Opisthoporus ngocngai (Thach & Huber, 2018)

Tongkerd, Piyoros, Tumpeesuwan, Sakboworn, Inkhavilay, Khamla, Prasankok, Pongpun, Jeratthitikul, Ekgachai, Panha, Somsak & Sutcharit, Chirasak, 2023, Systematic revision of the snorkel snail genus Rhiostoma Benson, 1860 (Gastropoda, Caenogastropoda, Cyclophoridae) with descriptions of new species, ZooKeys 1142, pp. 1-144 : 1

Opisthoporus ngocngai (Thach & Huber, 2018)

Fig. 58C

Rhiostoma ngocngai Thach & Huber in Thach, 2018: 17, figs 81b, 82b, 83c. Type locality: Ninh Tan Commune, Ninh Hao District, Central Vietnam [Khanh Hao Province].

Type material.

Holotype FMNH 386291 (Fig. 58C ) from Ninh Hòa, Khánh Hòa, Vietnam.

Remarks.

This species was described based on a single specimen. Although Do et al. (2020a) treated this as a junior synonym of O. herosae , it differs by having larger shells (width 30 mm), tubular-shaped breathing device located perpendicular to the last whorl, detached whorl short, and lip slightly thickened but not expanded. These minor differences have been used as diagnostic characters of Opisthoporus species in Vietnam (see Do et al. 2020a). In addition, this species differs from Rhiostoma in having a multispiral, slightly concave, plate-shaped operculum ( Do et al. 2020a). Therefore, we have retained this species as valid, but transferred it to the genus Opisthoporus . Further systematic work and more specimens of the species will verify the species status and relationship with other taxa.

Figures

Figure 58. A, B Opisthoporus herosae A holotype MNHN-IM- 2000 - 33198 from Ninh Binh, Vietnam and B holotype FMNH 386285 of Rhiostoma ninhbinhensis Thach & Huber, 201, from Ninh Binh, Vietnam C Opisthoporus ngocngai holotype FMNH 386291 from Ninh Hao, Vietnam D Opisthoporus ngocthachi holotype MNHN-IM- 2000 - 35508 from Khanh Hoa, Vietnam E Opisthoporus thorsengi holotype BOR / MOL 14587 from Dak Nong, Vietnam F Opisthoporus tener specimen NHMUK ex. Cuming collection. Photographs: M Caballer, A Lardeur and V Heros, MNHN (A, D, F), J Gerber, FMNH (B, C), T-S Liew, BORNEENSIS (E).