The relictual fern genus Loxsomopsis

We conducted a systematic revision of the genus Loxsomopsis H. Christ (Loxo mataceae) based on 99 herbarium sheets representing about 52 separate gathe rings. Many morphological characters varied considerably, but as much of th is variation was found within individual collections it was of little taxon omic relevance. Characters that varied between specimens but remained rough ly constant within individual gatherings included the pubescence of lamina, petiole, and sorus, hair size and coloration, presence or absence of glauc ous layers on the lamina surface, and spore surface structure. However, rye found no correlation in the occurrence of two or more of these characters and were unable to morphologically define discrete species within the genus . Thus, we consider Loxsomopsis to include one variable species, L. pearcei (Baker) Maxon. The morphological variation is probably the result of the d istribution of the species in small, isolated populations in ephemeral earl y successional habitats, leading to continuous population extinction and es tablishment of new population based on few propagules. Notes on ecology and distribution, full taxonomy, and specimen citations are provided.