Diancta Martens, 1864

Neubert, Eike & Bouchet, Philippe, 2015, The Diplommatinidae of Fiji - a hotspot of Pacific land snail biodiversity (Caenogastropoda, Cyclophoroidea), ZooKeys 487, pp. 1-85 : 6

Taxon classification Animalia Mesogastropoda Diplommatinidae

Diancta Martens, 1864

Diancta Martens 1864, Monatsberichte der Königlichen Preussischen Akademie der Wissenschaften zu Berlin, (1864): 119. [Type species: Diplommatina constricta Martens, 1864, by monotypy; Moluccas, Indonesia].

Diagnosis.

Shell dextral or sinistral, constriction easily visible to reduced, umbilicus always closed; protoconch usually with a pitted microsculpture; aperture shifted right or left of shell axis; no pleats visible in the aperture, columella reinforced by 1-2 plates situated right or left of the columella, often with a palatal callosity in opposition, parietalis can be present, often reduced; operculum corneous, multispiral, flat, with an elongate internal apophysis.

Remark.

Martens (1864: 119) defined the genus Diancta by "penultimate whorl with a constriction". Quadras and Möllendorff (1895) added the new subgenus Paradiancta (type species Diancta philippinica Quadras & Möllendorff, 1895, from the Philippines), which is characterised by dextral shells with a long palatalis and columellaris. Kobelt (1902: 419) added to the general definition that the shell of Diancta is oval and somewhat irregularly coiled. This short summary shows that the definition of these genera is based on taxonomically unimportant shell characters. Constriction of the shell is not an autapomorphic but a plesiomorphic character; for example, it is found in other genera like Opisthostoma Blanford, 1860 ( Vermeulen 1991: 140) and Diplommatina Benson, 1849 ( Vermeulen 1993, 1996: 116).

The diplommatinid species of Lord Howe Island were also placed in Diancta by Stanisic et al. (2010). The shells of these species show some resemblance to those from Fiji, and may be closely related to the Fiji radiation. An analysis of the inner lamellar system of these species would be desirable.