Deepor Beelrevisited: new records of rotifers (Rotifera: Eurotatoria) with remarks on interesting species
B.K. Sharma 1 & Sumita Sharma 2
1 Freshwater Biology Laboratory,
Department of Zoology, North-Eastern Hill University, Permanent Campus, Shillong, Meghalaya 793022, India
2 North Eastern Regional Centre,
Zoological Survey of India, Risa Colony, Fruit
Gardens, Shillong, Meghalaya 793003, India
Email: 1 profbksharma@gmail.com (corresponding
author), 2 sumitasharma.nehu@gmail.com
Date
of publication (online): 26 January 2011
Date
of publication (print): 26 January 2011
ISSN
0974-7907 (online) | 0974-7893 (print)
Editor: Willem H. De Smet
Manuscript
details:
Ms # o2482
Received 11
June 2010
Final received
18 October 2010
Finally
accepted 22 December 2010
Citation: Sharma, B.K. & S. Sharma (2011). Deepor Beel revisited: new
records of rotifers (Rotifera: Eurotatoria)
with remarks on interesting species. Journal of Threatened Taxa3(1): 1437-1444.
Copyright: © B.K. Sharma & SumitaSharma 2011. Creative Commons Attribution 3.0 Unported License. JoTTallows 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.
Acknowledgement:This study is undertaken under
the “University with Potential for Excellence Program (Focused Area:
Biosciences)” of North-Eastern Hill University, Shillong.
Thanks are due to 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 and the Officer-in-charge, NERC, Zoological Survey
of India, Shillong. The
authors express sincerest thanks to three anonymous referees for valuable
comments and suggestions.
Abstract: Plankton samples collected (April 2009 - March 2010) from Deepor Beel, a Ramsar site, revealed 21 species of the Phylum Rotifera belonging to 12 genera and eight families as new
records. Amongst these, Brachionus durgae is a new record for northeastern
India. The recorded species
included the Australasian Brachionus dichotomus reductus and Notommata spinata; two Oriental endemics, namely, Keratella edmondsoni and Lecane blachei while Lecane lateralis, L haliclysta, Lepadella benjamini, Platyias leloupi, Mytilina acanthophora, Macrochaetus longipes, Trichocerca bicristata and T. flagellata are examples of regional distribution interest. The
present report increases the number of species recorded from this important
wetland of northeastern India to 134 species which, in
turn, is the richest rotifer diversity known till date from any aquatic
ecosystem of South Asia.
Keywords: Deepor Beel,
interesting species, new records, Ramsar site, Rotifera.
Deepor Beel, a Ramsar site of India and an important floodplain lake of
northeastern India, is an interesting ‘hot-spot’ for its aquatic
biodiversity. This largest wetland
of the Brahmaputra River basin of Assam is under severe environmental stress because
of general habitat degradation and various anthropogenic activities. The authors conducted a limnological survey of this beelduring November 2002 - October 2003 and reported (Sharma & Sharma 2005) 110
species of Phylum Rotifera, while (Sharma & Sharma
2010) added three species to the earlier list based on samples collected in
2006.
During
the course of our recent limnological reconnaissance
of Deepor Beel (April 2009
- March 2010), the authors initiated work on invertebrate faunal diversity and
documented 116 species of Rotifera, including 21
species as new records from this Ramsar site with one
new record from northeastern India. Various new records are briefly diagnosed and comments are made on
occurrence of biogeographically interesting elements.
Materials and Methods
The
present study is a part of limnological survey,
undertaken during April 2009 - March 2010, in Deepor Beel (910 35’-91043’E
& 26005’-26011’N; area 40km2;
elevation 42m), located in the Kamrup District of
lower Assam, India. This
floodplain lake is covered with various aquatic macrophytesnamely Hydrilla verticillata,Eichhornia crassipes, Vallisneria spiralis, Utricularia flexuosa, Trapa bispinosa, Euryale ferox, Najas indica,Monochoria hastaefolia, Ipomea fistulosa, Hygrorhiza aristata, Polygonum hydropiper and Limnophila sp.
Qualitative
plankton samples were collected by towing a nylobolt plankton net (No. 25) from different parts
of this Ramsar site and were preserved in 5%
formalin. The samples were
screened for rotifers and the species were isolated and mounted individually in
polyvinyl alcohol-lactophenol mixture. The species were identified following Koste (1978), Segers (1995),
Sharma (1998), and Sharma & Sharma (1999, 2000, 2008). Photographs were taken with a Leica DM 1000 image analyzer. Segers (2002) is followed for the
recent system of nomenclature of Rotifera and remarks
on the distribution are made vide Segers (2007). The reference materials are deposited
in the holdings of Freshwater Biology Laboratory, Department of Zoology,
North-Eastern Hill University, Shillong.
