Rissoidae

Abstract: Rissoidae is a family of small to minute marine gastropods distributed worldwide. The generic composition of the family was revised by Ponder (1984) based on characters of external morphology and internal anatomy. However, species level taxonomy within the family is still based mainly on conchological characters, which are less informative and usually not sufficient for resolving the systematic relationships of species. Northern Atlantic representatives of the family were revised by Waren (1974; 1996) and Bouchet & Waren (1993) based on shape and sculpture of both proto- and teleoconch, and were suggested to be members of several genera, widely distributed in boreal or even tropical Atlantic environments. These include Alvania Risso, 1826; Onoba H. & A. Adams, 1852; Obtusella Cossmann, 1921 and a few more. However, it was recently demonstrated that some these genera are not monophyletic (Criscione et al. 2016).

Abstract: Micropilina minuta gen. et sp.n. (Monoplacophora); Osleopelta ceticola sp.n. (Gastropoda, Osteopeltidae, living on whale skeletons); Retigyra gen.n. (Archaeogastropoda, family uncertain); Trochaclis islandica sp.n. (Trochaclididae, Archaeogastropoda); Larsenia scalaroides gen. et sp.n. (Vanikoridae, Mesogastropoda); Pseudotorellia fragilis gen. et sp.n. (Velutinidae, Mesogastropoda); Bogasonia volutoides gen. et sp.n. (Diaphanidae, Opisthobranchia); Atomiscala islandica sp. n., and Rissopsetia islandica sp. n. (both Pyramidellidae, Opisthobranchia) are described from material obtained from Icelandic amateur collectors. The family Trochaclididae is transferred from Mesogastropoda to Archaeogastropoda. mainly based on shell morphology. Cingula tumidula G.O. SARS, 1878 (Rissoidae, Mesogastropoda) is transferred to Obtusella COSSMANN, 1921. recorded from Iceland and Setia griegi FRIELE. 1879 is considered a synonym. The family Lyocyclidae (Mesogastropoda; deep water. East Africa) is transferred to th...