174 NEOTROPICAL PSELAPHIDAE 



Casey (1897) 



Raffray (1891, 1896, 1900, 1904, 1908, 1911, 1912) 



Leng (1920) 



Bowman (1934) 



This is a genus of moderate size, holding eleven species. The group is wholly 

 neotropical with the exception of the genotype, Pselaptus belfragei LeConte 

 which is distributed sparingly from central Texas to southern California. This 

 latter species has apparently evolved from the Central American group, as the 

 center of the genus appears to be in northern South America, the species hav- 

 ing radiated south into Brazil and Argentina, north-east via the Lesser Antilles 

 into Cuba, westward into Venezuela and Columbia and from this point up 

 the Isthmus into Guatemala and Mexico. 



The genus is specialized and belongs to a section of the tribe {Xybarida, 

 Berdura, Scalenarthrus, Pselaptus, Mitona, Xybaris, Cryptorhinula) holding 

 species which have many features in common, and very difficult to separate 

 effectually. Pselaptus has been isolated in the key by certain structural char- 

 acters, from its allies. The size is small (1.0 to 1.4 mm. in length), with smooth 

 integuments which are usually glabrous and shining, but may be dull and un- 

 polished in some species. The metasternum is large and usually concave in 

 the male sex, variously formed. Thus the male politissimus has the metasternum 

 elevated and triangular ; in the male sternalis and cristatus the metasternum is 

 concave, and in sternalis at least this concavity is wide, squamous. The females 

 have the metasternum flattened (grouvellei) . 



The key is both tentative and incomplete, although it will serve to isolate 

 the majority of the known species. I have found that the group of genera 

 clustering about Scalenarthrus is one of the more difficult taxonomic areas 

 in the family, generic limits not being too well drawn and many new species 

 undoubtedly awaiting discovery. 



Species known only from the Antilles 2 



Species of Central and South America 3 



2. Male metasternum large, entirely and deeply concave, with carinoid 



lateral margins, the concavity provided with squamous pubescence ; 

 1.4 mm. long; known only from the southeastern end of the Antilles 



(Grenada) sternalis 



Metasternum not of this character; known only from Cuba, .longiclava 



3. Base of pronotum with a fine crest anteriad of scutellum; area of pro- 



notum occupied by lateral subbasal foveae of other genera here oc- 

 cupied by confluent punctures; 1.25 mm. long; known from Mexico 

 and said by Raffray (1904, p. 250) to resemble the Grenadine 



sternalis! cristatus 



Pronotum without these features 4 



4. Species known only from Guatemala 5 



Species known south of the Isthmus of Panama 6 



5. Antennal segments III-VIII small; IX slightly wider than eighth, 



quadrate, as long as wide; X similarly quadrate but larger than 



