An annotated checklist of opisthobranch fauna (Gastropoda:
Opisthobranchia) of the Nicobar Islands, India
C.R. Sreeraj 1, C. Sivaperuman 2& C. Raghunathan 3
1,2,3Zoological Survey of India, Andaman
and Nicobar Regional Centre, National Coral Reef Researh Institute, Port Blair,
Andaman and Nicobar Islands 744102, India
Email: 1 crsreeraj@gmail.com (corresponding
author), 2 c_sivaperuman@yahoo.com, 3 raghuksc@rediffmail.com
Date of publication (online):26 April 2012
Date of publication (print): 26 April 2012
ISSN 0974-7907 (online) | 0974-7893 (print)
Editor: Deepak
Apte
Manuscript details:
Ms # o2783
Received 03 April 2011
Final received 05 January 2012
Finally accepted 27 February 2012
Citation:Sreeraj, C.R., C. Sivaperuman & C. Raghunathan (2012). An annotated
checklist of opisthobranch fauna (Gastropoda: Opisthobranchia) of the Nicobar Islands,
India. Journal of Threatened Taxa 4(4): 2499–2509.
Copyright: ©
C.R. Sreeraj, C. Sivaperuman & C. Raghunathan 2012. Creative Commons
Attribution 3.0Unported 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 authors are
thankful to Dr. K. Venkataraman, the Director, Zoological Survey of India for
the facilities provided. The financial assistance supported by the Ministry of
Environment and Forests, Government of India is also acknowledged.
Abstract: This
paper presents 52 species of opisthobranchs recorded from the Nicobar group of
Islands. Of these, Aldisa erwinkoehleri,Dermatobranchus rodmani,Glossodoris pallida,Noumea simplex,Pectenodoris trilineata,Okenia kendi,Tambja morosa,Phyllidia elegans,Phyllidiopsis annae,Flabellina riwoand Phidiana indicarepresent new records for Indian waters.
Keywords:India, opisthobranch, Nicobar, nudibranch.
For
figures, images, tables -- click here
The Andaman and Nicobar archipelago consists of 572 islands,
islets and rocky outcrops with an aggregate coastline of 1,962km. The continental shelf area is very
limited with an estimated area of 16,000km2 and the sea is very deep
within a few kilometers from the shore. The Exclusive Economic Zone (EEZ) around the islands encompasses around
0.6 million km2, which is again around 30% of the EEZ of India. This
provides a great opportunity to explore the vast diversity of the seas around
these islands. Opisthobranchs
are one of the less studied groups of molluscs in Andaman and Nicobar Islands.
The earliest opisthobranch study in Indian waters dates back to
1864 with the work of Alder & Hancock. The knowledge about opisthobranchiate faunal diversity
of Indian subcontinent is too little to interpret. Although variegated, these organisms could drag the
attention of only a few scientists. In recent times Apte (2009), Apte et al. (2010), Raghunathan et al.
(2010), Ramakrishna et al. (2010), Sreeraj et al. (2010), Apte & Salahuddin
(2011), and Matwal & Joshi (2011) studied opisthobranch fauna of India.
The molluscan studies of Andaman and Nicobar Islands were started
in the late 19th century. The available literature shows that the earliest molluscan study was on
a collection of marine shells made by E.A. Smith in 1878. The first report on nudibranch from
these Islands was published by Eliot (1910), which deals with a collection of
nudibranchs by Annandale. Opisthobranchiate taxonomy and ecology of these Islands has recently
commenced (Raghunathan et al. 2010; Ramakrishna et al. 2010; Sreeraj et al.
2010) including the discovery of many new records for the Indian subcontinent.
There has been no research on the community structure and
population dynamics of opisthobranchs from Andaman and Nicobar Islands.
Quantitative studies on opisthobranch populations in Indian waters are
scarce. This is due to
opisthobranchs’ inherent low numerical density; individuals are small and often
cryptic, and mostly sub-tidal. No
studies are available on the opisthobranchs of the Nicobar group of Islands;
therefore the present attempt has been made to compile the list on the
occurrence of this group of animals based on the field surveys conducted during
2009–2011.