Systematic list of new records of Rotifera from Deepor Beel
Phylum: Rotifera
Class: Eurotatoria
Subclass:Monogononta
Order: Ploima
Family: Brachionidae
1. Anuraeopsis navicula Rousselet,
1911
2. Brachionus dichotomus reductus Koste & Shiel,
1980
3. B.durgae Dhanapathi, 1974
4. Keratella edmondsoni Ahlstrom, 1943
5. Platyias leloupi Gillard, 1957
Family: Mytilinidae
6. Mytilina acanthophora Hauer, 1938
Family: Trichotriidae
7. Macrochaetus longipes Myers, 1934
Family: Lepadellidae
8. Colurella sulcata (Stenroos,
1898)
9. Lepadella benjamini Harring,
1916
10. L. eurysterna Myers, 1942
Family: Lecanidae
11. Lecane arcula Harring, 1914
12. L. blachei Berzins, 1973
13. L. doryssa Harring,
1914
14. L. haliclysta Harring& Myers, 1926
15. L. lateralis Sharma, 1978
Family: Notommatidae
16. Notommata spinata Koste & Shiel, 1991
Family: Trichocercidae
17. Trichocerca bicristata (Gosse, 1887)
18. T. flagellata Hauer, 1937
19. T. iernis (Gosse, 1887)
20. T. pusilla (Jennings, 1903)
Family: Dicranophoridae
21. Dicranophoroides caudatus (Ehrenberg, 1834)
Taxonomic notes
Various
interesting species observed presently are briefly diagnosed below:
Anuraeopsis navicula Rousselet,
1911
Characters: Lorica boat-shaped and granulated; dorsal plate with
two longitudinal ridges running parallel to each other and then united at the
posterior end to form a single ridge.
Distribution: Pantropical. India: Assam,
Gujarat, Orissa, Meghalaya, Tripura and West Bengal.
Brachionus dichotomus reductus
Koste & Shiel, 1980
(Image
1)
Characters: Lorica dorso-ventrally
compressed, stippled, and with maximum width in its posterior region. Anterior occipital
margin with distinct median spines. Posterior spines moderately long and
divergent.
Distribution: Australasia. India: Assam, Meghalaya and Tripura.
Brachionus durgae Dhanapathi,
1974
(Image 2)
Characters: Loricaalmost oval, smooth, compressed dorso-ventrally.
Anterior occipital margin with six saw-tooth like spines of
nearly equal length. Foot-opening situated ventrally in posterior region.
Distribution: African, Neotropical, Oriental
and Palearctic regions. India: Andhra Pradesh, Orissa
and Tamil Nadu.
Keratella edmondsoni Ahlstrom, 1943
(Image 3)
Characters: Lorica elongated and granulated; with six anterior occipital spines, median occipitals
longest and curved. Dorsum with characteristic pattern of carinal plaques. Posterior spines
equal and divergent.
Distribution: Oriental region. India: Assam, Orissa, Rajasthan and
Tamil Nadu.
Platyias leloupi Gillard, 1957
Characters: Loricabroadly circular, granulated and moderately compressed. Anterior dorsal
margin with two blunt spines, posterior end with two long and parallel spines. Dorsum with distinct
keel under the triangular frontal dorsal plaque.
Distribution: Tropicopolitan. India: Assam.
Mytilina acanthophora Hauer,
1938
Characters: Loricagranulated, dorsally arched and laterally compressed; anterior ventral corners
with triangular cusps. Toes long and ending into acute points.
Distribution: Pantropical. India: Assam, Punjab and West Bengal.
Macrochaetus longipes Myers, 1934
Characters: Lorica shield-shaped, with serrate external
margins and dorsum with 12 long spines. Head
protruded. Anal segment flanked by
long spines. Toes long and pointed.
Distribution: Cosmopolitan. India: Assam and
Meghalaya.
Colurella sulcata (Stenroos, 1898)
Characters: Lorica elongated, with a longitudinal cleft; anterior
margins of lorica rounded, posterior angles not
produced. Foot and toes directed forwardly; toes long.
