30 NEOTROPICAL PSELAPHIDAE 



body; the eleven-segmented antennae and well-developed vertexal foveae of 

 euasthetines are especially pselaphoid. 



Finally, a summary of the pselaphid anatomy and ecology suggests the 

 following definition of the family: Pselaphidae is a consistent assemblage of 

 some 4700 described species of brachyelytrous beetles belonging to the super- 

 family Staphylinoidea ; the family has a cosmopolitan distribution, reaching a 

 maximum of speciation and complexity in the tropical regions; the stratum of 

 competition is chiefly the forest floor mold, although grassland and the so- 

 cieties of ants and termites have been invaded; as a group, the family is 

 predaceous, with well-developed mandibles; the active period is during the 

 night, especially the hours at and after dusk; they are characterized by a 

 compact body plan in which there is a tendency for sutures, especially gular 

 and sternal, to be reduced or absent, with foveae abundantly and diversely 

 developed ; the vertex almost always bears a pair of vertexal foveae ; antennae 

 are highly variable, usually clavicom, of from two to eleven segments, and 

 diverse in stmcture; form may be both specific and sexual; the articulation 

 of antennae to head is usually more restrictive than in allied families, being 

 by means of a flexure of the basal antennomere to the dorsal surface of the 

 acetabulum; labial palpi are small and conservative, of from one to two seg- 

 ments; maxillary palpi are peculiarly labile, usually four-segmented, and 

 usually with an apical palpal cone; the abdomen has little dorso-ventral play, 

 and typically has five visible tergites and six visible sternites; the aedeagus 

 is a specialized organ of oxyteline affinities, tending to reduction of parts and 

 bilateral asymmetry; the tarsi are three-segmented with the possible ex- 

 ception of two aberrant genera; the larval stage is staphyliniform, similar to 

 larvae of Bledius in the two species investigated by Boving and Craighead 

 (I.e.) ; the size range of pselaphid imagines varies from 0.6 to 5.5 millimeters. 



