Sierracapnia, Bottorff & Baumann, 2015

Bottorff, Richard L. & Baumann, Richard W., 2015, Sierracapnia, A New Genus Of Capniidae (Plecoptera) From Western North America, Illiesia 11 (9), pp. 104-125 : 105-108

Sierracapnia , new genus

Type Species. Sierracapnia barberi (Claassen 1924) .

Adults. Body length 5-7 mm; color dark brown to black; wings macropterous, forewing R1 vein curved forward near origin of RS vein and A 1 curved beyond crossvein a; cerci long, 14-18 segments. Ventral sclerites of adult thorax identical to those reported for Arsapnia and Capnia s. s. ( Table 1 in Murányi et al. 2014). Drumming signals unknown.

Male. Median knobs absent on terga 1-6; large median raised knob present on tergum 7; median knob absent on tergum 8; pair of smaller raised knobs present on tergum 9, located on each side of epiproct apex; tergal knobs densely covered with rounded tubercles of conical sensilla. Epiproct a single sclerotized member, elongated and laterally compressed, with a curved ventral keel (deep or shallow) positioned between tergum 9 knobs; pair of dorsolateral horns pointing anteriorly and with slightly divergent tips. Epiproct basal sclerite present (small to large) and fused to main epiproct sclerite; laterobasal sclerites large and fused to main epiproct sclerite. Epiproct base with a narrow or thick neck in lateral view. Epiproct apex thin, rounded, or wedge-shaped in dorsal view. Epiproct glabrous, except caudal setae present. Anterior half of epiproct surface covered with numerous shallow sensory pits, each with a small pointed projection in the center; sensory pits less abundant or absent from epiproct neck and base. Epiproct dorsal membrane extends longitudinally for more than one-half epiproct length; membrane linearly folded and with anterior eversible crest that expands or contracts in size. Subgenital plate broadly fused with sternum and tergum 9 (see Fig. 35 in Murányi et al. 2014 for definition of terms). Ventral vesicle absent. Fusion plate ( Hanson 1946) a long narrow internal structure largely hidden behind broad triangular paraprocts that are covered with stout hairs or spines, fusion plate apex exposed with a small tubular opening that fits into epiproct base, retractoral plate a thin sclerite separated from fusion plate ( Figs. 4 , 12 , 32 , and see Figs. 23 -31 in Murányi et al. 2014).

Female. Subgenital plate large and heavily sclerotized, covering all of sternum 8 and posterior margin of sternum 7; division line between sterna 7 and 8 not always obvious; posterior margin of plate broadly truncated at posterior edge of sternum 8, plate not projecting onto sternum 9. Dorsum of abdominal segments 1-8 with median membranous band; posterior margin of segment 8 with small median V-shaped sclerite.

Larva. Unknown.

Diagnosis. Murányi et al. (2014) provided a diagnosis of Capnia s. s. Pictet 1841 and concluded that eight species, primarily from the Palaearctic, were included in this restricted concept of the genus. Capnia nearctica Banks 1919 , the only Holarctic species, has a distribution in North America that includes Alaska and northwestern Canada ( Nelson and Baumann 1989, Stewart and Oswood 2006, DeWalt et al. 2015).

Males of Sierracapnia differ from Capnia s. s. by their epiproct and knobs on tergum 9. Sierracapnia males have an undivided epiproct with distinct dorsolateral horns and prominent knobs on tergum 9. Capnia s. s. males have an epiproct divided into upper and lower members, but lack dorsolateral epiproct horns and knobs on tergum 9. In addition, Sierracapnia males have a basal sclerite and large laterobasal sclerites fused to the main epiproct sclerite, whereas in Capnia s. s. the basal sclerite is vestigial and the laterobasal sclerites are divided from the main epiproct sclerite ( Murányi et al. 2014). The retractoral plate is separated from the fusion plate in Sierracapnia males, but the retractoral plate is fused to the fusion plate in Capnia s. s. males. The subgenital plate of Sierracapnia female adults is broad, heavily sclerotized, and extends from sternum 8 to the posterior half of sternum 7, whereas in species of Capnia s. s. this plate is small and does not extend onto sternum 7.

