Isoperla acula Jewett, 1962

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 : 41

Isoperla acula Jewett

( Figs. 1 a-d)

Isoperla acula Jewett 1962 .

Holotype ♂, California, Fresno County, Dry Creek , 7 mi NE Academy.

Male. Aedeagus: sclerotized posterior process absent; body a long recurved tube without major lobes, tapering to a multi-lobed apex ( Fig. 1a ); a pair of long, nearly parallel patches of fine spinulae along posteroapical margin ( Figs. 1 a-b). Ninth tergum with mesoposterior bipartite to oval patches of stout dark spinulae and long fine scattered setae, tenth tergum with only a few small spinulae ( Fig. 1c ). Posterolateral margins of at least abdominal segment 8 with scale-like setae clustered in brushes of several setae ( Fig. 1d inset). Paraprocts: curved dorsally, length if straightened longer than combined first and second cercal segments, tapering gradually to long sharp apices ( Fig. 1c ). Vesicle: rectangular, length half as long as wide ( Fig. 1d ).

The male of I. acula ( I. quinquepunctata complex) is most similar to I. mormona and I. quinquepunctata , all lacking an aedeagal sclerotized process ( Table 1 ). However, the similarity in other male taxonomic characters of the three species varies with I. acula and I. mormona possessing patches of fine spinulae near the apex of aedeagus; vesicle shape varies from lobelike ( I. quinquepunctata ) to rectangular ( I. acula ) and trapezoidal ( I. mormona ); abdominal terga 9-10 variable posteriorly with patches of stout setae ( I. quinquepunctata ) or patches of stout spinulae and scattered long setae ( I. acula , I. mormona ); paraproct length> than first and second cercal segments ( I. acula ) or subequal to first and second cercal segments ( I. mormona , I. quinquepunctata ); and paraproct shape variable, tapering gradually to sharp apices ( I. acula ), tapering abruptly to blunt apices ( I. mormona ) and in I. quinquepunctata , tapering gradually to blunt apices. The current study I. acula description agrees with those of Jewett (1962), Szczytko & Stewart (1979), and Bottorff et al. (1990).

Additional Material Examined. CALIFORNIA, Shasta Co., Rock Creek, West Redding , 05/ VI /2011, larvae, ( ABLC).

Figures

Figs. 1-2. Adult male characters of Isoperla acula, Deadman Cr., El Dorado Co., CA and I. adunca, Campbell Cr. & Trib., Butte Co., CA, 32-50x. Fig. 1a. I. acula aedeagus, lateral; fine spinule patch (arrow). Fig. 1b. Aedeagus, ventral; fine spinule patches (arrow & inset-posterior view). Fig. 1c. Paraprocts, (black arrow); abdominal spinules (white arrow). Fig. 1d. Vesicle; brush setae (inset). Fig. 2a. I. adunca aedeagus, lateral; sclerotized process (arrow & inset-lateral view). Lobes A: posterobasal, B: posteromedian, C: anterior, D: dorsomedian pair. Fig. 2b. Aedeagus, ventral; sclerotized process (arrow & inset-posterior view). Fig. 2c. Paraprocts (arrow). Fig. 2d. Vesicle.