Opisthoporus birostris (L. Pfeiffer, 1854) Figures 7B, 46D

Cyclostoma birostre Pfeiffer, 1854b: 300.

Type locality.

"Sarawak, Borneo".

Material examined.

Bukit Sekunyit: ME 4735. Gunung Doya: ME 1312. Gunung Kapor: ME 4731, ME 4736, ME 4737, ME 8072, ME 8495, ME 8755, ME 8758, ME 9605. Lobang Angin: ME 4738. Gunung Batu: ME 4732, ME 4734, ME 4739, ME 8830.

Distribution in Borneo.

Sarawak: Kuching Division. Endemic to Borneo.

Remarks.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. It differs from other Bornean Opisthoporus species by having a large shell, short sutural tube projecting downwards, and a thick brown periostracum can be seen on fresh shells.