Lednia sierra, Baumann & Kondratieff, 2010

Baumann, Richard W. & Kondratieff, Boris C., 2010, The Stonefly Genus Lednia In North America (Plecoptera: Nemouridae), Illiesia 6 (25), pp. 315-327 : 322-325

Lednia sierra sp. n.

( Figs. 23 -32)

Material examined. Holotype ♂, USA: California: Inyo County, South Fork Big Pine Creek, 1.5 miles west of Willow Lake , 11,000’, Sierra Nevada, 27 August 1985, D. Giuliani . Paratypes: California: Inyo Co., same collection data as holotype, 1♂, 5♀ ( BYUC); Ruby Creek, 11,319’, 37° 24’ 41” N 118° 46’ 13” W, Sierra Nevada, 20 August 2010, L.E. Serpa, 1♀ ( BYUC). Mono Co., Cold Water Creek, 10,049’, 39° 34’ 27” N 118° 59’ 17” W, Sierra Nevada, 19 August 2010, L.E. Serpa, 1 larva ( BYUC); stream above Coness Lakes , 11,200’ Sierra Nevada, 11 August 1986, D. Giuliani, 1♀, 6 larvae ( BYUC). The holotype is deposited at the United States National Museum, Smithsonian Institution, Washington, D.C.

Male. Macropterous, wings hyaline, with darker veins near cord. Length of body 4.5-5.0 mm, color dark brown, anterior abdominal segments lightly sclerotized. Epiproct bilaterally symmetrical, with median dorsal groove; ventral sclerite flat, thin and darkly sclerotized, with few small spines near tip, apex of sclerite extending forward beyond anterior margin of dorsal sclerite, tip grooved dorsally ending in sharp arrowhead-like point, apex narrow and elongate; dorsal sclerite with broad bare triangularshaped lobes laterally at base, narrowing gradually toward apex, possessing deep longitudinal grooves with few hairs, located on large, paired dorsolateral lobes, bearing patches of long thin spines medially at base of lobes, numerous large stout spines on lateral margins near base of epiproct ( Figs. 23 , 25-28 ). Hypoproct sclerotized, broad at base, narrow towards apex, vesicle absent ( Fig. 29 ). Paraprocts bilobed, inner lobe long thin and darkly sclerotized, tip sharply pointed, outer lobe short broad, lightly sclerotized and bearing numerous hairs ( Fig. 29 ). Tergum ten divided anteriorly by large median groove, bordered by paired mace-like spines that approach tip of epiproct ( Figs. 28, 30 ).

Female. General color of body and wings similar to male. Length 5.0-6.5 mm. Sternum seven with broadly rounded, lightly sclerotized lobe near junction of sternum eight. Subgenital plate covering most of sternum eight, bearing sparse long hairs, triangle-shaped, broad at base and narrow at apex that reaches margin of sternum nine, apex pointed and sometimes with small median groove, lateral posterior margins of sternum eight with enlarged sclerotized lobes on both sides of apex of subgenital plate ( Figs. 24 , 31, 32).

Larva. Gills absent. Length: mature male 5.0-6.0 mm, mature female 6.5-7.5 mm. Dorsal surface of thorax and abdomen mostly naked of spines. Female with large truncate, plate-like lobe present on posteriormedian margin of sternum eight. Legs with few medium sized spines on dorsal margins of femora. Cerci with whorls of small spines on posterior margins of segments and intercalary spines tiny and scattered.

Etymology. This specific epithet refers to the California Sierra Nevada where all of the specimens have been collected to this time. The name is used as a noun in apposition.

