Rissoella longispira Kay, new species. Length, 1.5 mm; diameter, 1 mm. Shell: minute, conic-elongate; umbilicate; thin, semitransparent. Spire: protoconch of about one whorl not well separated from the teleconch; teleoconch of three slightly inflated whorls; suture impressed. Sculpture: microscopic growth striae on an otherwise smooth and shiny surface. Aperture: ovate; outer lip thin; columellar raised forming a ridge next to the umbilical shelf; umbilicus elongate. Operculum: ovate; with a peg. Color: transparent, glassy, abapical whorls lightly false-margined. Animal: gray spotted with rose; head lobes shorter than the cephalic tentacles.
These rissoellids are common in seaweed in tide pools, and the shells are found in sediments to depths of about 10 m.
Type locality: Diamond Head Beach Park, Oahu. Holotype: Bernice P. Bishop Museum No. 9772. Paratypes: Australian Museum; British Museum (Natural History);
U. S. National Museum,
In shape the shells resemble those of R. caribbaea Rehder, 1943, from Florida, but the Florida animals have a black body and white tentacles. The shells are also similar to those of R. micra (Finlay, 1924) from New Zealand, but in the New Zealand animals both the oral lobes and cephalic tentacles are short and club-shaped, and the animal is gray (Ponder, 1966a). Derivation of name: longus, Latin — long; spira, Latin — a coil. Refers to the comparatively long spire.