Pseudosinella dubia Christiansen 1960 was described from specimens collected in four caves of Washington County, Arkansas (Christiansen, 1960). Christiansen and Bellinger (1998) documented another Washington County cave record, and Peck and Peck (1982) recollected the species from one of the original four localities. Gardner (1986) reported a Pseudosinella collection from a cave in Dent County, Missouri, which was subsequently identified as P. dubia by K. Christiansen (pers. comm., 2009). Although two recent biological inventories have been conducted in Arkansas caves, no additional records of P. dubia were reported (Graening et al., 2003; Graening et al, 2006). On 11 January 2003, GOG, DBF, R. Stark, and A. Harris collected various collembolans from Oklahoma's largest cave, the Duncan Field System (Adair County), in an attempt to acquire specimens needed to describe a new species endemic to this cave (Pseudosinella sp. nov. “AB”, reported in Christiansen and Bellinger, 1996). Instead, 5 specimens of Pseudosinella dubia were collected (out of 20 observed) and identified by K. Christiansen (Grinnell College, Grinnell, Iowa). This is the first record of P. dubia in Oklahoma and represents a western range extension of 27 km from the cluster of caves in Arkansas. Although P. dubia shows no clear troglomorphism, it has never been collected outside caves (K. Christiansen, per. comm., 2009). Specimens are retained in the personal collection of K. Christiansen.