THE GENERA LEIOMITRIUM AND CARDOTIELLA GEN. NOVA (ORTHOTRICHACEAE)

Abstract

  Of the nine species names that have been placed in the genus Leiomitrium Mitt. (= Coleochaetium (Besch.) Ren. & Card.) only L. plicatum (P.-Beauv.) Mitt. can taxonomically be retained in the genus. The remaining eight species are more correctly considered either as synonyms of other names in Macrocoma, or in the genus Cardotiella Vitt gen. nova. Leiomitrium is a taxon closely related to Macrocoma with its one species restricted in distribution to the Mascarene Islands. This monotypic genus is best distinguished by creeping stems; a tendency to have imbricate, rounded-obtuse branch leaves; very long ocrea; cylindric, exserted, deeply ribbed capsules; a peristome of 8, reflexed exostome teeth, and 8 (or 16) endostome segments; and plicate, hairy, campanulate calyptrae. Historically, the characters which distinguish this genus have not been interpreted entirely correctly and a discussion of these is given, along with typification of the names that have been placed in the genus. Five of these species form a natural assemblage and deserve to be recognized in a separate genus - Cardotiella - distinguished by creeping stems, uniformly-rounded-quadrate leaf cells with the tendency to be strongly unipapillose; long decurrencies of inflated, tuberculate, hyaline cells; peristome of unfused parts; and non-plicate, basally lobed calyptrae. These features ally this genus to Schlotheimia.