24 
John R. Holsinger and David C. Culver 
Class Ostracoda 
Hobbs (1975) alluded to the presence of the ectocommensal ostracod 
Phymocythere phyma (Hobbs and Walton) (Entocytheridae) in Virginia 
and West Virginia caves but gave no specific records. Because a 
principal host of this species is Cambarus bartonii, a crayfish found in 
caves of the study area (see below), the occurrence of this ostracod in 
Virginia and east Tennessee caves should be expected. However, to our 
knowledge there are no published records. 
Class Malacostraca 
Malacostracan crustaceans are represented in study-area caves by 
three orders: Amphipoda (2 families, 3 genera, 21 species), Isopoda (6 
families, 10 genera, 23 species), and Decapoda (1 family, 1 genus, 2 
species). 
Order Amphipoda 
Amphipods are common faunal components of cave waters where 
they are usually found among gravels or under small rocks in streams, 
on the organically enriched mud substrate of pools fed by drips and or 
seeps, and rarely in deep phreatic lakes. A total of 21 species, all in the 
suborder Gammaridea, have been recorded, of which 20 are of troglobitic 
facies and known only from groundwater biotopes. The troglobitic 
species belong to the genera Stygobromus, Bactrurus, and Crangonyx , 
all in the family Crangonyctidae; the single troglophile, Gammarus 
minus , is in the family Gammaridae. 
A majority of the species (18) have been assigned to Stygobromus , a 
large, exclusively subterranean genus that is distributed throughout a 
large part of North America (Holsinger 1977, 1978, 1986a, 1986b). Most 
species of Stygobromus from the study area have narrowly circumscribed 
ranges (Fig. 8, 9), and many are local endemics; three are known only 
from their type localities. Only four species listed below occur outside 
the study area, and none extends beyond this area for a great distance. 
The most common and widespread species is S. mackini, which is 
distributed from Monroe County in southern West Virginia (New River 
drainage) southwestw'ard to Roane County in eastern Tennessee 
(Tennessee River drainage) (Holsinger 1978). 
Bactrurus is represented by a single, undescribed (provisionally 
recognized) species that is recorded to date from only three caves in the 
Pow'ell Valley (Fig. 8). This is one of five or six undescribed species in 
the genus (Holsinger 1986b) and the first to be found in the Appalachian 
Valley. Three described species are reported from caves and other 
groundwater biotopes in the eastern and central United States (see 
Holsinger 1972, 1986a, 1986b). 
