Diversity and taxonomy of rocky‐intertidal Bryozoa on the Island of Hawaii, USA

Abstract

This study examines the diversity of bryozoans found at four rocky intertidal sites (Kiholo Bay, Whittington Beach Park, Kealakekua Bay, and Kapa'a Beach Park) on the Island of Hawaii, USA. Bryozoans were patchily distributed, with few or no bryozoans, or low species diversity, at three protected or semi‐protected sites, and unexpectedly high diversity at one exposed site. Species richnesses at the four sites were zero, one, five, and 32 species, respectively. Species diversity at the richest site was within the range of single‐site diversities previously reported from optimal sites in temperate latitudes. We provide descriptions and SEM illustrations for 32 species recorded, which include a new genus (Junerossia) in the Family Stomachetosellidae and 10 new species (Alderina flaventa, Corbulella extenuata, Puellina septemcryptica, Junerossia copiosa, Calytpotheca kapaaensis, Bryopesanser serratus, Cribellopora souleorum, Metacleidochasma verrucosa, Disporella compta, and Favosipora adunca). The species encountered included 23 (72%) ascophorans, four (13%) anascans, two (6%) cribrimorphs, three (9%) cyclostomes, but no ctenostomes. All species were encrusting and essentially two‐dimensional in growth form. Most species occurred on a substratum of lava rock, though not exclusively so. Of 23 species distributed outside the Hawaiian Islands, five (22%) have putatively cosmopolitan distributions and 18 (78%) Indo‐West Pacific distributions; 19 (83%) are new records for the Hawaiian Islands. We briefly discuss freshwater influence and predation as possible factors in the patchy distribution of the intertidal bryozoans, and stress tolerance and larval‐settlement specificity as factors in the composition of the intertidal assemblage.