The genus Radula Dumort. (Marchantiophyta: Radulaceae) in Madagascar, with a key to the tropical African species

A taxonomic study of the Radulaceae from Madagascar leads to the recognition of thirteen species, in five subgenera. Radula evelynae, R. lindenbergiana and R. retroflexa are new to Madagascar, R. fulvifolia is excluded from the Madagascan flora and R. javanica is considered a doubtful record. Radula ankefinensis is a new synonym of R. mexicana and its distribution is extended to the Neotropics, R. silvestris and R. comorensis are new synonyms of R. appressa, and R. bipinnata and the neotropical R. gottscheana are placed in the synonymy of R. boryana following Castle (1936). Four new lectotypfications are proposed. The species usually grow as epiphytes in mid-elevation forests, more rarely in lowland forests; one species, the Holarctic R. lindenbergiana, is restricted to the upper montane belt. Radula marojezica and R. pinnata are endemic to Madagascar and about 70% of the species have wide, intercontinental ranges. The commonness of intercontinental ranges in Madagascan Radula may be explained by the old age of the Radula lineages, their good dispersibility and habitat preferences. Descriptions and selected illustrations of the species are provided together with a key to the Radula species of tropical Africa. Surface wax, observed on the leaves of R. appressa, is reported for the first time in the family Radulaceae.

Automated summary

A taxonomic study of the Radulaceae from Madagascar identifies thirteen species and provides information on their distribution, habitat preferences, and characteristics. The study also proposes the exclusion or synonymy of certain species and introduces new lectotypifications. This study contributes to our understanding of the taxonomy and diversity of Radulaceae in Madagascar.