Fourteen reciprocal crosses between 11 populations (demes) of troglobitic (obligately cavernicolous) Ptomaphagus beetles were made. Numbers of F1 and F2 larvae and adults are reported. Markedly lower fecundity (but not fertility), viability, and longevity in the hybrids between morphologically distinct populations from Alabama caves indicate substantial reproductive isolation. This and distributional data suggest that the morphologically distinguishable populations are full species.
The Canadian Entomologist
Department of Biology

Peck, S. (1983). Experimental hybridizations between populations of cavernicolous ptomaphagus beetles (Coleoptera: leiodidae; cholevinae). The Canadian Entomologist, 115(5), 445–452. doi:10.4039/Ent115445-5