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John R. Holsinger and David C. Culver 
Shenandoah Valley from small springs and seeps in alluvium underlain 
by Martinsburg shale (Holsinger and Steeves 1971). The relatively long 
range of this species, i.e., Rockbridge County, Va., northeastward to 
southeastern Pennsylvania, can probably be attributed to its ecological 
flexibility to live in both interstitial and hypotelminorheic habitats 
between karst areas. Several other troglobitic isopods in the study area 
have also been collected from non-cave groundwater habitats. 
The occurrence of the cirolanid isopod Antrolana lira in a single, 
isolated subterranean groundwater aquifer in the Shenandoah Valley is 
one of the most intriguing zoogeographic problems in North American 
biospeleology. This unique, monotypic form is the only subterranean 
freshwater cirolanid isopod found in North America north of Texas, 
Mexico, and the West Indies, and is probably a very old relict. The 
family Cirolanidae is predominantly marine and only a small number of 
species live in freshwater, all of which, except for two poorly known 
forms from Africa and one from Cuba, are eyeless, unpigmented species 
obligatory to subterranean groundwaters. A total of 17 species in 10 
genera have been described to date from subterranean waters in the 
Western Hemisphere, and several additional forms from the Bahamas, 
Grand Cayman Island, and Haiti are being described. Other genera 
and species have been reported from groundwater habitats in southern 
Europe and the Mediterranean region. 
With the notable exception of A. lira , troglobitic cirolanids live in 
areas that are either presently near coastal marine zones or were 
exposed to shallow marine transgressions in the Cretaceous or Tertiary. 
Because a majority of the cirolanids are marine and the troglobitic species 
live either in close proximity to the sea or in old marine embayment 
areas, many workers have hypothesized that the subterranean fresh- 
water species were derived directly from marine ancestors during the 
recession of seawater from limestone regions (Bowman 1964, Vandel 
1965b, Cole and Minckley 1966, Carpenter 1981, Contreras-Balderas 
and Purata-Velarde 1982, and others). The presence of troglobitic ciro- 
lanids in the saline water of a small cave on San Salvador Island in the 
Bahamas (see Carpenter 1981) and in the brackish water of a limestone 
tunnel on the island of Aruba (see Botosaneanu and Stock 1979) offers 
additional support for this hypothesis. Since these troglobitic cirolanids 
live in brackish or saline water, they may well represent ecological tran- 
sition stages in the evolution of subterranean freshwater forms from 
preadapted marine ancestors (Carpenter 1981). 
If the prevailing hypothesis for the origin of troglobitic cirolanids is 
applied to A. lira , then this species would have to be regarded as the 
derivative of an ancient lineage dating back to the Paleozoic, when what 
is now the Appalachian Valley was last subjected to marine transgres- 
sions (Collins and Holsinger 1981). The evidence, however, argues 
