Revision of the Eurycea quadridigitata (Holbrook 1842) Complex of Dwarf Salamanders (Caudata: Plethodontidae: Hemidactyliinae) with a Description of Two New Species

Abstract: The Eurycea quadridigitata complex is currently composed of the nominate species and E. chamberlaini, with no other species recognized. However, recent molecular studies have revealed at least five genetic lineages within this species complex, with one lineage more closely related to the neotenic Eurycea species of central Texas and E. chamberlaini nested within E. quadridigitata sensu lato. We use large-scale geographic sampling in combination with a multilocus species delineation method and morphology to test whether these genetic lineages represent distinct species under the general lineage concept of species. We describe two new species of salamander from this complex, resurrect and elevate a former subspecies to full species status, add to the diagnosis of E. chamberlaini, and redefine E. quadridigitata in the context of this revision. All five species are diagnosable from one another through a number of meristic, morphometric, molecular, and ecological criteria.