Materials and Methods
The Nicobar Islands are situated in the south-east of the Bay of
Bengal between 6–10 0N and 92–94 0E. There are altogether 22 large and small
islands, out of which only 12 are inhabited. The most northerly island of the group is Car Nicobar, which
is 225km from Port Blair and the ten degree channel (about 120km wide)
separates this Island from Little Andaman. Chowra, Teressa, Bompoka, Katchal, Kamorta, Nancowry and
Trinket form the central group of Nicobar Islands; while in the southern group
are Pulo Milo, Little Nicobar, Kondul, and Great Nicobar. The extreme southern point of Great
Nicobar, previously known as Pygmalion Point and now Indira Point, is about
145km from Pulo Brass of Achin Head of Sumatra. The uninhabited islands in the central and southern groups
are Batti Malv, Tileangchong and Meroe, Trak, Treis, Menchal and Kabra,
respectively.
Survey sites were selected based on the habitat features and
accessibility (Fig 1). Sampling
was carried out primarily by scuba diving up to a depth of 30m. Most of the specimens were measured and
photographed in their natural habitat and collected in a plastic jar before
being brought to the laboratory for examination. Animals were fixed in a solution of 5% formaldehyde and seawater. Before placement in the fixative solution
the animals were narcotised with a solution consisting of 72g/l of MgCl2. The formaldehyde fixed animals were
transferred to 95% ethanol for long term preservation. All the collected specimens are
deposited in the National Zoological Collections of the Zoological Survey of
India, Port Blair.
Identification was carried out based on the external morphology
only and using following literature; Gosliner et al. (2008), Rudman (1982, 1983, 1984, 1986, 1995),
and Brunckhorst (1993); and two web-based portals, the Australian Museum’s
Seaslug Forum (http://www.seaslugforum.net/) and Nudi Pixel (http://www.nudipixel.net). Taxonomic changes published recently
are incorporated.
Many of these species have wider distribution globally. However, in the present paper we have
provided its occurrence in Indian waters only.
Results and Discussion
A total of 161 specimens belonging to 52 species were recorded
during the study period. These
belong to three orders, namely; Cephalaspidea (four species), Sacoglossa (four
species), and Nudibranchia (44 species). The Nudibranchia was the most dominant taxon in this study. The distribution of the species along
different islands of Nicobar group is presented in Table 1. A systematic account of the species
recorded is given below and detailed descriptions have been given only for the
newly reported species.
Cephalaspidea Fischer, 1883
Bullidae Gray, 1827
1. Bulla ampullaLinnaeus, 1758. Material examined: 16.ii.2011, two
specimens, Champion, Nancowry Island. Distribution in India: All
along the west and east coast including Lakshadweep and Andaman Islands
(Satyamurti 1952; Rao & Dey 2000; Rao 2003; Apte 2009).
Haminoeidae Pilsbry, 1895
2. Atys naucum(Linnaeus, 1758). Material examined: 16.ii.2011, one
specimen, Champion, Nancowry Island. Identification: Shell is thin
and globose. The spire is deeply
submerged within the body whorl. Shell is smooth in appearance superficially. Faint growth lines cross the spiral grooves. (Image 1). Distribution in India: Andaman Islands
(Rao & Dey 2000;
Rao 2003).
Aglajidae Pilsbry, 1895
3. Chelidonura punctataEliot, 1903. Material examined: 19.xi.2009, five specimens, Car
Nicobar. Distribution in India: Andaman and Lakshadweep Islands (Apte
2009; Ramakrishna et al. 2010).
4. Philinopsis
gardineri (Eliot, 1903). Material examined: 21.ii.2011,
two specimens, Safed balu, Trinket Island. 01.i.2010, one specimen, Campbell Bay, Great Nicobar. Distribution
in India: Andaman Islands.
Sacoglossa (von lhering,
1876)
Plakobranchidae Gray, 1840
5. Elysia
pusilla Bergh, 1872. Material examined:12.viii.2010, two specimens, Car Nicobar. Distribution in India: Nicobar
Islands.
6. Plakobranchus
ocellatus Van Hasselt, 1824. Material examined:12.viii.2010, four specimens, Car Nicobar. Distribution in India:Andaman Islands, Tamil Nadu, Lakshadweep Islands (Rao 1961; Apte 2009;
Ramakrishna et al. 2010).
7. Thuridilla cf.bayeri (Er.
Marcus, 1965). Material examined: 28.ii.2010, two
specimens, Kamorta Island; 21.ii.2011, one specimen, Safed Balu, Trinket
Island. Distribution in India: Andaman Islands (Ramakrishna et al.
