64 NEOTROPICAL PSELAPHIDAE 



The so-called second claw is always in the nature of an appendage, even 

 in Trichonyx, Oropits and other typical trichonychide genera. That is to say — 

 the large claw is in every case perfectly in the plane of the axis of the tarsus, 

 the auxiliary claw projecting laterally from its base." 



I have the same feeling concerning the evaluation of the tarsal claws as 

 Casey, and consequently treat the two groups of genera as one tribe, Euplectini. 

 Without going into lengthy detail here, since species descriptions can be studied 

 by anyone interested in the problem, slide mounts of tarsi under high magnifica- 

 tion show the truth of the inapplicability of the secondary tarsal claw as a prime 

 character. Thus the North American specialized Rhinoscepsis histriatus Le- 

 Conte has a secondary claw over half as long and a third as thick as the primary 

 claw. Again, although one of the new species from Central America, Panara- 

 mecia williamsi, has a secondary claw fully half as long as the primary claw, 

 most of its anatomy indicates a position near such euplectine genera as Bib- 

 loplectus, Pteroplectus and Rameda. 



The Euplectini is a very large tribe, with an average size which is small, 

 even for the family; they are very difficult to study. Of cosmopolitan distribu- 

 tion, the group has a combination of characters which almost always renders 

 tribal designation simple. Few pselaphid genera of other tribes are confused 

 with euplectines, although exceptions can be found; for example, Eupsenius of 

 the Brachyglutini has many characteristic euplectine features. 



Euplectines have the typical three-segmented pselaphid tarsus, with the 

 first tarsomere very minute, and the second and third tarsomeres relatively very 

 much larger than the basal segment. The articulation of the trochanters with 

 the femora is typically brachysceline ; that is, the trochanter is short and not 

 clubbed apically but very obliquely articulated with the femur so that the latter 

 closely approaches the coxa. The mentum is not greatly expanded transversely 

 to cover the mouth-parts as in the Jubinini, but is normally small, and the 

 cardo of each maxillary palpus is also normally small and not externally pro- 

 duced at the base in a long spinoid process. Finally, the posterior (metatho- 

 racic) coxae are very transverse, save at the mesial face where they articulate 

 with the trochanter of the posterior legs; this mesial, articulating face is ab- 

 ruptly conical, or conically produced instead of being globular or broadly tri- 

 angular. 



The maxillary palpi are relatively primitive for the great majority of the 

 species, being four-segmented with the first segment very minute; second seg- 

 ment elongate, slightly arcuate, narrow basally and slightly clubbed or inflated 

 apically; third segment shorter than second, globular, triangular or pyriform; 

 fourth segment largest, oval or fusiform, more or less rounded-truncate at base, 

 acuminate at apex, the latter bearing a small, usually aciculate palpal cone. 



The dorsal surface of the head (vertex, front), antennal insertions, form 

 of the antennal segments, pronotum, abdomen and tarsal claws are diverse in 

 the tribe. Such variation is specific, but in many instances sexual, and this- 

 diversity is demonstrated in the keys, descriptions and illustrations which 

 follow. 