Diagnosis. Lednia sierra differs from both L. borealis and L. tumana by the following characters. The epiproct of L. sierra has a dorsal sclerite that is deeply grooved with few hairs present and bears a fringe of long thin spines along its posterior margin ( Figs. 23 , 25, 28 ). In addition, the ventral sclerite is more elongate where it extends beyond the apex of the dorsal sclerite and there is a row of large stout spines on each basal lateral margin of the epiproct ( Figs. 23 , 26, 27 ). Lednia tumana has an epiproct where the dorsal sclerite has two oblong patches of spines of equal size, is not grooved, and bears few small hairs ( Figs. 1 , 5, 6, 9). The epiproct of L. borealis has a dorsal sclerite that is grooved, bears many long hairs and 2- 4 large long black spines that are located at the posterior margin of the sclerite ( Figs. 13 , 15-18 ). Females of L. sierra cannot be identified without associated males. The larva has fewer distinct cuticular spines when compared to the larvae of L. borealis and L. tumana .

Discussion. Before the description of the two new species herein, L. borealis and L. sierra , the genus Lednia included a single species, L. tumana , restricted to the Glacier-Waterton Lakes International Peace Park region spanning the border of northern Montana and southern Alberta. This area has a pivotal position in the Western Cordillera of North America ( Chase et al. 1998). Maritime weather systems unimpeded by mountain ranges to the north and south allow floras and faunas characteristic of the Pacific Northwest to extend to and across the continental divide in the Park ( Chase et al. 1998). This area is especially rich in alpine and glacial features. Ricker (1964) hypothesized that as Pleistocene ice margins receded northward, there were postglacial faunal invasions forming East-Cordilleran and West-Cordilleran stonefly distributions. The current distribution of the three species of Lednia seems to support the above hypothesis. The specimens collected in Wyoming near the Idaho border occur only a few kilometers west of Grand Teton National Park and not too far from Yellowstone National Park. Similar alpine habitats in northwestern Montana and northern Idaho may also have Lednia populations. Lednia borealis is known from the northern Cascade Range in Washington, but it could also occur in the southern Cascade Range in Oregon and northern California. Lednia sierra has been collected from only two counties in the California Sierra Nevada, but should occur in similar habitats nearby. Finally, the Canadian Rockies in both Alberta and British Columbia offer a vast area that should be searched for the presence of this interesting genus.

The moniker “Meltwater Stonefly” has been proposed for this genus ( United States Federal Register 1991) because of its supposed occurrence near melting glaciers at high elevations. However, both L. borealis and L. sierra have been collected from 1 st order rheocrenes draining into alpine lakes. As Fagre et al. (1997) and Hall and Fagre (2003) reported, under possible future climate scenarios, all glaciers are predicted to disappear by the year 2030 in the Glacier-Waterton Lakes International Peace Park region, resulting in increased water temperatures in streams draining this region, directly affecting the long-term survivability of stenothermic aquatic invertebrates, no doubt including Lednia . There are similar scenarios for high elevation watersheds in the Cascade Range ( Nolin and Daly 2006) and the California Sierra Nevada ( Maurer 2007). It is imperative that the life history and ecology of the species of Lednia be understood before they disappear.

Figures

Figs. 23-24. Lednia sierra. 23. male epiproct, dorsal. 24. female terminalia, ventral.

Figs.25-30.Lednia sierra male genitalia: 25. terminalia, dorsal.26. epiproct, dorsal.27.epiproct apex, dorsal.28.epiproct, lateral.29. terminalia, ventral. 30. prong on tergum 10. 31.female terminalia, ventral.32. female subgenital plate, ventral.

Figs. 1-3. Lednia tumana male genitalia: 1. Dorsal. 2. epiproct, dorsal. 3. lateral. Fig. 4. Lednia tumana female terminalia, ventral.

Figs. 13-14. Lednia borealis. 13. Male epiproct, dorsal. 14. female terminalia, ventral.

Figs. 15-21.Lednia borealis male genitalia: 15. terminalia, dorsal. 16. epiproct, dorsal. 17. epiproct, dorsal.18. epiproct, lateral. 19. terminalia, ventral. 20. right paraproct. 21. prong on tergum 10. 22. female terminalia, ventral.