2010)
8. Thuridilla
moebii (Bergh, 1888). Material examined: 28.ii.2010,
three specimens, Kamorta Island; 20.ii.2011, three specimens, Kapang, Katchall
Island; 21.ii.2011, two specimens,
Safed Balu, Trinket Island. Distribution in India: Andaman Islands.
Nudibranchia Blainville,
1814
Hexabranchidae Bergh, 1881
9. Hexabranchus sanguineus(Rűppell & Leuckart, 1830). Material examined:12.viii.2010, One specimen, Car Nicobar. Distribution in India: Andaman
Islands, Lakshadweep Islands, Kerala (Eliot 1906; Narayanan 1968; Narayanan
1970; Ramakrishna et al. 2010; Apte & Salahuddin 2011)
Polyceridae Alder &
Hancock, 1845
Nembrothinae Burn, 1967
10. Tambja
morosa (Bergh, 1877). Material examined:19.viii.2011, three specimens, Kapila, Trinket Island; 22.ii.2011, three
specimens, Kamorta Jetty. Identification: Body dark blue or more
commonly black with blue markings on the head, notum and foot. Rhinophores and
gills black (Image 2). Natural history: A common inhabitant of
muddy bottomed reefs and vertical substrata like wharfs where it is found on
arborescent bryozoans. Comparatively a fast moving nudibranch. Distribution in India:Nicobar Islands, a new record from the present study. Remarks: New
record for Indian waters.
Goniodorididae H. Adams
& A. Adams, 1854
11. Okenia kendiGosliner, 2004. Material examined: 20.ii.2011, one
specimen, Kapang, Katchall Island. Identification: It can be
identified by its white body with brown and purple pigment on the back and
slender appendages (Image 3). Natural history: Found on the rocks with
sponges, where it feeds on encrusting bryozoans. Distribution in India:Nicobar Islands, a new record from the present study. Remarks: New
record for the Indian Ocean.
Gymnodorididae Odhner, 1941
12. Gymnodoris citrina(Bergh, 1875). Material examined: 20.ii.2011, two
specimens, Kapang, Katchall Island. Distribution in India: Andaman
Islands (Ramakrishna et al. 2010). 13. Gymnodoris
impudica (Rűppell & Leuckart, 1828). Material
examined: 15.xi.2009, one specimen, Kamorta Island. Distribution
in India: Andaman Islands (Ramakrishna et al. 2010).
Cadlinidae Bergh, 1891
14. Aldisa erwinkoehleriPerrone, 2001. Material examined: 17.ii.2011, one
specimen, Kardip, Kamorta Island. Identification: This species can be
easily distinguished by its dark colored rhinophores and yellow pigment on the
tubercles immediately posterior to the rhinophores (Image 4). Natural
history: This is one among the three species of Aldisa which mimics Phyllidia coelestis. Distribution
in India: Nicobar Islands, a new record from the present study. Remarks:Previously known only from Thailand.
Discodorididae Bergh, 1891
15. Discodoris
boholiensis Bergh, 1877. Material examined: 16.ii.2011,
one specimen, Champion, Nancowry Island. Distribution in India: Andaman
Islands, Tamil Nadu, Gujarat (Rao 1960; Narayanan 1968; Dayrat 2010).
16. Halgerda
tessellata (Bergh, 1880). Material examined:20.ii.2011, four specimens, Kapang, Katchall Island. Distribution in India:Andaman Islands, Lakshadweep Islands (Apte 2009; Ramakrishna et al. 2010).
17. Jorunna
funebris (Kelaart, 1858). Material examined:12.ix.2010, one specimen, B. quarry, Campbell Bay, Great Nicobar. Distribution
in India: Andaman Islands, Tamil Nadu, Lakshadweep Islands, Andhrapradesh,
Kerala, Gujarat (Alder & Hancock 1864; Eliot 1906; Narayanan 1968; Fontana et al. 2001; Apte 2009; Apte et
al. 2010; Ramakrishna et al. 2010)
Chromodorididae Bergh, 1891
18. Chromodoris conchyliataYonow, 1984. Material examined: 22.ii.2011, one specimen, Kamorta
Jetty. Distribution in India: Andaman Islands
19. Chromodoris
elisabethina Bergh, 1877. Material examined:19.ii.2011, three specimens, Kapila, Trinket Island. Distribution in India:Andaman Islands (Ramakrishna et al. 2010).
