KEYWORDS A B S T R A C T

The intertidal belt at the confluence of Subarnarekha estuary, a transboundary Brachiopoda; with Bay of Bengal is an example of physically stressed heterogeneous Lingula anatina; habitats possessing a number of mudflats and sand flats that support the lives Living fossil; of an assemblage of diversified macrobenthic fauna. The Brachiopods West Bengal; (Lampshells) make up a major macrobenthic faunal group in this area which Subarnarekha estuary. includes several morphotypes of Lingula anatina distributed in some restricted areas of the world. The morpho-anatomic study of Lingula anatina- a Precambrian living fossil as a new record from the eastern part of West Bengal has been undertaken in the present study.

Introduction

The intertidal belt of Midnapore coast, shelled marine animal. About 30000 especially the studied area supports species and 120 genera under the phylum diversified forms of macrobenthic fauna of brachiopoda have been described in a which include good number of fossil record which extends into the lower brachiopodans which has not been reported Cambrian period of which 300 or so earlier from West Bengal coast-Talsari species of brachiopods remain. mudflats. Brachiopods (from Latin- (Pennington, J.T. et al., 1999; Stricker, brachium; poda-foot) make up one of the S.A., 1999 and Emig et al., 2013). Most important minor animal phyla, also known living brachiopods are articulate, there as lamp shells are sessile benthos and two being only about 50 species of inarticulate

(Rupert,Fox, Barnes,2004). The inarticulate arm; poda-foot), are sessile benthos, and brachiopod of family Lingulidae has only inhabit mostly in tidal mud-flats, containing two living genera- Glottida and Lingula hard calcareous shell covering the anterior (Emig and Bitner, 2005). This rare group of part. The inarticulate brachiopod belonging benthic animal is reported from some river to the family Lingulidae has only two mouth of Indian coasts (Godavari, Krishna, living genera-Glottida and Lingula (Emig Ganges and Gujrat coast) (Rao, 2004). But and Bitner, 2005). Lingula anatina is being reported from the confluence of Subarnarekha estuary near The first descriptions of Lingula were New Digha. made from then extant specimens by three famous French scientists: Bruguière, Cuvier, and Lamarck. In 1812 the first Materials and Methods fossil lingulids were discovered in the Mesozoic and Palaeozoic strata of the U.K. Lingula anatina was studied over a stretch and were referred to Lingula on the basis of of 3 km along the Talsari(21036 N and similarity in the form of the shell. In the 87027 E) during July 2010 to Jun 2011 1840's other linguliform brachiopods from employing 0.5 m2 quadrant from the the Palaeozoic were described. Darwin in lowest low tide level to the highest high 1859 described Lingula as "living fossil" in tide mark of the intertidal belt at three his book "On the Origin of Species (Emig, different study sites, located at an interval 2008). Although they were extremely of 1 km distance. Specimens after being common throughout the palaeozoic, today collected were preserved in 4% formalin they are considered a minor phylum, and solution with glacial acetic acid for the only five orders have extant further studies at laboratory. The species representatives. Among these Lingulida was identified. with the technical assistance comprises two families, 6 genera and 25 and standard literatures of Dr. Christian C. species (Emig, 2013). Emig, Directeur de Recherches Honoraire- C. N. R. S., 20, Rue Chaix, 13007 Observation suggests that the Lingula Marseille, France. anatina (Fig: 1)shell composed of two separate bilaterally symmetrical, little Result and Discussion dissimilar valves. Anterior margin of which are marked with bristles. Lower side of the Lophophorates, a unique group of aquatic valves is enriched with signs of muscle invertebrates, characterized in having a flap scars and canals. The valves are of muscle endowed spiral feeding structure collagenous chitinophosphatic in of ciliated tentacles around the mouth composition (Williams et al., 1994) .The known as lophophore. Traditionally this anterior body wall extended forming group includes the brachiopod or lamp mantle. As an elevation of ventral mantle shell, the bryozoans or moss animals and lobe a long extension is formed from the the phoronids. Among these Lingula posterior end of ventral valve called anatina (Inarticulate brachiopoda) is being pedicle. Mainly three different types of reported presently from the confluence of muscles (viz. - one pair of anterior adductor Subarnarekha estuary (Talsari 21º36´ N & muscle, one pair of posterior adductor 87º27´E) near New Digha, West Bengal, muscle and three oblique muscles). India. Brachiopods (from Latin: brachium- Besides one pair of lateral muscle have also

