1968] 
Peck — Catopid Beetle 
97 
forced into caves to find these conditions, and the populations were 
isolated by extinctions of the local epigean species members. This 
phenomenon also seems to be responsible for the evolution of most of 
the few tropical troglobitic beetles. 
Perhaps the best faunaliy explored tropical caves are in the Congo 
Republic of Africa. A number of beetles live in these caves, but very 
few display any degree of cave adaptation (Leleup 1956). Most 
troglobites of temperate caves are derived from groups which are 
extensively humus and moss inhabitants in montane forests. The high 
forests of the central African mountains support a rich humus-in- 
habiting beetle fauna. The lack of African cave beetles may then 
be explained by the possibility that Pleistocene climatic alterations 
were not severe enough in the central African mountains to sufficiently 
depress the montane forest zones. The forests and their humus 
faunas were not able to reach into the lowland Congo cave region. 
The preadapted humus fauna never had access to the caves (Leleup 
1956). 
The possible climatic changes during the Pleistocene in Mexico 
are poorly documented. However, since glacial moraines exist some 
2000 m below the present glaciers of some of the highest Mexican 
mountains, we may assume that the montane forests of the past en- 
joyed conditions that were cooler and more moist than today. It is 
significant that in the known Mexican cave carabid beetle fauna, 
reviewed by Barr (1966b), the majority of the troglobites are from 
caves at high altitudes. It is similarly significant that P. troglomexi- 
canus , the first described Mexican troglobitic catopid, occurs in a 
cave at an elevation of 2160 meters. All other Mexican cave Ptoma- 
phagus that I have seen (six undescribed species from 12 caves) are 
from lower elevation caves and with one exception do not display 
modifications for cave life. These latter species may not display cave 
adaptations because they may be only recently isolated in caves by 
extinctions or emigrations of the surface populations, or they may 
be species that find caves to be as suitable a habitat as nearby 
epigean environments. The suggested moss or humus-inhabiting 
epigean species, or its descendant, ancestral to P. troglomexicanus, 
may still exist at higher elevations. These possibilities can be an- 
swered only by further collecting in the rich and varied environ- 
ments found in Mexico. 
Literature Cited 
Barr, Thomas C., Jr. 
1963. Studies on the cavernicole Ptomaphagus of the United States 
(Coleoptera: Catopidae). Psyche, 70: 50-58. 
