First report on the occurrence of free-living marine Nematode Oncholaimellus brevicauda Timm 1969 (Oncholaimidae: Enoplida) from India

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1 Indian Journal of Geo-Marine Sciences Vol. 43(10), October 2014, pp First report on the occurrence of free-living marine Nematode Oncholaimellus brevicauda Timm 1969 (Oncholaimidae: Enoplida) from India Tridip Kumar Datta 1, Sivaleela Gunasekher 2 & Anil Mohapatra 1* 1 Marine Aquarium and Regional Centre, Zoological Survey of India, Digha, West Bengal , India 2 Marine Biology Regional Centre, Zoological Survey of India, Chennai , India *[ anil2k7@gmail.com] Received 3 April 2012; revised 30 May 2013 Occurrence of free-living marine Nematode Oncholaimellus brevicauda Timm, 1969 is recorded with morphological description of both male and female for the first time from India. Genus is characterized by a massive right subventrolateral tooth and transverse band in buccal cavity. Species is different from the other Indian species of same genus in having long spicules with two-waved upward directing end part in male and short tail with spinneret at the tail end. [ Key words: Free-living marine Nematode; Oncholaimellus brevicauda ; Bay of Bengal, India] Introduction Northern-East coast of India is having special ecological characteristics with number of river run-off to sea and offers a different ecological habitat with mudflats, sandy and clayey intertidal regions. These unique habitats offer a different ecological niche for several meiofauna which might be unique by their own characteristics. Taxonomic description and distributional record of free-living marine Nematodes from coastal India is inadequate. Taxonomic work by Timm 1,2,3 from the seas around the Indian waters, Gerlach 4 from Maldives Islands and Warwick 5 from Indian oceans recorded more than one hundred and thirty species. Later specialized work on the nematofaunal ecology and taxonomy were restricted mostly at Western continental shelf 6,7,8 and Southeast Coast 9 of India. There are ten valid species belonging to genus the Oncholaimellus recorded from worldwide 10, among them only two species i.e Oncholaimellus calvadosicus De Man, ,12,9 and Oncholaimellus carlbergi Allgén, were recorded from the Indian subcontinent. Rao and Misra 14 did a comprehensive study on the meiofauna of Digha all most three decades ago and recorded eleven species of Nematodes from this area. No species of the present genus was recorded during that survey. During the present study of meiobenthic fauna along the Northern-East coast of India three specimens of the genus Oncholaimellus were collected and identified as Oncholaimellus brevicauda Timm, 1969 which was not yet reported from any part of India. Present recorded species is the first report from Indian coasts thus adding the third species to the genus Oncholaimellus. Materials and Methods Sediment samples were collected from the intertidal areas from two locations (Digha and Shankarpur) of West Bengal and one location (Talsari) from Odisha, India. Collection sites are located between to N and to E (Fig. 1). Study areas are mainly influenced by fresh water inflows through river Subarnarekha, Champa canal and Ramnagar canal. Beaches of these areas are silt loaded through freshwater flow. At Digha, beach material is generally siliciclastic, quartzofeldspathic in composition with well sorted, medium to fine sand 15. Shankarpur has some characteristic mudflats with sandy beach. The beach of Talsari is generally flat, low lying and basically sandy. Mud deposition occurred at the mouth where Subarnarekha River meets with the Bay of Bengal. Collections were done from selected intertidal stations with the help of a hand corer. Sediment samples were sieved by decantation procedure 16 with two brass sieves, upper one of 500 µm pore size and lower one of 63 µm pore size 17. Nematodes were fixed in 5% neutral formalin solution and transferred to a solution of glycerol alcohol (90 parts 70% alcohol and 10 parts glycerin) which was then placed in desiccators for few days. Solution slowly evaporated to anhydrous glycerol. After evaporation, specimens were mounted on glass slides in anhydrous glycerin supported by paraffin wax ring 18. To facilitate measurements of the major body parts, photomicrographs were taken