20. Chromodoris
fidelis (Kelaart, 1858). Material examined: 26.ii.2010,
one specimen, Kamorta Island; 16.ii.2011, one specimen, Champion, Nancowry
Island; 18.ii.2011, three specimens, Alukiya, Kamorta Island; 19.ii.2011, two
specimens, Kapila, Trinket Island. Distribution in India: Andaman
Islands, Tamil Nadu, Lakshadweep Islands (Eliot 1906; Apte 2009; Ramakrishna et
al. 2010)
21. Chromodoris
geometrica (Risbec, 1928). Material
examined: 21.ii.2011, one specimen, Safed Balu, Trinket Island; 22.ii.2011,
one specimen, Kamorta Jetty. Distribution in India: Andaman Islands.
22. Glossodoris
atromarginata (Cuvier, 1804). Material examined:19.xi.2009, one specimen, Car Nicobar; 16.ii.2011, one specimen, Champion,
Nancowry Island. Distribution in India: Andaman Islands,
Tamil Nadu, Kerala (Eliot 1906; Fontana et al. 1999; Ramakrishna et al. 2010)
23. Glossodoris
pallida (Rűppell & Leuckart, 1830). Material
examined: 18.ii.2011, one specimen, Alukiya, Kamorta Island. Identification:It has a translucent white body with central opaque markings and a yellow
marginal band. (Image 5). Natural history: Inhabits patch reefs,
where it is found on the encrusting sponges which it feeds up on. Distribution
in India: Nicobar Islands, a new record from the present study. Remarks:New record for Indian waters
24. Hypselodoris
bullockii (Collingwood, 1881). Material examined:19.ii.2011, six specimens, Kapila, Trinket Island. Distribution in India:Andaman Islands (Ramakrishna et al. 2010).
25. Hypselodoris
maculosa (Pease, 1871). Material examined: 19.ii.2011,
one specimen, Kapila, Trinket Island; 22.ii.2011, one specimen, Kamorta
Jetty. Distribution in India: Andaman Islands, Lakshadweep Islands
(Apte 2009; Ramakrishna et al. 2010).
26. Hypselodoris
maridadilus Rudman, 1977. Material examined:16.ii.2011, two specimens, Kamorta Jetty; 18.ii.2011, one specimen, Alukiya,
Kamorta Island. Distribution in India: Lakshadweep Islands
(Apte 2009)
27. Hypselodoris
nigrostriata (Eliot, 1904). Material examined:19.ii.2011, one specimen, Kapila, Trinket Island. Distribution in India:Andaman Islands (Ramakrishna et al. 2010)
28. Noumea
simplex (Pease,
1871). Material examined: 20.ii.2011, one specimen, Kapang, Katchall
Island. Identification: Body colour pink. Gill and rhinophores tipped
with deep orange. The gills
vibrate while crawling; a typical character of the genus (Image 6). Natural
history: It is reported to feed on pink sponges (Gosliner et al.
2008). Distribution in India: Nicobar Islands, a new record from the
present study. Remarks: New record for Indian waters
29. Pectenodoris
trilineata (A. Adams & Reeve, 1850). Material
examined: 20.ii.2011, one specimen, Kapang, Katchall Island. Identification:Body coloration highly variable, purple with a thin marginal white line. It has three longitudinal lines on the
dorsum. The lines are dark blue
and interrupted in the specimen observed in Katchall Island, instead of the
yellow line seen in Pacific. The
gills and rhinophores are orange (Image 7). Natural history:It was found in shallow reef where it was feeding on encrusting sponge. Distribution
in India: Nicobar Islands, a new record from the present study. Remarks:New record to Indian Ocean.
30. Risbecia
ghardaqana (Gohar & Aboul-Ela, 1957). Material
examined: 21.ii.2011, one specimen, Safed balu, Trinket Island. Distribution
in India: Andaman Islands (Ramakrishna et al. 2010).
31. Risbecia
pulchella (Rűppell & Leuckart, 1828). Material examined: 22.ii.2011, two
specimens, Kamorta Jetty. Distribution in India: Andaman Islands
(Ramakrishna et al. 2010).
