Shear, W.A. & Marek, P.E. (2026) Additions to the millipede family Caseyidae Verhoeff, 1909. VI. Proposal of the new subfamily Opioninae, new species and records of the genus Opiona Chamberlin, 1951 and synonymy of Speyosia Causey, 1963 with Opiona (Diplopoda, Chordeumatida, Striariidea). Zootaxa, 5792 (1), 35–60.