Packardesmus, Shear & Shelley, 2019

Shear, William A. & Shelley, Rowland M., 2019, Solved after 140 years: the identity of the millipede Polydesmus cavicola Packard, 1877, and proposal of Packardesmus n. gen. (Diplopoda: Polydesmida: Macrosternodesmidae), Zootaxa 4559 (2), pp. 384-390 : 386

Packardesmus , new genus

Type species: Polydesmus cavicola Packard, 1877 .

Diagnosis. At this time, Packardesmus is the only known North American polydesmidan genus in which the males have 18 trunk rings (females have 19 rings); a few polydesmidan species with 18-ringed males are found in Mexico, the West Indies and elsewhere. In addition, the gonopods have a unique, hand-like appearance (with only four fingers; Figs. 4–7 ) due to the elongated femoral region of the gonopod and the basal fusion of the branches; only the solenomere branch (s, Fig. 6 ) can be confidently homologized with the branches of the gonopod in other macrosternodesmid genera due to this fusion. Other characters as described for the lectotype and newly collected material.

Distribution. Known only from the type locality of the single included species, but possibly more widely distributed.

Etymology. Named for pioneering speleobiologist A. S. Packard, with the combining stem – desmus, used frequently for polydesmidan millipedes.

Figures

FIGURES 1–7. Packardesmus cavicola. Fig. 1. Head, antennae, collum and first three rings of male, ventrolateral view. Fig. 2. Head, collum and first four rings of male, dorsal view. Fig. 3. Rings 12 and 13 of male, dorsal view. Fig. 4. Gonopods, ventral view. Fig. 5. Right gonopod, posteroventral view. Fig. 6. Apex of left gonopod, ventral view; s, solenomere, p, pore. Fig. 7. Gonopods, posterior view.