Amphithalamus inclusus
| Amphithalamus inclusus | |
|---|---|
| |
| Shell of Amphithalamus inclusus | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Family: | Anabathridae |
| Genus: | Amphithalamus |
| Species: | A. inclusus
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| Binomial name | |
| Amphithalamus inclusus P. P. Carpenter, 1864
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| Synonyms[1] | |
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Amphithalamus inclusus is a species of minute sea snails, marine gastropod mollusks or micromollusks in the family Anabathridae.[1]
Description
[edit]The length of the shell attains 1.1 mm, its diameter 0.9 mm.
(Original description) The shell has the habit of a minute Stenothyra W. H. Benson, 1856; the outer lip is not contracted, but the columellar lip um in adults travels forward to meet it, leaving a chamber behind. The nucleus is cancellated, and the base is bluntly ribbed.[2]
(Described as Amphithalamus stephensae) The shell is minute and pale brown with an ashy tinge, except for the columellar region, which is flesh-colored. When the animal is present, the early whorls appear much duskier. The nuclear whorls number 1.5; the first half is smooth, while the rest are marked by rather distantly spaced, poorly developed, rather broad spiral lirations, of which nine are present between the summit and the periphery. In addition to this, inconspicuous lines of growth are visible.
Post-nuclear whorls and sculpture: The post-nuclear whorls are strongly rounded and narrowly shouldered at the summit, with the portion appressed to the preceding whorl appearing as a band through the substance of the shell. The periphery features a weak keel that is truncated rather abruptly posteriorly but grades gently into the substance of the shell toward the base. The suture is well marked. The base is short, inflated, strongly rounded, and marked by lines of growth only. A heavy callus is present at the insertion of the columella, which at its posterior termination almost forms a cord. The columella itself is very heavy and oblique.
Aperture and operculum: The conformation of the aperture is characteristically Amphithalmid; that is, the aperture, which is oval, is much contracted by a shelf extending out from the columellar and parietal wall toward the outer lip, thus contracting the aperture. This shelf forms a decided pit behind its edge. The inner and parietal lip of the aperture, therefore, are not in contact with the columellar or parietal wall, but are at some distance from it. The posterior portion of the outer lip, however, extends upward to the preceding turn, which it joins immediately below the peripheral keel, as in mollusks with a normal aperture. The operculum is thin and paucispiral.[3]
Distribution
[edit]This species occurs off the western coast of North America.
References
[edit]- ^ a b Amphithalamus inclusus P. P. Carpenter, 1864. 24 May 2025. Retrieved through: World Register of Marine Species.
- ^ Carpenter, P.P. (1864). "Supplementary report on the present state of our knowledge with regard to the Mollusca of the West Coast of North America". Reports of the British Association for the Advancement of Science. 1863 (33): 656. Retrieved 24 May 2025.
This article incorporates text from this source, which is in the public domain.
- ^ Bartsch, P. (1927). "New west American marine mollusks". Proceedings of the United States National Museum. 70 (11): 2/. Retrieved 24 May 2025. This article incorporates text from this source, which is in the public domain.
- Strong, A. M. & Hertlein, L. G. (1939). Marine mollusks from Panama collected by the Allan Hancock Expedition to the Galapagos Islands, 1931-1932. Allan Hancock Pacific Expeditions,. Los Angeles: University of Southern California Press. pp. 177–245.
{{cite book}}: CS1 maint: multiple names: authors list (link)
External links
[edit]- Bartsch, P. (1911). "The west American mollusks of the genus Amphithalamus". Proceedings of the United States National Museum. 1854 (41): 263265.
- Ponder, W.F. (1983). "Review of the genera of the Barleeidae (Mollusca: Gastropoda: Rissoacea)". Records of the Australian Museum. 35: 252.