Isoperla roguensis Szczytko & Stewart, 2002

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: 244-245

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Isoperla roguensis Szczytko & Stewart


Isoperla roguensis Szczytko & Stewart  

( Figs. 2n View Figs , 16 View Figs a-h, 20 View Figs n)

Isoperla roguensis Szczytko & Stewart 1984   , 77:260-262. ♂, ♀, ovum.

Isoperla roguensis: Szczytko & Stewart 2002   , 128:2-3. Larva (not reared).

Isoperla karuk Baumann & Lee 2009   , 5:5-9. ♂, ♀, ovum. NEW SYNONOMY.

Material examined. TYPES: I. roguensis   , Holotype ♂   , Allotype ♀   , OR: Curry Co., Mouth of the Rogue River   , 30/III/1949, S. Jewett Jr. ( NMNH #10469 View Materials ). Paratype ♂ (2 of 3 cleared with KOH)   , same as Holotype (Stan Szczytko Collection – University of Wisconsin-Stevens Point). Additional Specimens. CALIFORNIA: Butte Co., Butte Creek , Butte Creek Ecological Preserve , Honey Run Road , 2.9 mi (4.7 km) E of intersection with Skyway   , 13/I/2007, 05/II/2007, J. Sandberg, Larvae; 04/III/2007, J. Sandberg, D. Pickard, Larvae (reared); 07/IV/2007, J. Sandberg, ♂ ♀, Larvae (reared)   ; 13/IV/2007, J. Sandberg, ♂ ♀; 18/I/2008, J. Sandberg, D. Pickard, Larvae; 30/III/2008, J. Sandberg, ♂ ♀, Larvae   ; 30/IV/2008, J. Sandberg, ♀; 27/III/2009, J. Sandberg, Larvae; 03/IV/2009, J. Sandberg, ♂ ♀; 19/II/2010, J. Sandberg, S. Hassur, Larvae; 22/II/2010, J. Sandberg, Larvae (reared); 11/III/2010, J. Sandberg, J. York, Larvae (reared); 14/III/2010, J. Sandberg, Larvae (reared); Big Chico Creek, Big Chico Creek Ecological Reserve , N39.86909°, W121.70760°, near north boundary GoogleMaps   , 27/IV/2010, R. Baumann, B. Kondratieff, J. Sandberg, ♀   ; Big Chico Creek , Five-Mile Recreation Area, Centennial Ave & Crow Canyon Ct, Chico   , 27/III/2010, J. Sandberg, ♂ ♀, Larvae (reared); Humboldt Co., Klamath River , Aikens Creek Campground, Hwy 96, 4.7 mi (7.6 km) NE Weitchpec   , 09/IV/2010, J. Sandberg, ♂ ♀, exuviae; Mad River, Arcata Bottoms, Mad River Road , N40.91578°, W124.10618° GoogleMaps   , 10/IV/2010, J. Sandberg, ♂ ♀; Plumas Co., Spanish Creek, Spanish Creek Campground, 3 mi (4.8 km) N Keddie   , 04/III/2007, J. Sandberg, D. Pickard, Larvae (reared); Tehama Co., Mill Creek, 1000 ft (305 km) upstream of Sacramento River confluence, Elev. 208 ft (63.4 m)   , 13/IV/2011, J. Dittes. OREGON: Curry Co., Rogue River, Orchard Bar , Cty Hwy 595 (Agness Road), 8.9 mi (14.3 km) NE Hwy 101, J. Sandberg, Larvae (reared)   ; 20/III/2010, J. Sandberg, ♀, Larvae (reared); Rogue River, Rotary Riverside Trail , Cty Hwy 595 (Jerry’s Flat Road), 0.35 mi (0.6 km) NE Hwy 101   , 21/III/2010, J. Sandberg, ♀.

