A new species of Riccia (Ricciaceae: Marchantiophyta) from the Western Ghats of Kerala

Abstract. A new species of Riccia, R. keralensis sp. nov. of the subgenus Riccia of section Riccia and group Squamatae is described from the disturbed low land areas of Kozhikode and Malappuram districts of Kerala, India. Riccia keralensis resembles species in the group Squamatae such as R. billardieri Mont & Nees., R. gangetica Ahmad ex L.Soderstr. and R. treubiana Steph. in external appearance and internal structure of the thallus, but distinctly differs in the spores which have a distinct triradiate mark in almost all spores, prominent wing and fewer areolae across the diameter. Riccia keralensis is also similar to R. pandei Udar of the subgenus Ricciella and section Spongodes and group Crystallina in its external thallus morphology, monoicous sexuality and form and number of areolae in the spores, which are 5–6 across diameter. But it differs from R. pandei Udar in the internal anatomy of thallus, the spore size and the smooth-vermiculose texture of the spores.