Old-growth habitat associations and phylogeography of Phellopsis obcordata (Coleoptera: Zopheridae) in the southern Appalachian Mountains

The zopherid beetle, Phellopsis obcordata (Kirby 1837), is a flightless, fungivorous species that is thought to be an indicator of old-growth forest (i.e., with no history of logging) throughout its range. We found 144 individuals of P. obcordata on or around host fungi in high elevation zones from western North Carolina to southern Virginia. The 15 sites where beetles were found represented three forest communities: northern hardwood (n=5), conifer-northern hardwood forest (n=5), and montane spruce-fir (n=5). All sites were either reference old-growth sites or were determined to be likely old-growth sites based on host tree diameter and stand basal area. Phellopsis obcordata adults were most commonly found on a newly documented host, Fomitopsis ochracea, which grows on dead and dying softwood trees, including Eastern Hemlock (Tsuga canadensis) and Fraser Fir (Abies fraseri). Using 36 haplotypes of the mitochondrial COI gene, we find that northern and southern clades were likely isolated across the Ashville Basin 3.7 million years ago. Range expansion and contraction likely influenced the current genetic patterns seen in the southern clade, but more data is needed to investigate this fully.