A Revision of Tomoceridae (Insecta: Collembola) in Great Smoky Mountains National Park and Southern Appalachians Using Morphological and Molecular Approaches

Large, heavily scaled tomocerid springtails (Collembola) are abundant in eastern forests, and are important components of the detrital food web. The genus Pogonognathellus predominates in the southern Appalachians While a number of well-delimited tomocerid species have been described, others have vague morphological boundaries and appear to be species complexes. Before this study began in 2005, four species were known to occur in Great Smoky Mountains National Park (GSMNP) and the surrounding Appalachians (P. bidentatus, dubius, elongatus, flavescens). Also occurring throughout the area is Tomocerus lamellifera, a widespread and distinctive species. The goals of this project were to correlate scale patterns and colors, ground color, morphology, and DNA sequences for separation of species; to describe any new species detected; and to redescribe known species. Scale patterns and molecular sequences have not been previously studied in North American Tomoceridae.
We collected 432 specimens from diverse localities and maintained them in culture containers. After a specimen molted, it was photographed to capture the pristine scale pattern and color, then preserved in 100% ethanol (EtOH). The preserved specimen then was re-photographed for ground color (most scales are dislodged in preservative). Selected specimens were dissected and the various appendages (legs, mouthparts, furcula) were slide-mounted for morphological analysis. The torso was used to obtain DNA, from which the 5’-3’ exoribonuclease II gene was amplified, sequenced, and analyzed phylogenetically. Freshly collected specimens of P. flavescens from the type locality (Sweden), preserved in 100% EtOH, were provided by Arne Fjellberg and included in the analysis. Tomocerus minor and Harlomillsia oculata (Oncopoduridae) were used as outgroups for the phylogenetic analysis.
A phylogenetic tree based on the molecular sequences was used to indicate relationships that then were tested with morphological characters, chaetotaxy, scale pattern, and color. Putative P. flavescens from North America were not grouped with Swedish specimens, raising the possibility that P. flavescens does not occur in North America. Pogonognathellus nigritus, previously synonymized with P. elongatus, was determined to be a valid species, and P. elongatus itself was found to be mis-described in most accounts. Two new species were identified: one from a cave in GSMNP which is closely related to a California cave species, and a second from several forest localities (i.e. GSMNP and Mount Mitchell, NC). A group of specimens ascribed to the flavescens/dubius complex also appear to represent several undescribed species, but more specimens are needed for further analysis.