32. Thorunna
australis (Risbec, 1928). Material examined:16.ii.2011, one specimen, Champion, Nancowry Island; 20.ii.2011, four
specimens, Kapang, Katchall Island. Distribution in India:Karnataka (Zacharia et al. 2008)
33. Thorunna
florens (Baba, 1949). Material examined: 20.ii.2011,
one specimen, Kapang, Katchall Island. Distribution in India: Andaman
Islands.
34. Thorunna
horologia Rudman, 1984. Material examined: 20.ii.2011,
two specimens, Kapang, Katchall Island.
Distribution in India: Andaman Islands.
Phyllidiidae Rafinesque,
1814
35. Phyllidia marindica(Yonow & Hayward, 1991). Material examined: 13.ix.2010, one
specimen, Campbell Bay, Great Nicobar; 16.ii.2011, one specimen, Champion,
Nancowry Island; 19.ii.2011, one specimen, Kapila, Trinket Island; 21.ii.2011,
two specimens, Safed balu, Trinket Island. Distribution in India:Andaman Islands, Lakshadweep Islands, Tamil Nadu (Apte 2009; Ramakrishna et al.
2010).
36. Phyllidia
coelestis Bergh, 1905. Material examined: 17.ii.2011,
one specimen, Kardip, Kamorta Island. Distribution in India: Andaman
Islands, Lakshadweep Islands (Apte 2009; Ramakrishna et al. 2010).
37. Phyllidia
elegans Bergh, 1869. Material examined: 19.ii.2011,
one specimen, Kapila, Trinket Island. Identification: Body with
black lines and spots. The tubercles are opaque white and the larger ones are
tipped with yellow. The
rhinophores are yellow. A thick
median stripe of black on the sole of foot (Image 8). Natural history:Found on open reef slopes where it is frequently observed on the walls. Distribution
in India: Nicobar Islands, a new record from the present study. Remarks:New record for Indian waters.
38. Phyllidia
varicosa Lamarck, 1801. Material examined: 19.ix.2009,
one specimen, Car Nicobar; 26.ii.2010, one specimen, Kamorta Island; 28.ii.2010, one specimen, Kamorta
Island; 20.ii.2011, one specimen,
Kapang, Katchall Island; 21.ii.2011, one specimen, Safed balu, Trinket Island;
22.ii.2011, two specimens, Kamorta
Jetty. Distribution in India: Andaman Islands, Lakshadweep Islands,
Tamil Nadu, Karnataka (Rao et al.
1974; Zacharia et al. 2008; Apte 2009; Ramakrishna et al. 2010).
39. Phyllidiella
pustulosa (Cuvier, 1804). Material examined:22.ii.2011, one specimen, Kamorta
Jetty. Distribution in India: Andaman Islands, Lakshadweep Islands
(Apte 2009; Ramakrishna et al. 2010).
40. Phyllidiella
rosans (Bergh, 1873). Material examined: 26.ii.2010,
one specimen, Kamorta Island.Distribution
in India: Andaman Islands, Lakshadweep Islands, Tamil Nadu (Apte 2009;
Ramakrishna et al. 2010).
41. Phyllidiella
rudmani Brunckhorst, 1993. Material examined:13.xi.2010; three specimens, B. quarry, Campbell Bay, Great Nicobar;
19.xi.2009, one specimen, Car Nicobar; 19.ii.2011, one specimen, Kapila,
Trinket Island; 20.ii.2011, one specimen, Kapang, Katchall Island; 22.ii.2011,
one specimen, Kamorta Jetty. Distribution in India: Andaman Islands.
42. Phyllidiella
zeylanica (Kelaart, 1859). Material examined:19.ii.2011, six specimens, Kapila, Trinket Island; 20.ii.2011, two specimens,
Kapang, Katchall Island; 21.ii.2011, one specimen, Safed balu, Trinket
Island; 22.ii.2011, two specimens,
Sanuh, Kamorta Island; 22.ii.2011, three specimens, Kamorta Jetty. Distribution
in India: Andaman Islands, Lakshadweep Islands, Tamil Nadu, Karnataka,
Andhra Pradesh, Gujarat (Rao et al. 1974; Eliot 1906; Narayanan 1968; Zacharia
et al. 2008; Apte 2009; Ramakrishna et al. 2010).
