Cyclophoroidea
The Pupinidae belong to the Architaenioglossan superfamily Cyclophoroidea, a group of land snails evolved from marine and freshwater snails, with only modest adaptation for life on land. The efficiency with which these animals are able to regulate water loss is marginal, and as a general rule activity in Cyclophoroidea is confined to periods of very high humidity. When the humidity is low, the animals remain retracted within their shell, with the aperture sealed by the operculum to prevent moisture loss. While widely distributed, these land snails are most diverse in the tropics. In the New Zealand terrestrial land snail fauna, the Cyclophoroidea are represented by the genera Liarea Gray, 1852 and Cytora Kobelt & Möllendorff, 1897, which are presently assigned to the family Pupinidae, subfamily Liareinae. These New Zealand snails occur primarily in the leaf litter on the floor of forests.
The systematic relationships of the families in the Cyclophoroidea is presently poorly understood and there is uncertainty as to the true affinities of the New Zealand genera. Gary Barker and Martyn Kennedy are presently collaborating on a molecular study of phylogenetic relationships in the Cyclophoroidea, drawing on material from around the world.
The genus Cytora was recently revised by Bruce Marshall and Gary Barker based on conchological characters. A total of 42 species were recognised.
That study showed the genus Cytora to be widely distributed in New Zealand, with species represented in the Three Kings, North, South, Stewart and Auckland islands. Highest species richness occurs in the northern North Island and north-western South Island. Cytora species are notably absent from much of mid-Canterbury (including Banks Peninsula) and Central Otago in the South Island, the upper montane areas of both North and South islands, and from the offshore Kermadec, Chatham and Campbell islands.
The genus Liareaoccurs only in the North Island, with extensive species radiation in Northland. Fred Brook, Gary Barker and Thomas Buckley are presently collaborating on a revision of this genus, using morphological and genetic characters.
Several Cytora and Liarea species are identified of conservation concern in the New Zealand Threat Classification System Lists (Hitchmough et al. 2007).
Suggested further reading:
Barker GM 2001. Gastropods on land: phylogeny, diversity and adaptive morphology. In: Barker GM ed. Biology of terrestrial molluscs. Wallingford, UK, CAB International. Pp. 1–146.
Climo FM 1975. The land snail fauna. In: Kuschel G ed. Biogeography and ecology in New Zealand. The Hague, Junk. Pp. 459–492.
Marshall BA, Barker GM 2007. A revision of New Zealand landsnails of the genus Cytora Kobelt & Möllendorff, 1897 (Mollusca: Gastropoda: Pupinidae). Tuhinga 18: 49–113.