Brachycentrus (Oligoplectrodes) americanus (Banks 1899)

Brachycentrus (Oligoplectrodes) americanus (Banks)

Oligoplectrum americanum Banks, 1899:210.

Brachycentrus americanus (Banks).—Milne, 1936:112.—Ross, 1944:266.—Fischer, 1970:100.—Denning, 1971:210.—Wiggins, 1977:56.—Roy and Harper, 1979:158.

Brachycentrus similis Banks, 1907a:124.—Ross, 1938:42.

This species is very distinctive, both as a larva and an adult. One larval structure is unique, namely the short carina on the gena just mesad of the eye. This structure, in conjunction with the uniformly brown sclerites, two enlarged setae on the first abdominal sternum, and presence of three enlarged setae on the femora of the mid- and hindlegs, permits ready and positive identification of the larva.

The genitalia of the adult male are equally diagnostic. The cerci are fused mesally, there are paired, rodlike processes between the cerci and tenth tergites, and the clasper bears a large, ovoid flap from near its apex. The tibial spurs of this species are unusually variable (Parker and Wiggins, pers. comm.) with the majority being 2,2,3, but certain populations being mostly 2,3,3 or even 2,2,2, and frequently different on the two sides of the same individual.

ADULT.—Length of forewing, 7–10 mm, 11–13 mm. Color brown, body slightly darker; forewing extensively maculate with pale flecks, especially around the apex. Male abdomen without sternal process.

Male Genitalia: Ninth segment with a distinct, rounded, ventromesal lobe from anterior margin. Cerci elongate, fused mesally. Tenth tergum elongate with an upturned tip in lateral aspect; in dorsal aspect with a U-shaped mesal incision, lateral arms truncate, no macrochaetae; with a pair of elongate, rodlike processes between cerci and tenth tergum. Clasper with basal area small; apex appearing concavely truncate in lateral aspect with a distinct apicoventral lobe; in posteroventral aspect apex produced into a sharp point, with a large, subapical, rounded lobe.

LARVA.—Length to 12 mm. Sclerites dark brown, slightly paler at muscle scars on head; legs uniformly dark brown. Femora of mid- and hindlegs with three enlarged setae, dorsal setae at apex and subbasally also distinctly enlarged. A single submesal pair of large setae on first abdominal sternum; remaining setae on first and second sterna very small. Lateral fringe reduced to a scattering of short hairs on posterior halves of segements 3–7. Gills single.

TYPE MATERIAL.—Holotype, male, MCZ, O. americanus Banks, “Type,” “Franconia, N.H.,” “Collection N. Banks,” “Type 11705,” “Oligoplectrum americanum Bks. Type.” Pinned, abdomen cleared, studied.

Lectotype, male, MCZ, B. similis Banks, “Type,” “Tabernash, Col. Aug. E.S. Tucker,” “Collection N. Banks,” “Type 11684,” “Lectotype B. similis Bks. Ross 1937.” Pinned, abdomen cleared, studied.

MATERIAL EXAMINED.—USA, ALASKA, Po poff Island, 9 Jul 1899, T. Kincaid, 1. Palmer, 10 Jul 1963, 2. Anchorage, 15 mi. NE station 55, 9 Jul 1948, Sailer and Sommerman, 1; same, but 11–15 Aug 1948, 37; same, but 17–22 Aug 1948, 8. Valdez-Fairbanks Hwy., M.P. 139, 12 Aug 1947, A.H. Storm, 7 larvae. Bear River, Alaska Peninsula, 2 Aug 1958, J.D. Fiske, 5 larvae; same, but 11 Jun 1958, 1 larva. Chena River, Fairbanks, 11 Aug 1966, P.J. Frey, 3 larvae. 1 mi. E Northway Airport, 25 Jun 1954, R. Coleman, 2 larvae. Hidden Creek, Sterling Hwy. M.P. 59, 9 Jul 1954, R. Coleman, 1 larva. Alaska Hwy. M.P. 54, near Jack Wade, 26 Jun 1954, R. Coleman, 4 larvae. Beaver Creek, Sterling Hwy., Kenai Peninsula, 5 Jun 1977, D.A. Etnier, 30 larvae (UTK). Hidden Creek at Skilak Lake road, Kenai Peninsula, 7 Jun 1977, D.A. Etnier, 65 larvae, 8 pupae (UTK). Russian River at campground, Kenai Peninsula, 7 Jun 1977, Etnier and Bogardus, 1 genitalia and larval sclerites from decayed pupa (UTK). Kotzebue, 2 Jul 1957, T. Emerson, 10 larvae (INHS).

