Odostomia excisa

Odostomia excisa
Drawing of Odostomia excisa
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Heterobranchia clade Euthyneura clade Panpulmonata
Superfamily:	Pyramidelloidea
Family:	Pyramidellidae
Genus:	Odostomia
Species:	O. excisa
Binomial name
Odostomia excisa Bartsch, 1912
Synonyms
Odostomia (Menestho) excisa Bartsch, 1912

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

Description

The yellowish-white shell is moderately large and measures 3.9 mm. It is elongate-ovate. The nuclear whorls are decollated. The six post-nuclear whorls are well rounded, appressed at the summit. They are marked by four equally strong but not equally spaced, incised, spiral lines between the sutures. The fourth of these is immediately above the periphery, while the first is as far below the summit as the third is posterior to the fourth. The second line divides the space between the first and third into equal halves, which are about one and a half times as wide as the spaces included between the third and fourth incised spiral. In addition to the spiral sculpture the whorls are crossed by numerous, fine, decidedly retractive, incremental lines. The periphery of the body whorl is somewhat inflated, well rounded. The base of the shell is moderately long and moderately rounded, crossed by 8 strongly incised, equal, spiral lines, which are a little stronger than those occurring on the spire. These lines become exceedingly closely spaced between the periphery and the umbilical area. The axial sculpture on the base is of the same character and strength as that appearing on the spire. All of the incised, spiral lines on base and spire are crossed by very slender, axial threads, which lend these channels a somewhat pitted appearance. The sutures are well impressed. The aperture is moderately large, oval, and effuse anteriorly. The posterior angle is acute. The outer lip is thin, showing the external sculpture within. The inner lip oblique, moderately long, somewhat reflected, and re-enforced for the greater part of its length by the attenuated base, provided with an oblique fold at its insertion. The parietal wall is glazed with a thin callus. ^[3]

Distribution

This species occurs in the Pacific Ocean off Catalina Island, California.

References

1. Rosenberg, G. (2011). Odostomia excisa Bartsch, 1912. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=581202 on 2011-11-10
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. Paul Bartsch, Additions to the West American Pyramidellid Mollusk Fauna, with Descriptions of New Species, Proceedings of the United States National Museum 42; pages 276-277; 1903

External links

• To World Register of Marine Species