Testate amoebae (Protozoa: Rhizopoda) of Deepor Beel
(a Ramsar site), Assam, northeastern India
B.K.
Sharma 1 & Sumita Sharma 2
1,2 Freshwater
Biology Laboratory, Department of Zoology, North-Eastern Hill University,
Permanent Campus, Shillong, Meghalaya 793022, India
Email: 1probksharma@gmail.com (corresponding author), 2 sumitasharma.nehu@gmail.com
Date of publication (online): 26
July 2011
Date of publication (print): 26
July 2011
ISSN 0974-7907 (online) |
0974-7893 (print)
Editor: Humphrey Smith
Manuscript details:
Ms # o2664
Received 31 December 2010
Final received 25 May 2011
Finally accepted 21 June 2011
Citation: Sharma, B.K. & S. Sharma (2011). Testate amoebae (Protozoa: Rhizopoda) of Deepor Beel (a Ramsar
site), Assam, northeastern India. Journal of Threatened Taxa 3(7): 1947–1950.
Copyright: © B.K. Sharma & Sumita Sharma
2011. Creative Commons Attribution 3.0 Unported License.JoTT allows unrestricted use of this article in any medium for non-profit
purposes, reproduction and distribution by providing adequate credit to the
authors and the source of publication.
Acknowledgements: The senior author is thankful to
the Coordinator, UPE (Biosciences) and the Head, Department of Zoology,
North-Eastern Hill University, Shillong for necessary facilities. One of the
authors (SS) is also thankful to the Director, Zoological Survey of India,
Kolkata and the Officer-in-charge, North Eastern Regional Centre, Zoological
Survey of India, Shillong.
Testate
amoebae or testaceans, a group of free-living Protozoa belonging to the
superclass Rhizopoda, form an important micro-faunal component of aquatic,
semi-aquatic and soil communities and provide integral links of the food chain
in their respective environments. Taxonomic studies on Indian freshwater Rhizopoda were initiated by Naidu
(1966) and followed by Mahajan (1971), Nair et al. (1971) and Mishra et al.
(1977). In addition, certain
contributions under the state fauna series (Das et al. 1993, 1995, 2000, 2003,
2004) dealt with limited freshwater collections. In spite of these studies
freshwater Rhizopoda from different states of India are poorly documented,
while their ecosystem diversity is practically neglected except for the works
of Sharma & Sharma (2008), Bindu (2010) and Bindu & Das (2010). Our study on the Rhizopoda of Deepor
Beel, a Ramsar site and an important floodplain lake of the Brahmaputra River
basin of Assam, merits biodiversity interest in view of the stated
lacunae. The listed species are
briefly diagnosed and comments are made on the nature and composition of the
Rhizopoda fauna.
Material
and Methods: Qualitative samples were collected (August
2008–July 2010) by towing a nylobolt plankton
net (No. 25) from the littoral and limnetic regions of Deepor Beel (91035’–91043’E
& 26005’–26011’N; area 40km2;
altitude 42m), Assam and were preserved in 5% formalin. Special attention was paid to disturb
aquatic macrophytes before sampling. Different species were sorted with a wild stereoscopic binocular
microscope and permanent mount specimens were prepared in polyvinyl
alcohol-lactophenol. Rhizopoda
species were identified with a Leica DM 1000 image analyzer following the works
of Cash et al. (1919), Deflandre (1929, 1959), Decloitre (1962), Ogden &
Hedley (1980), and Chattopadhyay & Das (2003).
Systematic account
Sub Kingdom: Protozoa
Phylum: Sarcomastigophora
Sub Phylum: Sarcodina
Super Class: Rhizopoda
Class: Lobosea
Order: Arcellinida
Arcellidae
1.Arcella discoidesEhrenberg, 1843
Characters:
Test yellow, smooth, flattened, circular in front view and plano-convex in
lateral view; height about 1/3 to 1/4 of its diameter. Oral aperture large
and circular.
Distribution:
India - Assam, Meghalaya, Mizoram, Arunachal Pradesh, Tripura, Nagaland, Sikkim
and West Bengal.
2.Arcella hemisphericaPerty, 1809
Characters:
Test yellow, distinctly hemispherical and circular in lateral and front
views. Surface
of test with more or less fine areoles.
Distribution: India - Assam, Manipur, West Bengal,
Odisha and Andhra Pradesh.
3.Arcella vulgaris Ehrenberg, 1830
Characters: Test light yellow, discoid or
hemispherical in front or lateral views; height about half of its diameter;
test surface with large areoles. Mouth circular and central.
Distribution: India - Assam, Meghalaya, Manipur,
Arunachal Pradesh, Nagaland, Sikkim, Himachal Pradesh and West Bengal.