Sierracapnia and Arsapnia adults also differ. The glabrous epiproct of Sierracapnia males is laterally compressed and the ventral surface is most often deeply curved (less deeply curved in S. palomar ), while for Arsapnia males the epiproct has a narrow apical tip, laterally expanded bulb-like midsection (often with a row of stiff setae or spines), narrowed posterior neck, and straight ventral surface (Figs. 209-210 in Nelson and Baumann 1989). The epiproct of Sierracapnia males has a basal sclerite, but this sclerite is lacking or vestigial for Arsapnia males ( Murányi et al. 2014). The dorsolateral horns of Sierracapnia are prominent, long structures that originate near mid-epiproct and project or arch forward about 15-30% of epiproct length. In contrast, the dorsolateral epiproct projections of Arsapnia are small, closely appressed to the main body, and confined to the anterior quarter. The dorsal epiproct membrane of Sierracapnia is often clearly exposed for over one-half of the epiproct length and the apex forms an eversible crest of linearly folded tissue that expands and contracts in size. In contrast, the epiproct dorsal membrane of Arsapnia is confined to a small, narrow area near the tip and the large eversible crest is absent. Sierracapnia males have well-developed knobs on tergum 9, with prominent rounded conical sensilla. These knobs are lacking on most species of Arsapnia , but tiny processes are present on three species: A. pileata (Jewett 1966) , A. teresa (Claassen 1924) , and A. utahensis (Gaufin and Jewett 1962) . Sierracapnia female adults have a broad, heavily sclerotized subgenital plate that extends onto the posterior margin of sternum 7, while this plate is small and does not extend onto sternum 7 in Arsapnia females.

Both S. palomar and Arsapnia arapahoe ( Nelson and Kondratieff 1988) have linear or fusiform epiprocts that differ from the typical forms found in all other species of both genera. Yet each species has characters that are most similar with their respective genus. That is, S. palomar has a laterally compressed, glabrous epiproct with shallow ventral keel, a large basal sclerite fused to the epiproct, and a median dorsal groove that extends the full epiproct length ( Figs. 13-15 ). In addition, median knobs are present on terga 7 and 9. In contrast, A. arapahoe has a slightly recurved epiproct that lacks a ventral keel ( Fig. 4 in Nelson and Kondratieff 1988) and exhibits some dorsoventral flattening in the anterior third. Its median dorsal groove extends to one-half the epiproct length and a dorsal row of 4-6 anteriorly directed stiff setae or spines occur on each side of the median groove in the anterior third. A median knob is present on tergum 7, but the pair of knobs is absent from tergum 9.

Sierracapnia demonstrates similarities with the three species of the Capnia mariposa species group sensu Nelson and Baumann (1989), especially with C. giulianii Nelson and Baumann 1987 and C. mariposa Nelson and Baumann 1987 . In these two species, the epiproct exhibits varying degrees of lateral compression, a keeled ventral surface, dorsolateral horns, a large exposed dorsal membrane, and an eversible crest, plus tergum 9 has a pair of median knobs. Additionally, the C. mariposa species group is restricted to the Sierra Nevada. The Capnia mariposa group was excluded from Sierracapnia because all three species lack a knob on tergum 7 and the dorsolateral horns are small and restricted to the tip of the epiproct.

The identification key for Capnia males in Nelson and Baumann (1989) separates Sierracapnia (then defined as the C. barberi species group) from nine other Capnia species groups and several unplaced species found in North America, but does not separate Capnia species groups found in the Palaearctic. With the exceptions noted above for three Arsapnia species , Sierracapnia differs from Arsapnia and all other Capnia species groups of North America by having distinct median knobs on terga 7 and 9, and lacking knobs on tergum 8. Further, except for two species of the Capnia mariposa group, Sierracapnia is unique among all other Capnia species groups of North America by having a laterally compressed epiproct.

Distribution. The greatest diversity of Sierracapnia species is found in the Sierra Nevada; this includes S. barberi , S. mono , S. shepardi , and S. yosemite ( Figs. 39 , 40 ). Closely adjacent to the eastern Sierra Nevada, two species, S. hornigi and S. washoe , occur in the White Mountains and northwestern Nevada, respectively. The distribution of S. barberi extends northward into the southern Cascade Range. Sierracapnia palomar , which occurs on several mountains of southern California, lies outside the rather compact distribution of the other six species of the genus. In addition to the distributional separation of S. palomar , the shallow ventral curve and general linear proportions of its epiproct are obvious differences from the typical form of Sierracapnia . Nevertheless, this species was included in Sierracapnia because it bears knobs on terga 7 and 9 and its glabrous narrow epiproct has a ventral curved surface, dorsolateral horns, long membrane groove, and an apical eversible crest.

The distributions of Capnia s. s. and Sierracapnia do not overlap in western North America: Capnia s. s. occurs in the far north; Sierracapnia is found much further south in California and Nevada. In contrast, overlap exists in the distributions of some Sierracapnia and Arsapnia since the latter has a wide range in western North America, occurring from the central and southern Rocky Mountains to the Coast Range. Members of several other Capnia s. l. species groups overlap broadly in their ranges with Sierracapnia , Arsapnia , and Capnia s. s. in western North America. Sierracapnia species inhabit midelevation, perennial, streams and creeks.

Etymology. The name Sierracapnia reflects the primary Sierra Nevada distribution of the genus.

