Angustopila milium (Benson, 1853)

Pall-Gergely, Barna, Hunyadi, Andras, Vermeulen, Jaap J., Grego, Jozef, Sutcharit, Chirasak, Reischuetz, Alexander, Dumrongrojwattana, Pongrat, Botta-Dukat, Zoltan, Oerstan, Aydin, Fekete, Judit & Jochum, Adrienne, 2023, Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae), ZooKeys 1147, pp. 1-177 : 1

Angustopila milium (Benson, 1853)

Fig. 18

Cyclostoma Cyclostoma Milium Benson, 1853: 285.

Hydrocena milium - W.T. Blanford 1864: 464. (perhaps Georissa ); Godwin-Austen 1872: 515, pl. 30, fig. 3.

Cyathopoma milium - W.T. Blanford 1869: 178.

Georissa milium - Pfeiffer 1875-1876: 292.

Acmella milium - Gude 1921: 362; Ramakrishna et al. 2010: 111.

Angustopila milium - Das et al. 2021: 329; Preece et al. 2022: 154, fig. 70A.

Type locality.

"in muscis arborum ad Musmai, prope Cherra-poonjee" (India, Meghalaya, Cherrapunji, approximate GPS coordinates: 25°16.6'N, 91°44'E).

Material examined.

One syntype, possibly holotype, with no locality data (UMZC I.103805). An old label in unknown handwriting reads " Hydrocena milium Bs." and on the reverse side: "original shell described".

Distribution.

Known from a single shell only (Fig. 19 ).

Remarks.

Angustopila milium was described as a Cyclostoma (caenogastropod) species. Even Godwin-Austen (1872) was convinced that this was an operculate species when he examined Benson’s type specimens. Gude (1914) considered it as juvenile Boysidia plicidens . However, the combination of the shell characters (small, conical shell, narrow, deep umbilicus, toothless, subcircular aperture, expanded aperture, sparsely arranged spiral striae) indicates that this species represents an adult hypselostomatid, which undoubtedly fits to the genus Angustopila , significantly extending the genus distribution.

Here, we do not present a formal redescription because the type specimens could not be examined by SEM, and therefore, some important details cannot be seen. However, due to the large geographic distance between A. milium and other species discussed herein, it is highly unlikely that A. milium would be conspecific with any of them.

Figures

Figure 18. Angustopila milium (Benson, 1853) (syntype, UMZC I. 103805). Photos: H. Taylor (NHM). Scale bar 1 mm.

Figure 19. Distribution of Angustopila species.