22 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



The discovery of the long-misplaced type specimen of P. kerri 

 creates some doubt about the vahdity of Silvestri's Barydesmus 

 tenebrosus, also described as from Ecuador. The doubt cannot be 

 settled, of course, until the type of the latter form is restudied, but 

 the similarities of the two are striking. 



Attems (1938, p. 234) placed Platyrhacus fraternus Carl in the 

 synonymy of tenebrosus, but I believe without much justification, 

 Carl's species was from Costa Rica and was well described; Attems. 

 subsequent account was apparently based on specimens from the 

 same country. But the original description of tenebrosus is not 

 sufficiently detailed to form the basis of such a combmation, particu- 

 larly since species in Platyrhacus are often separable by a 

 combination of small characters rather than by any one conspicuous 

 feature. The geographical difference involved here also militates 

 against the likeliliood of specific identity. 



Platyrhacus acanthopleurus, new species 



Figure Ic 



Holotype, male, USNM 2535, Cauca Valley, Colombia, 3,000 ft. 

 (date and coDector not indicated) . 



Diagnosis: A small species of Platyrhacus, dorsally bilineate, the 

 lower pleural areas with numerous stout, acute tubercules in a com- 

 pact field above the posterior leg pair; gonopods typical of the genus, 

 the tibiotarsus dra^vn out into a fine point, without a terminal second- 

 ary dentation. 



Description: Length, 62 mm.; greatest width, 12.0 mm. at the 

 12th metatergite. 



Color pattern largely faded, most of dorsal surface now a dirty 

 yellowish white; paranota brown, beset with numerous white tuber- 

 cules; caudal edge of most tergites with a broad, transverse, dark 

 brown band; middorsum with a light brown, median band extending 

 from coUum to epiprost, somewhat wider on prozonites (1.8 mm.) 

 than on metazonites (1.5 mm.). Head, antennae, legs, and under- 

 parts yellowish gi-ay except for bro^^Tl caudal edges of the pleurites. 



Head capsule strongly granulate except for the depressed and 

 polished clypeal area. Interantennal ridges low and inconspicuous; 

 subantennal ridges not developed. Subantennal swellings large, 

 transverse, ovoid, tuberculate. Lower halves of genae depressed or 

 flat, the lateral edges sinuate. Labral setae 8-8; clypeal 3-3, the 

 outermost on each side remote from the other two; a pair of widely 

 spaced frontal setae and a pair each of closer-set subantennal and 

 vertigial setae; no interantennal setae or their sockets detected. 

 Width of head across genae, 6.0 mm. 



