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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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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. © 2014, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.
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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: 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 Timm1,2,3 from the seas
around the Indian waters, Gerlach4 from
Maldives Islands and Warwick5 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 worldwide10, among them only two
species i.e Oncholaimellus calvadosicus De Man,
189011,12,9 and Oncholaimellus carlbergi Allgén,
194713 were recorded from the Indian
subcontinent. Rao and Misra14 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 21°35′ to 21°38′ N and 87°26′ to
87°35′ 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
sand15. 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
procedure16 with two brass sieves, upper one of
500 µm pore size and lower one of 63 µm pore
size17. 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 ring18. 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
CH20i attached with a digital camera.
Results
Identification and classification of the
specimen is followed here given by Platt and
Warwick16, Hodda19, Keppner20 and Timm21.
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, 2012. 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
14-18 µm, Transverse band dividing the buccal
cavity into two halves. Ten equal length cephalic
setae of 5.2 µm long in both sexes; four sub-
median 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 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
outstretched testis, extending almost oesophagus
base. Long, slender equal spicules of 53-62 µm,
reddish-brownish in colour. Spicules are 1.6-1.7
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,
Fig. 1Study area is showing sampling stations (closed
circles) around the coast of West Bengal and Odisha
INDIAN J. MAR. SCI., VOL. 43, NO.10, OCTOBER 2014
1924
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
M A L E F E M A L E
Oncholaimellus
calvadosicus (Ansari et
al. 2012)12
Oncholaimellus
carlbergi (Sajan 2003)
13
Present
Specimen
(average)
Original Description
(Timm, 1969)21
Present
Specimen
Original Description
(Timm, 1969)21
Holotype
Ranges of all
specimens
including
Holotype
Allotype
Ranges of
all
specimens
including
Allotype
total body
length 1411.59 1950 1480 - 1950 1830.8 1730 1620 -
2200 1500 1550
maximum body
diameter 20.39 24 22 - 26 27.83 29 27 - 35 20 85
length of
oesophagus 321.24 380 340 - 410 414.92 410 390 - 430 847 245
length of tail 32.24 32 26 - 35 35.36 32 29 - 41 253 111
vulva to anus 612.26 640 610 - 810 ND ND
a* 69.23 81.3 56.92 - 88.63 65.79 59.7 46.28 -
81.48 72.15 43
b* 4.39 5.1 3.6 - 5.73 4.41 4.2 3.76 - 5.64 1.77 6.3
c* 43.78 60.9 42.28 - 75 51.78 54.1 39.51 -
75.86 5.94 14
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 14.56 19.76
Head diameter 14.56 17.68
Head length 13 16.64
Length of Right subventrolateral tooth 7.28 8.84
Buccal cavity maximum diameter 7.28 9.36
Length of cephalic seta 5.2 5.2
Spicule length 57.77 -
c' 2.21 1.79
v - 64.63
v’ - 65.9
DATTA et al FIRST REPORT OF ONCHOLAIMELLUS BREVICAUDA TIMM 1969 FROM INDIA
1925
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.
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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)
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... Sinha et al. [77] discovered free-living marine nematode Anoplostoma macrospiculum from Indian coast after independence. Some research studies undertaken by Datta et al. [79], Datta et al. [80][81][82], Jacob et al. [83][84][85] have been able to describe some free-living marine nematodes in recent time from North-East coast, West coast and around Andaman sea of India respectively. ...
... Rushikulya, Devi and Gahirmata. Datta et al. (2014) made a new record of a nematode species Oncholaimellus brevicauda from sediments of Talsari. Baliarsingh et al. (2015) reported a first record of Desmoscolex falcatus (nematode: Adenphorea: Desmoscolecida: Desmoscolecidae) from Rushikulya estuary, Odisha, India. ...
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