Isoperla tilasqua Szczytko & Stewart, 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 : 57

Isoperla tilasqua Szczytko & Stewart

( Figs. 17 a-d, 20f)

Isoperla tilasqua Szczytko & Stewart 1979 .

Holotype ♂, Oregon, Benton County, Oak Creek.

Male. Aedeagus: sclerotized posterior process absent; body with two large posterior lobes and expanded apex, apex deeply inverted, with a pair of small conical lobes at apicolateral margins ( Fig. 17a ); one large patch of spinulae concentrated below posteromedian lobe ( Fig. 17b ), and a long thin patch along posteroapical margin ( Fig. 17c ). 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 first cercal segment, tapering abruptly to blunt apices ( Fig. 17c ). Vesicle: rounded lobe, widest at base with broadly rounded apical margin ( Fig. 17d ).

Isoperla tilasqua is not known from California, recorded from Oregon and Washington ( Szczytko & Stewart 1979, Sandberg 2011b) and is most similar to I. baumanni . See comments under I. baumanni .

After live eversion, the extended tube-like lobes described in Szczytko & Stewart (1979, fig. 116) remained inverted, their locations could be identified by small inverted membrane areas (openings). After clearing in KOH, a pair of tube-like internal processes was discernible within the body of the aedeagus, with openings along the anteroapical margin ( Fig. 20f ).

Additional Material Examined. OREGON, Harney Co., Trout Creek, NFD 395 Rd 4.25 mi (6.8 km) E Idlewild CG ( Hwy 395), 43.80484°N, 118.91082°W, 21/ V /2013, J.B. Sandberg, B.C. Kondratieff, 4 Larvae, 2♂, 3♀ (reared) ( JBSC); Umatilla Co., Camas Creek, Hwy 395 Ukiah-Dale Forest State Park 1.1 mi (1.8 km) S Hwy 244 intersec, 45.1241°N, 118.97251°W, 22/ V /2013, J.B. Sandberg, B.C. Kondratieff, 2♂, 1♀ ( JBSC).

Figures

Figs. 17-18. Adult male characters of Isoperla tilasqua, Meacham Cr., Umatilla Co., OR and I. umpqua, Muir Cr., Douglas Co., OR, 25-40x. Fig. 17a. I. tilasqua aedeagus, lateral; large basal spinule patch & thin apical patch (arrows). Lobes A-B: posterior. Fig. 17b. Aedeagus, posterior; large basal spinule patch (arrow). Fig. 17c. Paraprocts (white arrow); apical thin spinule patch (right arrow); large basal patch (left arrow). Fig. 17d. Vesicle. Fig. 18a. I. umpqua aedeagus, lateral; sclerotized process (arrow). Lobe A: dorsoanterior. Fig. 18b. Aedeagus, ventral; sclerotized process (arrow & insetposterior view). Fig. 18c. Paraproct (left white arrow); sclerotized process (right white arrow); abdominal tergite 9 spinulae (black arrow). Fig. 18d. Vesicle.

Figs. 20a-f. The cleared aedeagus of six western Nearctic Isoperla species after live evertion; membranous opening of internal tube like process or apex (white arrows); tube like internal process (black arrows). 50x (20b, d & e, cropped and enlarged). 20a. I. baumanni, lateral view, partially everted; 20b. I. fulva, lateral view; 20c. I. marmorata, lateral view; 20d. I. miwok, dorsoapical view, tube like process openings along anteroapical margin; 20e. I. roguensis, ventral view, tube like process openings along anteroapical margin; 20f. I. tilasqua, lateral view.