Orchesella celsa: A hyper-variable species or a loosely defined species group?

Orchesella celsa sensu Christiansen and Bellinger (Collembola: Entomobryidae) is a widespread species exhibiting a broad array of color patterns and occupied habitats. Generally, species exhibiting these characteristics are species complexes. To assess whether O. celsa is really a clade of distinct cryptic species, we conducted a rigorous molecular phylogeographic investigation with cytochrome oxidase II and 5'-3' exoribonuclease II sequences acquired from exemplars from numerous recent collections of Orchesella made throughout the southeastern United States. Our results indicate that O. celsa is actually a group of at least seven species having distinct color patterns, chetotaxy, and often discernible habitat preferences, and that high-elevation species  O. gloriosa is a member of what we now refer to as the O. celsa species group.  Research into the other North American species of Genus Orchesella shows that multiple cryptic species exist within each currently described species, as well as numerous undescribed species.