ARIZONA, Little Colorado, Sheeps Crossing, 6 Jul 1961, 25 larvae (INHS). Apache Co., North Fork White River, Hwy. 473, 19 May 1970, R.W. Baumann, 2 larvae. Apache Co., Little Colorado River, Hwy. 373, Greer, 9 Apr 1968, Koss and Baumann, 2 larvae.

CALIFORNIA, Kern River Power Tunnel, 14 May 1939, 2 larvae. Modoc Co., South Fork Pit River, 5 mi. E Likely, 5 Sep 1969, A.B. Gurney, 1, 4. Mono Co., Convict Creek, 7200 ft., 16–24 Jul 1963, H.D. Kennedy, 6, 11; same, but Jul 1963, 1 larva, 1 pupa; same, but 24 Jul 1958, J. Maciolek, 15 larvae. Plumas Co., Benner Creek, 7 mi. N Chester on Juniper Lake Road, 28 Aug 1963, L.J. Erwin, 10 larvae. Shasta Co., 14 mi. SE Burney, 24 Aug 1959, E. Ordway, 4. Shasta Co., Hat Creek, 2.9 mi. S Old Station, 5 Jul 1977, J.W. Chapin, 3 larvae (CUC). Siskiyou Co., Shadow Creek, 7 mi. E Cecilville, 5 Sep 1968, Gurney and Buxton, 1.

COLORADO, Tabernash, Aug, E.S. Tucker, 1 (lectotype B. similis, MCZ). Boulder, 9 Aug, T.D.A. Cockerell, 1 (lecto-allotype B. similis, MCZ). Four Mile and Boulder Creek, Boulder, 10 Jun 1906, 6 larvae. Custer Co., 10 mi. SW Wetmore, 10 Aug 1971, G.F. Hevel, 1, 4. Eagle Co., Eagle River, Gypsum, 10 Aug 1973, Baumann and Stark, 7, 9. Jefferson Co., Lookout Mountain, 7000 ft., 3 Jul 1922, 1, 1. Jefferson Co., Elk Creek, Hwy. 285, 8 Aug 1973, Bauman and Stark, 1. Larimer Co., North Fork Big Thompson River, E Glen Haven, 13 Jul 1977, Morse and Chapin, 3 larvae (CUC). San Miguel Co., Telluride, 8745 ft., 8–11 Jul 1977, D.C. Ferguson, 6, 6.

FLORIDA. The record of B. americanus from Florida (Denning, 1971) is far to the south of its known range in eastern North America. It undoubtedly represents a mislabeled specimen, and the record of the species from Florida should be deleted.

IDAHO, Salmon River, Challis, 26 Aug 1969, A.B. Gurney, 1. Snake River, 13 Aug 1928, E.O. Essig, 3. Boise National Forest, S. Fork Salmon River Camp, 5000 ft., 13 Aug 1953, C.P. Alexander, 2, 1. Custer Co., 5 mi. NW Stanley, 6300 ft., 28 Jul 1977, J.F.G. Clarke, 1. Idaho Co., Buffalo Hump, 23 mi. SW Elk City, 8300 ft., 16 Aug 1971, Gurney and Brusven, 3. Lemhi Co., Lemhi R., 31 Jul 1964, S.D. Smith, 20 larvae, 1 pupa (ROM).

