Rowlandesmus Shear & Marek, 2021

Shear, William A. & Marek, Paul E., 2021, Three new genera and eighteen new species of miniature polydesmid millipedes from the northwestern United States (Diplopoda, Polydesmida, Polydesmidae), Zootaxa 4975 (1), pp. 81-126 : 111

Rowlandesmus Shear & Marek , new genus

Type species: Rowlandesmus millicoma Shear & Marek , new species.

Species included: Rowlandesmus millicoma n. sp. and R. dentogonopus, n. sp.

Diagnosis. In their somatic characters, the two species of this genus are similar in nonsexual traits to the others described here, except that the metzonital tubercles carrying setae are generally lower and the surface of the metazonites of the midbody rings nearly smooth. The distinction lies in the gonopods Figs 88–90 , 93, 94 , 131, 132 ), in which the acropodite is sharply bent and reflexed in its distal third to half. Just distal or just proximal to this "kink" in the gonopod (k, Fig. 88 ) is a short process. The pulvillus is basal to the “kink” and in R. millicoma , much expanded.

Etymology. The genus is named for our late and much respected colleague, Rowland M. Shelley (1942–2018), one of the most productive millipede taxonomists of 20th and 21st centuries. He initiated the modern study of the small polydesmids of western North America with careful redescriptions of known genera and species and the description of Retrorsia Shelley, 2003 .

Distribution. Douglas and Coos Cos., Oregon.

Notes. We are placing both of these species in Rowlandesmus due to the similarity of the gonopods, with a sharp bend or “kink” in the acropodite causing the distal third to be reflexed at a right or lesser angle in relation to the basal part. Nevertheless there are some differences, and subsequent species discoveries may result in the two species being separated.

Figures

FIGURES 85–90. Rowlandesmus millicoma, n. gen., n. sp. 85. Head and anterior rings, dorsal view. 86. Midbody ring, dorsal view. 87. Pygidium, lateral view. 88. Gonopods in situ, lateral view. 89. Same, ventral view. 90. Same, ventrolateral view. SEM stub 33-5. Abbreviations: k, “kink” in gonopod; p, pulvillus; x, y, z, processes of terminal zone.

FIGURES 91–95. Rowlandesmus dentogonopus, n. gen., n. sp. 91. Head and anterior rings, dorsal view. 92. Pygidium, lateral view. 93. Right gonopod, mesal view. 94. Left gonopod, lateral view. 95. Midbody ring, dorsal view. SEM stub WS33-4. Abbreviations: k, “kink” in gonopod, p, pulvillus; x, y, processes of terminal zone.

FIGURES 127–132. Drawings of gonopods of polydesmid species. 127. Tip of gonopod of Retrorsioides castellum, n. sp., mesal view. 128. Right gonopod of Retrorsioides linnensis, n. sp., lateral view. 129. Left gonopod of Retrorsioides kittitas, n. sp., lateral view. 130. Right gonopod of Retrorsioides bannerti, n. sp., lateral view. 131. Right gonopod of Rowlandesmus millicoma, n. sp., mesal view. 132. Right gonopod of Rowlandesmus dentogonopus, n. sp., lateral view. Abbreviations: adp, anteriorly directed process; p, pulvillus; pf, prefemorite; pp, pulvillar process; tz, terminal zone.