Ascidians from the tropical western Pacific

A large collection of 187 identified ascidian species is added to the records published in 1996 from the same tropical western Pacific islands. Most of the specimens were collected by the US Coral Reef Research Foundation (CRRF). They come from depths accessible by SCUBA diving. Most of the collection’s species are described and figured, their color in life is illustrated by 112 underwater photographs; among them 48 are new species representing a fourth of the material collected. This demonstrates how incomplete the knowledge of the ascidian diversity in this part of the world remains. Moreover, very small or inconspicuous species were seldom collected, as compared to the highly coloured and large forms. Many other immature specimens were also collected but their precise identification was not possible. Almost all littoral families are represented with the exception of the Molgulidae which are more characteristic of soft sediments, a biotope which was not investigated. Among the very diversified genera, the colonial forms largely dominate, including not only all the Aplousobranchia genera but also some Phlebobranchia and Stolidobranchia.Very often only one specimen was available, so a detailed biogeographical distribution cannot be given, and no island endemism can be defined.