Opisthoporus biciliatus (Mousson, 1849) Figures 7A, 46C

Pterocyclos biciliatum Mousson, 1849: 49-50, pl. 20, fig. 9.

Type locality.

“Java” [= Borneo (Metcalfe, 1851)].

Material examined.

Gunung Doya: ME 4744, ME 9144, ME 9192. Gunung Kapor: ME 3723, ME 4742, ME 4746, ME 5973, ME 8073, ME 8460, ME 8754, ME 8757, ME 8777. Lobang Angin: ME 4743, ME 8725, ME 8729, ME 8739, ME 9484. Gunung Batu: ME 4745, ME 4748, ME 8806.

Distribution in Borneo.

Sarawak: Kuching, Samarahan, Serian, and Sibu divisions. Kalimantan: West Kalimantan Province. 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 moderately large shell, short sutural tube projecting upwards, and long, double, deciduous appendages along the first peripheral ridge and below the periphery that can be seen on a fresh shell.