Sweltsa yurok, Stark & Baumann, 2007

Stark, Bill P. & Baumann, Richard W., 2007, Sweltsa Yurok (Plecoptera: Chloroperlidae), A New Stonefly From California, U. S. A., Illiesia 3 (10), pp. 95-101 : 98-100

Sweltsa yurok , sp. n.

( Figs. 13-22 )

Material examined. Holotype ♂ and ♀ paratype from California, Humboldt Co., 2.3 miles E Berry Summit, Hwy 299, 20 May 2001, B. Stark, K.W. Stewart, deposited in the United States National Museum ( USNM). Additional paratypes: California: Humboldt Co. , Captain Creek , Chezam Rd, 13 May 2006, J.J. Lee, 8 ♂, 1 ♀ ( BYU). Humboldt Co. , unnamed stream, Redwood Creek Trailhead, near Orick, Redwood National Park , 1 June 1991, R.W. Baumann, B.P. Stark, 2 ♂, 4 ♀ ( BYU). Same site, 20 May 2006, J.J. Lee, 2 ♂ ( BYU). Humboldt Co. , Willow Creek , Hwy 299, 2.7 miles E Berry Summit, 19 May 1998, B.P. Stark, C.R. Nelson, S.W. Szczytko, I. Sivec, 2 ♂, 2 ♀ ( BPS, BYU). Humboldt Co. , tributary seeps Willow Creek , Hwy 299, 2.4 miles E Berry Summit, 19 May 1998, B.P. Stark, C.R. Nelson, S.W. Szczytko, I. Sivec, 50 ♂, 29 ♀ ( BPS, BYU, SWS). Humboldt Co. , tributary seeps Willow Creek , Hwy 299, 2.5 miles E Berry Summit, 19 May 1998, B.P. Stark, C.R. Nelson, S.W. Szczytko, I. Sivec, 2 ♂, 5 ♀ ( BYU, SWS). Humboldt Co. , Spring stream, Hwy 299, mile 31.33, upper Willow Creek drainage, 13 May 2006, J.J. Lee, 14 ♂, 7 ♀ ( BYU). Same site, 19 May 2006, J.J. Lee, 13 ♂, 5 ♀ ( BYU). Same site, 3 July 2007, J.J. Lee, 6 ♂, 4 ♀ ( BYU). Humboldt Co. , Slide Creek , near Fish Lake , Rd 13 N01, 23 June 2005, J.J. Lee, 3 ♂, 5 ♀ ( BYU). Humboldt Co. , unnamed creek, mile 4.1 near Fish Lake , Rd 13 N01, 20 April 2006, J.J. Lee, 8 ♂, 4 ♀ ( BYU). Humboldt Co. , seep near Fish Lake , Rd 13N01, 0.25 miles from Hwy 96, 20 April 2006, J.J. Lee, 1 ♂ ( BYU). Humboldt Co. , Mason Gulch Creek , Hwy 299, mile 29.68, near junction Willow Creek , 3 July 2007, J.J. Lee, 21 ♀ ( BYU). Lake Co. , East Fork Middle Creek, 0.5 mile above Middle Creek Campground, 23 April 1987, R.W. Baumann, B.P. Stark, C.R. Nelson, S.A. Wells, 3 ♂, 1 ♀ ( BYU).

Adult habitus. General color pale yellow brown with dusky brown markings on head and pronotum ( Fig. 13 ). Head and pronotal disk setae with brown freckle spots around base. Legs pale, wings transparent with pale brown veins; M and CuA veins darker. Dark brown median abdominal stripe extends through tergum 7 on female and to anterior margin of tergum 8 in male.

13

16

Male. Forewing length 8.0-9.0 mm. Bare epiproct tip rounded or triangular in dorsal aspect, wide basally and narrowed apically ( Figs. 14 , 17-18 ); lateral margins slightly curved beyond midlength in some specimens; dorsal and much of lateral surfaces clothed with dense pile of golden brown setae except for tip ( Figs. 17-19 ); apex of epiproct foot shaped in lateral aspect and upturned near tip, but without setae on “heel” and on ventrolateral surface ( Fig. 19 ); ventral margin strongly narrowed and blade like; epiproct base wider with bare shoulders ( Figs. 17, 20 ); stalk of epiproct densely hairy. Tergum 9 with a median, bare knob near anterior margin ( Fig. 15 ). Aedeagus membranous but with a pair of small, ventroapical lobes bearing a few setae.

Female. Forewing length 9.0-10.0 mm. Subgenital plate outline triangular, apex entire or with a shallow apical notch ( Figs. 16 , 21 ). Plate extends over basal third of sternum 9.

Egg. Length about 0.31 mm, width about 0.25 mm. Outline oval, collar absent, but a bare low knob is present in the collar region. Chorion coarsely punctate throughout; pit size variable but largest pits about 4-5 µm in diameter ( Fig. 22 ). Micropylar orifices small and strongly slanted.

Larva. Unknown.

Etymology. The species name, used as a noun in apposition, honors the Yurok people of California.

Diagnosis. The new species is most similar to S. tamalpa but males of these species are distinguished on the basis of epiproct shape and setation. In S. tamalpa the epiproct base is usually completely bare, and the epiproct tip is not bent dorsad at the “ankle” region, whereas in S. yurok the epiproct base has a setose band extending between the bare lateral shoulders to the base, and in lateral aspect the epiproct apex is distinctly foot shaped with tip upturned at the “ankle”. The third member of the group, S. pisteri , differs from both species in lacking the foot shaped apical region of the epiproct, and in having more-or-less parallel margins for most of the dorsal length of the epiproct. Females of these species may be inseparable based on subgenital plate morphology, however the eggs of S. pisteri ( Fig. 6 ) have much more prominent and numerous chorionic punctations than do those of S. yurok ( Fig. 22 ) and S. tamalpa ( Fig. 12 ), and the latter species has a more conspicuous non-punctate apical area than S. yurok . The following key is offered to assist in identification of males of this group.

Figures

Figs. 13-16. Sweltsa yurok. 13. Head and pronotum, 14. Male terminalia, dorsal, 15. Male terminalia, lateral, 16. Female terminalia, ventral.

Figs. 17-22. Sweltsa yurok (17, 22: tributary Willow Creek, 2.4 miles E Berry Summit, Humboldt Co., CA; 18-20: Mile 4.1, Rd 13N01, Humboldt Co., CA; 21: Slide Creek, Humboldt Co., CA). 17. Dorsal aspect male epiproct, 18. Lateral aspect epiproct, 19. Epiproct apex, lateral aspect, 20. Epiproct base, dorsal aspect, 21. Female terminalia, ventral, 22. Egg.

Figs. 1-6. Sweltsa pisteri (1-5: Irish Gulch Creek, Mendocino Co., CA; 6: Caspar Creek, Mendocino Co., CA). 1. Male terminalia, dorsal aspect, 2. Epiproct, dorsal aspect, 3. Epiproct, lateral aspect, 4. Epiproct apex, lateral aspect, 5. Epiproct base, dorsal aspect, 6. Egg.

Figs. 7-12. Sweltsa tamalpa (Woodacre, Marin Co., CA). 7. Male terminalia, dorsal aspect, 8. Epiproct, dorsal aspect, 9. Epiproct, lateral aspect, 10. Epiproct base, dorsal aspect, 11. Female abdominal sterna 8-9, 12. Egg.