A taxonomic revision of the genus Odontoschisma (Marchantiophyta: Cephaloziaceae)

A world-wide revision of the liverwort genus Odontoschisma (Cephaloziaceae) based on morphological and molecular evidence, leads to the recognition of 21 species in 5 sections: sect. Odontoschisma (3 spp.), sect. Iwatsukia (3 spp.), sect. Neesia (1 sp.), sect. Cladopodiella (1 sp.) and sect. Denudata (13 spp.). Odontoschisma is the single genus in Cephaloziaceae subfam. Odontoschismataceae. Anomoclada, Cladopodiella and Iwatsukia are part of Odontoschisma based on molecular evidence. The genus is separated from other members of Cephaloziaceae by ventral stolons, stems without hyalodermis, frequent presence of large trigones, large oil bodies and non-tiered antheridial jacket cells. Wax crystals are newly reported in sect. Iwatsukia. Thirteen species occur in tropical America, 8 in the holarctic region, 4 in tropical Asia, 3 in Africa and one in the Pacific region. The genus is absent in temperate regions of the southern hemisphere. Six species are endemic: O. brasiliense (SE Brazil), O. cleefii (Colombia), O. purpurattun (Malaysia), O. soratamum (Colombia), O. spinosum (Venezuela) and O. steyermarkii (Venezuela). Odontoschisma steyermarkii is described as new to science. The species usually grow on acid substrates such as rotten wood, humus, moist sand or peat, acid rock and tree bases; O. macounii prefers calcareous habitats.