138 
Richard L. Hoffman 
tions within the original concept of cottus engenders the question of their 
relative status, both to each other and to the closely allied P. scrutorum. 
Although no decisive answer can be advanced at the present, the point 
nonetheless merits consideration if for no other reason than the edifica- 
tion of possible future students of the group. 
On the basis of differences in dorsal ornamentation (30-40 small, well- 
defined metatergal tubercles in scrutorum, 4-16 longitudinal rugosities in 
fracta) and in gonopod structure (median branch of colpocoxite with an 
acute subapical projection in scrutorum, lacking in fracta), it is probable 
that these two taxa can be distinguished as two distinct species. Differ- 
ences in gonopod structure (e.g., lateral colpocoxite branches not caudo- 
dorsally deflexed in cocytus, prominently decurved in fracta) as well as 
the apparent sympatry of these taxa, suggest that they, too, differ at the 
level of species. 
On the other hand, the general external similarity of the several popu- 
lations to be recognized within fracta, overall concordance in gonopod 
structure, and apparent allopatry, suggest that, for the present, subspe- 
cific status best expresses the degree of relationship. This estimation 
requires future confirmation by field work in the region south and east of 
Knoxville to establish whether the present distributional hiatus is real or 
illusory. If the former be true, a good case might be made for full specific 
status on the grounds of effectual geographic reproductive isolation of 
the components. 
The distributional pattern shown by fracta (i.e., northwest to southeast 
trend across the Tennessee Valley) is paralleled in a number of other 
groups. Amongst trechine carabids, which seem to have ecological con- 
straints like those of pseudotremias, Barr (1969, 1979) demonstrated sim- 
ilar disjunctions in the case of Trechus tennesseensis Barr, the nominate 
subspecies of which occurs in a cave in Roane County, Tennessee, and T. 
t. tauricus in a cave near the Great Smokies in Blount County. In the 
Trechus schwarzi group, T. schwarzi (several subspecies) is restricted to 
the southern Blue Ridge, and the closely related vicar, T. cumberlandus, 
to the Cumberland Plateau in Tennessee and Kentucky. Barr postulated 
that such patterns developed during the Wisconsin glacial period, when 
cool or subarctic environments must have been prevalent in the southern 
Appalachian region generally. 
Pseudotremia fracta fracta Chamberlin, new status 
Figs. 1, 5 
Pseudotremia fracta Chamberlin 1951:25. Chamerlin & Hoffman 1958:94. 
Inmature female holotype (USNM) labeled “Gatlinburg Tenn / 
Cove hardwoods / B/ 6-24-47”; a second label has the notation 
