Charisma carinata
Minute marine snail with carinate shell, endemic to South Australia.
Charisma carinata, called the carinate charisma, is a very small marine snail in the top snail family Trochidae. Its shell reaches 1.1 mm tall and 1.4 mm wide, with three and a half whorls. The first two whorls are smooth, white, and convex. On the spire whorl, three rounded ridges run around the shell: one just below the suture, another about a third of the way between sutures, and a third about a quarter from the lower suture. The spaces between these ridges are concave and contain evenly spaced spiral cords—two in the upper space (with the rear one smaller) and three small, equal cords in the middle space. The body whorl has seven ridges that become lower and closer together toward the base. Their concave gaps hold spiral lirae, numbering from six down to two depending on the space width. The lowest ridge forms the edge of a wide umbilicus, which is marked by about eight spiral lirae. These spirals are cut at irregular intervals by radial incisions and covered with very fine, crowded microscopic radial scratches. The circular aperture has a smooth inner surface and a scalloped outer edge shaped by the spirals. Color is very light amber; some shells are white, others faintly pink. This marine species is endemic to Australia, found off South Australia.
Quick Facts
- Taxon
- Charisma carinata
Facts from the source article.
Lore & Background
The shell of Charisma carinata is solid and minute, containing three and a half whorls. The first two whorls are smooth, white, and convex. The spire whorl bears three rounded carinations: one just below the suture (which is channelled by it), a second about one-third the distance between the sutures, and a third about one-fourth the distance from the lower suture. The interspaces are concave and have equidistant spiral cords—two in the upper space (the posterior smaller) and three small equal cords in the middle space. The body whorl has seven carinations that become gradually lower and closer toward the base. The interspaces are concave and provided with spiral lirae, varying from six to two depending on the width of the spaces. The lowest carina forms a margin to the umbilicus, which is wide and sculptured with about eight spiral lirae. The spirals are cut up at irregular intervals by radial incisions and marked by very fine crowded microscopic radial scratches. The aperture is circular, with a smooth inner surface and an outer edge scalloped by the spirals. Colour is very light amber; some examples are white, others faintly tinged with pink.
Reader's Guide
Charisma carinata is documented in the scientific literature through works by Verco (1907) and Cotton (1959), both focusing on South Australian marine mollusks. The species is endemic to Australia, occurring specifically off South Australia. Its minute size and elaborate shell sculpture—featuring multiple carinations, spiral cords, lirae, and microscopic radial scratches—make it a distinctive member of the Trochidae family. The shell's colour varies from very light amber to white or faintly pink. The species is known only from the described morphological features and geographic range; no further ecological or behavioral data are provided in the source. Its significance lies in its contribution to the taxonomic understanding of small trochid gastropods in southern Australian waters.
Did You Know?
- The shell height is 1.1 mm and diameter is 1.4 mm.
- The spire whorl has three rounded carinations, with the lowest forming a margin to the umbilicus.
- Colour ranges from very light amber to white, with some faintly tinged with pink.
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