142 
John R. Holsinger and David C. Culver 
that Nesticus tennesseensis has more reduced eyes, lighter pigmentation, 
and longer legs in the southern part of its range than in the northern 
part. In addition, this species has been collected occasionally from deep 
ground litter outside caves in the northern part of its range. Of the 
three troglobitic nesticids in the study area, Nesticus holsingeri has the 
most reduced eyes and pigmentation and also the most limited range. 
Reductions in eye structure, pigment, and geographic distribution may 
be positively correlated with a relatively advanced level of cave 
specialization. 
In the eastern United States Nesticus is represented by 24 species 
that inhabit both caves and the rich ground litter of mesic forest floors, 
largely in the southern Appalachian region (Gertsch 1984). Troglobitic 
nesticids have apparently evolved from troglophilic ancestors as the 
latter became progressively more restricted to caves. The moderately 
widespread troglophile Nesticus earteri may very well be a good example 
of a troglobite in statu nascendi in a portion of its range, inasmuch as it 
is represented by numerous cavernicole populations, some of which are 
large and feed and reproduce in caves. 
Millipeds constitute one of the most significant groups of 
cavernicoles in the eastern United States, but unfortunately they remain 
one of the most underworked taxonomically. Probably more than 50% 
of the species known from caves are undescribed, which makes 
zoogeographic analysis difficult. The genus Pseudotremia is represented 
by many species that inhabit both caves and epigean habitats in parts of 
the Appalachian Valley, Appalachian Plateau, and Interior Low 
Plateaus. The range of the genus forms a distributional track across the 
Appalachian Plateau similar to that of Pseudanophthalmus and 
Kleptochthonius ( Chamberlinochthonius ). Of the 34 species of Pseudo- 
tremia recognized by Shear (1972), 15 are obvious troglobites, 7 are 
questionable troglobites, 8 are troglophiles, and 4 are apparently strictly 
epigean. Ranges of both the troglobites and the troglophiles are generally 
localized; but without further taxonomic refinements, it cannot be 
determined how closely the geographic distributions of troglobites 
coincide with isolated exposures of limestone. 
In the study area, the most highly specialized troglobitic pseudo- 
trimiids are in the nodosa complex, a group of closely allied species that 
are unpigmented and have greatly reduced eyes (ca. 10-11 ocelli per 
eye). They are common in caves in the Clinch and Powell valleys. 
Presumably, colonization of caves by members of this complex predates 
that of the less specialized troglobites, which are pigmented and have 
more ocelli. In caves of the Clinch and Powell valleys, it is not 
uncommon to find both pigmented and unpigmented species in the 
same cave, but the latter (species of the P. nodosa complex) are usually 
more abundant and often occur at greater distances from cave entrances. 
