COLLONIIDAE Cossmann, 1916

Mclean, James Hamilton, 2012, New species and genera of colloniids from Indo-Pacific coral reefs, with the definition of a new subfamily Liotipomatinae n. subfam. (Turbinoidea, Colloniidae), Zoosystema 34 (2), pp. 343-376 : 346

Family COLLONIIDAE Cossmann, 1916

DIAGNOSIS. — Shell with or without interior nacreous layer; aperture nearly radial to oblique; aperture circular with complete peristome, to oval with interrupted peristome. Operculum calcified, circular to oblong; aperture conforming to outline of operculum, which is enveloped on outer side by foot; pattern of outer side varies by genus; inner surface conical or flat, multispiral or multispiral becoming paucispiral.

REMARKS

This group was originally intended to apply to non-nacreous genera, in contrast to the nacreous Homalopomatinae Keen, 1960 , but Hickman & McLean (1990: 47) included both non-nacreous and nacreous genera in the group. The operculum is known in Cretaceous to Recent groups. Paleontologists concerned with Mesozoic faunas have recognised the family Colloniidae in the Jurassic, for groups with the operculum unknown, as discussed by Monari et al. (1966). Such groups are not further mentioned here.

In the typical subfamily Colloniinae , which applies to most living genera, apertures can vary from circular in outline, to elongate; the operculum is flat-surfaced on the inner side, multispiral in early stages and changing to paucispiral in the final whorl.

The Cretaceous subfamily Petropomatinae , as treated by McLean & Kiel (2007), has dominant spiral sculpture and an operculum that is circular in outline, with the inner surface multispiral and conical, and the outer side with fewer whorls and a central pit. Genera include Petropoma Gabb, 1877 , and Sohlipoma McLean & Kiel, 2007 , in which spiral sculpture is dominant. The genus Liotipoma McLean & Kiel, 2007 was originally assigned to Petropomatinae , but is here assigned to a new subfamily: