Plesiocystiscinae is a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

of minute sea

predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s or

micromollusk A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also ...

s in the infraorder

Neogastropoda Neogastropoda is an order of sea snails, both freshwater and marine gastropod molluscs. Description The available fossil record of Neogastropoda is relatively complete, and supports a widely accepted evolutionary scenario of an Early Creta ...

. The genus name on which this subfamily name is based is derived from the Greekword ''plesios'', near, in the sense of plesiomorphic, in other words having characters close to those of the ancestor, combined with ''Cystiscus'' the name of a closely related genus. Sometimes the single

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

in this subfamily is simply left in the larger family

Marginellidae Marginellidae, or the margin shells, are a Taxonomy (biology), taxonomic family (biology), family of small, often colorful, sea snails, Marine (ocean), marine gastropod molluscs in the clade Neogastropoda. Taxonomy The higher classification of ...

. (Note: Gastropod

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

has been in flux for more than half a century, and this is especially true currently, because of new research in

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

. Because of all the ongoing changes, different reliable sources can yield very different classifications.)

Shell description

Shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard ou ...

minute to small, white, hyaline; last

whorl A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

rapidly expanded then lip abruptly swept posteriorly giving characteristic shape;

spire A spire is a tall, slender, pointed structure on top of a roof of a building or tower, especially at the summit of church steeples. A spire may have a square, circular, or polygonal plan, with a roughly conical or pyramidal shape. Spires are ...

flat to low; lip thickened posteriorly, smooth, lacking

lira Lira is the name of several currency units. It is the current currency of Turkey and also the local name of the currencies of Lebanon and of Syria. It is also the name of several former currencies, including those of Italy, Malta and Israe ...

e or denticulation, external

varix A varix (pl. varices) is an abnormally dilated vessel with a tortuous course. Varices usually occur in the venous system, but may also occur in arterial or lymphatic vessels. Examples of varices include: * Varicose veins, large tortuous veins usua ...

absent; siphonal notch absent; posterior notch absent; columella multiplicate with combined total of 3-8 plications plus parietal lirae; internal

s cystiscid type.

Description of soft parts

Animal

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s and siphon are moderately long. The mantle is translucent, and in some species it is not readily extended over the external shell surface. The foot is relatively narrow. The internal anatomy is unknown.

Genus

Genus in this subfamily: * ''

Plesiocystiscus Plesiocystiscus is a genus of minute predatory sea snails, marine (ocean), marine gastropod mollusks or micromollusks in the family Cystiscidae. Etymology The genus name is derived from the Greek language, Greek ''plesios'', near, in the sense o ...

'' Coovert and Coovert, 1994

References

* Coovert G. A. & Coovert H. K. (1995). "Revision of the Supraspecific Classification of Marginelliform Gastropods". ''The Nautilus'' 109(2-3): 43–110. {{Taxonbar, from=Q7204651 Cystiscidae