Ethminolia
A genus of small top snails with broad umbilicus and multispiral operculum.
Ethminolia is a genus of small sea snails, marine gastropods belonging to the subfamily Umboniinae within the family Trochidae, commonly known as top snails. Their shells are typically less than 10 mm in diameter and are noticeably wider than they are tall. The whorls are rounded and often have a shouldered appearance, with surface sculpture made up of spiral cords or lirae and very fine axial threads. The umbilicus is wide, with a rounded rim that is not thickened, and there is no internal funicle. The outer lip is simple, and the shell interior is nacreous, lacking any inward ridges.
The operculum is horny and multispiral, featuring a well-developed peripheral fringe with radial striations that remain visible on the earlier whorls, along with spiral microsculpture. In the radula, the rachidian and lateral teeth have thin base plates that narrow toward the front; their outer edges are rounded, raised anteriorly, and somewhat twisted. The fifth lateral tooth is barely noticeable. The inner marginal tooth is transitional, with a reduced cusp. The cusps of the inner marginal teeth are short and broad, with cusps 2 through 10 being the largest and coarsely toothed. The central denticle is asymmetrical and slightly broader than the others, and additional narrower denticles appear on both margins. The ctenidium has not been described.
This marine genus is found in the Red Sea, the Gulf of Oman, the Arabian Sea, and off the coasts of Australia (New South Wales, South Australia, Victoria, Western Australia) and Tasmania.
Species within Ethminolia include: Ethminolia akuana, Ethminolia degregorii, Ethminolia doriae, Ethminolia durbanensis, Ethminolia elveri, Ethminolia eudeli, Ethminolia gravieri, Ethminolia hemprichii, Ethminolia hickmanae, Ethminolia hornungi, Ethminolia impressa, Ethminolia iridifulgens, Ethminolia ornatissima, Ethminolia probabilis, Ethminolia sculpta, Ethminolia vanxinhi, Ethminolia vitiliginea, and the extinct Ethminolia wareni.
Several species have been moved to other genera. Ethminolia bysma is now Ethalia bysma; Ethminolia cincta is now Spectamen cinctum; Ethminolia glaphyrella is now Kanakina glaphyrella; Ethminolia mayi is a synonym of Ethminolia probabilis; Ethminolia nektonica is now Tylorhaphe nektonica; Ethminolia stearnsii is now Sericominolia stearnsii; and Ethminolia tasmanica is a synonym of Ethminolia vitiliginea.
Quick Facts
- Taxon
- Ethminolia
- Type Species
- Ethminolia probabilis
- Type Species Authority
- Iredale, 1924
Facts from the source article.
Lore & Background
The shell of Ethminolia is small, usually less than 10 mm in diameter, and wider than high. The whorls are rounded and often shouldered, with sculpture consisting of spiral lirae or cords accompanied by microscopic axial threads. The umbilicus is broad, its rim rounded and not thickened, and it lacks any internal funicle. The outer lip is simple, and the interior is nacreous without inrunning ridges. The operculum is corneous and multispiral, with a well-developed peripheral fringe that is radially striate; these striations remain visible on the earlier whorls, and spiral microsculpture is present. The radula has thin base-plates on the rachidian and lateral teeth that narrow anteriorly, with the outer edge rounded, raised anteriorly, and somewhat twisted; the fifth lateral tooth is scarcely evident. The inner marginal tooth is transitional, with a reduced cusp. The cusps of the inner marginal teeth are short and broad, with cusps 2–10 the largest and coarsely dentate; the central denticle is asymmetrical and somewhat broader than the others, and additional narrower denticles are present on both margins. The ctenidium remains unknown.
Reader's Guide
Ethminolia is a genus of marine gastropod mollusks within the subfamily Umboniinae of the family Trochidae. Its significance lies in its distinctive shell morphology: small, wider than high, with a broad umbilicus lacking an internal funicle, and a nacreous interior. The operculum is notable for its multispiral structure and radially striate peripheral fringe. The radula exhibits specialized features, including thin base-plates on the rachidian and lateral teeth, a scarcely evident fifth lateral tooth, and asymmetrical central denticles on the inner marginal teeth. The genus occurs in the Red Sea, Gulf of Oman, Arabian Sea, and off Australia (New South Wales, South Australia, Victoria, Western Australia) and Tasmania. The source article lists 18 accepted species, including Ethminolia akuana, Ethminolia degregorii, and Ethminolia vitiliginea, among others, as well as several species brought into synonymy. The ctenidium remains unknown, indicating an area for further research.
Did You Know?
- The shell of Ethminolia is usually less than 10 mm in diameter and appreciably wider than high.
- The ctenidium of Ethminolia remains unknown.
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