Centropyxidae
4.Centropyxis aculeata (Ehrenberg, 1830)
Characters:
Test brownish, cap-shaped; encrusted with quartz crystals and sometimes with
admixture of diatoms and sand particles. Fundus obtusely rounded and usually
with 4-6 divergent spines at the border, arranged in a single and somewhat
regular row.
Distribution: India - Assam, Arunachal Pradesh,
Meghalaya, Mizoram, Manipur, Nagaland, West Bengal, Andhra Pradesh and Himachal
Pradesh.
5.Centropyxis ecornis (Ehrenberg, 1843)
Characters: Test large, discoid or elliptical; without any spine and covered with quartz grains. Dorsal
surface slightly arched and more elevated at posterior part. Oral
aperture circular and much eccentric.
Distribution: India - Assam, Arunachal Pradesh,
Meghalaya, Manipur, Mizoram, Sikkim, Himachal Pradesh, Uttarakhand and West Bengal.
6.Centropyxis oblonga(Deflandre, 1929)
Characters: Test grayish, oblong-elliptical or oval;
with 3-6 divergent spines located in the distal part. Fundus of the test more elevated. Oral aperture elliptical and eccentric.
Distribution: India - Assam, Meghalaya, Manipur, Sikkim
and Andhra Pradesh.
7. Centropyxis orbicularisDeflandre, 1929
Characters:
Test almost circular in ventral view and semi-circular in lateral view, ventral
surface flat; oral aperture semi-circular, plagiostomic; test with large stony
particles.
Distribution:
India - Assam, Uttarakhand and Andhra Pradesh.
8.Cyclopyxis eurystoma (Deflandre, 1929)
Characters: Test brownish, encrusted with quartz
particles; hemispherical in lateral view. Oral aperture central, circular and slightly
invaginated with regular smooth edge.
Distribution: India - Assam, Arunachal Pradesh and
Odisha.
Difflugidae
9.Difflugia acuminataEhrenberg, 1838
Characters: Test cylindrical, with pointed ‘horn’ like
extension; horn straight and differentiated from the base. Quartz
crystals big; some even projecting out of the margin.
Distribution:
India - Assam, Meghalaya, Manipur, West Bengal and Andhra Pradesh.
10.Difflugia corona Wallich, 1864
Characters: Test broadly spherical, slightly narrow
near oral aperture; with 5–10 smooth test spines formed by quartz
crystals. Oral aperture wide and crenulated.
Distribution: India - Assam, Manipur and West Bengal.
11.Difflugia oblonga Ehrenberg, 1838
Characters: Test typically oblong, with smooth margins
and rounded base; composed of big angular quartz crystals. Oral aperture
circular and without any lobe.
Distribution: India - Assam, Meghalaya, Manipur, West
Bengal and Andhra Pradesh.
12. Difflugia tuberculata (Wallich, 1864)
Characters:
Test ovoid, with wide base; oral aperture hexagonal and surrounded by a short
collar; test covered with tubercles and small platelets uniting the tubercles.
Distribution:
India - Assam and Meghalaya.
13.Difflugia urceolata Carter, 1864
Characters: Test ovoid-spherical, composed of angular
quartz crystals and diatoms. Oral aperture circular; its
collar around re-curved or rolled towards exterior.
Distribution:
India - Assam, Manipur and West Bengal.
Nebelidae
14.Lesquereusia spiralis(Ehrenberg, 1830)
Characters:
Test transparent, semi-spiral and composed of closely arranged vermiform
pellets; neck continued in a straight line down to mouth. Oral
aperture circular.
Distribution:
India - Assam, Meghalaya, Manipur, West Bengal and Andhra Pradesh.
Class: Filosea
Order: Gromiida
Cyphoderiidae
15.Cyphoderia ampulla (Ehrenberg. 1840)
Characters: Test yellowish or brownish, covered with
distinct circular or oval scales or plates; oral aperture circular, terminal,
with a curved neck; fundus obtusely rounded.
Distribution: India - Assam, Uttarakhand and
Maharashtra.
Euglyphidae
16.Assulina muscorumGreef, 1888
Characters: Test yellowish, oval, compressed and
truncate anteriorly; composed of imbricate oval platelets usually arranged in
alternating diagonal rows. Terminal, elliptical aperture bordered by a thin
chitinous membrane with undulate margin.
Distribution: India - Arunachal Pradesh, Manipur,
Mizoram, Sikkim, Tripura West Bengal and Himachal Pradesh.
17.Assulina seminulum(Ehrenberg, 1848) Leidy, 1879
Characters: Test yellow or brown, pyriform or ovoid,
compressed and composed of imbricate oval or elliptical siliceous platelets. Aperture terminal, oval and bordered by a thin chitinous membrane
with irregularly dentate margin.
