1977] 
Peck — Small Carrion Beetle 
305 
A large number of cave populations are known. It could be 
expected that the beetles might be reproductively active in caves 
throughout much (if not all) of the year, because of the decreased 
seasonal variation of climatic factors in cave environments. How- 
ever, collections or observations are not adequate enough to test 
this suggestion. 
Reproduction. Larvae for the species have been long known, 
and are illustrated in Boving and Craighead (1931). Although it 
should not be difficult to keep and rear the beetles (methods in 
Peck, 1973, 1975) I know of no data on eggs, egglaying, or larval 
stages and their biology, other than Johnson’s (1975) observation 
that larvae are most commonly associated with the dry stage of 
decomposition. 
Evolution and Biogeography. The distribution of Prionochaeta 
and of other members of the Cholevini suggests that they origi- 
nated in the Old World. Probably only one species of Priono- 
chaeta migrated into the New World across a Bering land bridge in 
the Tertiary (see Hopkins, 1967, for a discussion of the Tertiary 
Bering Bridge). Although the genus must then have lived in 
western North America, it became extinct there (probably by the 
Pleistocene), and survived only in eastern North America. The 
resulting generic distribution in eastern North America and in 
eastern Asia is a not uncommon type of disjunct pattern (Darling- 
ton, 1957). It is believed here that the abundance of cave popula- 
tions in the southern part of the species range is a reflection of 
distributional adjustments in the present post-glacial. Since the 
beetles apparently require a cool and moist temperate habitat, as 
climatic conditions have warmed, the beetles have become less able 
to survive in the now less-temperate southern forests where they 
lived during the Wisconsinan glacial. Caves, with their seasonally 
more uniform, cool and moist conditions, have thus become 
Recent southerly refugia for this beetle (although some southern 
forest populations yet remain) as they have for several other insects 
(Peck and Russell, 1976). 
Acknowledgements 
Henry Dybas, Hugh B. Leech, Vern Pechuman, John Law- 
rence, Herbert Boschung, John Kingsolver, Milton W. Sanderson, 
Roland L. Fischer, and J. M. Campbell allowed study of the 
collections under their care. 
