Biodiversity of coastal polyclad flatworm assemblages in the wider Caribbean
2008
Rawlinson, Kate A.
Polyclads are mobile predators and possibly an important functional component of hard substrate marine environments globally. To understand the natural patterns of spatial differences, polyclad assemblages were sampled in seven coastal regions across the wider Caribbean spanning 15° latitude and 24° longitude between May and June 2005 and May and September 2006. In total, 67 species in 28 genera and 17 families were recorded from 62 sites. Only two species were found in all surveyed regions, Melloplana ferruginea and Pseudoceros bicolor. Conversely, 41 species were restricted to one or two sites, and 34 species were represented by one or two individuals. The distribution and abundance of species varied between the two suborders. Cotyleans were most species rich and had a higher number of species of restricted range, while Acotylea showed a higher proportion of rare species; however, two species were highly abundant comprising over half of the individuals counted. In most habitats, polyclads were rare, but in some intertidal habitats two species, Styloplanocera fasciata and Boninia divae were densely aggregated and dominant members of the benthic epifauna. Alpha diversity was variable but showed no evidence of a relationship with latitude, longitude or depth. Beta diversity increased with the number of habitats sampled and was highest for cotyleans. Highest gamma diversity was recorded in Jamaica and the US Virgin Islands and was not significantly correlated to alpha diversity. Overall assemblages from the seven regions were similar, revealing faunal homogeneity across the wider region. Reef assemblages were distinct from other habitats dominated by species of the Cotylea. Reefs from Panama and the US Virgin Islands were the most species rich.
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