Journal of the Marine Biological Association of India

Volume 16 Issue 3

On some aspects of taxonomy, structure and early development of the nudibranchiate gastropod Discodoris fragilis (Alder & Hancock)

K. Virabhadra Rao and L. Krishna Kumary

The present paper deals with observations on specimens of a doridacean nudibranch, Discodoris fragilis (Alder & Hancock) found among the sea grass Cymodocea ciliata in the Palk Bay lagoons along the south eastern coast of India. D.fragilis is a widely distributed spB:ie3 in the Indo-Pacific. The species has often been confused by same workers with other species having certain outward resemblances. With the help of photographic representations the taxonomic characters of the species have clearly been described. The morphological characters of this species with related species have been compared. The nature of the dorsal tubercles which are low conical speculate and with blunt white tips, the foot with a frontal groove but without a median notch, the rhinophores each with a white line on its posterior face, the labial disc having paired elongated triangular patches of close-set rodlets, the radula with a varying number of lateral hamate teeth in numerous transverse rows but without the rachidial teeth, an enlarged prostate in two distinct lobes and a conical penis without armature among the reproductive organs are good taxonomic characters when taken along with the distinct pattern of colouration of the mantle and the foot. The mantle is very fragile and the animal often autotamizes it in portions.

The mating habits, spawn and early developmental stages have been described. The just hatched veliger measured about, 180 µ on its long axis, having rather a broad spiral shell of a pale pinkish hue.

Date : 31-12-1974