2 DATTA et al FIRST REPORT OF ONCHOLAIMELLUS BREVICAUDA TIMM 1969 FROM INDIA 1923 of each specimen under the microscope, Olympus CH20i attached with a digital camera. Fig. 1 Study area is showing sampling stations (closed circles) around the coast of West Bengal and Odisha Results Identification and classification of the specimen is followed here given by Platt and Warwick 16, Hodda 19, Keppner 20 and Timm 21. Phylum Nematoda Cobb, 1932 Class Enoplea Inglis, 1983 Subclass Enoplia Pearse, 1942 Order Enoplida Filipjev, 1929 Suborder Enoplina Chitwood & Chitwood, 1937 Superfamily Oncholaimoidea Filipjev, 1916 Family Oncholaimidae Filipjev, 1916 Subfamily Oncholaimellinae Filipjev, 1916 Genus Oncholaimellus De Man, 1890 Specimen O. brevicauda Timm, 1969 The identification was based on three specimens of which one was female and two were males. Two specimens were collected from Digha and Shankarpur of West Bengal during August, 2011 and June, 2012 respectively. Another specimen was collected from Talsari of Odisha during July, Specimens were deposited to Marine Aquarium and Regional Centre, Zoological Survey of India, Digha bearing registration numbers N2848, N2849 & N2850. Cuticle smooth and clear without any striation. Head truncate with maximum diameter µm, Transverse band dividing the buccal cavity into two halves. Ten equal length cephalic setae of 5.2 µm long in both sexes; four submedian cervical setae are present at the opposite base of stoma. Buccal cavity maximum diameter varies 7-9 µm; a massive right subventrolateral tooth of 7-9 µm in length present. Two equal but shorter than right subventrolateral tooth arising from almost same level; one left subventral and other is dorsal. Tiny faint granulation on the surface of stoma. Oesophagus cylindrical, 25-33% wide of corresponding head diameter. Cardia cylindrical. Nerve ring at 29%-33% of oesphagus length. Any part of oesophagus not attached with the body wall. Tail is short, conico-cylindrical in both sexes with cuticularised spinneret at narrowrounded tip. Tail is 2-3 times longer than anal body diameter. Caudal gland extending anterior to anus. Female specimen was 1831 µm long. Female with two opposed reflexed ovaries. Vulva at 65% from head end, transverse and deeply indented. The size of the male specimen varies from 1389 µm to 1434 µm. Males with single outstretched testis, extending almost oesophagus base. Long, slender equal spicules of µm, reddish-brownish in colour. Spicules are times longer than tail. Spicules with distinct capitulum and two-wave upward directing tip. Gubernaculum absent in males. Copulatory bursa granulated with thin genital papillae, most of them protruding beyond the margin of bursa. One pair of long ventrolateral papillae just anterior to anus. Body Colour of fresh specimens of both sexes are faint tan-yellow in colour. Distribution of the same is in Cox s Bazar, Bangladesh; Northern- East coast of India. Discussion Major body parts of male and female are shown in the Fig. 2 (a-h). Some major measurements taken were compared with the earlier description (Table 1) and some additional measurements / proportions of different body parts (Table 2) are also given. Male specimens were quite shorter in length than the specimens described in the original description of the species. But in case of both sexes all the proportions measured in the present specimens are falling in the ranges given in the earlier description. Oesophagus of the male specimen is shorter than the female specimen. Comparative measurements and proportions of some major characters of the present specimens are given in the Table 1 in compare with the original description. It showed that the present specimens are undoubtedly matching with the original description. Present specimens are most closely related to Oncholaimellus coxbazari Timm, 1969 but distinguished by the shorter tail bearing mammillate papillae and longer spicules with wavy tips in male. The present specimens also differ primarily from the other two species found in India viz. Oncholaimellus calvadosicus De Man, 1890 and Oncholaimellus carlbergi Allgén, 1947 by the differential number of cephalic setae,

3 1924 INDIAN J. MAR. SCI., VOL. 43, NO.10, OCTOBER 2014 longer equals spicules with wavy tips and shorter tail bearing mammillate papillae in male. Comparative measurements of some characters of Oncholaimellus brevicauda Timm, 1969 with other two species of Oncholaimellus recorded previously from Indian waters are given in Table 1. Present species was earlier reported from Coxbazar, Bangladesh which indicates the possible range of the species to Indian coastal areas as West Bengal coast is very near to the Table 1 Comparative measurements and proportions of some major characters of Oncholaimellus brevicauda with the original description (Timm) 21 as well as with the other two species of Oncholaimellus viz. Oncholaimellus calvadosicus (Ansari et al.) 12 and Oncholaimellus carlbergi (Sajan) 13 recorded from Indian water are given below. Measurements were taken in µm. - means absence of character; ND means data not available; de Man s a, b and c are recalculated only for original described specimens for comparison with the present specimens indicated by *. Abbreviations used in the table : a: Total body length / Maximum body diameter ; b: Total body length / Oesophagus length ; c: Total body length / Tail length Measurements / Proportions Present Specimen (average) M A L E F E M A L E Original Description (Timm, 1969) 21 Holotype Ranges of all specimens including Holotype Present Specimen Original Description (Timm, 1969) 21 Ranges of all Allotype specimens including Allotype Oncholaimellus calvadosicus (Ansari et al. 2012) 12 Oncholaimellus carlbergi (Sajan 2003) 13 total body length maximum body diameter length of oesophagus length of tail vulva to anus ND ND a* b* c* Table 2 Measurements (in µm) of some other body parts of the present specimens. - represents the absence of character Abbreviations used in the table: c : Tail length / Anal body diameter; v: ( head end to vulva / Total body length ) 100 ; v : ( head end to vulva / head end to anus) 100 Counts/ Proportions male (average) female anal body diameter Head diameter Head length Length of Right subventrolateral tooth Buccal cavity maximum diameter Length of cephalic seta Spicule length c' v v

