3. Rauiella Reimers, Hedwigia. 76: 287. 1937. • [For Eugene Abraham Rau, 1848-1932, American bryologist].
Rauia Austin, Bull. Torrey Bot. Club 7: 16. 1880, not Nees & Martius 1823 [Rutaceae] William R. Buck
Plants medium-sized. Stems creeping, ± regularly 1-pinnate; paraphyllia ± filamentous, not or weakly branched; axillary hairs 3-celled. Stem leaves broadly ovate to cordate-deltoid; margins plane or recurved, crenulate to crenulate-papillose; costa ending near base of acumen; laminal cells ± quadrate, multipapillose on both surfaces. Branch leaves ovate; margins plane to irregularly recurved, crenulate to crenulate-papillose; apex acute or gradually broadly acuminate; costa 4/5 leaf length, covered with cells apically; laminal cells quadrate to isodiametric, multipapillose on both surfaces. Sexual condition autoicous; perichaetial leaves lanceolate, margins crenulate, not ciliate, costa subpercurrent, laminal cells smooth. Seta smooth. Capsule suberect to horizontal, short-cylindric, arcuate; annulus 2- or 3-seriate; operculum stoutly and obliquely apiculate to rostrate; endostome segments not or narrowly perforate, cilia in groups of 1-3.
Species 8 (2 in the flora): North America, Mexico, West Indies, Central America, South America, Asia, Africa.
Rauiella has frequently been confused with Haplocladium (Leskeaceae) and Thuidium. The genus is characterized in the flora area by leaves multipapillose on both sides, well-developed papillose paraphyllia of oblate cells on the stems (sparse on the branches), a smooth seta, and autoicous sexuality. The distal part of the costae on branch leaves is covered by laminal cells (as seen in Cyrto-hypnum), but in Rauiella the cells are also bulging on both surfaces (flat in Cyrto-hypnum). The paraphyllia are 2- or sometimes 3-seriate proximally and 1-seriate distally. The stem leaves of Rauiella are erect when dry, somewhat decurrent, and 0.5-0.6 mm in length, with pellucid costae not covered by cells apically and laminal cells bulging on both surfaces. The perichaetial leaves are enlarged and more or less plicate, with rectangular to long-rectangular laminal cells.