A specimen mentioned as being the syntype of “Pterocyclos marioni Ancey, 1898” NMW 1955.158.24090. B–F shell of Rhiostoma marioni B published figure of the type specimen (after Ancey 1898: pl. 9, fig. f.) and C–F specimens CUMZ 10210 from Feuang, Vientiane, Laos.

 
 
  Part of: Tongkerd P, Tumpeesuwan S, Inkhavilay K, Prasankok P, Jeratthitikul E, Panha S, Sutcharit C (2023) Systematic revision of the snorkel snail genus Rhiostoma Benson, 1860 (Gastropoda, Caenogastropoda, Cyclophoridae) with descriptions of new species. ZooKeys 1142: 1-144. https://doi.org/10.3897/zookeys.1142.90097