HAPLOSTOMA HUMESI, NEW SPECIES (COPEPODA: CYCLOPOIDA: ASCIDICOLIDAE), ASSOCIATED WITH A COMPOUND ASCIDIAN (APLIDIUM SP.) FROM MADAGASCAR

Abstract

ABSTRACT Haplostoma humesi, new species, is described on the basis of females found in a compound ascidian (Aplidium sp.) collected in Madagascar. The female carries a single egg sac on the urosome. This feature has not been reported in any of the 12 named species of the genus Haplostoma; all those whose egg sacs have been described possess 2. In spite of its unique feature, H. humesi is closely related to H. canui, from the French Channel coast, described by Chatton and Harant (1924) and restudied by Ooishi (1994). Like H. canui, legs 1-4 of H. humesi have the endopods reduced (without a distal protrusion) and have the exopods armed only with bifurcate spines (lacking a lateral seta). Nevertheless, H. humesi can be distinguished from H. canui by minute differences in the legs, as well as by differences in the body form, rostrum, antennule, labrum, and caudal ramus. This is the first haplostomatin to be reported from the Indian Ocean.