74 NEOTROPICAL PSELAPHIDAE 



EURHEXIUS (Sharp, 1887) 



This is the largest of American eurhexiform genera (Raffray's second 

 group of Trichonychini, 1908), containing about 25 species. Its central taxo- 

 nomic position (analogous to Jubus in Jubinini) in the eurhexi forms, numer- 

 ous species and wide distribution (Uruguay to Guatemala) make its exami- 

 nation necessary. The species all have a homogeneous habitus. Size range is 

 large, from one to nearly four millimeters, with a thick body and integument 

 more or less granulate and pubescent. The head is very transverse, subreni- 

 form, with prominent tempora. Maxillary palpi typically four-segmented, first 

 segment small, short; second longer than wide, slender basally, inflated apically, 

 sinuate; third small, much shorter but slightly wider than second; fourth 

 large, ovoid-acuminate to subsecuriform, heavily pubescent. Antennae eleven- 

 segmented as usual, slightly geniculate, first segment relatively long and 

 cylindrical; second globular; third to seventh submoniliform, narrower than 

 second, with some variation in the species as to length and width of seg- 

 ments; club foraied of the last three segments which gradually increase in 

 width and length as a rule, the last segment being much larger than the tenth 

 as a rule, acute-pyriform to obtuse-conical. Ventral surface of the head with 

 the sulciform fossa for reception of the maxillary palpus on each side, well 

 developed as typical for the eurhexiform genera. Pronotum (PI. VIII, 10) 

 cordiform, conspicuously narrowed anterior of the middle, but not forming a 

 small pedunculate lobe as in Rhexius; disc crossed by a narrow, deep, entire 

 longitudinal median sulcus and a subbasal transverse sulcus; lateral margins 

 always armed with teeth, usually six in number, these teeth varying in size 

 from very large spine-like projections {sexpunctatus Raffray) to minute teeth 

 {muticus Raffray), but always present and always discrete, not merging to 

 form a crenulate margin as in the North American Rhexidius and the neo- 

 tropical Rhexinia and Aporhexius. Elytra subquadrate, with rounded humeri; 

 each elytron with three or four basal foveae (usually four). Abdomen large, 

 usually longer than elytra, and strongly margined. Tergites subequal or slightly 

 shorter in progression. Six relatively simple sternites in both sexes, making 

 sexual differentiation difficult or very doubtful without dissection. Prosternum 

 flat, transverse, laterally carinated on each side. Tarsi three-segmented, first 

 tarsomere small, second and third much longer than the first, with the second 

 usually slightly thicker and much longer than third; two unequal claws, the 

 external claw large, over half as long as the inner claw. 



With his usual acumen, Fletcher (1928) has observed that in setting up 

 the genus Eurhexius, Sharp (1887) did not specify lateral pronotal teeth in 

 vestitus, parviceps, ventralis, and trimiodes, nor show pronotal teeth in his 

 figure of vestitus. Such negligence on the part of Sharp has left some doubt as 

 to the composition of Eurhexius, and as Fletcher noted, if Sharp's species (of 

 which I have not seen the types) do not have pronotal teeth, then Rhexidius 

 Casey (August, 1887) of North America becomes a synonym of Eurhexius 

 Sharp (April, 1887) of the American tropics. I doubt this very much, especially 

 since Raffray (1903, 1908) definitely allocates Sharp's four species in Eur- 



