98 NEOTROPICAL PSELAPHIDAE 



primary claw and the accessory is little more than a bristle, visible under high 

 magnification. The eleventh antennal segment often has a distinct sensory 

 patch on the apico-lateral face. The ventral surface of the head bears a few 

 spiniform, strongly capitate setae, quite different from the simple aciculates 

 of Euplectus, or the simple capitulates of the melbaforms. 



The neotropics have but two species: 



argus (Reitter). 1883. Chile. (Euplectus) 

 liliputanus Raffray. 1904. Grenada, Windward Islands. 

 Both of these belong in Group I of Raffray (1904, p. 543) , having the head 

 as long as wide, relatively small, strongly narrowed apically; the antennal 

 club large with the ninth and tenth segments transverse ; the first two tergites 

 transversely impressed at base. It is of interest to point out that this first 

 generic group also includes the North American species [atratus Casey, 

 debilis (LeConte), fossulatus (Brendel), and pumilus (LeConte), indicating 

 that the American species as a whole have a common ancestry, with the 

 neotropical forms having migrated southward. 



PTERACMES (Raffray, 1890) 

 schaufussi Raffray. 1890. Chile. Genotype. 



LIOPLECTUS (Raffray, 1898) 



This strange genus is confined to Argentina and since all of the species 

 have been described by Raffray, his 1908 key is given with slight modification: 



Body very flat 2 



Body more or less convex 4 



2. Abdomen much longer than elytra; head much larger than wide; 



antennal segments IV to VIII moniliform, IX transverse. . .nitidus 

 Abdomen slightly longer than elytra; head not longer than wide 3 



3. Antennal segments IV to VII moniliform, VIII not much wider but 



slightly transverse, IX similar to eighth but a little wider, X strongly 

 transverse and nearly concave, close to the eleventh; 1.8 mm. long 



longulus 



Antennal segments IV to VII moniliform but progressively more 

 transverse, IX and X very transverse and nearly lenticular; 1.9 

 mm. long lenticornis 



4. Body elongate and parallel but slightly convex; length 1.8 mm. 



simplex 



Body less elongate, less parallel and much more convex 5 



5. Head normal with a simple parabolic sulcus and the front not exca- 



vated ; length 1.75 mm bicolor 



Head very flat, occiput transversely impressed and the front of the 

 head (anterior of middle of vertex) slightly excavated; length 2.2 

 mm capitatus 



