Genitalia of Amphidromus spp A–D Amphidromus thachi Huber, 2015 A general view of genitalia of specimen from Krong Bong, Dak Lak, Vietnam (NMNS-8764-274) B–D specimen from Buon Don, Dak Lak, Vietnam (NMNS-8764-271), showing B general view of genitalia C interior structures of penis D interior structures of vagina chamber E–G Amphidromus metabletus Möllendorff, 1900 from Nha Trang, Khanh Hoa, Vietnam (NMNS-8764-130), showing E general view of genitalia F interior structures of penis G interior structures of vagina chamber. Green arrows indicate the genital openings. Abbreviations: ap, appendix; e, epiphallus; fl, flagellum; fo, free oviduct; gd, gametolytic duct; gs, gametolytic sac; ov, oviduct; p, penis; pp, penial pilaster; pr, penial retractor muscle; pv, penial verge; v, vagina; vd, vas deferens; vp, vaginal pilaster.