Stegostriaria dulcidormus Shear & Marek, 2022

Shear, William A. & Marek, Paul E., 2022, The milliped family Striariidae Bollman, 1893. V. Stegostriaria dulcidormus, n. gen., n. sp., Kentrostriaria ohara, n. gen., n. sp., and the convergent evolution of exaggerated metazonital crests (Diplopoda, Chordeumatida, Striarioidea), Zootaxa 5094 (3), pp. 461-472 : 463-467

Stegostriaria dulcidormus Shear & Marek , new species

Figs 1–18

Types: Male holotype and male paratype from Sweet Home Road , 4 miles WNW of Upper Soda, Linn Co., Oregon, USA, 44.40845°N, - 122.3843°W, 1680’ asl, collected 2 July 2001 by Jessica Rykken. Parts of the holotype are mounted on SEM stub WS34-2 and parts of the paratype on SEM stub WS10-1. Male and female paratypes from Forest Road 14, 2.2 miles NE of State Route 22, Siuslaw National Forest, Tillamook Co., Oregon, USA, 45.22483°N, - 123.83867°W, 900’ asl, collected 10 December 2005 by C. Richart and W. Leonard. Parts of the male paratype are mounted on SEM stub WS34-3. Male paratype from Munson Creek Falls State Natural Site, Munson Creek Road, 1.5 miles E of Federal Highway 101, Tillamook Co., Oregon, USA , 45.3650°N, - 123.7790°W, 1710- 1750’ asl, collected 3 April 2008 by C. Richart and S. Derkarabetian. All types including SEM stubs deposited in the California Academy of Sciences , San Francisco, California, USA .

Etymology: The species name is a Latin neologism, a noun in apposition composed of the words dulcis (sweet) and dormus (home), and refers to the holotype locality.

Diagnosis: See the diagnosis of the genus, above. This is the only known species.

Description: Male paratype from Sweet Home Road. Length ca. 8.5–9.0 mm, width ca. 0.8–1.0 mm. Thirty postcephalic rings including telson.

Head densely setose, with light, pebbled sculpture; labrum (lab) smooth, labral corners rounded, without projecting hook ( Fig. 1 ); 5–7 poorly pigmented ommatidia on each side.Antennae short, robust. Mandibular stipes with finely saw-toothed distal edge and blunt apical lobe ( Fig. 1 ).

Collum broadly expanded, with 10 low crests occupying posterior 5/6 th. Second ring with all crests subequal. Second crests slightly exaggerated on third ring; on subsequent rings second crests 4–5 times higher than others, intercalary crests developing between median sulcus and first pair of crests ( Figs 2–4 ). Limbus of metazonites serrate ( Fig. 5 ). Metazonital setae not observed, possibly absent.

Telson with deep incisions between lobes ( Fig. 4 ); without crests, sculpture of low tubercles each with two posterior-pointing, acute processes ( Fig. 6 ).

First legpair enlarged, larger than second or third legpair, set with long, needle-like, apically bifurcate setae; tarsi with ventral comb of flattened, twisted setae ( Fig. 1 ). Second leg pair with reduced telopodites ( Fig. 7 ); coxae (cx2) enlarged, bearing opening of vas deferens (vd), with prominent anterior process (cp2) set with long, serrate setae; prefemora (tr2) somewhat enlarged, also with serrate setae ( Fig. 8 ). Third legpair with long, curved coxal flasks (cf) directed posteriorly, anterior row of curled setae, telopodites a little larger than those of second legs ( Figs 7, 9 ). Fourth legpair coxae (cx4) bearing posteriodistal lobe (cxl4), telopodites enlarged ( Fig. 7 ). Fifth and sixth legpairs with enlarged, but not flattened telopodites ( Fig. 7 ). Seventh legpair with enlarged coxae (cx7) bearing strong lobes ( Fig. 10 ), telopodites elongate, prefemur distally swollen ( Fig. 7 ). All legs with scattered, flattened setae with finger-like projections ( Fig. 11 ) becoming longer and more slender on distal podomeres, transitioning on tarsi to flattened, serrate-edged setae with long, filamentous projections ( Fig. 12 ).

Gonopods ( Figs 13–17 ) small, complex. Gonopod sternum completely encircling gonopods but for small median posterior gap, with central knob and lateral flaring wings (s, Figs 13, 14 ). Coxae elongate laterally, possibly fused in midline, with two groups of setae (cx, Fig. 14 ). Anterior angiocoxites (aac, Figs 13–17 ) divided, anterior branch (ab, Fig. 17 ) apically blunt, posterior branch (pb, Fig. 17 ) with 3 or 4 long, acute apical processes; seen basally in anterior view, anterior angiocoxite supports linear array of long, thin, curved processes forming a comb ( Fig. 17 ). Posterior angiocoxites (pac, Figs 13–17 ) complexly lobed, basally with irregular array of fimbriae ( Figs 15 , 17 ). Colpocoxites not divided, present as acuminate lobe divided into many fimbriae (cc, Figs 15 , 17 ). Ninth leg pair strongly reduced, sternum (s9), coxae (cx) and telopodites (t9) fused ( Fig. 18 ); coxae with bifurcate distomesal processes (cp, Fig. 18 ); telopodites largely smooth, lobed, with tuft of stout setae (t9, Fig. 18 ).

Female paratype closely similar to male in all nonsexual characters.

Distribution: Known only from Linn and Tillamook Counties in Oregon, USA. The Tillamook localities are within 10 miles of each other, but are separated by about 90 miles from the Linn locality; despite this distance, specimens from the two regions are morphologically inseparable. This species should be looked for in the intervening region.

Figures

FIGURES 1–6. Stegostriaria dulcidormus n. gen., n. sp., male paratype. 1. Head and leg 1, ventral view. 2. Midbody rings, lateral view. 3. Midbody rings, oblique dorsal view. 4. Rings 25–29 and telson, dorsal view. 5. Limbus, dorsal view. 6. Sculpture of telson, dorsal view.

FIGURES 7–11. Stegostriaria dulcidormus n. gen., n. sp., male paratype. 7. Legpairs 2–7, ventral view. 8. Coxae and prefemora of legpair 2, ventral view. 9. Sternum and coxae of legpair 3 and coxae and prefemora of legpair 4, ventral view. 10. Coxae of legpair 7, anterior view. 11. Setae from prefemur of legpair 6, ventral view.

FIGURES 12–15. Stegostriaria dulcidormus n. gen., n. sp., male paratype. 12. Tarsal setae of legpair 34, lateral view. 13. Gonopods, anterior view. 14. Gonopods, ventral view. 15. Gonopods, posterioventral view.

FIGURES 16–23. New species of striariid millipeds. Figs 16–18. Stegostriaria dulcidormus n. gen., n. sp., male paratype. 16. Right gonopod, lateral view, anterior to the left. 17. Left gonopod, mesal view, anterior to the left. 18. Legpair 9, anterior view. Figs 19–23. Kentrostriaria ohara n. gen., n. sp., male holotype. 19. Left leg 2, posterior view. 20. Gonophore, anterior view. 21. Right gonopod, anterior view. 22. Left gonopod, anteriomesal view.