Isoperla acula Jewett 1962
Creators: name: Sandberg, John B.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Plecoptera
Perlodidae
Isoperla
Isoperla acula

description: <i>Isoperla acula</i> Jewett (Figs. 2a, 3 a-h, 20 a) <i>Isoperla acula</i> Jewett 1962, 38:18. <i>Isoperla acula</i>: Szczytko &amp; Stewart 1979, 32:77. <i>Isoperla acula</i>: Bottorff et al. 1990, 92:291-294. Larva (reared). <b>Material examined.</b> TYPE: <i>I. acula</i>, Holotype &amp;male;, CA: <b>Fresno Co.</b>, 7 mi NE Academy, elev. 800 feet, Dry Cr., 19/IV/1955, D.L. Abell (CAS #8591). <b>Additional Specimens.</b> CALIFORNIA: <b>Amador Co</b>., Big Indian Creek, 2 km S NF Cosumnes R., Hwy 49, 25/IV/1986, R. L. Bottorff, Larvae (NMNH); Big Indian Creek, Hwy 49, 2.9 mi N Plymouth, unnamed rd. xing, 25/IV/2009, J. Sandberg, Larvae; Little Indian Creek, 3 km W Plymouth, 25/IV/1986, R. L. Bottorff, Exuviae (NMNH); Little Indian Creek, 3 km W Plymouth, 12/V/1987, R. L. Bottorff, &amp;male; &amp;female; reared, Larvae (CAS); Little Indian Creek, 3 km W Plymouth, 12/V/1987, R. L. Bottorff, &amp;male; &amp;female; reared (NMNH). <b>Butte Co</b>.,?, 9 mi N Oroville, 24/IV/1955, S.W. Hitchcock, &amp;male;, Larvae (NMNH); <b>El Dorado Co</b>., Cooper Canyon Creek, Rattlesnake Bar Rd. xing, 2.25 mi SE Hwy 49, 30/III/2009, J. Sandberg, Larvae; Deadman Creek, Church Mine Rd. xing, 2.45 mi SE El Dorado, 30/III/2009, J. Sandberg, Larvae; J. Sandberg, D. Pickard, 04/IV/2009, Larvae; 05/IV/2009, Larvae; 25/IV/2009, Larvae (reared); 10/V/2009, Larvae (reared); 16/V/2009, Larvae (reared); 23/V/2009, &amp;male; &amp;female;, Larvae (reared); Martinez Creek, Martinez Cr. Rd., 3.5 mi SE El Dorado, 04/IV/2009, J. Sandberg, D. Pickard, Larvae; NF Cosumnes River, Hwy 49 cattle coral, 1.7 mi S Nashville, below confluence w/ MF Cosumnes R., 28/III/2009, J. Sandberg, Larvae; Tributary of NF Cosumnes River, ~ 2 km W Martinez Cr., S El Dorado, 12/V/1987, R. L. Bottorff, 12/V/1987, &amp;male; &amp;female;, Larvae (CAS); Tributary of NF Cosumnes River, Union Mine Rd., 3.4 mi (5.5 km) N Nashville at McNulty Mine Rd. xing, 25/IV/2009, J. Sandberg, Larvae (reared). <b>Male larva. Body length</b> of mature larva 10–11 mm. <b>Dorsum of head</b> with contrasting pigment pattern and fine dark clothing setae, anterior frontoclypeus margin unpigmented; light M shaped pattern anterior to median ocellus connected to light frontoclypeus area by median longitudinal light band, lateral thin arms directed posterolaterally, extending to antennal bases; posterior ocelli with partially enclosed large light areas along outer lateral margins; interocellar area partially light and generally diamond shaped, completely enclosed by dark pigment, light area extending past posterior ocelli, reaching dark pigment below the arms of the epicranial suture; occiput with irregular spinulae band extending from below eye to near median epicranial suture, not enclosed completely by dark pigment (Fig. 3a). <b>Lacinia</b> bidentate, total length 687– 786 µm (Fig. 2a, 3e- h, Tables 2-4); submarginal row (A+B) with 4 setae, groups A-B interrupted by gap below subapical tooth (SAT) inner margin (Fig. 3h); 1–2 submarginal setae (A), the first inserted at base of apical tooth (AT) inner margin, the second when present, located between AT and SAT inner margins, plus 1 thin marginal seta (TMS) adjacent to AT inner margin, sometimes obstructed from view by AT or broken, and 1 dorsal seta (DS) located below SAT inner margin sometimes obstructed by SAT (Figs. 3 gh); 2–3 submarginal