Botelloides chrysalidus

Lore & Background

The shell of Botelloides chrysalidus is stoutly built and polished, with a pupiform shape. It has four depressed convex whorls and a spiral and helicoid apex consisting of 2½ turns. The shallow sutures are excavated, and the circular aperture has a thick lip. Some specimens show faint colour bands parallel with and near to the sutures. Under high magnification, fine growth lines are visible on the surface.

The species was originally described as Rissoa (Onoba) chrysalidus by Chapman & Gabriel in 1914. Two subspecies are recognized: Botelloides chrysalidus chrysalidus and Botelloides chrysalidus kendricki, the latter described by Ponder in 1985. The species is endemic to Australia, occurring off South Australia and Western Australia.

Reader's Guide

Botelloides chrysalidus is a small marine gastropod in the family Trochidae, known as top snails. Its significance lies in its taxonomic history: originally placed in the genus Rissoa, it was later revised into the genus Botelloides by Ponder in a 1985 revision. The species includes two subspecies, one of which (Botelloides chrysalidus kendricki) was newly described in that revision. The shell dimensions—height 3.1 mm and diameter 1.5 mm—and its pupiform shape distinguish it from related species. Its distribution is restricted to southern Australia, specifically South Australia and Western Australia, making it an endemic component of the region's marine fauna. The species was first documented in a 1914 publication by Chapman and Gabriel, based on fossils obtained from deep boring in the Mallee. The polished shell with faint colour bands and fine growth lines under magnification are characteristic features noted in the original description.

Did You Know?

• The shell height of Botelloides chrysalidus attains 3.1 mm and its diameter 1.5 mm.
• It has four whorls and a helicoid apex of 2½ turns.