116 



NEOTROPICAL PSELAPHIDAE 



Table II 



COMPARISON OF DALMOSELLA AND MELBA 



Dalmosella tenuis Casey 



Capitulate setae on ventral face of head. 



Melba thoracica (Brendel) and 

 Melba sulcatula Casey- 

 Capitulate setae on ventral face of head. 



Tenth antennal segment transversely tri- 

 angular and bilaterally asymmetrical. 



Tenth antennal segment lenticular and prac- 

 tically bilaterally symmetrical. 



Vertexal foveae large and pubescent. 



Vertexal foveae smaller and nude. 



Arcuate vertexal sulcus wide, coarse, distinc- 

 tive. 



Arcuate vertexal sulcus simple, only mod- 

 erately developed. 



Pronotum with a strong, biarcuate trans- 

 verse sulcus which cuts the lateral wall 

 near base each side, the resulting constric- 

 tion being distinctive. The anterior margin 

 at the lateral end of the sulcus is dis- 

 tinctly tufted with setae. 



Pronotum with the biarcuate transverse sul- 

 cus near basal third, narrowing the pro- 

 notal outline but not cutting the lateral 

 margin in this manner, but passing simply 

 down each pronotal flank. The sulcus not 

 tufted laterally with setae. 



Lateral pronotal foveae not visible from 

 above, but pubescent. 



Lateral pronotal foveae not visible from 

 above, and nude. 



Basal elytral foveae pubescent. 



Basal elytral foveae nude. 



Elytral flank with a cariniforra line which is 

 parallel to the margin from origin at basal 

 third to apex. 



Elytral flank with an oblique line which 

 arises near middle of flank and extends 

 obliquely to apex. A striking structural 

 difference. 



First tergite slightly constricted at base. 



First tergite not constricted at base. 



Males with seven, females with six ster- 

 nites. Seventh male stemite a simple oval, 

 asymmetrically articulated pygidium. 



Males with seven, females with six ster- 

 nites. Seventh male sternite a simple, oval 

 to suboval, asymmetrical articulated 

 pygidium. 



Male mesothoracic femora simple. 



Male mesothoracic femora inflated and with 

 sensory pores, under high magnification. 



Male tibiae simple. 



Male second sternite very greatly modified: 

 integument extended into a broadly tri- 

 angular lobe which extends posteriorly 

 from basal two-thirds for the median fifth 

 of width; this lobe is heavily pubescent 

 and overhangs an equal depression pos- 

 teriorly. In lateral view this pubescent 

 lobe is distinctive. On each side of the 

 apical depression is a small, erect, obtuse 

 spine. (See plates). 



Male mesothoracic tibiae with a copula- 

 tory pad on mesial face at apical third, 

 the pad being made up of a differential 

 number of padules, at high magnification. 



