TROCHOMORPHIDAE Von Moellendorff

Vermeulen, Jaap J., Liew, Thor-Seng & Schilthuizen, Menno, 2015, Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species, ZooKeys 531, pp. 1-139 : 95

Taxon classification Animalia Stylommatophora Trochomorphidae

Family TROCHOMORPHIDAE Von Moellendorff

Short description.

Snails, rarely semi-slugs. Shell medium-sized to very large, dextral or sinistral, (low-)conical, to lenticular or discoid. Sculpture usually inconspicuous to distinct, fine spiral striation and/or radial riblets; in some species coarser sculpture is present, for instance spiral ridges or nodular structures on the intersection of spiral and radial sculpture. Aperture without teeth or lamellae, peristome thin or thick, reflected or not. Umbilicus closed or open, narrow (Family description adapted from Baker 1941; Van Benthem Jutting 1952; Solem 1959; Vaught 1989; Abbott 1989).

Habitat and distribution.

Most species are found on understorey vegetation. Widely distributed in Southeast Asia and Oceania.

Remarks.

The genera reviewed are Trochomorpha Albers, and Geotrochus Van Hasselt. Van Benthem Jutting (1952: 407) and Solem (1959: 107) include both genera in the Zonitidae , subfamily Trochomorphinae, in recent literature ( Vaught 1989: 98) raised to family level: Trochomorphidae . The Sabah species are generally known by their shell only. An exception is Trochomorpha rhysa ; dissection by Tillier and Bouchet (1988) confirmed its position in the Trochomorphidae .

Generally, the two genera include species with conical shells, not unlike Kaliella Blanford ( Helicarionidae ) or Philalanka Godwin Austen ( Endodontidae ), but consistently larger. Several species, for instance Geotrochus conicoides , Geotrochus labuanensis , and Geotrochus scolops , have shells of very characteristic appearance, with a prominent, sharp peripheral keel.