Marine Plants of Pohnpei and Ant Atoll: Rhodophyta, with biogeographic comparisons to other Pacific atolls and island groups

This is the second paper resulting from a study of marine benthic plants collected from Pohnpei Island and Ant Atoll in the Caroline Islands, Federated States of Micronesia, between 1994 and 1997. It documents the occurrence of 113 species of red algae (Division Rhodophyta), exclusive of crustose coralline algae. Of these, 56 are new records for Pohnpei, 76 are new records for Ant Atoll, and 53 are new records for Micronesia (here including the Caroline, Mariana, Marshall, Gilbert, and Ellice Islands). A previous paper reported 80 species of green and brown algae and seagrasses from Pohnpei and Ant, of which 8 were new records for Micronesia. Added to reports from the literature, the total known marine benthic flora of Ant and Pohnpei (exclusive of Cyanobacteria and crustose coralline algae) now stands at 244. The high volcanic nature of Pohnpei is very different from the low calcareous Ant Atoll, which led us to expect higher species numbers for Pohnpei relative to Ant, and greater differences in their algal floras than we found. Comparisons of the Ant-Pohnpei algal flora were also made, using the Jaccard and Sorensen’s indices, to Ifaluk Atoll (Caroline Islands), Enewetak Atoll (Marshall Islands), the Northern Mariana Islands, and the distant south Pacific island groups of Fiji and French Polynesia. Biogeographic investigation of the marine plant flora revealed that Ant Atoll and Pohnpei have a large number of widespread and Indo-Pacific species, but very few probable regional endemics