Isoperla adunca Jewett, 1962

Sandberg, John B., 2011, The Isoperla Of California (Plecoptera: Perlodidae); Larval Descriptions And A Key To 17 Western Nearctic Species, Illiesia 7 (22), pp. 202-258 : 214-216

Isoperla adunca Jewett

( Figs. 2b , 4 a-h, 20 b)

Isoperla adunca Jewett 1962, 38 :19.

Isoperla adunca: Szczytko & Stewart 1979 , 32:80.

Isoperla adunca: Bottorff et al. 1990 , 92:294-299. Larva (reared).

Material examined. TYPES: I. adunca , Holotype ♂ , CA: Santa Clara Co., 5 mi E Mt. Hamilton, Isabel Creek ?, 31/ V/1949 ( CAS #8592 ) . Paratype ♂, CA: Tuolumne Co., Keystone , 25/IV/1951 , J.W. MacSwain ( CAS). Paratype ♂ and ♀, same as Holotype, ( CAS). Additional Specimens. CALIFORNIA: Alameda Co., Indian Creek, 1.8 mi (2.9 km) upstream of San Antonio Reservoir , 25/ V/2010, Larva (ABL); Amador Co., Big Indian Creek, N Plymouth , 25/IV/1986 , R. L. Bottorff, Larvae ( NMNH); Big Indian Creek, N Plymouth , 9/ V/1986, R. L. Bottorff, ♀, Larvae ( NMNH); Big Indian Creek , N Plymouth, 30/ V/1986, R. L. Bottorff, Larvae ( NMNH); Big Indian Creek, Hwy 49, 2.9 mi (4.7 km) N Plymouth , 4/IV/2009 , J. Sandberg, D. Pickard, Larvae; Big Indian Creek, Hwy 49, 2.9 mi (4.7 km) N Plymouth , 25/IV/2009 , J. Sandberg, Larvae (reared); Little Indian Creek , 3 km W Plymouth, 25/IV/1986 , R. L. Bottorff, ♂ (everted), Larvae ( NMNH); Little Indian Creek , 3 km W Plymouth, 12/ V/1987, R. L. Bottorff, ♂ ♀, Larvae ( NMNH); Little Indian Creek, Old Sacramento Rd xing, 1.5 mi (2.4 km) W Plymouth , 4/IV/2009 , J. Sandberg, D. Pickard, Larvae; Butte Co., Clear Creek, at Hwy 149, between Hwys 99 & 70 , T1-3 , 4/IV/2004 , Larvae (ABL); Dry Creek, at Hwy 149, between Hwys 99 & 70 , T1-2 , 4/IV/2004 , Larvae (ABL); Campbell Creek & tributary, North Table Mountain Wildlife Area, Cherokee Rd , 5 mi (8 km) S Cherokee , 3/III/2007 , J. Sandberg, Larvae (reared); 7/IV/2007, Larvae (reared); 13/IV/2007, ♂ ♀, Larvae (reared); 18/IV/2007 , Larvae; 23/II/2008, Larvae; 24/III/2008, Larvae; 30/III/2008, Larvae; 30/IV/2008, Larvae; 2/V/2010, J. Sandberg, A. Richards, Larvae (reared); Contra Costa Co., Mitchell Creek, 0.5 mi (0.8 km) below Uncle Sam Canyon , R1 , 22/IV/2009 , Larvae (ABL); Mitchell Creek, 250m upstream of bridge at Mt. Diablo State Park entrance, 24/ V/2010, Larva (ABL); El Dorado Co., SF Cosumnes River, Site 22 , R2 , 28/ V/1995, Larvae (ABL); Deadman Creek, Church Mine Rd xing, 2.4 mi (3.9 km) SE El Dorado , 10/V/2009, 16/V/2009, 23/V/2009 , J. Sandberg, ♂ ♀, Larvae (reared); Greenwood Creek, Greenwood Creek Park, Hwy 49, 4 mi (6 km) E Pilot Hill, 10/ V/2009, J. Sandberg, Larvae; Fresno Co., Mill Creek, Rt 180, E Fresno, 1800 feet, 7/ VI/1963 , C.P. Alexander, ♂ ♀ ( NMNH); Sacramento Co., Cosumnes River, at Michigan Bar , 6/VII/1982 , R. L. Bottorff, Larvae (ABL); San Diego Co., Nobel Canyon Creek, 0.8 mi (1.3 km) above Pine Valley Cr ., R1 , 28/IV/2009 , Larvae (ABL); San Diego River, Headwaters above Hwy 79, 04/ V/2010 , Larvae (ABL); San Luis Rey River WF, 1 mi (1.6 km) N Mendenhall Valley , R1 , 28/IV/2009 , Larvae (ABL); Santa Clara Co., Coyote Creek, Gilroy Hot Springs Road, 1.4 mi N Gilroy Hot Springs, 26/ VI/2010 , J. York, ♂ ♀; Ventura Co., Sespe Creek, Hwy 33, approximately 19.5 mi (31.4 km) NW of Wheeler Springs, 07/ VI/2010, Larvae (ABL) .