Distribution: India - Manipur, Sikkim, Nagaland, West
Bengal and Andhra Pradesh.
18.Euglypha acanthophoraDujardin, 1841
Characters: Test ovoid; aperture circular, bordered by
finely serrated platelets. Test platelets elliptical, posterior half and at the
base of fundus prolonged into 4-7 spines.
Distribution: India - Assam, Mizoram, Meghalaya,
Nagaland, West Bengal and Andhra Pradesh.
19.Euglypha laevis (Ehrenberg, 1845)
Characters: Test oviform, glabrous and elliptical or
sub-circular; aperture elliptical or sub-circular, bordered by a single row or
platelets pointed terminally. Test platelets oval.
Distribution: India - Assam, Meghalaya, Tripura, Sikkim,
Uttarakhand, West Bengal and Andhra Pradesh.
20.Euglypha tuberculataDujardin, 1841
Characters: Test elongate-oviform, glabrous; test
platelets round or oval, imbricating and forming a hexagonal pattern. Aperture circular,
bordered by 8–12 finely serrated platelets.
Distribution: India - Assam, Arunachal Pradesh,
Meghalaya, Mizoram, Nagaland, Tripura, Jammu and Kashmir, Himachal Pradesh,
Sikkim, West Bengal and Andhra Pradesh.
21.Trinema lineare Penard, 1840
Characters: Test small, hyaline, elongate, composed of
small circular platelets. Oral aperture circular, oblique, invaginated and
bordered by toothed platelets.
Distribution: India - Assam, Arunachal Pradesh,
Meghalaya, Manipur, Mizoram, Nagaland, Tripura, Himachal Pradesh, Sikkim and
West Bengal.
Discussion
Our collections show 14 species of Lobosea
and seven species of Filosea, the L/F ratio of 2 is close to the 3.0 reported
by Sharma & Sharma (2008) from various floodplain lakes of Assam but
exceeds the range of 0.5–1.4 reported for moss-dwelling rhizopods
(Chattopadhyay & Das 2003). Euglyphidae > Centropyxidae = Difflugidae, three speciose families,
comprise the dominant fraction (76.2%) of the reported species. Cyphoderiidae and Nebelidae, the least
species-rich families, include one species each. Further, Difflugia > Centropyxis are relatively diverse genera (42.9%)
while Arcella = Euglypha also form a notable fraction (28.6 %) in
this study.
The total Rhizopoda richness of Deepor
Beel is higher than the 16, 12, 7 and 19 species examined from the freshwater
biotopes of Meghalaya (Das et al. 1995), Tripura (Das et al. 2000), Sikkim (Das
et al. 2003) and Manipur (Das et al. 2004) respectively. Further, the richness is higher than
the reports of 16 species from Loktak Lake - a Ramsar site (
refer Das et al. 2004); 10 species from Melghat Wildlife Sanctuary
(Bindu 2010), Maharashtra; 13 species from Pench National Park, Maharashtra and
also 7–16 species listed from 15 floodplain lakes of the Brahmaputra
river basin of Assam (Sharma & Sharma 2008). However, we caution against over-emphasizing the importance
of these comparisons without considering sampling intensity and the nature of
different ecosystems. In analyzing
the comparative species-richness of our and other communities, it also needs to
be emphasized that the number of species recorded to date are yet provisional
and these may well be revised in light of future research.
Whilst Centropyxis orbicularis and Cyphoderia ampulla currently exhibit
restricted occurrence in India with reports from Sikkim and Uttarakhand
respectively, their distribution ranges were extended recently to Assam (Sharma
& Sharma 2008). The
moss-dwelling Cyphoderia ampulla was
recently observed in freshwater from Assam (Sharma & Sharma 2008) and
Maharashtra (Bindu 2010); the present report re-affirming its occurrence in
freshwater environs merits ecological interest. Our report also endorses an identical report (Sharma & Sharma
2008) of Cyclopyxis eurystoma which
was known from soil and mosses in India (Chattopadhyay & Das 2003). Arcella hemispherica, Centropyxis cassis, Difflugia corona, D.
tuberculata, D. urceolata, Cyclopyxis eurystoma, andEuglypha laevis comprise
examples of local or regional distributional interest. Further, these species exhibit rare
occurrence in our collections. On
the other hand, Arcella discoides, Avulgaris, Centropyxis aculeata, C. ecornis, Difflugia acuminata, D. oblonga,
Euglypha acanthophora and E. tuberculata exhibit relatively frequent
occurrence.
The present report raises the total number
of Rhizopoda so far known from different ecosystems of Assam to 49 species,
affirming the biodiversity value of this Ramsar site. The observed association of Rhizopoda with different aquatic
macrophytes merits future interest, and studies of this and other ecological
aspects have been initiated by the authors.
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