EUPLECTINI 99 



This key does not take into account myrmecophilus, 2 mm. long, erected 

 on the male sex and said by Raffray to be near nitidus but to have a shorter, 

 more anteriorly narrowed head and rounder tempora. 



The species of the genus may be listed as follows: 



bicolor Raffray. 1909. Argentina. 



capitatus Raffray. 1909. Argentina. 



lenticornis Raffray. 1909. Argentina. 



longulus Raffray. 1909. Argentina. 



myrmecophilus Raffray. 1912. Argentina, (con Atta hystrix) 



nitidus Raffray. 1898. Argentina. Genotype. 



simplex Raffray. 1909. Argentina. 



EUPLECTUS (Leach, 1817) 



Like Juhus and Eurhexius, this is an important genus in the grasping of a 

 generalized conception of the family (PI. XII, 5, 6; XIII, 8; V, 3). Not only 

 is it one of the older genera in the taxonomic literature, but it is one of the 

 largest genera in the family. It contains some 102 described species, and is 

 practically cosmopolitan in distribution. The taxonomy of the genus is in a 

 highly confused state, and much research needs to be done on the fauna, from 

 a world viewpoint, before subgeneric division can be thoroughly attacked, and 

 certain constituents placed in new genera to give a homogeneous assemblage. 

 Virtually all students of the family have had the genus under study and have 

 contributed to our sum of information. 



The faunal area under discussion here, namely the American neotropics, 

 is much more easily handled, since Euplectus is relatively very poorly repre- 

 sented. This is oddly similar to the situation in Thesiastes, suggesting again 

 that Euplectus has had its center of dispersal elsewhere, and has spread slowly 

 from North America into the neotropics. 



In this vast region being examined there are certainly five, possibly seven, 

 species of Euplectus, as contrasted with some twenty-three to twenty-seven 

 species known in North America north of the Rio Grande river. Despite this 

 small number of neotropical species, it is difficult to key out the species without 

 direct examination of the types, since descriptions of several are generic rather 

 than specific; the species are based on a specimen of unknown sex in some 

 cases, in one case on a single female, and the males of only four species are 

 known. 



Sex in Euplectus is quickly diagnosed. The females have six visible ster- 

 nites; the males have seven visible sternites, of which the seventh is longi- 

 tudinally carinate. This carina may be median or slightly asymmetrically 

 placed ; it may be straight or oblique ; it may be convex to the right or convex 

 to the left. These variations of the carina of the seventh stemite are species 

 specific, and should form the basis for a reexamination of the genus. The carina 

 of the seventh stemite, as noted previously, is not in reality a true carina, 

 but marks the median union of a right and left pygidial plate or valve of the 



