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First Report on the Occurrence of Free-Living Marine Nematode Oncholaimellus Brevicauda Timm 1969 (Oncholaimidae: Enoplida) from India

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First Report on the Occurrence of Free-Living Marine Nematode Oncholaimellus Brevicauda Timm 1969 (Oncholaimidae: Enoplida) from India Indian Journal of Geo-Marine Sciences Vol. 43(10), October 2014, pp. 1922-1926 First report on the occurrence of free-living marine Nematode Oncholaimellus brevicauda Timm 1969 (Oncholaimidae: Enoplida) from India Tridip Kumar Datta1, Sivaleela Gunasekher2 & Anil Mohapatra1* 1Marine Aquarium and Regional Centre, Zoological Survey of India, Digha, West Bengal-721428, India 2Marine Biology Regional Centre, Zoological Survey of India, Chennai-600028, India *[Email: [email protected]] 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 adding the third species to the genus Northern-East coast of India is having Oncholaimellus. special ecological characteristics with number of river run-off to sea and offers a different Materials and Methods ecological habitat with mudflats, sandy and Sediment samples were collected from the clayey intertidal regions. These unique habitats intertidal areas from two locations (Digha and offer a different ecological niche for several Shankarpur) of West Bengal and one location meiofauna which might be unique by their own (Talsari) from Odisha, India. Collection sites are characteristics. Taxonomic description and located between 21°35′ to 21°38′ N and 87°26′ to distributional record of free-living marine 87°35′ E (Fig. 1). Study areas are mainly Nematodes from coastal India is inadequate. influenced by fresh water inflows through river Taxonomic work by Timm1,2,3 from the seas Subarnarekha, Champa canal and Ramnagar around the Indian waters, Gerlach4 from canal. Beaches of these areas are silt loaded Maldives Islands and Warwick5 from Indian through freshwater flow. At Digha, beach material oceans recorded more than one hundred and thirty is generally siliciclastic, quartzofeldspathic in composition with well sorted, medium to fine species. Later specialized work on the 15 nematofaunal ecology and taxonomy were sand . Shankarpur has some characteristic restricted mostly at Western continental shelf 6,7,8 mudflats with sandy beach. The beach of Talsari and Southeast Coast 9 of India. There are ten valid is generally flat, low lying and basically sandy. species belonging to genus the Oncholaimellus Mud deposition occurred at the mouth where recorded from worldwide10, among them only two Subarnarekha River meets with the Bay of species i.e Oncholaimellus calvadosicus De Man, Bengal. 189011,12,9 and Oncholaimellus carlbergi Allgén, Collections were done from selected 194713 were recorded from the Indian intertidal stations with the help of a hand corer. 14 Sediment samples were sieved by decantation subcontinent. Rao and Misra did a 16 comprehensive study on the meiofauna of Digha procedure with two brass sieves, upper one of 500 µm pore size and lower one of 63 µm pore all most three decades ago and recorded eleven 17 species of Nematodes from this area. No species size . Nematodes were fixed in 5% neutral of the present genus was recorded during that formalin solution and transferred to a solution of survey. During the present study of meiobenthic glycerol – alcohol (90 parts 70% alcohol and 10 fauna along the Northern-East coast of India three parts glycerin) which was then placed in specimens of the genus Oncholaimellus were desiccators for few days. Solution slowly collected and identified as Oncholaimellus evaporated to anhydrous glycerol. After brevicauda Timm, 1969 which was not yet evaporation, specimens were mounted on glass slides in anhydrous glycerin supported by paraffin reported from any part of India. Present recorded 18 species is the first report from Indian coasts thus wax ring . To facilitate measurements of the major body parts, photomicrographs were taken DATTA et al FIRST REPORT OF ONCHOLAIMELLUS BREVICAUDA TIMM 1969 FROM INDIA 1923 of each specimen under the microscope, Olympus surface of stoma. Oesophagus cylindrical, 25-33% CH20i attached with a digital camera. 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 narrow- rounded 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 Fig. 1—Study area is showing sampling stations (closed outstretched testis, extending almost oesophagus circles) around the coast of West Bengal and Odisha base. Long, slender equal spicules of 53-62 µm, reddish-brownish in colour. Spicules are 1.6-1.7 Results times longer than tail. Spicules with distinct Identification and classification of the capitulum and two-wave upward directing tip. specimen is followed here given by Platt and Gubernaculum absent in males. Copulatory bursa Warwick16, Hodda19, Keppner20 and Timm21. granulated with thin genital papillae, most of them protruding beyond the margin of bursa. One pair Phylum Nematoda Cobb, 1932 of long ventrolateral papillae just anterior to anus. Class Enoplea Inglis, 1983 Body Colour of fresh specimens of both sexes are Subclass Enoplia Pearse, 1942 faint tan-yellow in colour. Distribution of the Order Enoplida Filipjev, 1929 same is in Cox’s Bazar, Bangladesh; Northern- Suborder Enoplina Chitwood & Chitwood, 1937 East coast of India. Superfamily Oncholaimoidea Filipjev, 1916 Family Oncholaimidae Filipjev, 1916 Discussion Subfamily Oncholaimellinae Filipjev, 1916 Major body parts of male and female are Genus Oncholaimellus De Man, 1890 shown in the Fig. 2 (a-h). Some major Specimen O. brevicauda Timm, 1969 measurements taken were compared with the earlier description (Table 1) and some additional The identification was based on three measurements / proportions of different body specimens of which one was female and two were parts (Table 2) are also given. Male specimens males. Two specimens were collected from Digha were quite shorter in length than the specimens and Shankarpur of West Bengal during August, described in the original description of the 2011 and June, 2012 respectively. Another species. But in case of both sexes all the specimen was collected from Talsari of Odisha proportions measured in the present specimens are during July, 2012. Specimens were deposited to falling in the ranges given in the earlier Marine Aquarium and Regional Centre, description. Oesophagus of the male specimen is Zoological Survey of India, Digha bearing shorter than the female specimen. Comparative registration numbers N2848, N2849 & N2850. measurements and proportions of some major Cuticle smooth and clear without any characters of the present specimens are given in striation. Head truncate with maximum diameter the Table 1 in compare with the original 14-18 µm, Transverse band dividing the buccal description. It showed that the present specimens cavity into two halves. Ten equal length cephalic are undoubtedly matching with the original setae of 5.2 µm long in both sexes; four sub- description. Present specimens are most closely median cervical setae are present at the opposite related to Oncholaimellus coxbazari Timm, 1969 base of stoma. Buccal cavity maximum diameter but distinguished by the shorter tail bearing varies 7-9 µm; a massive right subventrolateral mammillate papillae and longer spicules with tooth of 7-9 µm in length present. Two equal but wavy tips in male. The present specimens also shorter than right subventrolateral tooth arising differ primarily from the other two species found from almost same level; one left subventral and in India viz. Oncholaimellus calvadosicus De other is dorsal. Tiny faint granulation on the Man, 1890 and Oncholaimellus carlbergi Allgén, 1947 by the differential number of cephalic setae, 1924 INDIAN J. MAR. SCI., VOL. 43, NO.10, OCTOBER 2014 longer equals spicules with wavy tips and shorter previously from Indian waters are given in Table tail bearing mammillate papillae in male. 1. Present species was earlier reported from Comparative measurements of some characters of Coxbazar, Bangladesh which indicates the Oncholaimellus brevicauda Timm, 1969 with possible range of the species to Indian coastal other two species of Oncholaimellus recorded 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
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