Petra sierwaldae 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 : 289-290

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

Figs 1–14

Types: Male holotype, two male paratypes and three female paratypes from Beauty Creek , Panhandle National Forest , 47.6018°N, - 116.6405°W, collected 4 November 2004 by W. Leonard, C. Richart and J. Baugh; male paratype from Beauty Creek Road ( FSR438 ), 1.3 mi SE of SR97, 698' asl, 47.6015°N, - 116.6579°W collected 18 October 2009 by W. Leonard and C. Richart; Beauty Creek , 2.5 mi E of Lake Coeur d'Alene, 3202' asl, 47.6124°N, - 116.6355°W, 14 April 2004, W. Leonard, J. Baugh; male paratype from Bumblebee Creek , Panhandle National Forest , 2240' asl, 47.6325°N, - 116.2965°W, 6 November 2004, W. Leonard, C. Richart, J. Baugh. All localities are in Kootenai County, Idaho, USA. Parts of a male paratype are on SEM stub WS36-16. All specimens, including SEM stubs, deposited in Field Museum of Natural History , Chicago IL, USA ( FMNH) .

Etymology. As for the genus, the specific epithet is a patronym in honor of Petra Sierwald.

Diagnosis. As for the genus, see above.

Description. Based on male holotype from Beauty Creek. Length, 3.8 mm, greatest width 0.56 mm. Twentyeight rings (collum + 26 leg-bearing rings + telson).

Head ( Figs 1, 2 , 5 ) densely setose, with single ommatidium (om, Fig. 2 ) on each side. Lateral corners of labrum (lab, Fig. 5 ) rounded. Mandibular stipes (m, Fig. 5 ) with distal, short, acute process.

Collum (col, Fig. 1 ) with distinct anterior rim, notched at position of lateralmost segmental seta (cn, Fig. 2 ), crests short, limited to posterior fourth of collum, sixth crest marginal.

Subsequent rings ( Figs 1, 3 ) with crests extending full length of metazonite, subequal in height. Metazonital setae long, with brush-like tips.

Telson (tel, Fig. 4 ) short, lacking crests, lateral lobes suppressed but middle lobe obvious. Spinnerets directed posterioventrad. Paraprocts (pp, Fig. 4 ) with three setae, ornamented with elongate tubercles. Hypoproct (hp, Fig. 4 ) with two setae, similar tubercles.

First leg pair (L1, Fig. 5 ) encrassate, without needle-like setae, few flattened, twisted setae on distal podomeres. Second leg pair (L2, Fig. 1 ) reduced, femora clavate. Leg pairs 3–7 strongly encrassate, third leg pair (L3, Fig. 6 ) lacking coxal flasks; fourth leg pair (L4, Fig. 6 ) the largest, coxae slightly excavated anteriorly; coxae of fifth leg pair (L5, Fig. 6 ) enlarged, with blunt anterior lobes set with acute tubercles ( Fig. 7 ); sixth and seventh leg pair coxae unmodified. Proximal segments of all legs ornamented with typical flattened setae ( Fig. 8 ).

Gonopods ( Figs 9, 10, 12, 13 ) with broad sternum (s, Fig. 9 ) bearing lobes extending laterally. Coxae (cx, Figs 9, 13 ) with 3–5 setae, long coxal process (cxp, Figs 10, 12, 13 ) parallels anterior angiocoxites (aac, 9, 10, 12, 13). Posterior angiocoxae (pac?, Fig. 12 ) sheaths single, large flagellocoxite (fc, Figs 12, 13 ). Colpocoxite (cc, Figs 10, 12, 13 ) as elongate, fimbriate, weakly sclerotized branch. Tips of gonopod elements insert into cavities in ninth leg pair telopodites (see Fig. 9 ). Ninth leg pair ( Figs 11, 14 ) with weak, narrow sternum, coxae and telopodites appearing fused; coxal part with mesal group of acute setae, telopodite portion laterally heavily tuberculate, with setae somewhat ensiform, mesally a large, smooth lobe envelopes tips of gonopods. Tenth coxae unmodified, with gland openings.

Female paratype similar to male but lacking secondary sexual modifications, 4.2 mm long.

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.