Rhytidarex
Rhytidarex is a genus of giant land snails belonging to the family Rhytididae. Both members of the genus are endemic to Manawatāwhi / Three Kings Islands in New Zealand.
Description
In the original description, Powell described the genus as below:Shells of the species are moderately large, tending to be in size, but can reach a size of. Members of the genus have umbilicate, brown shells, with angled, one-keeled or two-keeled periphery, and can be identified by radula that have a large number of evenly graded aculeate teeth, and by having a highly calcified shell structure.
Taxonomy
Rhytidarex was first described by A. W. B. Powell in 1948 as a subgenus. Powell named Rhytida (Rhytidarex) johnsoni as the type species. Rhytidarex was raised to genus status by Frank Climo in 1977. The holotypes of both known species are held by the Auckland War Memorial Museum.Phylogenetic analysis suggests that the genus is one of the most basal genera of New Zealand Rhytididae, splitting from mainland New Zealand members of the family between 3.4-11.6 million years before the present.