Pages 671-696

Taxonomic investigations of members of the family Gracilariaceae of the seas around India are very limited and many of the Gracilaria species hitherto reported from this area are inadequately described. During the course of studies on the agar-yielding seaweeds, different species of Gracilaria and Gracilariopsis were collected from the east and west coasts of India, Laccadives, Andaman and Nicobar Islands. In this paper seventeen species and two varieties of Gracilaria and two species of Gracilariopsis are described in detail. The

species of these two genera are as follows: Gracilaria arcuata v. typica Zanardini, G. arcuata V. attenuata var. nov., G. cacalia (J. Agardh) Dawson, G. canaliculata (Kuetzing) Sonder, G. corticata v. typica J. Agardh, G. corticatav. cylindrica var. nov., G. cylindrica Boergesen, G. disticha J. Ajjardh, G. edulis (Gmelin) Silva, G. foliifera (Forsskal) Boergesen, G.indica sp. nov., G. kanyakumariensis sp. nov., G. mannarensis sp. nov., G. millardetii (Montagen) J. Agardh, G. obtusa (Kuetzing) De Toni, G. opuntia (Svedelius) Durairatnam, G. textorii (Suringer) J. Agardh, G. verricosa (Hudson) Papenfuss, Gracilaria sp., Gracilariopsis megaspore Dawson and Gr. sjoestedtii (Kylin) Dawson.

Of the 21 algae reported in this paper, three species and two varieties of Gracilaria are new taxa and G. cylindrica, G. millardetii, G. opuntia and Gracilariopsis megaspora are the first records from the Indian waters. Cystocarps of G. canaliculata ; antheridia of G. corticata, G. foliifera, G. canaliculata, G. obtusa, G. edulis, G. cylindrica, Gracilariopsis megaspora and tetrasporangia of Gr. megaspora and other species were observed and these have been described here for the first time. Details regarding the habitats of the species and their distribution in India and other geographical areas are also included here.