4 DATTA et al FIRST REPORT OF ONCHOLAIMELLUS BREVICAUDA TIMM 1969 FROM INDIA 1925 Fig. 2 Different body parts of Oncholaimellus brevicauda Timm 1969 ; a. a male specimen ; b. massive right subventrolateral tooth (arrow) and transverse band in buccal cavity ; c. Spicules with two-waved tip in male ; d. spinneret at tail end ; e. mammillate papillae behind anus of male ; f. vulva opening (arrow indicating italic v ) of female with one side reflex ovary (arrow indicating italic o ) ; g. testis in male ; h. nerve-ring around oesophagus. (Scale bars are represented by micron meter given in each photograph) Coxbazar. Some additional characters of male and female are given in Table 2. Acknowledgement Authors wish to express sincere gratitude to Dr. K. Venkataraman, Director, Zoological Survey of India for his kind support and facilities. First author is thankful to Zoological Survey of India for Senior Research fellowship to carry out the work. References 1 Timm R W, Marine nematodes from the Bay of Bengal, I-Phasmidea. J. Bombay. Nat. Hist. Soc. 54 (1) (1956) Timm R W, The Marine Nematodes of the Bay of Bengal. Proc. Pakist. Acad. Sci., 1 (1961) Timm R W, Some estuarine nematodes from Sunderban. Proc. Pakist. Acad. Sci., 4 (1967) Gerlach S A, Freilebende Meeresnematoden von Malediven. Kieler. Meeresforsch., 18 (1962) Warwick R M, Free-living marine nematodes from Indian Ocean. Bulletin. Br. Mus. Nat. Hist. (Zool)., 25 (1973)

5 1926 INDIAN J. MAR. SCI., VOL. 43, NO.10, OCTOBER Harkantra S N, Nair A, Ansari Z A & Parulekar A H, Benthos of the shelf region along the west coast of India. Indian J. Ma. Sci., 9 (1980) Ansari Z A, Parulekar A H & Jagtap T G, Distribution of sub-littoral meiobenthos off Goa coast, India, Hydrobiol., 74 (3) (1980) Sajan S. & Damodaran R. Faunal composition of meiobenthos from the shelf region off west coast of India, Mar. Biol. Ass. India., 49(1) (2007) Ansari K G M T, Manokaran S, Raja S., Khan S A & Lyla S, Checklist of Nematodes (Nematoda: Adenophora) from Southeast continental shelf of India. Check List, 3 (2012) WoRMS (2013), d=2569, date of access Shivaji A, Sanjeevan V N, Saravanane N, Shunmugaraj T & Gupta G V M, Achievements of FORV Sagar Sampada , Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi, Ansari K M G, Lyla P S & Khan S A, New records of free-living marine nematodes (Nematoda: Enoplida) from Indian waters. Mar. Biol. Ass. India. 54 (2) (2012) Sajan S, Meiobenthos of the shelf waters of west coast of India with special reference to free-living marine Nematodes. Ph. D thesis, Cochin University of Science and Technology, Department of Marine Biology, Microbiology and Biochemistry, 2003, pp Rao G C & Misra A, The meiofauna and macrofauna of Digha beach, West Bengal, India. Rec. zool. Surv. India., 83 (3 & 4) (1986) Bhattacharya A K, Sarkar S K & Bhattacharya A, paper presented at An assessment of coastal modificaion in the low lying tropical coast of northeast India and role of natural and artificial forcings, International Conference on Estuaries and Coasts, Hangzhou, China, November 9-11, 2003, pp Platt H M & Warwick R M, Freeliving Marine Nematodes Part-1, British Enoplids: Pictorial key to world genera and notes for the identification of British species, (Cambridge University Press, Cambridge) 1983, pp Coull B C, Estuarine meiofauna A review, trophic relationships and microbial interactions, in: Estuarine Microbial Ecology, edited by L. H. Stevenson & R. R. Colwell (University of South Carolina Press, Columbia) 1973, pp Hooper D J, Handling, fixing, staining and mounting nematodes. in: Laboratory Methods for Work with Plant and Soil Nematodes, edited by J. F. Southey (Her Majesty's Stationery Office, London) 1986, pp Hodda M, Phylum Nematoda Cobb, An outline of higher-level classification and survey of taxonomic richness. in: Animal biodiversity, edited by Z. Q. Zhang, Zootaxa (1932) (2011) Keppner E J, Five New and One Known Species of Free-Living Marine Nematodes of the Family Oncholaimidae (Nematoda: Enoplida) from Northwest Florida, U.S.A. T. Am. Microsc. Soc., 106 (3) (1987) Timm R W, Two new species of Oncholaimellus from the Bay of Bengal. Proc. Pakist. Acad. Sci., 4 (2) (1969)19-25.