Two new species of Riccardia (Aneuraceae, Marchantiophyta) from Eastern Himalaya, India with notes on the genus in Sikkim

Two new species of Riccardia (Aneuraceae, Marchantiophyta) from Eastern Himalaya, India with notes on the genus in Sikkim

The genus Riccardia Gray is represented in Sikkim by 10 species, including R. lachungensis D.Singh & D.K.Singh and R. udarii D.Singh & D.K.Singh described here as new from North and South district respectively. R. lachungensis is characterized by 9–10 mm long, 0.25–0.35 mm wide plants with usually bipinnate or sometimes tripinnately branched thalli with mamillate–papillate dorsal and ventral epidermal cells, mucilage papillae scattered on ventral surface of thallus, main thalli 10–12 cells thick in the middle with unistratose alar portion 1-celled, and the absence of gemmae. Whereas, R. udarii is distinct in dichotomously branched thalli with distinct midrib, or sometimes indistinct in apical portion, main thalli 6–8 (–9) cells thick in the middle in transverse section, unistratose alar portion of wing 4–9 cells wide and often presence of pigmented cells in the thallus. Sporophytic details in R. elata (Steph.) Schiffn. are provided for the first time and R. levieri Schiffn. is newly recorded from the State of Sikkim. Riccardia cardotii (Steph.) Pande & K.P.Srivast., earlier reported from the State by several workers, has been excluded from the Riccardia flora of Sikkim.