MAINE, Aroostook Co., Rocky Brook, 10 mi. S. Estcourt Station, 20 Oct 1978, T.M. Mingo, larvae (UMO). Piscataquis Co., Baxter State Park, McManus Brook at Perimeter Road, 16 Aug 1979, T.M. Mingo, larvae, 2 pupae (UMO, USNM); same, but Nesowadnehunk River, Kidney Pond Bridge, 23 May 1979, T.M. Mingo, larvae (UMO); same, but 14 Jun 1979, larvae (UMO); same, but Little Nesowadnehunk River, 7 Aug 1979, T.M. Mingo, larvae (UMO).

MASSACHUSETTS, Pittsfield, 31 Jul, R.A. Brovine, 1 (MCZ).

MICHIGAN, Au Sable River, Mio, 21 May 1936, Frison and Ross, 200 larvae (INHS). Au Sable River, Lovell, 22 May 1936, Frison and Ross, 30 larvae, prepupae and pupae (INHS). Manistee River near Grayling, 22 May 1936, Frison and Ross, 6 larvae (INHS); same, but 17 Jun 1935, T.H. Frison, 25 larvae (INHS). Gogebic Co., Duck Creek, US 45, S Watersmeet, 28 Jun 1982, M.G. DeViedma, 15 larvae.

MINNESOTA, Cook Co., Cascade River, 1938, C. Rief, 1 larva (UMSP). Houston Co., Beaver Creek, Valley State Park, 16–22 Jul 1972, 1 (UMSP); same, but 11–17 Jul 1971, 1, 4 (UMSP).

MONTANA, Bozeman, Experiment Station, 10 Aug 1925, 1 (UMSP). Glacier National Park, Flathead River at Starvation Creek, 28 Aug 1953, R. Coleman, 6 larvae; same, but Akakota Creek at Round Prairie truck trail, 28 Aug 1953, R. Coleman, 12 larvae. Yellowstone National Park, near Gardiner, 16 Aug 1962, P.J. Spangler, 28, 6; same, but Soda Butte Creek, 3 Jul 1978, D.C. Proper, 4 larvae; same, but Gallatin River and Rt. 191, 16 mi. NE Gallatin entrance, 22 Aug 1953. R. Coleman, 6 larvae. Gallatin Co., Gallatin National Forest, South Fork Madison River, Rt. 20, 12 Jul 1977, Chapin and Morse, 4, 30 larvae and pupae (CUC). Missoula Co., Miller Canyon Creek, 29 Aug 1968, R.W. Baumann, 1. Park Co., Armstrong Spring Creek, 5 mi. S., Livingston, 8 Jul 1977, D.C. Proper, 2, 1. Sanders Co., Thompson River, Clark Memorial Campground, 22 Jun 1977, Chapin and Morse, 7 larvae (CUC).

NEVADA, Elko Co., Lamoille Creek, Ruby Mts., SE Elko, 16 Jun 1978, C.M. Murvosh, 2 larvae (ROM). Elko Co., South Fork Humbolt River, Twin Bridges off Hwy. 46, 5200 ft., 17 Jun 1978, C.M. Murvosh, 1 larva (ROM). Lander Co., Big Creek, Big Creek Campground, 2 Aug 1968, R.W. Baumann, 1. Lander Co., Big Creek, 14 mi. S Austin, 6400 ft., 21 Jun 1978, C.M. Murvosh, 3 larvae, 1 prepupa, 1 pupa (ROM). Lander Co., Kingston Creek off Hwy 8A, Smokey Valley, S Austin, 6100 ft., 22 Jun 1978, C.M. Murvosh, 10 larvae (ROM). Nye Co., Peavine Creek, W Hwy. 8A, N Tonopah, Toiyabe National Forest, 22 Jun 1978, C.M. Murvosh, 5 larvae (ROM). White Pine Co., Snake Creek, S Baker and Lehman Caves National Monument, 25 May 1978, C.M. Murvosh, 3 larvae (ROM).