setae (B) located past SAT inner margin (Figs 3 g-h); 7–9 marginal setae (C) initially long-stout and widely spaced, last few shorter and closer, blending into and difficult to differentiate from dorsal surface setae (Fig. 3e); 28–41 ventral surface setae (D) scattered below submarginal and marginal setae, ending posteriorly at approximately ¾ the inner lacinia margin length (Fig. 3f); dorsal surface setae (DSS) continue from last marginal seta (C) as a single, laterally protruding, submarginal row along inner-lateral margin, ending before posteriormost ventral surface setae (Fig. 3f). <b>Galea</b> with 42–61 setae in thick ventral band, apex with 4–5 setae. <b>Maxillary Palp</b> segments 2–3 with curved, apically pointed setae. <b>Pronotum</b> with median light area bordered (at least partially) by thin, irregular dark bands; discs each with partially to totally enclosed light areas or “windows” and fine dark clothing setae, lateral margins with broad light bands (Fig. 3b). <b>Meso and metanotum</b> with contrasting pigment pattern and fine dark clothing setae (Fig. 3c). <b>Legs</b> with numerous fine dark clothing setae and scattered erect spines on outer surface of femora, erect spines longest and concentrated along dorsal surfaces; fine silky setae numerous and continuous on dorsal surfaces of femora and tibia (Fig. 20a); tibia with faint transverse bands near proximal end. <b>Abdominal terga</b> with three distinct longitudinal dark stripes; wide light median longitudinal band bisected with thin dark median longitudinal stripe; lateral pair of dark longitudinal stripes about twice as wide as median dark stripe, not extending to lateral margins; numerous fine dark clothing setae and erect spines scattered dorsally; posterior margin with scattered long and numerous short spines in a concentrated row (Fig. 3d). <b>Distribution.</b> California: Sierra Nevada foothills. <b>Diagnosis.</b> Among the male larvae with 2–4 submarginal row (A+B) setae (Table 2), <i>I. acula</i> is most similar to <i>I. bifurcata</i> (Figs. 3 a-h, 6a-h). Characters that distinguish this species from <i>I. bifurcata</i> include fine silky setae numerous and continuous on dorsal surfaces of femora and tibia (Fig. 20a), and abdomen with median longitudinal thin dark pigment band (Fig. 3d). <b>Remarks.</b> <i>Isoperla acula</i> co-occurred with <i>I. adunca</i>, <i>Isoperla miwok</i> Bottorff &amp; Szczytko, and <i>I. marmorata</i> in mostly non-perennial and one perennial central Sierra Nevada foothill streams. Emergence occurred in April–May (lasting to early June in wetter years) and life history studies are needed to determine how <i>I. acula</i>, <i>I. adunca</i> and <i>I. miwok</i> cope with shortened surface flow periods. It is suspected that larvae move to hyporheic zones when stream flow ceases in late summer.
description: Published as part of <i>Sandberg, John B., 2011, The Isoperla Of California (Plecoptera: Perlodidae); Larval Descriptions And A Key To 17 Western Nearctic Species, pp. 202-258 in Illiesia 7 (22)</i> on pages 210-214, DOI: 10.5281/zenodo.4760320
description: {"references": ["Szczytko, S. W. &amp; K. W. Stewart. 1979. The genus Isoperla (Plecoptera) of western North America; Holomorphology and systematics, and a new", "Bottorff, R. L., S. W. Szczytko, &amp; A. W. Knight. 1990. Descriptions of a new species and three incompletely known species of western Nearctic Isoperla (Plecoptera: Perlodidae). Proceedings of the Entomological Society of Washington, 92 (2): 286 - 303."]}