32 
Thomas C. Barr, Jr. 
KEY TO SPECIES AND SUBSPECIES OF 
SOUTHERN APPALACHIAN TRECHUS 
1. Males with two segments of protarsus enlarged 
{Trechus, sensu stricto) 2 
Males with only the first protarsal segment enlarged 
(subgenus Microtrechus ) 1 2 
2(1). Pronotum about 0.7-0. 8 times as long as wide, total length 
3. 5-5. 0 mm 6 
Pronotum (Fig. 1) very transverse, less than 0.7 times as long as wide; 
length 2. 5-3. 5 mm ( hydropicus ) 3 
3(2). Elytra with 5 well-developed striae and trace of sixth stria, inner intervals 
subconvex; aedeagal apex minutely knobbed (Fig. 18); western Virginia, 
Maryland, eastern West Virginia hydropicus hydropicus (Horn) 
Elytra with 4 or 5 complete striae, more shallowly impressed 4 
4(3). Pronotum with hind angles blunt or sharp, elytra with 4 or 5 striae, at least 
inner 3 striae moderately impressed; apex of aedeagus knobbed, 
or thickened and inflected (Figs. 19, 21) 5 
Pronotum with hind angles sharp, obtuse; elytra! striae very shallow, 
inner 3 more pronounced than 4th, at best a trace only of 5th stria 
present; apex of aedeagus unmodified (Fig. 20); Roan and Bald 
mountains of Tennessee-North Carolina border, southeast to Black 
and Great Craggy mountains, North Carolina 
hydropicus beutenmuellen Jeannel 
5(4). Elytra with 5 striae and trace of 6th (5th and 6th striae may both be very 
shallow in westernmost part of range); apical recurrent groove long; 
apex of aedeagus (Fig. 21) thickened and inflected; Grayson County, 
Virginia, to Harlan County, Kentucky hydropicus canus Barr 
Elytra with 4 striae and trace of 5th; apical recurrent groove short to 
moderate; aedeagus as in Fig. 19; Blue Ridge in Avery and Ashe coun- 
ties, North Carolina hydropicus avus Barr 
6(2). Pronotum (Fig. 2) with sides subparallel in basal fourth, hind angles large 
and nearly right; Roan Mountain, Tennessee, and adjacent North 
Carolina roamcus Barr 
Pronotum with sides convergent, hind angles small, various (Figs. 3, 4, 5) 
7 
7(6). Range: mountains of western North Carolina 8 
Range: Cumberland plateau from Rockcastle County, Kentucky, to 
Grundy County, Tennessee cumherlandus Barr 
8(7). Range: Black and Great Craggy mountains and vicinity 9 
Range: south and west of Asheville 11 
9(8). Smaller, 3. 4-4. 2 mm, eye diameter equal to or greater than scape length; 
pronotum sides feebly sinuate before hind angles; elytra with four 
complete striae and trace of 5th stria; apical groove ending well in 
advance of anterior apical puncture 10 
Larger, 4.4-4. 8 mm, eye diameter less than scape length; pronotum sides 
not sinuate, hind angles obtuse and sharp; elytra with five shallow, 
complete striae and traces of 6th and 7th striae; apical groove short, 
ending at level of anterior apical puncture carolinae Schaeffer 
