''Choristella'' is a

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 ...

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 ...

s, marine

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 in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Choristellidae Choristellidae is a family of gastropods in the superfamily Seguenzioidea Seguenzioidea is a superfamily of minute to medium-sized sea snails, marine gastropod mollusks in the clade Vetigastropoda.Gofas, S. (2010). Seguenzioidea. In: Bouchet, ...

.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 2020-08-11

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). Whorls in nature File:Photograph and axial plane floral ...

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. Spires are ...

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

body whorl The body whorl is part of the morphology of the 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. In gastropods In gastropods, the b ...

. The suture is very deep, and somewhat channeled. The umbilicus is small, round, deep, showing some of the whorls with rounded walls. The oblique

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

is nearly circular. The peristome 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 (, ; plural radulae or radulas) is an anatomical structure used by molluscs 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 ...

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 ''Choristella nofronii'' is a species of sea snail, a marine gastropod mollusk in the family Choristellidae. Description The shell grows to a size of 3 mm. Distribution This species occurs in the Northern Atlantic Ocean; off Spain and ...

'' 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) * ''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
{{Commonscat Choristellidae