68 NEOTROPICAL PSELAPHIDAE 



Ventral surface of head with no capitate setae, the setae present 

 being simple, acute, recurved; basal tergites with a pair of 



short basal carinae on disc of segment 



EUPLECTUS (in part) 



17 (15) . Pronotum with both the transverse sulcus and the median longi- 



tudinal sulcus rudimentary and just discernible. RHEXINIA 

 Pronotum with both transverse and longitudinal sulci strongly- 

 formed and clearly visible 18 



18 (17). Lateral pronotal margins entire 19 



Lateral pronotal margins either crenulate or dentate 20 



19 (18). Pronotum as wide as head; first tergite very large, much longer 



than second tergite ADROGASTER 



Pronotum much wider than head; first tergite only a little 

 longer than second tergite ANARMODIUS 



20 (18). Lateral pronotal margins crenulate APORHEXIUS 



Lateral pronotal margins with five to six teeth (PI. VIII, 10) 

 EURHEXIUS (in part) 



21 (10). Front of head prolonged into either (a) an elongate rostrum, 



or (b) a median spinoid process, or (c) a dilated process 



extending far beyond antennal insertions 22 



Front of head not abnormally prolonged in any of these ways. . 23 



22 (21). Restricted to termite nests; front irregular and abnormal, pro- 



longed far beyond antennal insertions PHTEGNOMUS 



Not inhabiting termite nests; front prolonged into a conspicu- 

 ous antennal rostrum, with antennae articulated at the distal 

 end of this tubercle, nearly contiguous; vextex and genae 

 with complex, tortuous sulci (PI. IX, 2) . . .RHINOSCEPSIS 



23 (21). First three tergites highly abnormal in male sex (female un- 



known), the lateral margins of first two tergites being deeply 

 concave and polished; sides of third sternite extending dor- 

 sally as an apically fimbriated, rounded lobe to clasp the pos- 

 terior angle of the second tergite; a tuft of scales in a slight 

 depression, above each lobe {ex Fletcher) ... .ALLOBROX 

 Tergites not so modified in either sex 24 



24 (23). Pronotum with a median, obtuse but well developed, longi- 



tudinal carina passing over the disc NEODALMUS 



Pronotal disc simple and unmodified, or centrally foveate, or 

 longitudinally sulcate, but never with a median longitudinal 

 carina 25 



25 (24). Pronotal disc simple, with no trace of fovea or sulcus 29 



Pronotal disc either centrally foveate, or longitudinally medi- 

 anly sulcate 26 



26 (25) . Pronotal disc with a median longitudinal sulcus 41 



Pronotal disc centrally foveate or with a central foveoid de- 

 pression 27 



