Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 25 Part 1: 23-36 - January 1963
A publication of the National Speleological Society
Annotated Checklist of
the Macroscopic Troglobites of Virginia with Notes on Their Geographic Distribution
John R. Holsinger
Extensive field work in recent years has facilitated the publication of a checklist of Virginia's troglobitic species. A large number of pertinent range extensions remain to be worked out, however, and in addition, several new species probably remain to be discovered. Forty-one troglobitic species are presently recognized from Virginia, including planarians (2), amphipods (4), isopods (3), millipeds (9), collembolans (4), beetles (10), pseudoscorpions (4), and spiders (5). At least fifteen more species are known but have yet to be described in the literature.
The isolation of certain species in caves and genetic changes within cave-dewelling animal populations are believed to be causative factors in troglobitic speciation. Many present-day cave species have probably evolved from surface forms already partially adapted for a subterranean existence. Certain cavernicolous groups like the anophthalmid beetles, pseudotremid millipeds, and cave pseudoscorpions are restricted to very small geographic areas and in some cases, only one cave system. Other cavericolous gorups like linyphiid spiders and various species of collembola are not restricted to isolated areas, but their range extends over a wide geographic region. With the exception of spiders and collembolans, aquatic troglobites seems to be more widely dispersed than terrestrial troglobites. The limestone region of Virginia which was remote from Pleistocene glaciation contains more than three times as many troglobitic species as the limestone area in Pennsylvania which was close to Pleistocene glaciation.
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18 July, 2002 9:42
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