''Turbonilla asser'' is a species of

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 ...

, a

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 in the family Pyramidellidae, the pyrams and their allies.Rosenberg, G. (2011). ''Turbonilla asser'' Dall & Bartsch, 1909. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=588587 on 2012-03-01

Description

The milk-white shell has an elongate-conic shape. Its length measures 8.3 mm. The two, small

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 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 depressed and helicoid. They have their axis at right angles to that of the succeeding turns, in the first of which they are about one-third immersed. The 14 whorls of the teleoconch are well rounded, slightly overhanging, and ornamented by well developed, somewhat sinuous, rounded, protractive axial ribs, of which there are about 14 upon the third, 16 upon the fourth and fifth, 18 upon the sixth to eighth, 20 upon the ninth to eleventh, and 22 upon the twelfth and penultimate turns. The intercostal spaces are almost equal to the ribs in width, shallow, terminating some little distance posterior to the summit of the succeeding whorl, thus leaving a rather broad, plain band above the suture in each turn. The sutures are strongly constricted. The periphery of the

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 ...

is well rounded. The base of the shell is short, and well rounded. The entire surface of the spire and the base is marked by very fine, closely spaced, spiral striations. The aperture is subquadrate. The posterior angle is obtuse. The outer lip is thin, showing the external sculpture within. The columella is slender, well curved and slightly revolute.Dall & Bartsch, A Monograph of West American Pyramidellid Mollusks, United States National Museum Bulletin 68, p.45: 1909
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Distribution

This species occurs in the Pacific Ocean off San Pedro, California.

References

External links

To World Register of Marine Species
{{Taxonbar, from=Q7853964 asser Gastropods described in 1909