Isoperla sobria (Hagen), 1979

Sandberg, John B. & Kondratieff, Boris C., 2013, The Isoperla Of California (Plecoptera: Perlodidae); Updated Male Descriptions And Adult Keys For 18 Western Nearctic Species, Illiesia 9 (5), pp. 34-64 : 55

Isoperla sobria (Hagen)

( Figs. 15 a-d)

Perla sobria Hagen 1874 .

Holotype ♀, “ Colorado mountains .”

Perla ebria Hagen 1874 .

Holotype ♀, “ Colorado mountains .”

Isoperla sobria: Szczytko & Stewart 1979 .

Male. Aedeagus: sclerotized posterior process absent; body of aedeagus typically with one anterior lobe and a pair of conical dorsal lobes ( Figs. 15 a-c); in one male collected in copula, a small posteroapical lobe was present ( Figs. 15 a-b); one long median patch of spinulae along posterior margin ( Figs. 15 a-c). Abdominal terga 8-9, 9, 9-10: without stout spinulae or long stout setae. Posterolateral margins of at least abdominal segment 8 with scale-like setae clustered in brushes of several setae. Paraprocts: curved dorsally, length if straightened subequal to combined first and second cercal segments, tapering abruptly to blunt points ( Fig. 15c ). Vesicle: lobe barely perceptible, at best represented by an area of lighter pigment ( Fig. 15d ).

Isoperla sobria is most similar to I. miwok ( Table 1 ), with both included in the I. sobria complex ( Bottorff et al. 1990). They differ most in the shape of the aedeagal spinule patch. In I. sobria , there is only one median patch on the posterobasal margin; in I. miwok , there is a posteroapical and a posterobasal patch, and the latter is concentrated into two nearly parallel bands. Isoperla sobria is distributed in higher elevation permanent streams in central to northcentral California. Isoperla miwok , as with I. acula and I. adunca , is usually associated with small intermittent streams of the Sierra Nevada foothills in north-central California, with one unconfirmed Lake County, Coastal Range location ( Sandberg 2011b).

Figures

Figs. 15-16. Adult male characters of Isoperla sobria, Tyee Spring, Skamania Co., WA and I. sordida, Cold Water Cr., Mono Co., CA, 25-40x. Fig. 15a. I. sobria aedeagus, lateral (Tyee Sp., in copula); spinule patch (arrow). Lobes A: anterior, B: dorsal pair, C: posteroapical (aberrant). Fig. 15b. Aedeagus, posterior; spinule patch (arrow). Fig. 15c. Paraprocts (black arrow), Lk. Davis-Corral Sp.; spinulae patch, lateral (white arrow); dorsal pair of lobes in typical position. Fig. 15d. Vesicle. Fig. 16a. I. sordida aedeagus, lateral; sclerotized process (white arrow); paraproct (black arrow). Lobes A: posteroventral, B: posteromedian, C: dorsal, D: anterior. Fig. 16b. Aedeagus ventral; sclerotized process (arrow & inset-posterior view).Fig. 16c. Paraprocts (black arrow); sclerotized process (white arrow). Fig. 16d. Vesicle.