Phylogeographic studies in the tropical seaweed Cladophoropsis membranacea (Chlorophyta, Ulvophyceae) reveal a cryptic species complex

The seaweed Cladophoropsis membranacea (Hofman Bang ex. C. Agardh) Borgesen is a widely distributed species on coral reefs and along rocky coastlines throughout the tropics and subtropics. In a recent population-level survey openface >1600 individuals with eight microsatellite loci, a number of isolates from biogeographically disjunct locations could not be amplified for any of the loci. Nonamplifiable and amplifiable isolates co-occurred within the Canary Islands, Cape Verde Islands, and in the Caribbean. These unexpected results led to question whether or not C. membranacea is a single species. Phylogenetic relationships were evaluated using rDNA ITS1 and ITS2 sequence comparisons from 42 isolates sampled from a subset of 30 of the 66 locations. Four well-supported clades were identified. Sequence divergence within clades was