Alloperla imbecilla (Say)

Stark, Bill P. & Kondratieff, Boris C., 2010, Larvae Of Eight Eastern Nearctic Alloperla Species (Plecoptera: Chloroperlidae), Illiesia 6 (20), pp. 267-276 : 271-273

Alloperla imbecilla (Say)

( Fig. 16-20 )

Sialis imbecilla Say, 1823:165 .

Type material lost, neotype ♂ ( United States National Museum), Ohio, Adams Co., Lower Twin Creek , Vastine Run, Designated by Baumann, 1974:258

Material examined. West Virginia: Wayne Co., tributary Millers Fork of Beech Fork , 15 May 1986, B.C. Kondratieff, 4 larvae ( CSU) .

Mature larva. Body length 6.5-7.5 mm. General color brown without distinctive pattern. Anterior pronotal margin with 6-9 moderately thick setae at corners and posterior margin with a pair of long setae at corners ( Fig. 16 ). Mesonotal wingpads with ca. 5-6 outer marginal setae, metanotal wingpads with ca. 7- 8 outer marginal setae beyond apex of mesonotal wingpad and 1 apparent inner marginal ( Fig. 17 ). Mid and hindlegs each with a sparse ventral fringe of long silky setae, forelegs without ventral fringe ( Fig. 19 ). Abdominal tergal fringes consist of stout setae with ca. 4-6 interspersed long thin setae; a few intercalary setae occur near lateral margins but none are located in median tergal field ( Fig. 18 ). Cerci consisting of 14-15 apparent segments ( Fig. 20 ), vertical fringe developed on segments 10-14, and a few fringe setae occur on segment 9; longest dorsal setae in segmental whorls of mid cercal segments about as long as segments.

Comments. Stewart & Stark (2002) provide a detailed larval description for this species based on Pennsylvania specimens and indicate the cerci are “approximately 14-16 segmented”. In our sample the apparent number of segments for three specimens was 14 but in one specimen a small fragment of segment 15 remained on the left cercus. The anterior pronotal setal count also varied in our sample for each specimen; the maximum number of anterior pronotal setae ranged from 6-9.

Figures

Figs. 16-20. Alloperla imbecilla larval structures. 16. Head and pronotum. 17. Mesonotum and metanotum. 18. Abdominal terga 8-9. 19. Right foreleg. 20. Lateral aspect of cercus, dorsum left.