Rissoella morrocoyensis Caballer, Ortea & Narciso 2011

Shell very small (Tab. 2), smooth, translucent and fragile (Fig. 13); protoconch about half a whorl after the nucleus (Fig. 14); teleoconch of two and a half whorls to two and three quarters, convex profile, well marked suture; aperture semicircular, columella almost straight; umbilicus small, very narrow and deep, partially closed by the expansion of the columellar edge, with a preumbilical cord (Figs 9–10, 15), average height of the last whorl, 85% of shell length; average height of the aperture, 60% of shell length (Tab. 2); shell length/width ratio = 1.32; spiral angle = 60°; umbilical angle = 21°–28°. Valid species of the genusRissoellaGray, 1847 in the Caribbean.SpeciesType localityRissoella caribaeaRehder, 1943USARissoella galbaRobertson, 1961BahamasRissoella gandocaensisOrtea & Espinosa, 2001Costa RicaRissoella ameliaeOrtea & Espinosa, 2004CubaRissoella belkisaeOrtea & Espinosa, 2004CubaRissoella dianaeOrtea & Espinosa, 2004CubaRissoella zaidaeOrtea & Espinosa, 2004CubaRissoella floraeOrtea & Espinosa, 2004CubaRissoella elsaeOrtea & Espinosa, 2004CubaRissoella taniaeOrtea & Espinosa, 2004CubaRissoella aliciaeEspinosa & Ortea, 2009CubaRissoella morrocoyensissp. n.VenezuelaRissoella venezolanicolasp. n.Venezuela Operculum semicircular, translucent amber, rather opaque in the center, 453 µm long by 255 µm wide in a shell of 0.92 mm length; inner side with a triangular projection with spearhead-shaped apex. Head dark brown to black; black eyes set in a circular area of translucent white colour; oral lobes wider and shorter than the cephalic tentacles; both translucent, dark brown orblack, completely or just at the base (Figs 1–2); foot slightly bilobed, with a white hyaline sole; dorsal part of the foot, white or with an irregular dark drawing (Fig. 3); flanks of the animal the same colour as the head (Fig. 4); mantle white, with several black blotches around the hypobranchial gland; hypobranchial gland translucent white, with white spots, irregular black blotches and a pale yellow band marking its boomerang-shaped contour with no transversal bands (Fig. 5); visceral mass in the first whorls, dark brown to black. Odontophoral cartilages rectangular, with polygonal uncini of 10–16 µm long, regularly imbricated (Fig. 16); radular formula of a specimen 1.02 mm shell length, 15 × 1.1.R.1.1; rachidian tooth wide, with bilobed apex forming two smooth cusps (Fig. 17), slightly shorter than marginal tooth; lateral tooth thorn-shaped, 34.2 µm long, with the apex hooked and smooth, imbricated with the opposite tooth above the rachidian; marginal tooth triangular, 26.1 µm long, with sharp apex.