Zoogeography of the echiuran fauna of the Indo-West Pacific Ocean (Phylum: Echiura)

Abstract

This report provides a checklist of the echiuran fauna of the Indo-West Pacific Ocean and analyses their distribution in relation to general biogeographic regions. Currently the echiuran fauna of the Indo-West Pacific comprises three families, 30 genera and 103 species. The family Bonelliidae contains 43 species in 21 genera; the Echiuridae is represented by eight genera and 58 species, and the Urechidae by two species, Urechis novaezealandiae (Dendy) and U. unicinctus (von Drasche). Investigations undertaken on this group of animals after the publication of the monograph by Stephen & Edmonds (1972) on the phyla Sipuncula and Echiura have revealed one new genus, 15 new species and several new records. This study shows that the Indo-Pacific has a high species diversity, comprising about 62% of the known world fauna. The West Indian Ocean is currently represented by 28 species; 55 species have been recorded in the Central Indo-West Pacific and 53 species in the West Pacific. Only four species are thought to be cosmopolitan while approximately 50 species appear to be endemic to the Indo-West Pacific Ocean. Members of the Echiuridae are usually found in shallow-waters of littoral and subtidal zones while bonelliids are inhabitants of deeper bottoms where cold temperatures prevail.