The geologic structure of the Appalachian Valley has contributed to intense speciation in Pseudanophthalmus. The process of imbricated thrust faulting has produced numerous small, isolated, irregularly distributed outcrops of caverniferous limestones. The cave systems of such areas have been independently colonized by endogenous, epigean, ancestral species.
These colonies have been extrinsically isolated and have undergone a limited amount of evolution since the time of their entry into the cave systems. The slight divergence between many closely related species and the presence of vestigial eyes in four species (petrunkevitchi, hoffmani, hortulanus, and vicarius) suggest relatively recent isolation in caves. Cave colonization almost certainly dates from the Pleistocene, and in many cases, probably from the Sangamon interglacial period. (Barr 1965)
Pseudanophthalmus petrunkevitchi is a rare species of cave beetle found in Virginia, in the Page and Warren counties. They are believed to inhabit less than a handful of sites, usually occupying the same cave as they have no intentional means of scattering between places. They have been found under rocks and other natural materials alongside moist and wet areas in dim lighting, as seen in the lower level of Skyline Caverns.
Only eight beetles have been found. A single female beetle was collected by J.R. Holsinger at Woods Cave and the rest at Skyline Caverns.
Pseudanophthalmus petrunkevitchi is born without eyes or an optic nerve due to its evolution in darkness. They lack flight wings as well. They measure around 3-7mm, similar to a grain of rice. They have a depigmented appearance, an amber-like color. These characteristics make it extremely difficult to spot them in the depths of a cave.
Not much is known about their life cycle, breeding, or feeding habits.
Most of what is known about this genus is from research by J. Manson Valentine and John R. Holsinger, along with studies by René Jeannel and Thomas C. Barr, Jr. about Appalachian Pseudanophtalmus.
Photo courtesy of James St. John
References:
Barr TC. 1965. The Pseudanophthalmus of the Appalachian Valley (Coleoptera: Carabidae). American Midland Naturalist. 73(1):41–72. https://doi.org/10.2307/2423320
St. John J. 2016. Pseudanophthalmus petrunkevitchi (Petrunkevitch’s cave beetle) (Skyline Caverns, Virginia, USA). https://www.flickr.com/photos/jsjgeology/26455791184/.
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