The species under the genus Stiliger Ehrenberg 1831 known hitherto from the coastal
waters or backwaters and estuaries of India are very few. S. pica Annandale and
Prashad (Sewell & Annandale, 1922) from Chilka Lake and S. gopalai Rao (1937)
from Madras backwaters are the only species on record. Stiliger viridis (Kelaart)
as described by Eliot (1906a) from the Ceylon coast of Gulf of Mannar and S. tentaculatus
Eliot (1916) from Siam are two other species known from regions very close
to Indian coasts. S. nigrovittatus described here is one of the few species collected
by the present writers from the Palk Bay and the Gulf of Mannar in the vicinity of
Mandapam. It has been experienced that a careful search among the members of
filamentous algae like Chaetamorpha revealed one or the other species of the sacoglossan
Opisthobranchs which feed on those algae. A few individuals of S. nigrovittatus
were obtained from the Gulf of Mannar close to the Central Marine Fisheries
Research Institute, Mandapam Camp, on November 29, 1962, for the first time.
Subsequently they were collected from the same locality and also from Kundagal
Point near Pamban in all months upto March 1963. They were observed on algal
growths of Cladophoropsis zoolingeri (Kuetz.) Boergs., covering the rocks in the intertidal
region. In captivity they were found feeding on this alga as also on
Chaetomorpha sp