NEW HAMPSHIRE, Franconia, 1 (holotype B. americanus (Banks), MCZ). White Mountains, [illegible word], 1, 1 (MCZ). Fabayan, 3 Aug 1958, O.S. Flint, Jr., 1, 1 pupa. Jefferson, 7 Jul 1963, light trap, 1, 2 (UNH); same, but 20 Jun 1964, 18, 10 (UNH); same, but 10 Jul 1964, 4, 12 (UNH); same, but 14 Jun 1966, 2, 2 (UNH); same, but 2 Jul 1966, 2, 4 (UNH); same, but 22 Jul 1966, 1 (UNH); same, but 24 Jul 1966, 3 (UNH); same, but 8 Aug 1966, 3, 3 (UNH). Colebrook, 26 Jun 1962, 18, 15 (UNH); same, but 17–24 Jul 1957, 2 (UNH).

NEW MEXICO, Cimarron Canyon, Sangre de Cristo Mountains, 7900 ft., 9 Jul 1962, E. and I. Munroe, 1, 1. Catron Co., 5 mi. E Glenwood, 29 Jun 1953, W.W. Wirth, 4 larvae. Colfax Co., 5 mi. W Ute Park, 13 Jul 1974, E.L. Todd, 14, 9. Colfax Co., Ute Park, 17–18 Jul 1974, E.L. Todd, 13, 25. Colfax Co., 2 mi. SE Eagle Nest, 15–16 Jul 1974, E.L. Todd, 4, 6.

NEW YORK, Camden Valley Creek, near Cambridge (S Saratoga Springs), summer 1979, C. Rodrigues, 7 larvae (ROM).

OREGON, Baker Co., Spring Creek, 1–16 Aug 1969, J.H. Baker, 3. Harney Co., 10 mi. SE Frenchglen, 1 Sep 1979, W.H. Rowe, 16, 9. Jefferson Co., Metolius River, I mi. N Camp Sherman, 28 Jun 1977, J.W. Chapin, 10 larvae (CUC). Lane Co., Oakridge, 24 Aug 1979, W.H. Rowe, 5. Wasco Co., Beaver Creek, MP77 Rt. 26, 27 Jun 1977, J.W. Chapin, 15 larvae (CUC).

UTAH, Beaver Canyon [no further data], 3, 1. Park City, 17 Jun 1891, 6 larvae. Logan River, 8 Jul 1952, D.J. King, 50 larvae. Timpanogos Cave National Monument, 27 Sep 1963, D.H. Huntzinger, 1; same, but 6 Aug 1963, 1. Wasatch National Forest, Shingle Creek Campground, 20 Aug 1953, R. Coleman, 6 larvae. Beaver Co., Beaver River at mouth Beaver Canyon, 4 Aug 1969, R.W. Baumann, 3. Cache Co., Logan, 13 Aug 1973, G.F. Knowlton, 3, 10. Cache Co., Logan Canyon, China Row, 9 Sep 1974, G.F. Knowlton, 1. Cache Co., Logan Canyon, Ricks Spring, 29 Aug 1964, A.V. Nebeker, 1. Cache Co., Logan River, 5 mi. below Ricks Spring, Logan Canyon, 5500 ft., 15 Oct 1961, A.V. Nebeker, 6 larvae. Carbon Co., Mud Creek, near Clear Creek, 30 Jul 1973, R. and W. Baumann, 4, 1, 5 larvae. Duchesne Co., Duchesne River, Duchesne, 3 Aug 1973, Baumann and Stark, 1. Emery Co., Huntington Creek, Huntington Canyon, 31 Jul 1973, R. and W. Baumann, 5, 5 larvae. Emery Co., Lowry Fork, near Joes Valley Reservoir, 31 Jul 1973, R. and W. Baumann, 1. Salt Lake Co., Mill Creek Canyon, 6000 ft., 28 Aug 1961, 8 larvae. Summit Co., Hayden Fork, Sulphur Forest Camp, 20 Aug 1961, D.W. Argyle, 8 larvae. Summit Co., Little Lyman Lake, Little Lyman Lake Camp, 21 Aug 1973, R. and W. Baumann, 1. Summit Co., East Fork Bear River, Hwy. 150, 21 Aug 1973, R. and W. Baumann, 4, 2, 4 larvae. Summit Co., Weber River, 1 mi. NW Peoa, 28 Jul 1973, B. Stark, 3, 3. Tooele Co., Clover Creek, 30 Apr 1960, D.W. Argyle, 5 larvae. Utah Co., Provo River, Upper Falls, 14 Aug 1973, R.W. Baumann, 1, 4. Utah Co., Soldier Creek, Hwy. 50, Tucker, 12 Aug 1973, Baumann and Stark, 7, 3. Utah Co., Thistle Creek, Thistle, 30 Jul 1973, R. and W. Baumann, 6 larvae.

