Odostomia trachis

Odostomia trachis
Drawing of a shell of Odostomia trachis
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Heterobranchia
Family:	Pyramidellidae
Genus:	Odostomia
Species:	O. trachis
Binomial name
Odostomia trachis Dall & Bartsch, 1909
Synonyms
Odostomia (Chrysallida) trachis Dall & Bartsch, 1909 (basionym)

Odostomia trachis is a species of sea snail, a marine gastropod mollusc in the family Pyramidellidae, the pyrams and their allies. ^{[1] [2]}

Description

The small shell has an elongate-conic shape. Its length measures 2.5 mm. The whorls of the protoconch are small, smooth, and strongly obliquely immersed in the first of the succeeding turns, above which only the tilted edge of the last volution projects. The five whorls of the teleoconch are moderately rounded, strongly contracted at the sutures, and slopingly shouldered at the summit. They are marked by strong, rounded, decidedly retractive axial ribs, of which 16 occur upon the second, 18 upon the third, and 20 upon the penultimate turn. In addition to the axial ribs the whorls are crossed between the sutures by four spiral cords, which are as strong as the ribs and render them nodulous at their junction. The second of these cords below the summit marks the angle of the shoulder. The spaces enclosed by the ribs and cords are deep, squarish pits. The sutures are subchanneled. The periphery of the body whorl are marked by a groove, crossed by the spiral ribs, which terminate at the extremity of the first basal cord. The base of the shell is well rounded. It is marked by four subequal, distantly spaced, narrow, spiral cords, the broad spaces between which are crossed by numerous axial threads. The aperture is oval. The posterior angle is obtuse. The outer lip is thin, showing the external sculpture within. The columella is slender, reflected, and reinforced by the base. It is provided with a fold at its insertion. The parietal wall is covered with a thin callus. ^[3]

Distribution

The type species was found in the Pacific Ocean off San Pedro Bay, California.

References

1. Rosenberg, G. (2011). Odostomia trachis Dall & Bartsch, 1909. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=581263 on 2012-01-12
2. Turgeon, D.; Quinn, J.F.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.; Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. (1998). Common and scientific names of aquatic invertebrates from the United States and Canada: mollusks. 2nd ed. American Fisheries Society Special Publication, 26. American Fisheries Society: Bethesda, MD (USA). ISBN   1-888569-01-8. IX, 526 + cd-rom pp.
3. Dall & Bartsch, A Monograph of West American Pyramidellid Mollusks, United States National Museum Bulletin 68, 1 p. 148; 1909

External links

• To World Register of Marine Species
• To ITIS