Tropical Atlantic Oceanic Islands and Archipelagos: Physical structures, plant diversity, and affinities of the bryofloras of northern and southern islands

We investigated the species richness, endemism, and similarities of the bryofloras on ten islands and archipelagos in the Atlantic Ocean to determine the floristic relationships among them using presence/absence. Cluster analysis was used to determine similarities among the bryofloras of ten islands and archipelagos. We examined the bryophyte species to address the following questions: (1) How many bryophyte species are there in the total area and on each island and archipelago? (2) Do mosses and liverworts share patterns of diversity? (3) What are their species distribution patterns? (4) How many endemic species are there on the islands? (5) Is there a high similarity among those bryophyte floras? We encountered 1,647 species, 325 genera, and 204 families, with the richest families (Lejeuneaceae, Lophocoleaceae, Plagiochilaceae, Brachytheciaceae, Bryaceae, Fissidentaceae, and Pottiaceae), representing 35% of all species. Over 12% of the bryophytes are African elements, 8% have global distributions, approximately 3% are Macaronesia elements, 5% are endemic, and 34% are included in other distributions. We present a checklist of 1,647 bryophyte species, of which 91 are endemic. Bryophyte richness and diversity differed significantly among the ten islands and archipelagos studied, and their low similarities illustrate their high degrees of heterogeneity. This paper is the first evaluation of bryophyte species on ten islands and archipelagos of the Atlantic Ocean, giving insight into their species richness, endemism and similarities, and providing information for analyzing species turnover, migration, invasion, etc., representing an increase in our general knowledge of the bryofloras of oceanic islands and archipelagos, contributing to the targets of the Global Strategy for Plant Conservation.