Rhiostoma

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.[1]

The name is derived from "rhion" meaning a promontory and "stoma" meaning hole.[2] 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.

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 (from the Chanthaburi province) 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."[3]

Species within the genus Rhiostoma include [4]

• Rhiostoma abletti Thach, 2016
• Rhiostoma asiphon
• Rhiostoma cambodjense Morelet, 1875
• Rhiostoma boxalli Godwin-Austen, 1893
• Rhiostoma chupingense Tomlin, 1938
• Rhiostoma dalyi Blanford, 1902
• Rhiostoma hainesi Pfeiffer, 1862
• Rhiostoma jalorense
• Rhiostoma jousseaumei
• Rhiostoma macalpinewoodsi Laidlaw, 1939
• Rhiostoma morleti
• Rhiostoma samuiense
• Rhiostoma simplicilabre L. Pfeiffer, 1862
• Rhiostoma smithi
• Rhiostoma spelaeotes