32 
Rowland M. Shelley 
The shelfordi problem has interested me since I examined the 
holotype in connection with a study of abnormal xystodesmids (Shelley 
1977). The eighth segment of this milliped is without legs or a sternum 
(Fig. 1), a condition unreported at that time in the Diplopoda. Of further 
interest, however, was the contrast between the large size of the shelfordi 
type and the brevity of the gonopods, which were the shortest I had seen 
on an aphelorine xystodesmid and seemed almost aborted. Because of 
this specimen and the nomenclatorial problem, I visited the type locality 
in 1976 and found congeneric material in a 64 km (40 mi.) section along 
the north side of the Savannah River in Abbeville and McCormick coun- 
ties. I investigated habitat on both sides of the river, but found pertinent 
forms only in a narrow strip, 32 km (20 mi.) wide, on the South Carolina 
side. One male from Oconee County is present in Hoffman’s collection, 
but field trips to this area and Anderson County have been unproductive. 
Superficial examination revealed that shelfordi requires a new genus, and 
I propose the name Brevigonus to emphasize this feature of the male 
genitalia. Still unresolved is the number of species comprising the taxon, 
and I have conducted meticulous field surveys to try to find out. My 
current conception of a monotypic genus may eventually be altered, since 
two basic gonopodal variants are evident in the material at hand. They 
share more features than most aphelorine congeners, however, and thus 
seem not to be reproductively isolated. Moreover, they occur sym- 
patrically throughout the range of the genus, and I know of no 
aphelorine genus in which all the species occur over the entire range. 
Sampling to date has been thorough, and additional collecting will 
probably not further clarify the situation. Consequently, I recognize only 
one species in Brevigonus, and the present contribution is offered mainly 
to redescribe shelfordi and to provide it with a generic name. 
Brevigonus, new genus 
Type species. — Cleptoria shelfordi Loomis, 1944. 
Description. —A genus of large, robust xystodesmids with the following 
characteristics: 
Body composed of head and 20 segments in both sexes; W/L ratio 
22-24%. Head of normal appearance, smooth, polished; epicranial suture 
distinct, not bifid; facial setae reduced, epicranial and interantennal ab- 
sent. Antennae relatively short, with four antennal cones. 
Terga smooth, polished. Collum large, broad, extending slightly 
beyond ends of following tergite on each side. Paranota moderately 
depressed, continuing slope of middorsum; peritremata flat on anterior- 
