A New Thai Millipede Species of the Genus Coxobolellus Pimvichai, Enghoff, Panha & Backeljau, 2020 (Diplopoda: Spirobolida: Pseudospirobolellidae)

A new millipede species of the genus Coxobolellus is described from Mae Hong Son Province, Thailand: Coxobolellus sirin-dhornae sp. nov. The new species is defined by its gonopod morphology and COI DNA barcodes. These latter place the new species within the well-supported Coxobolellus clade. The new species exhibits four gonopod synapomorphies that are diagnostic for the genus: (1) a protruding process on the coxae of the 3rd (and sometimes 4th) pair of male legs, (2) large, triangular coxae on the 4th and 5th pairs of legs, (3) a short process on the preanal ring extending to or slightly beyond the anal valves, and (4) the posterior gonopod telopodite divided into two parts, with a conspicuous pore opening at the mesal margin at the end of the coxal part. The new species is included in an updated morphological identification key for all currently recognized Coxobolellus species.