The vermetidae (Mollusca: Gastropoda) of the Hawaiian Islands

Abstract

The Hawaiian vermetid fauna comprises 8 species, 7 of which are here described as new. The generic distribution includes 5 species of Dendropoma and 1 each of Petaloconchus, Vermetus and Serpulorbis . The species descriptions rely little on conchology, stressing instead descriptions of animals, habitats and reproductive and developmental characteristics. Feeding is accomplished in all species by a combination of mucous nets and detrital collection by ctenidial cilia. Only in the single species of Vermetus , an inhabitant of quiet waters, does ciliary feeding predominate. Four small species of Dendropoma inhabit shallow, coralline algal-encrusted, wave-washed reef areas, while Serpulorbis and Dendropoma platypus are found not only in intertidal areas subjected to heavy surf, but subtidally to depths of 10 m or more. The single species of Petaloconchus is a characteristic associate of the 4 Dendropoma spp. of shallow waters but, being strongly associated with the coral Porites, Petaloconchus also extends subtidally. The Hawaiian vermetids are very abundant in some localities, with densities ranging up to 60,000/m 3 in one species of Dendropoma . Reproduction is continuous in all Hawaiian vermetids, most of which produce small hatching juveniles rather than swimming veligers. Only Serpulorbis and Vermetus have obligatory planktonic stages. Petaloconchus and Dendropoma species may produce a mixture of hatching juveniles and short-term planktonic veligers. Larval or juvenile size is correlated with available nurse yolk, not with egg size.