A fourth species of the stygobiontic elmid genus Typhloelmis Barr was discovered during a survey of groundwater-dependent invertebrates in the Trans-Pecos region of West Texas. Typhloelmis spangleri Barr, new species is herein described, diagnosed, and illustrated with images of the habitus and male genitalia. Notes on the morphology and an image of a larva collected in association with the adults, assumed to be that of the new species, are included. A revised key to the genus, with figures of all known species, and an updated distribution map are furnished. In addition, a second occurrence of Typhloelmis finegan Barr, previously known only from the type locality, is reported. Typhloelmis spangleri occurs at two springs adjacent to the Rio Grande/Rio Bravo in the Lower Canyons reach. The springs discharge from the western portion of the regional Edwards-Trinity Aquifer karst system, formed in Cretaceous-aged carbonates. The groundwatershed is unknown, but likely lies northwest of the springs. Species in the genus are isolated from one another, but all occur in springs of the Edwards-Trinity Aquifer within the Rio Grande/Rio Bravo watershed.