Saturday, 21 February 2015

A new subspecies of Polygyrid Snail from West Virginia.

The Appalachian Mountain of eastern North America are considered to be a hotspot for Land Snail biodiversity. There are currently at least ten described species of Polygyrid Snails in the genus Triodopsis in West Virginia alone, although there is considerable doubt about the validity of some of these species. The species Triodopsis juxtidens, Triodopsis discoidea, Triodopsis neglecta and Triodopsis pendula are currently collectively known as the ‘Triodopsis juxtidens subgroup’, though there are no clear morphological traits that separate these species, while a recent genetic study which included several specimens of Triodopsis juxtidens strongly suggested that these were not all member of the same species, strongly suggesting that the group is in need of revision.

In a paper published in the journal Zootaxa on 29 January 2015, Kenneth Hotopp of Appalachian Conservation Biology describes a new and distinctive population of Triodopsis Snails from the Bluestone River Valley in Mercer and Summers Counties, West Virginia. In the absence of a solid genetic or morphological foundation for the classification of Triodopsis Snails he takes a conservative approach, and assigns this population subspecies rank within the species Triodopsis juxtidens.

The new subspecies is named Triodopsis juxtidens robinae, in honour of Hotopp’s wife Mary ‘Robin’ Robertson Gorrell, on the occasion of their 25th wedding anniversary. The shells are 7.0-9.0 tall and 13.1-17.6 mm wide, have 4.75-5.5 whorls and are light or reddish brown in colour. The aperture of the new population is roughly triangular in shape, as opposed to rounded as seen in other specimens assigned to Triodopsis juxtidens.

Specimen of Triodopsis juxtidens robinae from Brush Creek in Mercer County, West Virginia. Charles Sturm in Hotopp (2015).

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