Male larva. Body length of mature larva 9–12 mm. Dorsum of head with contrasting pigment pattern and fine dark clothing setae, anterior frontoclypeus margin unpigmented; light M shaped pattern anterior to median ocellus variable, usually indistinct, not connected to light frontoclypeus area and completely enclosed in dark pigment, median longitudinal light band absent, lateral thin arms faint, lacking clothing setae, directed posterolaterally and extending to antennal bases; posterior ocelli with partially enclosed large light areas along outer lateral margins; interocellar area variable, from completely dark to partially light, when small light area present, completely enclosed by dark pigment and not extending posteriorly past posterior ocelli; occiput with irregular spinulae band extending from below eye to near median epicranial suture, not enclosed completely by dark pigment ( Fig. 16a View Figs ). Lacinia bidentate, total length 682–862 µm ( Figs. 2n View Figs , 16e- h View Figs , Tables 2-4 View Table 2 View Table 3 View Table 4 ); submarginal row (A+B) with 3 setae, groups A-B interrupted by gap below subapical tooth ( SAT) inner margin ( Fig. 16g View Figs ); 1 submarginal seta (A) inserted at base of apical tooth ( AT) inner margin, plus 1 thin marginal seta ( TMS) adjacent to AT inner margin, sometimes obstructed from view by AT, submarginal seta (A) or broken, and 1 dorsal seta (DS) located below SAT inner margin, partially obstructed by SAT or submarginal setae (B) ( Figs. 16 View Figs g-h); 2 submarginal setae (B) located past SAT inner margin ( Fig. 16h View Figs ); 5–9 marginal setae (C), initially long-stout and widely spaced, last few shorter and widely spaced, blending into and difficult to differentiate from dorsal and ventral surface setae ( Fig. 16e View Figs ); 48–88 ventral surface setae (D) forming dense longitudinal band below submarginal and marginal setae, ending posteriorly at approximately ¾ the inner lacinia margin length, setae closest to inner margin protrude laterally past lacinia margin ( Fig. 16f View Figs ); dorsal surface setae ( DSS) forming dense, laterally protruding, longitudinal band on and along inner-lateral margin, ending before posterior-most ventral surface setae ( Fig. 16f View Figs ). Galea with 19–27 setae in sparse ventral row, apex with 4–6 setae. Maxillary Palp segments 2–3 with curved, apically pointed setae. Pronotum with median light area occasionally with a thin central indistinct brown band bordered by wide dark irregular pigment bands typical of the I. marmorata   group; discs each with variable and irregular inner lateral dark pigment margins, variable light rugosites usually concentrated along inner dark band margins, fine dark clothing setae except over rugosites and lateral margins with broad light bands ( Fig. 16b View Figs ). Meso and metanotum with contrasting pigment pattern and fine dark clothing setae ( Fig. 16c View Figs ). Legs with numerous fine golden to light brown clothing setae and scattered erect spines on outer surface of femora, erect spines longest and concentrated on dorsal surface; fine silky setae sparse on dorsal surface of femora, numerous and continuous on tibia ( Fig. 20n View Figs ); tibia with extremely faint transverse bands near proximal end. Abdominal terga variable, usually with two distinct longitudinal dark stripes; wide light median longitudinal band sometimes bisected by faint, light brown longitudinal median band; lateral pair of dark longitudinal stripes usually 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. 16d View Figs ).

Distribution. California, Oregon. Widely distributed in northern California.

Diagnosis. Mature male larvae of I. roguensis   are most similar to I. fulva   and I. marmorata   . The larvae of this species can not be separated from I. fulva   but can be distinguished from I. marmorata   by the lack of or reduced M shaped light pattern not connected to unpigmented frontoclypeus ( Fig. 16a View Figs ). Pigment patterns are known to vary in Isoperla   and a nonpigment character must be found before increased species resolution can be achieved in the I. marmorata   complex.

Remarks. The three western species included in the I. marmorata   complex have similar dark larval pigment patterns. In several locations, I. roguensis   was found with one or more of the following: I. marmorata   , I. mormona   , I. pinta   or I. quinquepunctata   . Emergence was slightly extended and occurred in March–May. Isoperla karuk   is placed as a new junior subjective synonym of I. roguensis   based upon comparison with reared material from the type localities, additional California locations and comparison of the aedeagii with the everted and cleared I. roguensis   paratypes held in the collection of Dr. Stanley Szczytko, University of Wisconsin-Stevens Point. The authors of I. karuk   (Richard Baumann, Per. com) based their description upon an everted aedeagus of a live adult (Bauman & Lee 2009 - Figs. 17 View Figs -24) which seemed different from the hyper everted and cleared aedeagus of an already preserved adult in Szczytko & Stewart (1984 – Fig. 55). An important consideration for future adult taxonomy of this genus is that no two live adult males can be everted to the same extent. The adult male aedeagus is a thin membranous inverted sac, that when squeezed out of the posterior ninth sternal inter-segmental membrane (evertion), is filled with seminal fluid (like a balloon). The consistent evertion of lobes and placement of diagnostic setae patches or sclerotized posterior processes are confounded by 1) the amount and length of time of evertion (should take place under a dissecting microscope to ensure full evertion) and 2) whether the aedeagus was fixed in near boiling water. If less evertion pressure or no hot water fixation was used, the aedeagus will invert to some degree. The comparison of live everted versus preserved hyper everted males is further complicated by the clearing method used in Szczytko & Stewart (1979), which presumably allows internal lobes and lobe-like structures to become everted (See I. baumanni   ).


Departamento de Geologia, Universidad de Chile


Angelo State University


Toleco Museum of Health and Natural History














Isoperla roguensis Szczytko & Stewart

Sandberg, John B. 2011

Isoperla roguensis Szczytko & Stewart 1984

Isoperla roguensis Szczytko & Stewart 1984

Isoperla roguensis: Szczytko & Stewart 2002

Isoperla roguensis: Szczytko & Stewart 2002

Isoperla karuk

Isoperla karuk Baumann & Lee 2009