Alcyna subangulata
A minute marine snail with a deep red, spirally striated shell.
Alcyna subangulata is a marine gastropod mollusk belonging to the Trochidae family, commonly known as top snails. Its shell is minute, reaching 2½ mm in height and 1½ mm in diameter, with an ovate-turbinate shape and a narrow perforation. The shell is deep red, marked by oblique light red flames radiating from the suture, and is ornamented with raised spiral striae. The four whorls are slightly depressed in the center, and the body whorl is obtusely biangular, featuring about four low spiral cords above the upper angle and two (with a very weak third) between the angles. The base has numerous spirals, and the umbilicus is rather large. The aperture is circular, the outer lip is thickened externally with a swelling or varix, and the columella ends in a prominent tooth. This species is found in the waters off the Seychelles, Mauritius, Réunion, and Hawaii.
Quick Facts
- Taxon
- Alcyna subangulata
Facts from the source article.
Lore & Background
The shell of Alcyna subangulata is minute, rather solid, and narrowly perforate, with an ovate-turbinate shape. It is ornamented with raised spiral striae. The four whorls are depressed somewhat in the center, and the body whorl is obtusely biangular with about four low spiral cords above the upper angle, two and a very weak third between the angles. The base of the shell contains numerous spirals. The outer lip is thickened externally with a swelling or varix, and the umbilicus is rather large. The aperture is circular, and the columella ends in a prominent tooth. The color is deep red, with oblique light red flames radiating from the suture.
Reader's Guide
Alcyna subangulata was described by H. Adams in 1868 in the Proceedings of the Zoological Society of London, based on specimens collected by Geoffrey Nevill at Mauritius, the Isle of Bourbon, and the Seychelles. The species is also recorded from Hawaii in E.A. Kay's 1979 work on Hawaiian marine shells. Its small size and distinctive shell features, such as the obtusely biangular body whorl and the prominent columellar tooth, help distinguish it within the Trochidae family. The species' distribution across the western Indian Ocean and the central Pacific suggests a wide tropical range, though the article does not discuss its ecology or abundance. Its inclusion in both 19th-century and modern references indicates continued taxonomic recognition.
Did You Know?
- The shell height of Alcyna subangulata is only 2½ mm.
- This species occurs off the Seychelles, Mauritius, Réunion and Hawaii.
Frequently Asked Questions
What is Alcyna subangulata?
Alcyna subangulata is a tiny marine gastropod mollusk classified within the Trochidae family, the group commonly called top snails. It is distinguished by its extremely small, deep red shell and a narrow apical perforation.
How large is Alcyna subangulata?
The shell measures only about 2½ mm in height and 1½ mm in diameter, making it a genuinely minute specimen. Its overall shape is ovate-turbinate with four slightly depressed whorls.
What does Alcyna subangulata's shell look like?
The shell is a rich deep red color, crossed by oblique lighter-red flame-like markings that radiate outward from the suture. It is further textured with raised spiral striae, and the body whorl shows a distinctly biangular profile with low spiral cords above the upper angle and between the angles.
Where can Alcyna subangulata be found?
This species has been recorded from the Seychelles, Mauritius, Réunion, and Hawaii, suggesting a scattered distribution across the western Indian and central Pacific Oceans.
What makes Alcyna subangulata notable among top snails?
Its combination of an extremely small size, a vivid deep-red coloration with flame-like sutural markings, and a distinctive biangular body whorl sets it apart within the otherwise diverse Trochidae. Collectors and malacologists prize it as a striking example of how elaborate ornamentation can occur on a shell barely two and a half millimeters tall.
More in Marine Snails, Part 2 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced