Powellisetia
Powellisetia is a genus of minute sea snails, marine gastropod mollusks micromollusks in the family Rissoidae. The genus is primarily found in the Southern Hemisphere.
Description
In the original description, Ponder described Powellisetia as follows:Members of Powellisetia have a thin, horny operculum, which is transparent and ranges from ovate to ear-shaped, typically with two whorla and a wide nucleus. The genus can be distinguished due to having a large initial whorl on the protoconch of the shell, having more ovate shells than Onoba, and either having no teleoconch sculpture, or a sculpture of fine spiral lirae.
Taxonomy
The genus was first described by Winston Ponder in 1965, who named the genus after malacologist A. W. B. Powell, and named Rissoa porcellana as the type species. Many species had previously been described as members of Notosetia.Distribution
Most members of Powellisetia are found in the waters of New Zealand, Australia, Antarctica and sub-Antarctic regions of the world. Fossils of the species date to the Miocene.Species
Species within the genus Powellisetia include:Powellisetia arnaudi Powellisetia australis Powellisetia bilirata- † Powellisetia comes Powellisetia crassilabrum Powellisetia deserta Powellisetia epulata
- † Powellisetia europaea Powellisetia fairchildi Powellisetia fallax Powellisetia foveauxana Powellisetia gradata Powellisetia inornata Powellisetia lineata Powellisetia microlirata Powellisetia microstriata
- † Powellisetia paroeca Powellisetia pelseneeri Powellisetia philomelae Powellisetia ponderi Powellisetia porcellana Powellisetia porcellanoides Powellisetia principis
- † Powellisetia prisca Powellisetia retusa Powellisetia simillima Powellisetia subcarinata Powellisetia subgradata Powellisetia subtenuis Powellisetia tenuisculpta Powellisetia unicarinata Powellisetia varicosa
- † Powellisetia marshalli : synonym of ''Haurakia marshalli''