Distribution: Cosmopolitan. India: Assam, Gujarat, Meghalaya, Orissa,
Tripura and West Bengal.
Lepadella benjamini Harring, 1916
(Image
4)
Characters: Loricabroadly oval, with maximum width in its middle region. Head aperture with
ventrally directed rim; anterior dorsal margin nearly straight and ventral
margin with U-shaped sinus. Posterior end of loricaslightly concave. Foot-groove with divergent sides. Distal foot-segment elongated and projecting beyond lorica.
Toes long, pointed and gently ventrally curved.
Distribution: Cosmopolitan. India: Manipur.
Lepadella eurysterna Myers, 1942
Characters: Loricaalmost oval in outline; dorsal plate moderately arched. Posterior margin of loricaconvex in the region of its foot-opening. Toes elongated and pointed.
Distribution: Cosmopolitan. India: Assam, Delhi and
Meghalaya.
Lecane arcula Harring, 1914
Characters: Lorica small, elongate-oval; with straight
and coincident anterior margins. Ventral plate
elongated. Antero-lateral
occipital spines distinct. Toes parallel-sided; claw small.
Distribution: Tropicopolitan.
India: Assam and Meghalaya.
Lecane blachei Berzins,
1973
(Image
5)
Characters: Lorica oval, anterior dorsal margin nearly straight,
ventral margin with a shallow median sinus flanked by undulating sides and
blunt external angles. Dorsal plate with distinct surface markings. Toes fused partly at base, claws with
distinct basal spines.
Distribution: Oriental
region. India: Assam, Delhi and West Bengal.
Lecane doryssa Harring, 1914
Characters: Lorica with
few surface markings; anterior occipital margins straight and coincident. Toes slender and with pointed and
undifferentiated claws.
Distribution: Tropicopolitan.
India: Assam and Meghalaya.
Lecane haliclysta Harring & Myers, 1926
(Image 6)
Characters: Lorica elongate-oval; anterior ventral margin
with small spines at external angles. Dorsal and ventral plates with surface markings. Toes parallel-sided for more than 3/4
of their length and then terminating into small
undifferentiated pointed claws.
Distribution: Tropicopolitan. India: Assam and
Meghalaya.
Lecane lateralis Sharma, 1978
(Image 7)
Characters: Lorica ovate; anterior dorsal margin concave and
anterior ventral margin with a shallow sinus flanked by undulating sides. Ventral plate with
characteristic postero-lateral extensions. Toes long, parallel-sided along ¾
of their lengths, then tapering and terminating into stout claws; each claw
with one basal spicule.
Distribution: Palaeotropical. India: Assam,
Meghalaya, Orissa, Tripura and West Bengal.
Trichocerca bicristata (Gosse, 1887)
(Image 8)
Characters: Lorica slender and elongated; with two characteristic
distinct keels extending unto 2/3 the length of dorsum, separated by wide
depression of dorsum. Left toe
longer than body, right toe reduced; sub styles present.
Distribution: Cosmopolitan. India: Assam, Bihar and Orissa.
Trichocerca flagellata Hauer, 1937
(Image 9)
Characters: Body
ovoid and head indistinctly demarcated. Keel high vaulted with wide striated area extending to the beginning of
the short foot opening. Left toe longer and slightly sigmoid, right toe reduced
and stylet present.
Distribution: Tropicopolitan. India: Assam,
Meghalaya and Tamil Nadu.
Trichocerca iernis (Gosse, 1887)
Characters: Body elongate, slightly curved and
with a short spine at anterior margin of lorica. Striated keel extending from anterior margin to end of abdomen. Left toe
nearly ¾ of body length, right toe short, basal styletpresent.
Distribution: Cosmopolitan. India: Assam and Kashmir.
Trichocerca pusilla (Jennings, 1903)
Characters:Body cylindrical; anterior end straight but with
longitudinal folds. Toes unequal;
left toe long and ventrally directed, right toe very small.
Distribution: Cosmopolitan. India: Bihar, Meghalaya, Orissa, Tripura and
West Bengal.
Notommata spinata Koste & Shiel, 1991
(Image 10)
Characters: Body
laterally expanded into two distinct alae and without
dorsal hump. Lateral tip of each
ala armed with stout triangular cusp. Trophi modified virgate,
asymmetric.
Distribution: Australia. India: Assam.
Dicranophoroides caudatus (Ehrenberg,
1834)
Characters:Body cylindrical. Trunk with lateral sulci and longitudinal
folds. Tail prominent. Toes
long and terminating into acute tips. Trophi large and stout.
