Powellisetia paroeca

Powellisetia paroeca
Holotype of Powellisetia paroeca from Auckland War Memorial Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Littorinimorpha
Family:	Rissoidae
Genus:	Powellisetia
Species:	P. paroeca
Binomial name
Powellisetia paroeca (Finlay, 1924)
Synonyms [1]
Notosetia prisca paroecaFinlay, 1924

Powellisetia paroeca is an extinct species of marine gastropod mollusc in the family Rissoidae. ^[1] First described by Harold John Finlay in 1924, it is known to have lived in New Zealand during the early Miocene.

Taxonomy

The species was identified in 1924 by Harold John Finlay as a subspecies of Powellisetia prisca , ^[2] and later described as a species in its own right.

Description

Finlay described both Powellisetia paroeca and Powellisetia prisca as follows:

Shell minute, ovate, body-whorl large in proportion to rest of shell. Sculpture of faint growth-lines; at somewhat regular distances some appear more prominent, but are not raised; a faint furrow emerges from suture on body-whorl and marks periphery. Spire very little higher than aperture. Protoconch of 1½ smooth and polished whorls, marked off by a groove from whorls proper, of which there are 3, lightly convex, body-whorl very slightly subangled for a short distance in front of suture, which is deep and channelled. Aperture oval, oblique, angled above. Peristome discontinuous, outer lip with prominent varix behind, but sharp edge; slightly effuse basally, and angulated medially. Columella short, arcuate, rounded. Inner lip distinctly callous but not covering the narrow elongated umbilical chink. ^[2]

Finlay noted some differences between the two groups, namely that Powellisetia paroeca "...differs from the species only in slightly higher spire and more regularly curved outer lip, which slants downwards from suture without any medial angulation." ^[2]

Distribution

Fossils of the species have only been identified in New Zealand. ^[1] The holotype was collected from sandstone at Calamity Point in Clifden, Southland, which dates to the early Miocene era. ^{[3] [4]}

References

1. Bieler R, Bouchet P, Gofas S, Marshall B, Rosenberg G, La Perna R, Neubauer TA, Sartori AF, Schneider S, Vos C, ter Poorten JJ, Taylor J, Dijkstra H, Finn J, Bank R, Neubert E, Moretzsohn F, Faber M, Houart R, Picton B, Garcia-Alvarez O, eds. (2022). "Powellisetia paroeca Finlay, 1924". MolluscaBase. World Register of Marine Species . Retrieved 22 November 2022.
2. "New Zealand Tertiary Rissoids". Transactions and Proceedings of the Royal Society of New Zealand . 55: 480–494. 1924. ISSN   1176-6166. Wikidata   Q115385181.
3. Blom, Wilma (2022). "Fossil and Recent molluscan types in the Auckland War Memorial Museum. Part 4: Gastropoda (Caenogastropoda – Neocyclotidae to Epitoniidae). [Cyclophoroidea, Cerithioidea, Littorinimorpha]". Records of the Auckland Museum . 56: 39–62. doi:10.32912/ram.2020.55.7. ISSN   2422-8567 . Retrieved 20 October 2022.
4. "Powellia comes". Auckland War Memorial Museum . Retrieved 23 November 2022.