Sweltsa hoffmani Kondratieff & Kirchner, 2009

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

Sweltsa hoffmani Kondratieff & Kirchner

( Figs. 1-5 )

Sweltsa hoffmani Kondratieff & Kirchner, 2009:297 .

Holotype ♂ ( United States National Museum), West Virginia, Logan Co., Frogtown Hollow of Copperas Mine Fork

Material examined. WEST VIRGINIA: Cabell Co.: Lusher Hollow of Mud River , 24 April 1977, R . F. Kirchner, 3♂, 1♀ (reared), 6 pharate larvae ( RFK) .

Mature larva. Body length 7.0-8.0 mm. General color pale brown without distinctive pigment pattern except underlying adult pattern in pharate individuals. Pronotal grooves slightly darker than background pigment ( Fig. 1 ). Pronotum bearing ca. 10 anterolateral setae, ca. 18 posterolateral setae, and ca. 2 widely spaced lateral setae near margin; longest anterolateral and posterolateral setae subequal in length. Mesonotum with ca. 7 moderately long outer marginal setae ( Fig. 2 ); mesonotum and metanotum without conspicuous intercalary setae on wingpads. Fore femora with a few (ca. 7 long dorsal setae near margin and ca. 10 ventral setae; femoral fringe setae obscure but usually 2-3 present. Fore tibiae bearing a sparse outer fringe of short setae, inner margin with ca. 6 thick setae ( Fig. 3 ). Posterior fringe of abdominal terga 8-9 typically bearing 4 long setae and interspersed shorter setae; median field with thin setae and usually a grouping of 3-4 short thick setae between thin median setae and innermost long seta ( Fig. 4 ); lateral intercalary setae include 1-2 thick, long setae in each cluster. Cerci broken but basal 12 segments shown in Fig.5 ; longest dorsal setae in segmental whorls exceed segments in length and occur on segments 8-10.

Comments. Surdick (2004) recognized S. mediana (Banks) and S. onkos as sister species lacking dark pigment on the adult pronotal margins and Kondratieff & Kirchner (2009) recently recognized S. hoffmani as a third species sharing this feature. The three species appear to be allopatric, at least in the southern part of their ranges. Sweltsa hoffmani is not currently known to geographically overlap the range of S. mediana and does so uncommonly with S. onkos in the northeastern portion of their ranges. Sweltsa mediana is known from the Carolinas to Tennessee and southwestern Virginia (Grubbs 2010; Kondratieff & Kirchner 2009; Surdick 2004), S. onkos from north of the Mt. Rogers area of Virginia into Atlantic Canada ( Kondratieff & Kirchner 2009) and S. hoffmani is reportedly found from the unglaciated region of New York west through the Interior Plateau region in Indiana, and south to northwestern Alabama ( Grubbs 2011; DeWalt & Grubbs 2011); the species is also reported from Kentucky, Ohio, Tennessee and West Virginia ( Kondratieff & Kirchner 2009).

Larvae of these three species can be distinguished by length of the longest dorsal setae on mid-apical cercal segments. Those on S. onkos are about two segments in length, whereas those on S. hoffmani and S. mediana are generally less than 1.5 segments in length. Sweltsa hoffmani larvae are distinct from S. mediana and S. onkos in having the fore tibial fringe composed of short, sparse setae ( Fig. 4 ) and from all eastern Sweltsa examined on the basis of the lack of intercalary setae on the metanotal wingpads ( Fig. 2 ).

Figures

Figs. 1-5. Sweltsa hoffmani larval structures. 1. Head and pronotum. 2. Mesonotum and metanotum. 3. Right foreleg (m = median outer tibial seta). 4. Abdominal terga 8-10. 5. Lateral aspect of cercus, dorsum left.