Figures

Figs. 34-37. Sierracapnia yosemite. Male: Tuolumne River, California: 34. Genitalia, lateral, epiproct, knob on tergum 7 and knobs on tergum 9. 35. Genitalia, dorsal, epiproct and knobs on tergum 9. 36. Epiproct, lateral, apex. 37. Knob on tergum 7, anterior.

Fig. 1-4. Sierracapnia barberi. Male: 1. North Fork Cosumnes River, California. Genitalia, dorsal, epiproct. 2. North Fork Cosumnes River, California. Genitalia, lateral, epiproct and knob on tergum 7. 3. Sierra Canyon Creek, Nevada. Knob on tergum 7, dorsal, anterior. 4. Sierra Canyon Creek, Nevada. Tip of paraprocts and fusion plate (center prong), ventral, terminal.

Figs. 9-12. Sierracapnia mono. Male: 9. Zephyr Cove, Nevada. Genitalia, dorsal, epiproct and knob on tergum 7. 10. Zephyr Cove, Nevada. Genitalia, lateral, epiproct and knobs on tergum 9. 11. Slinkard Creek, California. Knob on tergum 7, anterior. 12. Clear Creek, Nevada. Tip of paraprocts and fusion plate showing tube, dorsal, terminal.

Figs. 26-33. Sierracapnia washoe sp. n. 26. Jenny Creek, Nevada. Male. Genitalia, dorsal, epiproct and knob on tergum 7. 27. Cedar Hill Canyon Creek, Nevada. Male. Genitalia, lateral, epiproct, knob on tergum 7 and knobs on tergum 9. 28. Cedar Hill Canyon Creek, Nevada. Male. Epiproct, dorsal. 29. Cedar Hill Canyon Creek, Nevada. Male. Epiproct, lateral and knobs on tergum 9. 30. Jenny Creek, Nevada. Male. Knob on tergum 7, anterior. 31. Jenny Creek, Nevada. Male. Epiproct with expanded eversible crest, dorsolateral, terminal. 32. Jenny Creek, Nevada. Male. Tip of paraprocts and fusion plate inserted into epiproct base, terminal. 33. Cedar Hill Canyon Creek, Nevada. Female. Genitalia, subgenital plate on sterna 7 and 8.

Figs. 21-25. Sierracapnia washoe sp. n. Cedar Hill Canyon Creek, Nevada. 21. Male. Genitalia, lateral, epiproct, knob on tergum 7 and knob on tergum 9. 22. Male. Genitalia, lateral, close up, eversible crest, dorsolateral horn, neck and caudal setae. 23. Male. Genitalia, dorsal, epiproct, knob on tergum 7 and knobs on tergum 9. 24. Male. Epiproct, dorsal, close up. 25. Female. Genitalia, subgenital plate, sclerotized areas on sterna 7 and 8.

Figs. 13-16. Sierracapnia palomar. Male: 13. Headwaters North Fork San Jacinto River, California. Genitalia, dorsal, epiproct and knobs on tergum 9. 14. Headwaters North Fork San Jacinto River, California. Genitalia, lateral, epiproct and knob on tergum 9. 15. Fry Creek, California. Terminalia, lateral, epiproct, knob on tergum 7 and knob on tergum 9. 16. Fry Creek, California. Knob on tergum 7, dorsolateral.

Fig. 39. Distributional map of Sierracapnia spp.: barberi (red), hornigi (purple), mono (dark green), palomar (light blue), washoe (yellow), and yosemite (dark blue).

Fig. 40. Distributional map of Sierracapnia shepardi.

Tables

Table 1. Characters of Sierracapnia adult males. Ab7=abdominal segment 7, EP=epiproct, and EP neck (see Fig. 22).

Sierracapnia	n	Ab7 knob	Ab7 knob width/ Ab7 width (%)	EP apex shape	EP width/ EP length (%)	EP depth/ EP length (%)	EP Membrane color	Horn length/EP length (%)	Horn tip/EP length (%)	EP Neck
barberi	5	thin, unnotched	9-13	thin, sharp	15-21	30-35	light	22-25	70-78	narrow
hornigi	5	thin, small notch	11-16	rounded	17-24	19-24	light	15-18	76-85	narrow
mono	5	wide, deep notch	30-40	thin, sharp	16-23	32-35	light	16-20	67-75	thick
palomar	5	thin, small notch	13-17	wedged	13-15	12-14	light	15-17	92-95	narrow
shepardi	5	wide, deep notch	29-32	rounded	17-25	18-20	dark	14-18	80-86	narrow
washoe	5	wide, deep notch	30-36	rounded	22-26	22-26	dark	24-29	83-88	narrow
yosemite	5	thin, notched tip	14-15	rounded	18-24	25-30	light	18-21	85-88	narrow