A PHYLOGENETIC ANALYSIS AND REVISED CLASSIFICATION OF THE NORTH-AMERICAN HAPLOTREMATIDAE (GASTROPODA, PULMONATA)

A revised classification of the North American Haplotrematidae (= Haplotrematinae) is presented, based on character compatibility analysis of 25 characters of the musculature, reproductive system, radula, kidney, pericardium, and shell. Two genera are recognized -- Ancotrema and Haplotrema, the latter with three subgenera, Ancomena, Geomene, and Haplotrema, sensu stricto. The hypothesized age of the Haplotrematinae is 42.5 million yr (late middle Eocene), when the temperate Haplotrematinae and its tropical out-group, the Austroselenitinae, are assumed to have diverged. The phylogenetic hypothesis indicates an early dichotomy between Ancotrema and Haplotrema, with the species of Ancotrema retaining more characteristics of the hypothetical ancestor. Other evolutionary trends include: (a) a tendency toward reduction of vaginal musculature; (b) a parallel tendency toward greater penial complexity; (c) migration of the origin of the penial retractor muscles from the columellar muscle bundle to the floor of the lung (presumably increasing mechanical efficiency); (d) parallel instances of gigantism in the Pacific Northwest; (e) size reduction southward along the Pacific Coast, correlating with the presence/severity of a summer dry season; (f) a homoplastic continuation of the loss or reduction of cusps on the teeth of the radula. A lectotype is designated for Selenites vancouverensis forma hybrida Ancey, 1888.