Sweltsa lateralis (Banks)

Stark, Bill P., Kondratieff, Boris C., Kirchner, Ralph F. & Stewart, Kenneth W., 2011, Larvae Of Eight Eastern North American Sweltsa (Plecoptera: Chloroperlidae), Illiesia 7 (4), pp. 51-64 : 52-54

Sweltsa lateralis (Banks)

( Figs. 6-10 )

Alloperla lateralis Banks, 1911:337 .

Holotype ♀ (Museum of Comparative Zoology), North Carolina, Black Mountains

Material examined. NORTH CAROLINA: Avery Co.: Gragg Prong Lost Cove Creek, Rosenborough Road , 19 April 2007 , B.C. Kondratieff, R.F. Kirchner, D. Lenat, 2♂, 3 larvae ( CSU). Macon Co.: Berties Falls, Wayah Bald , 23 May 1984 , B. Stark, 3♂ (1 reared), 2♀, 3 pharate larvae ( BPS). Rattlesnake Spring, Wayah Bald , 18 May 1983 , B. Stark, 2♂, 1 pharate larva ( BPS). Same site, 18 April 1981 , J.S.

Weaver, R. W. Holzenthal, 6 larvae ( BPS). Robin Branch, Wayah Bald, 19 May 1983, B. Stark, 1♂, 1 larva ( BPS). Yancey Co.: Mt. Mitchell State Park, 25 May 1994, B. Stark, S.W. Szczytko, J. Sandberg, 1♂, 1 larva ( BPS). WEST VIRGINIA: Pocahontas Co. : Right Fork Tea Creek , 9 May 1986, K.W. Stewart, R. F. Kirchner, 2♂, 4♀ (reared) ( KWS) .

Mature larva. Body length 7.0-8.0 mm. General color pale brown without distinctive pigment pattern except underlying adult pattern in pharate individuals. Head with a slightly paler area forward of median ocellus and pronotum with slightly darker submarginal grooves. Pronotum bearing ca. 15 anterolateral setae and ca. 15 posterolateral setae near margin ( Fig. 6 ); setal length variable but longest occur on posterolateral angles. Mesonotum bearing prominent setae scattered along outer margins from base to apex, and a few inner marginal setae are present above notch ( Fig. 7 ). Metanotum with several thin intercalary setae on wingpad and outer and inner margins scattered around wingpad; apex of wingpad with long and interspersed short setae. Fore femora without fringe setae, tibiae sparsely fringed on outer margin ( Fig. 8 ). Thick setae present along much of dorsal and ventral margins of femora and scattered on surface; tibiae bearing long thin setae interspersed within fringe setae on outer margin. Posterior abdominal fringe on tergum 8 with very thin setae between innermost long setae ( Fig. 9 ); intercalary setae clustered in lateral group of ca. 10. Cerci with 15-16 segments ( Fig. 10 ); each segmental whorl beyond segment 7 with 1 or 2 dorsal setae about two segments in length.

Comments. Sweltsa lateralis is widely distributed throughout much of eastern North America ( Surdick 2004). It is a common species of headwater seeps, rheocrenes and smaller streams of the higher Appalachians where it is often sympatric with all other eastern Nearctic Sweltsa . The male epiproct is generally similar to S. onkos , S. pocahontas Kirchner & Kondratieff and several other species, particularly in dorsal aspect ( Surdick 2004), however the presence of a pair of basolateral lobes on the epiproct are unique to this species. Larvae of S. lateralis are similar to S. naica and S. onkos in having the longest dorsal cercal setae subequal to two segments in length, but differs from both in having the fore tibial fringe setae sparse and about half as long as the median outer marginal seta. The larvae of S. lateralis share more features with S. pocahontas than with other species examined, but the longest dorsal cercal setae for that species are about 1.5 times as long as the midapical segments. The combination of short tibial fine fringe setae ( Fig. 9 ), few or no intercalary metanotal wingpad setae ( Fig. 7 ), and the long dorsal cercal setae ( Fig. 10 ) usually is sufficient to distinguish larvae. These characters, however, should be used with caution if larvae are immature or missing numerous cercal segments. Caution is also needed because larvae of two sympatric species, S. holstonensis Kondratieff & Kirchner and S. voshelli Kondratieff & Kirchner , are unknown.

Figures

Figs. 6-10. Sweltsa lateralis larval structures. 6. Head and pronotum. 7. Mesonotum and metanotum. 8. Right foreleg. 9. Abdominal terga 8-10. 10. Lateral aspect of cercus, dorsum left.