''Choristella'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s, marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Choristellidae.MolluscaBase eds. (2020). MolluscaBase. Choristella Bush, 1897. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=137780 on 11 August 2020

Description

(Original description by Bush) This genus is proposed for species of small shells of few convex

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). In nature File:Photograph and axial plane floral diagra ...

s forming a flattened, little elevated

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. Spire ...

with a minute, scarcely raised, nuclear whorl and a large

body whorl The body whorl is part of the morphology (biology), morphology of the gastropod shell, shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk ...

. The suture is very deep, and somewhat channeled. The

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

is small, round, deep, showing some of the whorls with rounded walls. The oblique

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

is nearly circular. The

peristome Peristome (from the Greek language, Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes. In mo ...

is simple, continuous, slightly attached to the body whorl, and reflected over the umbilicus. The operculum of the type species is thin, roundly ovate. it has a delicate horn color, of few abruptly enlarging whorls indistinctly defined by a spiral thread and showing sinuous transverse lines of growth. The nucleus is slightly excentric. The animal has a broad emarginate head with one pair of long slender tentacles. It has a rather broad, short, tapered, ciliated verge just beneath the base of the right one. There are no eyes. The gill is attached to the left side lying across the top of the body just within the mantle edge. The jaw plates are thin, delicate horn-color with a broad band of very dark brown along the strongly serrate, cutting edges. The inner surface is strongly reticulated, as in species of '' Velutina''. The form of these plates is quite irregular. The cutting edge is oblique, forming an angle of about 135° with the inner or middle, straight edge. The distal outline is very strongly sinuously curved, forming a wide, shallow upper portion and a much narrower basal portion. The

radula The radula (; : radulae or radulas) is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters ...

consists of numerous rows of delicate colored, rather stout, non-serrate teeth, each row having a series of thirteen: —a very small central or median tooth with rather long, strongly curved tip, placed a little above and alternating somewhat with the rest of the series. On either side, one broad strongly hooked lateral, and a much broader second lateral one with correspondingly broad, more pointed hook. Beyond, three, about equal, much narrower, somewhat sickle-shaped, marginal ones with a small triangular, scarcely perceptible, platelike one on the outer edge. The form of the shell and operculum strongly resemble a ''Choristes elegans'' var. ''tenera'' Verrill of medium size, but the radula shows marked and interesting differences. In that species, or rather variety, there are but eleven teeth in each series, the second or outer lateral tooth having a double or bilobed tip (these.

Species

Species within the genus ''Choristella'' include: * '' Choristella hickmanae'' McLean, 1992 * '' Choristella leptalea'' Bush, 1897 * '' Choristella marshalli'' McLean, 1992 * '' Choristella nofronii'' McLean, 1992 * '' Choristella ponderi'' McLean, 1992 * '' Choristella tenera'' (A. E. Verrill, 1882) * '' Choristella vitrea'' (Kuroda & Habe, 1971) ;Species brought into synonymy: * ''Choristella agulhasae'' (A. H. Clarke, 1961): synonym of '' Trenchia agulhasae'' (Clarke, 1961) (

superseded combination In taxonomy, a superseded combination is a notice of change to the binomial nomenclature of the accepted name of a species. This happens when a species is moved to a new genus after the initial species description. The original name is called a ...

) * ''Choristella brychia'' Bush, 1897: synonym of ''Choristella leptalea'' Bush, 1897

References

* Vaught, K.C. (1989). ''A classification of the living Mollusca''. American Malacologists: Melbourne, FL (USA). . XII, 195 pp. (look up in IMIS) * Haszprunar G. 1992. ''On the anatomy and relationships of the Choristellidae (Archaeogastropoda: Lepetelloidea)''. The Veliger 35(4): 295–307.

External links

Bush, K. (1897). Revision of the marine gastropods referred to Cyclostrema, Adeorbis, Vitrinella and related genera with dexriptions of some new genera and species belonging to the Atlantic fauna of America. Transactions of the Connecticut Academy of Arts and Sciences. 10: 97–144

McLean J.H. (1992). ''Systematic review of the family Choristellidae (Archeogastropoda: Lepetellacea) with descriptions of new species''. The Veliger 35(4): 273–294
{{Taxonbar, from=Q5105083 Choristellidae