A New Species of Riccia from Mount Abu (India)

Abstract

Riccia jluilans has been an object of controversy for a long time in spite of various contributions made by Familler (1920), Gaisberg (1921), Evans (1921 ), Carter (1935), etc. Recendy the species has been considered (Lorbeer, 1934; Muller, 1940, 1941) to be a composite of four species, viz. Riccio jiuilans L. emend. K. MUller, R. rhenana Lorb., R. cana/iculala Hoffm., and R. duplex Lorb. The pioneer work of K. MUller, based upon cytological and cultural eXPeriments in segregating the 'fluitans group' into four species, is quite authentic (Meijer, 1951; Schuster, 1953; Klingmuller, 1957, 1959). Klingmuller (1958), while studying the taxonomy of' ftuitans group', recently instituted a new species, R. media KlingmUller, whose status is doubtful' (Bapna, 1961). No work has been done in India regarding these observations on 'ftuitans group' and the Indian material needs re-investigation. Kashyap (1929) described R.fluitans L. to occur as a sterile floating form and a fertile terrestrial form. The terrestrial form (Kashyap, 1929, p. 97), seems to be R. duplex Lorb. and the sterile one R. fluitans L. emend. K. Muller, but this could not be confirmed as the author failed to obtain the material. While studying the hepatic flora of Mount Abu, a hill station in Rajasthan (India), the author found a Riccia specimen of the 'ftuitans group' and described it as R.fluitans L. (Bapna, 1958, 1960). However, a detailed study has revealed that this specimen is composed of two species. The sterile one is R. fluilans L. emend. K. Milller, whereas the fertile one differs from all other species of the genus and deserves a separate treatment. Dr Arnell, to whom the material was sent for his valuable suggestions and advice, has also confirmed the determination. The plant is named as R. abuensis sp.nov. after the place of its occurrence, Mount Abu. The type specimen is deposited at the Herbarium of the National Museum of Natural History of Stockholm, Sweden. Riccia abuensis sp.nov.