''Turbonilla guilleni'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

, a 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 ...

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 ...

Pyramidellidae Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs. The great majority of species of pyrams are micromol ...

, the pyrams and their allies.WoRMS (2011). ''Turbonilla guilleni'' Bartsch, 1917. Accessed through:

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

at http://www.marinespecies.org/aphia.php?p=taxdetails&id=576030 on 2012-03-01Keen M. (1971). Sea shells of Tropical West America. Marine mollusks from Baja California to Perú. (2nd edit.). Stanford University Press pp. 1064

Description

The milk-white shell has a conic shape. Its length measures 3 mm. The 2½

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 of the

protoconch A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called " ...

are well rounded. They form a depressed helicoid

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 ...

, the axis of which is at right angles to that of the succeeding turns, in the first of which it is about one-third immersed. The five whorls of the

teleoconch The gastropod shell is part of the body of many gastropods, including snails, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium ...

are somewhat inflated, well rounded, and almost appressed at the summit. They are marked on each whorl by 18 narrow, well developed, rounded, almost vertical axial ribs. Some of these ribs are developed into varices and these are distributed at irregular intervals. The intercostal spaces are about 2½ times as wide as the ribs. They are crossed by three spiral series of strong pits, of which one is at the periphery, the second a little anterior to the middle and the third about two-fifths of the space between this and the summit posterior to the median pit. In addition to these pits the intercostal spaces are crossed by many almost equally strong incised spiral lines of which 12 occur between the summit and the first pit, 7 between the first and median pit, and 8 between the median and peripheral pit. The suture is quite strongly constricted. The periphery of the

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 ...

is well rounded. The base of the shell is moderately long, and attenuated. It is marked by the feeble continuations of the axial ribs and numerous incised spiral lines of a little wider spacing than the fine

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

on the spire. The oval

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 rissoid. The posterior angle is obtuse. The outer lip is thick. The inner lip is short, curved, reflected over and appressed to the base. The parietal wall is covered with a thick callus. Paul Bartsch (1917), Descriptions of new West American marine mollusks and notes on previously described forms; Proceedings of the U.S. National Museum, vol. 52 p. 648
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Distribution

The type specimen was found in shallow water of the Pacific Ocean off Santa Maria Bay,

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

References

External links

USNM Invertebrate Zoology Mollusca Collection

World Register of Marine Species
{{Taxonbar, from=Q7854182 guilleni Gastropods described in 1917