43. Phyllidiopsis
annae Brunckhorst, 1993. Material examined: 17.ii.2011,
one specimen, Kardip, Kamorta Island. Identification: Body elongate
with arrangement of four black lines as in P. striata. Mantle perimeter granulose with few tiny black spots. Rhinophores black (Image 9). Natural
history: Found on shallow reef flat. Distribution in India: Nicobar
Islands, a new record from the present study. Remarks: New
record for Indian waters.
44. Phyllidiopsis
gemmata (Pruvot-Fol, 1957). Material examined:19.ii.2011, one specimen, Kapila, Trinket Island. Distribution in India:Lakshadweep Islands (Apte 2009).
45. Phyllidiopsis
phiphiensis Brunckhorst, 1993. Material examined:19.ii.2011, two specimens, Kapila, Trinket Island. Distribution in India:Andaman Islands, Lakshadweep Islands (Apte 2009; Ramakrishna et al. 2010).
46. Phyllidiopsis
xishaensis Lin, 1983. Material examined: 19.ii.2011,
one specimen, Kapila, Trinket Island. Distribution in India: Andaman
Islands, Lakshadweep Islands (Apte 2009; Ramakrishna et al. 2010).
Arminidae Iredale &
O’Donoghue, 1923
47. Dermatobranchus rodmaniGosliner & Fahey, 2011. Material examined: 18.ii.2011, two
specimens, Alukiya, Kamorta Island. Identification: The body is
elongated and triangular, flattened and narrow at posterior end. Notum is smooth and fleshy. Marginal sacs are visible along the
mantle edge and each contains elongate, stiff rodlets. The color is pinkish-white. One or two transverse brown patches are
present near the anterior and posterior thirds of the body. The notum and oral veil have a
yellowish-margin, which contains fine brown spots. (Image 10). Natural
history: Found on shallow patch reefs where they feed on soft corals.
Distribution in India: Nicobar Islands, a new record from the present study. Remarks:Previously known only from Madagascar and eastern Malaysia. This species was reported as Dermatobranchus sp.
16 in Gosliner et al. 2008 (page 313, bottom photo). This species is recorded for the first time after its
description (Gosliner & Fahey 2011) and is new record for Indian waters.
Flabellinidae Bergh, 1881
48. Flabellina
bicolor (Kelaart, 1858). Material examined: 20.ii.2011,
two specimens, Kapang, Katchall Island. Distribution in India:Lakshadweep Islands, Andhra Pradesh and Gujarat (Eliot 1906; Apte 2009; Apte et
al. 2010).
49. Flabellina
riwo Gosliner & Willan, 1991. Material examined:20.ii.2011, three specimens, Kapang, Katchall Island. Identification:The rhinophores are lamellate. The
network of opaque white lines on the body and the sub apical band on the cerata
are the distinctive characters (Image 11). Natural history:Found on shallow reef flats feeding on hydroids. Distribution in India:Nicobar Islands, a new record from the present study. Remarks: New
record for Indian waters.
50. Flabellina
rubrolineata (O’Donoghue, 1929). Material examined:16.ii.2011, eight specimens, Champion, Nancowry Island; 19.ii.2011, eleven
specimens, Kapila, Trinket Island. Distribution in India: Andaman
Islands.
Facelinidae Bergh, 1889
51. Phidiana indica(Bergh, 1896). Material examined: 16.ii.2011, two
specimens, Champion, Nancowry Island. 20.ii.2011, three specimens, Kapang, Katchall Island. Identification:Orange head with white and yellow markings and cerata with blue, yellow and red
(Images 12 & 13). Natural history: Found in shallow reefs
feeding on hydroids. Distribution in India: Nicobar Islands,
a new record from the present study. Remarks: New record for Indian
waters
52. Pteraeolidia
ianthina (Angas, 1864). Material examined: 26.ii.2011,
one specimen, Kamorta Island; 16.ii.2011, one specimen, Champion, Nancowry
Island. Distribution in India: Andaman Islands, Lakshadweep Islands,
Gujarat, Tamil Nadu (Eliot 1909; Apte 2009; Apte et al. 2010; Ramakrishna et
al. 2010).
