Description and affinities of the subterranean molluscan fauna of New Zealand

Abstract

The New Zealand subterranean molluscan fauna is described, and its systematic relationships with surface‐dwelling species in the Australasian region is superficially investigated. The subterranean elements are related to surface‐dwelling taxa in New Zealand, with one exception which shows relationships with a Dalmatian snail, and these New Zealand taxa have relatives confined to restricted areas of the south‐west Pacific. The Australasian members of Hydrobiidae (Prosobranchia: Rissoacea) examined in this study are attributed to subfamily Hydrobiinae, and are grouped in three nomen‐clatively informal tribes. Literature relating to phreatic and cavernicolous Mollusca from other parts of the world is briefly reviewed. It is concluded that phyletic links between taxa in New Zealand and the Northern Hemisphere rarely exist below subfamily level, and that morphological similarities are matters of convergence or parallelism; the southern genera are regarded, for purposes of this treatment, as endemic. A new phreatic stylommatophoran pulmonate genus, Hydrophrea, is erected for Laoma (Phrixgnathus) academia Climo, 1970. This is the first record of an aquatic subterranean stylommatophoran pulmonate. The following new taxa are described within Hydrobiinae: Potamopyrgus cresswelli n. sp.; P. manneringi n. sp.; P. gardneri n. sp.; Hadopyrgus anops n. gen. & n. sp.; H. brevis n. sp.; Kuschelita mica n. gen. & n. sp.; K. inflata n. sp.; Catapyrgus spelaeus n. gen. & n. sp.; Opacuincola troglodytes n. sp.; O. kuschelin. sp. Potamopyrgus subterraneus Suter, 1905 is reconstituted as a valid species.