Male larva. Body length of mature larva 9–10 mm. Dorsum of head mostly dark with fine dark clothing setae, anterior frontoclypeus margin unpigmented; light M shaped pattern anterior to median ocellus present but poorly defined, not connected to light frontoclypeus area, median longitudinal pigment band short, nearly square, lateral thin arms indistinct, directed posterolaterally and extending to antennal bases; posterior ocelli with completely enclosed small light areas along outer lateral margins; interocellar area mostly dark, usually a small unpigmented central area completely enclosed by dark pigment; occiput with irregular spinulae band extending from below eye to near median epicranial suture, partially to completely enclosed by indistinct dark pigment ( Fig. 4a ). Lacinia bidentate, total length 653–919 µm ( Fig. 2b , 4e- h , Tables 2-4 ); submarginal row (A+B) with 8–11 setae, groups A-B continuous below subapical tooth (SAT) inner margin ( Figs. 4 gh); 3–5 submarginal (A) setae and 4–6 (B) setae in a row without gap between setae until past SAT inner margin, row extending from base of apical tooth (AT) to nearly lacinia lateral margin, the last 3–4 setae becoming widely spaced, plus 1 thin marginal seta (TMS) adjacent to AT inner margin, sometimes obstructed from view by apical tooth, first submarginal seta or broken, and 1 dorsal seta (DS) located below subapical tooth inner margin, partially obstructed from view by first few submarginal setae ( Fig. 4h ); 10–13 marginal setae (C) initially long-stout and widely spaced, last few shorter, variably spaced and occasionally borne from dorsal surface ( Figs. 4e, 4g ); 12–27 ventral surface setae (D) scattered below submarginal and marginal setae, ending posteriorly at approximately ¾ the inner lacinia margin length, occasionally a few setae below submarginal row striated ( Fig. 4f ); dorsal surface setae (DSS) usually absent, sometimes last few marginal setae (C) form a short dorsal row ( Fig. 4f – arrow); 15–20 minute scale-like spinulae rarely present on and along ventral inner-lateral margin in basal half. Galea with 12–19 setae in sparse ventral row, apex with 2–3 setae. Maxillary Palp segments 2–3 with curved, apically pointed setae. Pronotum with indistinct and variable pigment pattern, median light area absent and fine dark clothing setae; discs occasionally with slightly darker comma shaped areas near lateral margins, lateral margins with broad light bands ( Fig. 4b ). Meso and metanotum with indistinct pigment pattern and fine dark clothing setae ( Fig. 4c ). Legs with numerous fine light brown clothing setae and scattered erect spines on outer surface of femora, erect spines longest and concentrated along dorsal surfaces; fine silky setae sparse on dorsal surface of femora, numerous and continuous on tibia ( Fig. 20b ); tibia with faint transverse bands near proximal end. Abdominal terga without distinct longitudinal dark stripes; numerous fine light clothing setae and erect spines scattered dorsally; posterior margin with scattered long and numerous short spines in a concentrated row ( Fig. 4d ).

Distribution. California: Sierra Nevada foothills.

Diagnosis. The lacinia of male I. adunca larvae are distinctive in that the entire submarginal row (A+B) is continuous from the base of the apical tooth continuing to almost the inner lacinia margin ( Figs. 4 g-h). Larvae lack distinct pigment patterns, especially longitudinal abdominal stripes. The lacinia of immature larvae are also distinct and resemble mature larvae, except that submarginal row (A+B) setae are more widely spaced.

Remarks. Isoperla adunca inhabits mostly nonperennial and a few perennial foothill streams of the central Sierra Nevada range. It co-occurred with the following species: I. acula , I. marmorata , I. miwok , and Isoperla mormona Banks and emergence occurred in April–June.

Figures

Figs. 2a-q. Isoperla lacinia habitus, 40x, Bar = 500µm. 2a. I. acula; 2b. I. adunca; 2c. I. baumanni; 2d. I. bifurcata; 2e. I. denningi; 2f. I. fulva; 2g. I. laucki; 2h. I. marmorata; 2i. I. miwok; 2j. I. mormona; 2k. I. muir; 2L. I. pinta; 2m. I. quinquepunctata; 2n. I. roguensis; 2o. I. sobria; 2p. I. sordida; 2q. I. tilasqua.

Figs. 4a-h. Isoperla adunca nymph and ventral maxilla, Campbell Creek, Butte County, CA. Submarginal setae groups A and B, Marginal setae C, and Ventral surface setae D. White bars = 1 mm, 4e-f 100x, 4g 200x, and 4h 400x.

Figs. 20a-q. Isoperla front right leg habitus, Larvae, 32–40x, Bar = 1mm. 20a. I. acula; 20b. I. adunca; 20c. I. baumanni; 20d. I. bifurcata; 20e. I. denningi; 20f. I. fulva; 20g. I. laucki; 20h. I. marmorata; 20i. I. miwok; 20j. I. mormona; 20k. I. muir; 20L. I. pinta; 20m. I. quinquepunctata; 20n. I. roguensis; 20o. I. sobria; 20p. I. sordida; 20q. I. tilasqua.