Conclusion
Most of the information available on the Indian opisthobranchs is
pertaining to the peninsular coast. Opisthobranchiate taxonomy and ecology in
Andaman and Nicobar Islands recently gained an attention. The present study represents the
largest survey, in terms of geography and time from the coasts of Nicobar Islands. Nonetheless, due to an insufficient number
of sampling dives, lack of dredge sampling as well as intertidal areas, the
total number of the species was not as high as expected. The lack of night sampling is another
factor limiting the quantity of identified species. Overall 52 opisthobranch species
were recorded, of which 11 were new records for the Indian waters. These
findings suggest that the Andaman and Nicobar Islands are indeed a region of
high opisthobranch diversity, although till date it remains understudied as
established by our new regional records. We expect to find as much as 400 species of opisthobranchs from the
Nicobar group of Islands with focused work for a few years.
The opisthobranch fauna of this archipelago shows the affinity
with species of neighboring countries bordering Andaman Sea rather than eastern
coast of India. It is interesting
to state that the opisthobranch species of Andaman have more similarity with
that of Thai waters of Andaman Sea whereas that of Nicobar has more species
similarity with Indonesian waters. However, the opisthobranch fauna of the
oceanic Nicobar Islands have very less similarity with that of the
opisthobranchs reported from the peninsular coast of India. In this context,
the information about the opisthobranchs of Nicobar Islands adds value to the
molluscan studies of Indian waters.
REFERENCES
Alder, J. & A. Hancock
(1864). Notice of a collection of
nudibranchiate Mollusca made in India by Walter Elliot Esq., with descriptions
of several new genera and species. Transactions
of the Zoological Society of London 5: 113–147
Apte, D. & V.K.
Salahuddin (2010). Record
of Hexabranchus sanguineus(Rüppell & Leuckart 1828) from Lakshadweep Archipelago, India. Journal of the Bombay Natural History Society107(3): 261–262.
Apte, D., V. Bhave & D.
Parasharya (2010). An annotated and
illustrated checklist of the opisthobranch fauna of Gulf of Kutch, Gujarat,
India with 21 new records for Gujarat and 13 new records for India: part 1. Journal of the Bombay Natural History
Society 107(1): 14–23.
Apte, D. (2009). Opisthobranch
fauna of Lakshadweep Islands, India with 52 new records to Lakshadweep and 40
new records to India. Journal of the Bombay Natural History Society 106(2): 162–175.
Brunckhorst, D.J. (1993). The systematics and phylogeny of phyllidiid nudibranchs
(Doridoidea). Records of the Australian Museum 16(Supplement): 1–107.
Dayrat, B. (2010). A monographic revision of basal discodorid sea slugs (Mollusca:
Gastropoda: Nudibranchia: Doridina). Proceedings of the California Academy of
Sciences Series 4, 61(1): 1–403.
Eliot, C. (1906). On the nudibranchs of south India and Ceylon, with special
reference to the drawings by Kelaart and the collection belonging to Alder and
Hancock preserved in the Hancock museum at New Castle-on-Tyne North. Proceedings
of the Zoological Society of London, 1906 pt. II: 636–691 and
997–1008.
Eliot, C. (1910). Notes on nudibranchs from the Indian Museum. Records of the Indian Museum, 5(4):
247–252.
Eliot, C.N.E. (1909). Report on the nudibranchs collected by Mr. James Hornell at
Okhamandal in Kattiawar in 1905–6. In: Report to the government of Baroda on the marine zoology of
Okhamandal 1:137–145.
Fontana, A., C.L. Maria, L.
D’souza, E. Mollo, G. Chandra, P.S. Naikk, Parameswaran, S. Wahidulla & G.
Cimino (2001). Selected chemo-ecological
studies of marine opisthobranchs from Indian coasts. Journal of the Indian Institute of
Science 81(4): 403–415.
Fontana, A., P. Cavaliere,
N. Ungur, L. D’Souza, P. Parameswaram & G. Cimino (1999). New scalaranes from the nudibranch Glossodoris atromarginata and
its sponge prey. Journal of Natural Products62: 1367–1370.
Gosliner, T.M. & S.J.
Fahey (2011). Previously undocumented
diversity and abundance of cryptic species: a phylogenetic analysis of
Indo-Pacific Arminidae Rafinesque, 1814 (Mollusca:Nudibranchia) with
descriptions of 20 new species of Dermatobranchus.Zoological Journal of the
Linnean Society 161: 245–356.
Gosliner, T.M., D.W.
Behrens & A. Valdes (2008). Indo Pacific
Nudibranchs and Sea Slugs. Sea Challengers, 425pp.
