244 NEOTROPICAL PSELAPHIDAE 



not visible from above ; base with a pair of small foveae on each side ; a second 

 pair of small horns or teeth on lateral margins, one of these small cusps being 

 near middle of each side. 



Elytra typical of genus with very oblique humeri; each elytron with a 

 single, large, circular, deep, nude basal fovea and an entire sutural stria. 



Abdomen elongate with five tergites having proportions as noted above; 

 first tergite with a straight external and an oblique internal carina each side; 

 second and third with a very short, straight carina each side at base; last 

 tergite distinctly, transversely impressed at base. Five clearly visible sternites 

 (morphological II-VI) without abnormalities, and of normal proportions. 



Metastemum with a very prominent spine at middle of apical margin, 

 this spine nearly as large as antebasal pronotal spines, laterally compressed, 

 with a sharp, slightly recurved apex. 



Intermediate trochanter with apex sharpened into a prostrate, acute tooth; 

 intermediate femur excavated in basal half of ventral face and with two con- 

 spicuous spines: a long, narrow, aciculate, erect spine at middle, and a lamel- 

 late, subtruncate spine at basal third; intermediate tibia contorted, apically 

 slightly inflated, basally flattened, with a short, strong tooth at apical three- 

 fourths of length, this tooth appressed and apically directed. 



Allotype Female. Similar to holotype male save that (1) antennae are 

 simple, (2) the tooth at pronotal margin each side is larger than in the male, 

 (3) metastemum not spined, and (4) intermediate legs not armed or abnormal. 



Described on a male and a female, collected by the author on Barro 

 Colorado Island, Gatun Lake, Panama Canal Zone. Holotype male on July 

 25, 1936, in stage 4 log mold at Drayton 12; allotype female on July 27, 1936, 

 beneath bark of a log at Zetek 23. 



Oddly enough this new species has little in common with rivularis of 

 Panama, and is more nearly allied with hamaticollis of Guatemala; from the 

 latter it differs in numerous structural details noted in the key. Among other 

 differences between the latter two species is a qualitative difference in the 

 armature of the intermediate legs of the males: hamaticollis has a single spine 

 on the femur, while sternadens has the femur strongly bispinose, and the 

 former has apparently simple tibiae which are apically cusped while the latter 

 has contorted tibiae with a strong appressed tooth at apical three-fourths. 



Subgenus Baroxarthrius new subgenus 

 This new subgenus is erected for the new species which follows, and is 

 characterized by (1) the distal segment of the maxillary palpi having a foveoid 

 scar on the external face; (2) elytra without a trace of basal foveae; (3) the 

 male sex having the lateral wings of the pronotum and the prosternum sec- 

 ondarily modified. 



Oxarthrius escharus new species 



Holotype Male. Measurements: Size and general proportions as in ster- 

 nadens, being slightly larger; total length 1.8 mm. Uniform reddish-brown with 

 palpi paler. Pubescence abundant, long, bristling, and rufous. 