VERMONT, Waits River, West Topsham, 21 June 1941, Frison and Ross, 1 and 1 metamorphotypes (INHS). Addison Co., small stream at foot of Moss Glenn Falls, Rt. 100, S Warren, 26 Jul 1969, T. Yamamoto, 4 larvae (ROM).

WASHINGTON, Jefferson Co., fork Quilcene River, Quilcene, 8 Aug 1971, A.B. Gurney, 1, 3.

WISCONSIN, Namekagon River, Spring Brook, 6 Jun 1936, Frison and Ross, 25 larvae (INHS). Manitowish River, Boulder Junction, 2 Oct 1937, T.H. Frison, 2 larvae (INHS). Westfield, 9 Apr 1937, Frison and Mohr, 15 larvae (INHS). Coloma, 1 Jul 1933, Frison and Mohr, 15 larvae (INHS). Adams Co., Carter Creek, 25 Jun 1970, 30 (UWM). Adams Co., Big Roche Creek, 27 May 1977, 15 larvae (UWM). Barron Co., Dorits Creek, 2 May 1979, 10 larvae (UWM). Bayfield Co., East Fork Cranberry, 7 Jul 1970, 75 (UWM). Bayfield Co., Pine Creek, 6 Oct 1979, 1 larva (UWM). Buffalo Co., Spring Creek, 6 Jun 1978, 4 larvae (UWM). Douglas Co., Ox Creek, 10 May 1979, 1 larva (UWM). Douglas Co., Brule River, 6 Oct 1979, 15 larvae (UWM). Dunn Co., Otter Creek, 1 May 1979, 5 larvae (UWM). Florence Co., White Popple River, 24 Aug 1970, 4 (UWM). Forest Co., Armstrong Creek, 23 Jun 1981, 1 larva (UWM). Iron Co., Vaughn Creek, Ashland, 22 Jun 1979, 5 larvae (UWM). Langlade Co., West Branch Eau Claire River, 19 Jul 1968, 2 (UWM). Langlade Co., East Branch Eau Claire River, spring 1979, 4 larvae (UWM). Marinette Co., Sidney Creek, 12 Jun 1978, 3 larvae (UWM). Marquette Co., Togatz Creek, 13 Aug 1970, 30 (UWM). Marquette Co., Lawrence Creek, 20 Jun 1973, 15 larvae (UWM). Oneida Co., Bearskin Creek, spring 1979, 50 larva (UWM). Polk Co., McKenzie Creek, 17 Aug 1970, 25 (UWM); same, but 6 Jun 1978, 1 larva (UWM). Portage Co., Little Plover River, 7 May 1979, 5 larvae (UWM). Richland Co., Melancthon River, 11 Jun 1970, 1, 2 (UWM). Sheboygan Co., Nichols Creek, 5 Nov 1979, 8 larvae (UWM). Vilas Co., Deerskin River, 23 May 1979, 3 larvae (UWM). Waushara Co., Mecan River, 27 May 1977, 25 larvae (UWM).

WYOMING, Yellowstone National Park, Old Faithful, 12 Aug 1927, J.M. Aldrich, 1; same, but Mammoth, 15 Aug 1962, P.J. Spangler, 1; same, but Madison River, 21 Aug 1955, K.M. Fender, 3, 3; same, but Madison Jct., 19 Aug 1962, P.J. Spanger, 10, 3; same, but Firehole River, 21 Aug 1962, P.J. Spangler, 3 larvae; same, but Gibbon River, 1965, E.R. Vincent, 20 larvae; same, but Gardner River, Indian Creek Campground, 12 Jul 1961, G.B. Wiggins, 100 larvae and pupae (ROM), same, but Soda Butte Creek, 2 Aug 1940, T.H. Frison and Jr., 5 larvae (INHS); same, but Black Sand Basin, 22 Jun 1977, Chapin and Morse, 50 larva (CUC); same, but 12 Jul 1977, 25 larvae (CUC). Grand Teton National Park, Cottonwood Creek, 5 Aug 1940, T.H. Frison and Jr., 50 larvae (INHS).

