Two New Species of Lecithotrophic Nauplius y with Remarkable Labra from Okinawa, Japan, and a Family-Group Name for y-Larvae (Crustacea: Thecostraca: Facetotecta: Hansenocarididae fam. nov.)

Two large (ca. 0.5 mm long), rare, and probably closely related species of Facetotecta (y-larvae), Hansenocaris cristalabri sp. nov. aquila nov., are described on the basis last-stage lecithotrophic nauplii reared from plankton at Sesoko Island, Okinawa, Japan. The two resemble each other in having a labrum with row spines long, attenuate trunk region that terminates heavily spinose dorsocaudal spine. H. has an enormous, cockscomb-like ventral process bears distally directed, dagger-like along its anterior side, while spine-bearing keel extends posteriorly into robust, eagle-like beak. labral “crest” no equivalent any y-larva, nor crustacean nauplius; possible functions discussed. Another diagnostic feature absent is pair shallow, rounded notches bounded by sharp spinules far posteriolateral margins cephalic shield. Both new have longitudinal spine rows dorsum, four something not previously documented for y-nauplii. plate arrangement shield detail, attempt to homologize pattern y-nauplii (especially furcifera Itô, 1989). body surface fewer setae pores than late- or facetotectan nauplius date, suggesting paedomorphic development. A formal diagnosis presented family-group taxon Hansenocarididae fam. nov.; this name, already use, until now been nomenclaturally unavailable.