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Studies in American Pselaphidae with Particular 

 Reference to the Tropical Areas 



Orlando Park 

 Northwestern University 



GENERAL CONSIDERATIONS AND THE COLLECTING OF 

 PSELAPHIDAE 



Twenty years ago I collected my first pselaphid beetle. Since then my 

 general interest in Coleoptera has narrowed gradually, and although other 

 groups have held my attention, I invariably returned to a study of the "ant- 

 beetles". The last ten years have been spent in a rather constant study of 

 this family of beetles. The word constant is used in a relative sense, implying 

 devotion to these insects as much as feasible amidst the normal confusion of 

 academic duties. 



Pselaphidae are difficult to collect. Their habitats are usually dark and 

 secluded. The species are inconspicuously colored, a yellowish or reddish brown 

 being the average color pattern. Pselaphids are of minute size and many 

 crouch when uncovered, often with the head, antennae, and legs more or less 

 concealed by the body. Some of the beetles letisimulate when touched {Tmesi- 

 phorus, Rhexidius, Melba). 



In general, for the purposes of collecting, the family can be divided into 

 two sections. This division follows a rather basic separation of the family 

 with regard to their ecological requirements, e.g. those forms inhabiting de- 

 caying plant debris (the mold species) and secondly, those forms entering into 

 the complex society of ants (the myrmecocolous species). However, some 

 pselaphids appear to be equally at home in both niches, e.g. Tmesiphorus 

 costalis (Park, 1933), Batrisodes globosus (Park, 1929, 1932b, 1935a, b), and 

 again, pselaphids may be found less frequently in the nests of termites and 

 other habitats not enumerated. 



I. The Mold Species. The majority of species of the family are found 

 in the various types of mold. The Euplectini and Trichonychini are especially 

 characteristic of plant debris, and with the exception of the Clavigerinae, most 

 of the other genera are found here at one time or another. 



Plant mold can be imperfectly divided into two closely related categories: 

 the mold of decaying logs (particularly the more advanced stages of the log 

 decay cycle, in which the sapwood and heartwood have undergone consider- 

 able decay and can be easily crumbled with the fingers, although the early 

 stage where the bark is loose and the sapwood still firm and moist may be rich 



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