Bryophytes of Cocos Island, Costa Rica: Diversity, biogeography and ecology

Abstract

A total of 98 liverwort species (43 genera, 10 families), 54 moss species (33 genera, 17 families) and one species of hornwort have been reported for Cocos Island (5°32'N, 87°04'W), Costa Rica. Over 60% of the bryophytes have a Neotropical or Pantropical distribution, about 10% are Caribbean, and less than 5% are endemic or subendemic. In comparison to the Galapagos Archipelago, Cocos Island harbors a more typical tropical bryoflora with foliose hepatics (e. g. Lejeuneaceae, Lepidoziaceae) constituting the bulk of diversity; fewer thallose liverworts and moss taxa as in the Archipelago were found. A richer habitat variety including wet and dry habitats, as well as its bigger area, seem to account for the higher number of bryophyte species in Galapagos Archipelago. Most bryophytes in Cocos Island are corticolous (46%), the remaining are epiphyllous (25%), saxicolous (23%) or terrestrial (12%). Bryophyte occurrence in eight plots (10 × 10m) with 20 quadrates (30 × 30 cm) were recorded at different habitats and altitudes (0-600 m). Bryophyte distribution within the island coincides with lowland forest (0-100 m), secondary lowland forest (0-200 m) and montane forest (to 600 m). Physantholejeunea portoricensis (Hampe & Gott.) Schust. is reported as new to Costa Rica.