Vansoestia caribensis gen. nov., sp. nov.: first report of the family Ianthellidae (Verongida, Demospongiae) in the Caribbean.

ABSTRACT

A thin fiber-less sponge from Caribbean reefs (Bocas del Toro, Panama) with close genetic affinities (based on 18S and 28S nuclear ribosomal RNA gene sequences) to large fan-shaped fiber-bearing sponges (Ianthella and Anomoianthella) from the Indo-Pacific Ocean is here presented. We describe its overall external morphology, histological features, and ultrastructure. Its genetic distance from the only previously known fiber-less verongid genus, Hexadella, prompted the need to erect a new genus to classify this species. This novel species constitutes the first record for a member of the family Ianthellidae in the Caribbean. The characterization of the family Ianthellidae (sensu Cook and Bergquist, 2000) is here modified by i) highlighting the cavernous nature of the choanosome, with many lacunae and channels reported for all genera included in the family; ii) extending the family distribution to the Caribbean; and iii) adding a fourth genus to the group of verongids with eurypylous chambers. The possession of a cellularized cortex (10-300 µm in thickness) is here proposed as a potential synapomorphic character of the Ianthella-Anomoianthella-Vansoestia clade. The main issues regarding the suprageneric classification of verongids are discussed.