Genus Halotudora Watters, 2006

Type species by original designation Cyclostoma radiosum Morelet, 1849 [= Cyclostoma gruneri Pfeiffer, 1846, herein].

Description. Turbinate to rather tall, some species are not decollated. 1.5–2 smooth nuclear whorls. Teleoconch whorls rounded, suture indented. Sculptured with axial lamellae that may form a serrated suture, but never with prominently fused tufts. Spiral sculpture of threads, forming a somewhat minutely serrate surface. Peristome double (very rarely single), aperture nearly circular. Outer lip usually broadly expanded more or less equally around aperture, adherent to body whorl. Umbilicus open. Shell lacking modifications for a breathing device. Usually patterned with interrupted spiral bands, which may continue adaperturally over the peristome. Operculum modified paucispiral with moderately acentric nucleus, with a reflected, narrowly or not sulcate calcareous lamella composed of numerous spiraling lamellae, forming a flattened, corrugated, plate-like structure.

Remarks. This genus differs from Gouldipoma in generally having a lower spire and often stronger spiral sculpture. Gouldipoma has an obviously multispiral operculum with an erect spiral lamella that is not reflected into a flattened plate and is not obviously composed of spiraling lamellae as in Halotudora. See remarks under Choanopomops. Some specimens of H. kuesteri (e.g., the sargi form) are nearly indistinguishable from Jamaican Annularia. It is likely that these genera have a common ancestor. Halotudora is endemic from the Yucatán Peninsula to the foothills of the Sierra Madre de Chiapas.

Etymology. Gr. halos, halo or corona, for the circular expanded lip + Tudora.