Rhiostoma
Rhiostoma is a genus of operculate land snails in the subfamily Cyclophorinae of the family Cyclophoridae, native to parts of Asia.
They are sometimes referred to as "snorkel snails" due to the tubular structure found on the final whorl of their shell, which resembles a snorkel.
Description
The shell is subdiscoidal with a broad umbilicus. The last whorl is separate from the rest of the shell and features a tube-like snorkel structure. The operculum is multispiral.Etymology
The name is derived from "rhion" meaning a promontory and "stoma" meaning hole. In anatomy, a promontory is another word for a protuberance, so Rhiostoma can be understood to mean "protruding hole." This name refers to the snorkel on the shell which is the defining characteristic of the genus.Ecology
Somwang Pathamakanthin of Thailand said about the ecology of Rhiostoma, "As we have kept some living animals of Rhiostoma species in our garden, we know that most of them burrow into the ground during the day and are active only when it is raining or-sometimes-during the night, when the temperature is lower and the humidity is higher. When it is extremely hot during the day, we observed that species of the large variety of Rhiostoma smithi preferred to move into water, where they stayed for days! Others have been resting under the shade of trees, under rocks and fallen wood. We have been informed that the bluish Rhiostoma from Songkhla province prefers to burrow into the soil underneath fallen wood or under stones close to the foot of limestone hills."Taxonomy
Species within the genus Rhiostoma include Rhiostoma abletti Thach, 2016- † Rhiostoma americanum G. D. Hanna, 1920 Rhiostoma asiphon Möllendorff, 1893Rhiostoma battambangense Thach & F. Huber, 2020Rhiostoma boxalli Godwin-Austen, 1893Rhiostoma cambodjense Morelet, 1875Rhiostoma chupingense Tomlin, 1938Rhiostoma dalyi Blanford, 1902Rhiostoma grohi Thach, 2020Rhiostoma hainesi Pfeiffer, 1862Rhiostoma haughtoni Benson, 1860Rhiostoma herosae Thach & F. Huber, 2017Rhiostoma housei Rhiostoma huberi Thach, 2018Rhiostoma jalorense Sykes, 1903Rhiostoma jousseaumei de Morgan, 1885Rhiostoma macalpinewoodsi Laidlaw, 1939Rhiostoma marioni Rhiostoma morleti Dautzenberg & H. Fischer, 1906Rhiostoma ngocngai Thach & F. Huber, 2018Rhiostoma ngocthachi F. Huber, 2020Rhiostoma ninhbien D. S. Do, T. S. Nguyen & H. L. Do, 2020Rhiostoma samuienseRhiostoma simplicilabre L. Pfeiffer, 1862Rhiostoma smithi Bartsch, 1932Rhiostoma strubelli Möllendorff, 1899Rhiostoma thachi F. Huber, 2018Rhiostoma thorsengi Thach, 2020Rhiostoma tomlini Salisbury, 1949
;Taxa inquirenda:Rhiostoma abletti Thach, 2016 Rhiostoma christae Thach, 2016 Rhiostoma ngocngai Thach & F. Huber, 2018 Rhiostoma ninhbinhense Thach & F. Huber, 2018 (debated synonym