Petra Shear, Marek, Bond & Wesener, 2022

Shear, William A., Marek, Paul E., Bond, Jason E. & Wesener, Thomas, 2022, The millipede family Striariidae Bollman, 1893. VII. Petra sierwaldae, n. gen., n. sp. a minute millipede from Idaho, USA (Diplopoda, Chordeumatida, Striariidae), Zootaxa 5213 (3), pp. 287-293 : 288-289

Petra Shear, Marek, Bond & Wesener , new genus

Type species: Petra sierwaldae Shear, Marek, Bond & Wesener , new species

Diagnosis. A genus of Striariinae composed of a single species, distinct from other small striariids in having a single ommatidium on each side of the head (om, Fig. 2 ), a notch in the collum at the position of the outermost metazonital seta (cn, Fig. 2 ), absence of coxal flasks on the third legs (L3, Fig. 6 ), characteristically modified coxae of the fifth legs ( Fig. 7 ) and the telopodites of the ninth legs enveloping the gonopods at rest ( Fig. 9 ). None of these characters are found in previously described genera of striariids.

Etymology. The genus name is feminine in gender and honors our respected colleague, mentor, and friend, Dr. Petra Sierwald, Curator of Arachnida and Myriapoda at the Field Museum of Natural History, Chicago, IL, USA, in recognition of her many contributions to Myriapodology, Arachnology, and to natural history collections and education.

Description. As for the single species described below.

Distribution. Currently known from only four localities in Kootenai County, Idaho, USA.

Notes. This genus is part of a complex of genera yet to be described that includes very small species (<5 mm long) with subequal crests, distributed from northern California to the Puget Sound region of Washington, but is a geographic outlier found in northern Idaho. The biogeographic connections between northern Idaho and the Cascade and Coast Ranges further west, despite the intervening arid Snake River Plain, are well known and extend to both floristic and faunistic evidence (Brunsfeld et al. 2011; Richart & Hedin 2013; Shelley 1990).

Figures

FIGURES 1–4. Male paratype (FMNH) of Petra sierwaldae n. gen., n. sp. 1. Lateral view of anterior end showing head, collum and anterior rings. 2. Collum, lateral view. 3. Rings 2–6, dorsal view. 4. Telson and posterior rings, oblique view. Abbreviations: numerals, ring numbers; cn, notch in collum; hp, hypoproct; L(numeral), leg numbers; om, ommatidium; pp, paraproct; tel, telson.

FIGURES 5–8. Male paratype (FMNH) of Petra sierwaldae n. gen., n. sp. 5. Labrum, mandible and first leg pair, ventral view. 6. Leg pairs 3–5, ventral view. 7. Coxae of leg pair 5, posterior view. 8. Specialized setae of base of prefemur 4. Abbreviations: L(numeral), leg numbers; lab, labrum; m, mandible.

FIGURES 9–14. Male paratype (FMNH) of Petra sierwaldae n. gen., n. sp. 9. Gonopods and leg pair 9, anterior view. 10. Right gonopod, mesal view, anterior to the right. 11. Coxotelopodites leg pair 9, posterior view. 12. Right gonopod, mesal view, anterior to the right. 13. Right gonopod, lateral view, anterior to the left. 14. Coxotelopodite of left leg 9, posterior view. Abbreviations: aac, anterior angiocoxite; cx, gonopod coxa; cc, colpocoxite; cxp, coxal process; fc, flagellocoxite; pac?, posterior angiocoxite; s, sternum; t9, telopodite of leg 9.