Matwal,
M. & D. Joshi (2011). Record of Phyllidiella
zeylanica (Mollusca:Gastropoda:Opisthobranchia) after 42 years
from Gujarat, India. Journal of Threatened Taxa3(7): 1951–1954.
Narayanan, K.R. (1968). On three opisthobranchs from the south-west coast of India. Journal of the Marine Biological Association of India10(2): 377–380.
Narayanan, K.R. (1970). On two doridacean nudibranchs (Mollusca:Gastropoda) from the Gulf
of Kutch, new to Indian coast. Advance
Abstracts of Contributions on Fisheries and Aquatic Sciences in India 4(4):
313–314.
Raghunathan, C., C.
Sivaperuman & Ramakrishna (2010). An account of newly recorded five species of nudibranch
(Opisthobranchia, Gastropoda) in Andaman and Nicobar Islands, pp
283–288. In: Recent Trends in Biodiversity of
Andaman and Nicobar Islands. Zoological Survey of India,
Kolkata.
Ramakrishna, C.R., C.
Sreeraj, C. Raghunathan, J.S. Sivaperuman, R. Yogesh Kumar, Raghuraman, T.
Immanuel & P.T. Rajan (2010). Guide to Opisthobranchs of Andaman and Nicobar Islands. Zoological Survey of India,
196pp.
Rao, K.V. 1962 (For 1961). On two opisthobranchiate molluscs, Placobranchus ocellatus
Hasselt and Discodoris boholiensis Bergh, from Indian waters not hitherto been
recorded. Journal of the
Marine Biological Association of India 3(1–2):
253–256.
Rao, K.V., P. Sivadas &
L.K. Kumari (1974). On three rare doridiform
nudibranch molluscs from Kavaratti Lagoon, Laccadive Islands. Journal of the Marine Biological
Association of India 16(1): 113–125.
Rudman, W.B. (1982). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West
Pacific: Chromodoris
quadricolor, C.lineolata andHypselodoris nigrolineata colour
groups. Zoological Journal of the Linnaean
Society 76: 183–241.
Rudman, W.B. (1983). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West
Pacific: Chromodoris
splendida, C.aspersa andHypselodoris placida colour
groups. Zoological Journal
of the Linnaean Society 78: 105–173.
Rudman, W.B. (1984). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West
Pacific: a review of the genera. Zoological
Journal of the Linnaean Society 81(2&3): 115–273.
Rudman, W.B. (1986). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West
Pacific: Noumea purpurea andChromodoris decora colour
groups. Zoological Journal
of the Linnaean Society 86: 309–353.
Rudman, W.B. (1995). The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West
Pacific: further species from New Caledonia and the Noumea romeri group. Molluscan Research 16: 1–43.
Satyamurti, S.T. (1952). The Mollusca of Krusadai Island (in the Gulf of Mannar). Bulletin Madras Government Museum, New
Series, Natural History Section 1(2) pt. 6, pp. 1–258,
pls. 1–34.
Smith, E.A. (1878). On a collection of marine shells from the Andaman Islands. Proceedings of the Zoological Society
of London 10: 804–821.
Sreeraj, C.R., P.T. Rajan., R. Raghuraman., C.
Raghunathan., R. Rajkumar, Titus Immanuel & Ramakrishna (2010). On some new records of sea slugs (Class: Gastropoda, Subclass:
Opisthobranchia) from Andaman and Nicobar Islands, pp. 289–298. In: Recent Trends in Biodiversity of
Andaman and Nicobar Islands. Zoological Survey of India,
Kolkata.
Rao, N.V.S. (2003). Indian Seashells (Part-1) Polyplacophora and Gastropoda. Records
of Zoological Survey of India. Z.S.I. Kolkata.
Rao, N.V.S. & A. Dey
(2000). Catalogue of marine
molluscs of Andaman and Nicobar Islands. Records of the Zoological Survey of India,Occasional Paper No. 187, x+323pp.
Zacharia, P.U., P.K. Krishnakumar, A.P.
Dineshbabu, K. Vijayakumaran, P. Rohit, S. Thomas, G. Sasikumar, P. Kaladharan,
R.N. Durgekar & K.S. Mohamed (2008). Species assemblage in the coral reef ecosystem of Netrani Island
off Karnataka along the southwest coast of India. Journal of the Marine Biological Association of India50(1): 87–97.