CANADA, ALBERTA, Calgary, 25 Jul 1902, 1 (MCZ).

BRITISH COLUMBIA, 111 Mile Creek, near crossing Cariboo Hwy., 25 June 1956, R. Coleman, 15 larvae. Coppermine Creek, Manning Park, 9 Aug 1950, H.H. Ross, 1 larva (INHS).

MANITOBA, Churchill, 14 Jul 1952, H.E. Welch, 4 larvae (ROM). Goose Creek, Churchill, 31 Jul 1980, 2 larvae (ROM). South Duck River, SD2–1, 27 Jul 1980, D.G. Cobb, 1 (FWI).

NEW BRUNSWICK, Kedgewick Ouest, 1 Sep 1962, D.R. Whitehead, 7 larvae.

NORTHWEST TERRITORIES, stream at S end Husky Lakes, 5 Sep 1955, J.G. Hunter, 30 larvae (ROM). Sagvacjuac, Chesterfield Inlet (63°30′N, 90°50′W), 3 Jul 1977, B. deMarch, 1 larva (ROM).

ONTARIO, Kenora District, Kiruna Lake, small stream in muskeg (54°30′N, 84°55′W), 22 Jul 1981, E. Fuller, 12 larvae (ROM); same, but 2 Aug 1981, 8 larvae (ROM).

QUEBEC, Rivière Ste. Anne, Parc Mt. Albert, 2 Aug 1974, D. Roy, , (UMQ).

SASKATCHEWAN, mossy stream on Hwy. 224, ∼4.5mi. N Meadow Lake Provincial Park, Goodsoil, 16 Aug 1970, ROM field party, 5 larvae (ROM). Lac Le Ronge Provincial Park, 10 Mile Creek, 18 Jun 1959, C.E. Cushing, 10 larvae (ROM).

YUKON TERRITORY, Judas Creek Camp, MP 872 Alaska Hwy., 12 Aug 1950, Hansen and Beer, 7 larvae (INHS).

ADULT.—Spurs 2,3,3, but smaller males often 2,2,3.

Male Genitalia: Ninth segment with ventral area not produced anteriad. Cerci in dorsal aspect mostly fused mesally. Tenth tergum elongate, with two accessory processes on midline. Claspers elongate, semierect; with a large lateroventral lobe.

LARVA.—Head with a distinct color pattern. Primary setae of head very short (e.g., no. 17). Mid- and hindfemora with a single large seta on ventral margin, and 3–5 extra setae on anterior and posterior faces; setae of filtering fringe virtually uniform in structure and length; apical and subbasal setae on dorsal margin distinctly enlarged. With 1 submesal pair of setae on first abdominal venter. Gills single.

TYPE-SPECIES.—Oligoplectrum echo Ross (here designated).

Common.

Adults can be found from late June to mid-September.

This species has a Holarctic distribution: in North America, from Alaska to New Mexico, in the east from Tennessee to Vermont. In Canada, it is transcontinental (Schmid, 1983).

The vertex of the adult head is reddish-brown with dense white and beige hairs. Antennae are brown, with reddish rings. Spur count is 2, 2, 3. Claspers of the males are irregularly shaped, dumb-bell like. Otherwise, the overall shape of the clasper is linear, with the extremities folded mesad.

Restricted to running waters.

The larvae are omnivorous, obtaining their food either by filter feeding or scraping.

Brachycentrus americanus is a species of humpless casemaker caddisfly in the family Brachycentridae. It is found in North America. It is most prolific in the West and Midwest of North America in July and August.