Alloperla imbecilla (Say)

Willett, Michele R. & Stark, Bill P., 2009, The Alloperla Leonarda Group Of Eastern North America, With Sem Images Of Four Out-Group Species (Plecoptera: Chloroperlidae), Illiesia 5 (11), pp. 108-127 : 123

Alloperla imbecilla (Say)

( Figs. 61-66 )

Sialis imbecilla Say, 1823:165 . Type lost, Ohio River, Cincinnati, Ohio

Alloperla imbecilla: Baumann, 1974:258 .

Neotype ♂ (United States National Museum), Vastine Run , Lower Twin Creek , Adams Co., Ohio

Alloperla imbecilla: Surdick, 2004:17 . Redescription and distribution update

Material examined. VA: Scott Co., Devils Fork, FR 619, 17 May 1997, B. Stark, 8 ♂, 8 ♀ ( BPS) . Same site, 19 May 2009, B. Stark, 10 ♂, 6 ♀ ( BPS) . Scott Co., Big Stony Creek , FR 657, 19 May 2009, B. Stark, 1 ♂ ( BPS) .

Epiproct. Length from base to tip, ca. 266-275 μm. Greatest width beyond base, ca. 39-46 μm. Greatest apical thickness, ca. 43 μm. Epiproct cowl without enlarged lobes ( Figs. 61-62, 66 ); densely setose over most of cowl surface but bare near base of epiproct. Epiproct widest at base (ca. 61 μm) and on subapical cap (ca. 39 μm), but similar in width through most of length ( Fig. 62 ). Most of dorsum covered with a closely appressed, densely setose mat ( Figs. 62-63, 66 ), but small basolateral and apical areas, and entire ventral surface bare; apex with a distinctive ventral row of long setae ( Figs. 63-65 ) and a median longitudinal patch of additional setae extends onto spiny process laterally or basolaterally ( Fig. 63 ); apex bearing a slightly thickened, multispined process ( Figs. 63-64 ).

Remarks. The specimens examined in this study represent the southern most population known for this species, and they exhibit subtle variations from the figures presented by Surdick (2004) and Baumann (1974). A comparative SEM study is needed for several populations to evaluate the extent of variation in the shape, setation and number of serrae for the apical spiny portion of the epiproct.

Figures

Figs. 61-66. Alloperla imbecilla epiproct structures, Devils Fork, Scott Co., VA. 61. Male terminalia, dorsal aspect. 62. Epiproct and cowl, dorsal aspect. 63. Apex of epiproct, dorsal aspect. 64. Apex of epiproct, lateral aspect. 65. Apex of epiproct, frontal aspect. 66. Detail of basal epiproct surface.