Distribution: Cosmopolitan. India: Assam.
Remarks
A
total of 116 species of Rotifera, belonging to 35
genera and 19 Eurotatorian families, are documented
from plankton samples collected from Deepor Beel during April 2009 - March 2010. Of these, 21 species belonging to 12
genera and eight families are new additions to our earlier species inventory
(Sharma & Sharma 2005) from this wetland while Brachionus durgae is a new record for northeastern
India.
Our
report includes a number of biogeographically interesting rotifers. Amongst these, the Australasian
elements Brachionus dichotomus reductus and Notommata spinata deserve special mention. Their occurrence highlights the affinity of Assam Rotifera with those of Southeast Asia and Australia
confirming the earlier generalization of Sharma (2005). Referring to the former brachionid, Segers (2001)
commented on the occurrence of the reductus vicariant ofB. dichotomusoutside Australia, hypothesizing the recent expansion of these populations to
Southeast Asia with Australia as possible origin of this taxon. The record of disjunctpopulations of the reductus vicariant from Deepor Beel lends support to Segers’s hypothesis. Interestingly, both Australasian elements show a distribution restricted
to northeastern India; the former is known from Assam, Meghalaya and Tripura
while the later is known only from Assam.
The
occurrence of two Oriental endemics i.e., Keratella edmondsoni and Lecane blachei is another salient feature of the
present study. The former was
described originally from Tamil Nadu (Ahlstrom 1943) as K. quadrata var. edmondsoni while Nayar(1965) subsequently proposed it to be raised to the status of a distinct
species. Besides the Indian
records from Assam, Rajasthan, Orissa and Tamil Nadu, K. edmondsoni is known from
northeastern Thailand. Lecane blachei, described as a new species from
Cambodia (Berzins 1973), was also recorded from
Thailand while its occurrence in India is confined to Assam, West Bengal and
Delhi.
Amongst
other interesting species, Brachionus durgae, Lecane lateralis, L haliclysta, Lepadella benjamini, Platyias leloupi, Mytilina acanthophora, Macrochaetus longipes, Trichocerca bicristata and T. flagellata are examples of regional distributional interest. Of these, the cosmo (sub)-tropical B. durgae was described as a new species from Andhra Pradesh (Dhanapathi 1976) while its current distribution extends to African, Neotropical,
Oriental and Palearctic regions (Segers2007). Besides the type-locality, the Indian reports of this brachionid are from Orissa while Sharma & Sharma (2009)
recently recorded it from Tamil Nadu. Sharma (1978) described Lecane lateralis from West Bengal as
an Indian endemic; Savatenalinton & Segers (2005) categorized it as an Eastern Hemispheric
rotifer while this lecanid is now considered as palaeotropical element (Sharma & Sharma 2008). This species is known to occur in the
Indian inland waters from Assam, Meghalaya, Tripura, West Bengal, Orissa and
Tamil Nadu. Lepadella benjamini, a cosmopolitan species, is examined
from the state of Manipur (Sharma 2007) from the Indian subcontinent. Besides, it is reported from China and
Thailand among the Asian countries. Besides, Lecane haliclysta, Platyias leloupi and Macrochaetus longipes are so far known from northeastern
India while Mytilina acanthophora, Trichocerca bicristata and T. flagellata show disjunct populations in India.
To
sum up, the present report of 21 new records of Rotiferafrom Deepor Beel raises the
number of species known from this important floodplain lake of northeastern
India to 134 and, hence, adds to the relevance of Deepor Beel as a Ramsar site. The richness is higher than the 120
species examined from Loktak Lake (Sharma 2009) -
another Ramsar site of India as well as the 106 taxa from Thale-Noi Lake, a Ramsar site in Thailand (Segers& Pholpunthin 1997). However, we should caution against over-emphasizing the
importance of the present record as Dumont & Segers(1996) argued that lakes in the tropics could contain 210+ species of
rotifers. Sampling intensity and
methodology can vastly influence the diversity encountered: the total species
reported for Deepor Beelincidentally coincides with the report obtained from two samples only from a
non-descript Laotian rice field and adjacent pond (Segers& Sanoamuang 2007). Nevertheless, the qualitative features of the rotifer fauna
of Deepor Beel hint at a
high biodiversity value. A more
extensive, sampling campaign, focusing in particular on quantitative aspects of
the fauna of this Ramsar site may corroborate these
initial findings.
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