New record of a
headshield slug Phanerophthalmus smaragdinus (Gastropoda:Opisthobranchia) from Andaman Islands, India
Sumantha Narayana 1 & Raju Mohanraju 2
1,2 Department of Ocean Studies and Marine Biology, Pondicherry
University, Brookshabad Campus, Port Blair, Andaman
and Nicobar Islands 744112, India
1 sumantha.narayana@gmail.com (corresponding author), 2 mohanrajupu@yahoo.com
doi: http://dx.doi.org/10.11609/JoTT.o3357.4113-4 | ZooBank: urn:lsid:zoobank.org:pub:4F81286E-11FF-4C0F-A287-E689A4631F82
Editor: Deepak Apte,
Bombay Natural Hisotry Society, Mumbai,
India. Date
of publication: 26 April 2013 (online & print)
Manuscript details: Ms #
o3357 | Received 21 September 2012 | Final received 21 February 2013 | Finally accepted
16 March 2013
Citation: Narayana,
S. & R. Mohanraju (2013).New record of a headshield slug Phanerophthalmus smaragdinus(Gastropoda: Opisthobranchia)
from Andaman Islands, India. Journal of Threatened Taxa 5(7):
4113–4114; http://dx.doi.org/10.11609/JoTT.o3357.4113-4
Copyright: © Narayana& Mohanraju 2013. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Funding: None.
Competing Interest: None.
Acknowledgements: The
authors are thankful to the Officer In-charge, Zoological Survey of India,
Andaman and Nicobar Regional Centre for permitting to use the lab facilities. Special thanks to C.R. Sreeraj for his
help in identification of the species and discussion during writing of the
article.
For image, table -- click here
Opisthobranchia, a subclass of gastropods,
differ from their relatives Prosobranchia by the
presence of a thin, reduced or absent shell, and are purely marine
animals. The term opisthobranch means “back or rear
gills”, which is a feature specific to these groups of animals. They are hermaphroditic animals. Opisthobranchsare small and often cryptic individuals that inhabit mostly sub-tidal regions
and have a low numeric density making their study difficult. Studies on opisthobranchsin India are sparse and patchy, and have only recently gained much attention
from researchers. Recent works on
Indian Opisthobranchia are by Apte(2009), Apte & Salahuddin(2010), Apte et al. (2010), Matwal& Joshi (2011), Sankar et al. (2011), and Bhave & Apte (2011), who have
studied the opisthobranchs off Lakshadweep Islands
and Tamil Nadu, Gujarat and Maharashtra coasts.
Studies on the opisthiobranchs of Andaman and Nicobar Islands have been
reported by Raghunathan et al. (2010), Ramakrishna et
al. (2010), Sreeraj et al. (2010, (2012 a,b) and Dhivyaet al. (2012).
The genus Phanerophthalmusbelongs to Cephalaspida, an opisthobranchclade most closely aligned with the shelled prosobranchs. These headshieldslugs are most primitive and one of the least modified formof gastropods, and exhibit great morphological diversity (Behrens et al.
2005). Phanerophthalmusspecies are long, cylindrical animals with very small headshield.
The current article reports a
new record of an opisthobranch, Phanerophthalmus smaragdinus (Rüppell& Leuckart, 1828) from Andamans,
India.
Materials and Methods: Sample was collected from
intertidal region of Burmanallah, South Andaman,
during low tide when most of the area was partially submerged. The animal was brought to the laboratory
for further examination and identification. Identification based on morphological
characters was carried out following Gosliner et al.
(2008) and C.R.Sreeraj (pers. comm. 14 July 2012). Morphology of the live specimen was
studied using a stereo-zoom microscope (Leica M205a). The specimen was
narcotized using few drops of magnesium chloride solution (72g/L), and
transferred into 5% formaldehyde solution. The formaldehyde fixed animal was later transferred to 95% ethanol for
long time preservation.
A specimen of the animal has
been deposited in the National Zoological Collections of Zoological Survey of
India, Andaman and Nicobar Regional Centre, for reference; registration number
ZSI/ANRC-7619.
Results: The specimen has been
identified as Phanerophthalmus smaragdinus (Rüppell &Leuckart, 1828) which is the
first record of this species from the Andaman Islands. These organisms are known from the western Indian Ocean of
South Africa, Madagascar and the Seychells and Lakshadweep
Islands (India) to the western Pacific of New Caledonia, Papua New Guinea,
Vanuatu, Indonesia, Reunion Island, Philippines, Japan, Guam, Palau. The systematic account of the species is given below. The taxonomic hierarchy of Bouchet & Rocroi (2005) is
followed.
Systematics
Informal Group: Opisthobranchia
Clade: CephalaspideaP. Fischer, 1883
Superfamily: Haminoeoidea Pilsbury, 1895
Family: SmaragdinellidaeThiele, 1925
Genus: PhanerophthalmusA. Adams, 1850
Phanerophthalmus smaragdinus(Rüppell & Leuckart,
1828)
Material examined: ZSI/ANRC-7619, 12.vii.2012, adult hermaphrodite, 11-034.274’N
& 92-044.212’E, 0.1m, Burmanallah,
South Andaman, Andaman and Nicobar Islands, India, coll. Sumantha Narayana.
Description: The animal was long and cylindrical with a very small headshield. The
mantle cavity was much reduced and occupied a terminal position at the end of
the body. The shell was small,
flattened and enclosed by the mantle. The sides of the foot extended into large parapodia which folded over
and enclosed the body (Rudman 1972). The uniform light greenish colour of this
species is distinctive (Image 1). It was found in the intertidal area, crawling through beds of algae over
rocks and dead corals. The
morphometric data of the specimen is shown in Table 1.
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