| Plesiocystiscus | |
|---|---|
 | |
| A drawing of the shell of P. jewettii | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Neogastropoda |
| Family: | Cystiscidae |
| Subfamily: | Plesiocystiscinae |
| Genus: | Plesiocystiscus Coovert & Coovert, 1995 [1] |
| Type species | |
| Marginella jewettii Carpenter, 1857 | |
Plesiocystiscus is a genus of minute predatory sea snails, marine gastropod mollusks or micromollusks in the family Cystiscidae. [2]
The genus name is derived from the Greek plesios, near, in the sense of plesiomorphic, of characters near the ancestor, combined with Cystiscus the name of another closely related genus. This indicates the relationship to the genus Cystiscus, type genus of the family. The gender of the name is masculine.
Sometimes this genus is simply left in the larger family Marginellidae. The type species is Marginella jewettii Carpenter, 1857.
(Note: Gastropod taxonomy has been in flux for more than half a century, and this is especially true currently, because of new research in molecular phylogeny. Because of all the ongoing changes, different reliable sources can yield very different classifications).
Shell minute to small (adult length 1,5 to 6.0 mm). Color white, hyaline; surface smooth, glossy. Shape cylindrical, elliptic, or obovate; weakly to distinctly shouldered. Suture rapidly descending on last half of last whorl, then abruptly sweeping upward just before lip, giving characteristic shape to adult shell. Spire nearly flat to low. Aperture moderately narrow, broader anteriorly. Lip thin anteriorly, gradually thickening tower shoulder, smooth, lacking denticulation or lirae, external varix absent. Siphonal notch and posterior notch absent. Shell often with a weak parietal callus wash or weak parietal callus deposits. Columella multiplicate, with combined total of 3-8 plications, usually occupying less than half to slightly more than half the aperture length. Shell with cystiscid internal whorls.
The triserial radula, found in many other cystiscids, is the most primitive in this family. This is the only genus of marginelliform gastropods with a triserial radula. This group is considered to be the most primitive in the family based on the radula and type of animal. The radular and shell features, including the presence of odontophoral cartilage hoods, possession of cystiscid internal whorls, and lack of an external varix, place this group in the Cystiscidae.
This genus lives from the intertidal zone to 80 m in depth.
This genus is found in the Eocene of France, the Miocene and Pliocene of Florida, and the Pleistocene of California, to the Recent.
Species within the genus Plesiocystiscus include: [2]
Marginellidae, or the margin shells, are a taxonomic family of small, often colorful, sea snails, marine gastropod molluscs in the clade Neogastropoda.
Gibberula is a genus of minute sea snail, a marine gastropod mollusk or micromollusk in the family Cystiscidae, previously placed in the family Marginellidae, the margin shells or marginellids.
Granulina is a genus of minute sea snails, marine gastropod mollusks or micromollusks in the family Granulinidae.
Volvarina is a genus of small to very small sea snails, marine gastropod molluscs in the family Marginellidae, the margin shells.
Cystiscidae is a taxonomic family of minute sea snails, marine gastropod mollusks or micromollusks.
Cystiscus is a taxonomic genus of minute sea snails, marine gastropod mollusks or micromollusks.
Crithe is a genus of minute sea snails, marine gastropod mollusks or micromollusks in the family Cystiscidae. This genus is sometimes still placed within the Marginellidae.
Persicula is a taxonomic genus of minute to small predatory sea snails, marine gastropod mollusks. It includes several species which are micromollusks.
Plesiocystiscinae is a subfamily of minute sea predatory sea snails, marine gastropod mollusks or micromollusks in the infraorder Neogastropoda.
Cystiscinae are a taxonomic subfamily of minute sea snails. These are marine gastropod mollusks or micromollusks in the family Cystiscidae, and the clade Neogastropoda.
Persiculinae is a taxonomic subfamily of minute to small predatory sea snails, marine gastropod mollusks. This subfamily includes several species which are micromollusks.
Canalispira is a genus of very small sea snails, marine gastropod mollusks or micromollusks in the family Cystiscidae.
Alaginella is a genus of sea snails, marine gastropod mollusks in the family Marginellidae.
Closia is a genus of sea snails, marine gastropod mollusks in the subfamily Pruninae of the family Marginellidae, the margin snails.
Dentimargo is a genus of sea snails, marine gastropod mollusks in the family Marginellidae, the margin snails.
Hyalina is a genus of sea snails, marine gastropod mollusks in the subfamily Pruninae of the family Marginellidae, the margin snails.
Prunum is a genus of sea snails, marine gastropod mollusks in the subfamily Pruninae of the family Marginellidae, the margin snails.
Serrataginella is a genus of sea snails, marine gastropod mollusks in the family Marginellidae, the margin snails.
Glabella is a genus of small tropical and warm-water sea snails, marine gastropod molluscs in the family Marginellidae, the margin snails.
Ovaginella is a genus of marginellid minute sea snails, marine gastropod mollusks in the subfamily Austroginellinae of the family Marginellidae, the margin snails.