been found in Lingula anatina. The in the centre of the lophophoral base outgrowth of the anterior body wall forms between the brachial fold and tentacular lophophore which acts as filtering device fringe and terminates after convolutions of during feeding in these animals. The intestine at the right side into the mantle digestive system originates from mouth cavity .There are two conspicuous digestive which is a transversely elongated slit found Figure.1 Lingula anatina, pre-cambrian inarticulate brachiopoda.

glands with four ducts surrounding the period. As a result new colony represents a stomach and pale yellowish in colour. The mixed colony containing young, middle coagulable pinkish coelomic fluid contains aged and aged individuals of Lingula spherical, amoeboid phagocytic anatina coelomocytes and spicules. A pair of Historically, the group has been well nephridium with nephrostome and studied by paleontologists but neglected by nephridiopore situating beneath the biologists. The present paper has attempted digestive gland on both side of intestine. to investigate on the morphology and Lingula anatina is dioecious animal (Emig, anatomy of Lingula anatina, brachiopodan 1997) and male have pale white testis and species having unique morpho-anatomic female contain deep yellowish red ovary. excellence, excellence, documented presently from midnapore (East), West The individual of these species collected Bengal- Orissa coast, India. from three different study sites possesses common morphoanatomic features. Acknowledgements Specimens occur in abundance in tidal creek. Field observations strengthen the Authors are thankful to Dept. of Zoology, fact that tidal waves and water current Vidyasagar University, Midnapore-721102, forced to uproot these infaunal animals and West Bengal, India for supporting causing reformation of their habitats every laboratory and library facilities. The year during monsoon and post monsoon authors are also grateful to

Dr. Christian C. Emig, Directeur de Treatise on Invertebrate Recherches Honoraire- C. N. R. S., 20, Rue Paleontology.Part H, Brachiopoda Chaix, 13007 Marseille, France for revised, Geological society of America, technical assiatance toward specimen Boulder and University of Kansan identification. Press, Lawrence., 1997, 1, 471-495. Emig,C and Bitner, A M., The Brachiopod References Lingula in the middle Miocene of the Central Paratethys, Acta Emig, C. C., Ecology of inarticulate Palaeontologica Polonica, 2005, brachiopods, In: R. L. Kaesler (ed.), 50(1):181-184. Emig C.C., On the history of the names Lingula anatina and on the confusion of the forms assigned them among the Brachiopoda.- Carnets de Géologie / Notebooks on Geology, Brest, 2008, Article 2008/08 (CG2008_A08). Emig, C. C., Bitner, M. A. and Alvarez, F., Phylum Brachiopoda. Zootaxa, 2013, 3703 (1): 75-78. Willium, A., Cusack, M. and Mackay, S, Collagenous chitinophosphatic shell of the Brachiopod Lingula. Phill. Trans. Roy. Soc. Lond. B. BiolSci, 1994, 346: 223-266. Rao Nagaeswara,C.A., Faunal Diversity:Estuarine Ecosystem. Freshwater biological Station, Zoological Survey of India, 1-1-300/B, Ashoknagar, Hyderabad-500020. EPTRI-ENVIS Newsletter, 2004, Vol.10, No 3, pp-9. Rupert,E.E., Fox, R.S. and Barnes, R.D., Invertebrate zoology: A Functional Evolutionary Approach. 7th ed., 2004, Thomson, Brooks/Cole vii-xvii, 1-963, 11-126.