Remenus bilobatus ( Needham & Claassen, 1925 )

Verdone, Chris J. & Kondratieff, Boris C., 2018, Holomorphology And Systematics Of The Eastern Nearctic Stonefly Genus Remenus Ricker (Plecoptera: Perlodidae), Illiesia 14 (5), pp. 81-125 : 93-99

Remenus bilobatus ( Needham & Claassen, 1925)

( Figs. 3–18 , 20–40 )

http://lsid.speciesfile.org/urn:lsid: Plecoptera .speciesfile.org: TaxonName:608

Perla bilobata Needham & Claassen (1925: 95)

Holotype ♂: New York, Herkimer County, Old Forge (Cornell University Insect Collection). Figures: adult– fore- and hindwing, male stern 7–9, male terminalia (lateral), female subgenital plate.

Perla bilobata: Claassen (1931: 54) . Figures: larva– labrum, mandibles, labium, maxilla, lacinia.

Diploperla bilobata: Frison (1942: 302) . Figures: larva– habitus, female sterna, mandibles, labium, maxilla, lacinia.

Isogenus (Remenus) bilobatus: Ricker (1952: 122) Remenus bilobatus: Illies (1966: 376)

Remenus bilobatus: Hitchcock (1974: 214) . Figures: larva–habitus, female sterna ( Frison 1942); adult–male terminalia (dorsal, lateral), female subgenital plate (incorrectly associated).

Remenus bilobatus: Surdick & Kim (1976: 9)

Remenus bilobatus: Lake (1980: 43)

Remenus bilobatus: Tarter & Kirchner (1980: 49) Remenus bilobatus: Kondratieff & Voshell (1982: 761) . Figures: adult–head and pronotum, male terminalia (dorsal), female subgenital plate.

Remenus bilobatus: Stewart & Stark (1984: 406) . Figures: larva–head and pronotum, mandible, lacinia, foreleg, mesosternum, male and female sterna 7–10, cercus (basal, middle, apical).

Remenus: Stewart & Stark (1988: 402) . Figures: larva– male habitus, and figures from Stewart & Stark (1984). Remenus bilobatus: Kondratieff & Nelson (1995: 596) . Figures: adult–male terminalia (dorsal, lateral), female subgenital plate, ova (dorsal, ventral).

Remenus bilobatus: Grubbs (1997: 81)

Remenus bilobatus: Stewart & Stark (2002: 437) Figures: larva–figures from Stewart & Stark (1984, 1988) Remenus bilobatus: Kondratieff (2004: 164) . Figures: adult–figures from Kondratieff & Nelson (1995) Remenus bilobatus: DeWalt & Heinold (2005: 40) Remenus bilobatus: DeWalt et al. (2007: 142)

Remenus bilobatus: Parker et al. (2007: 171)

Remenus bilobatus: Tarter & Nelson (2010: 162) Remenus bilobatus: Grubbs (2011: 29)

Remenus bilobatus: Li & Murányi (2015: 47) . Figures: adult–male epiproct, basal anchor.

Remenus bilobatus: Tarter et al. (2015: 170)

Remenus bilobatus: Stark (2017: 236) . Figures: larva– cercus (basal, middle)

Material examined: Alabama, Cleburne Co., small stream above lake, Cheaha State Park, [N 33.47396, W 85.82077], 14 May 1988, B.C. Kondratieff, R.F. Kirchner, 3♂, 3♀ ( CSUIC) . Connecticut, Middlesex Co., brooklet, Rte 148, Killingworth [No GPS], 18 June 1965, S.W. Hitchcock, 4♂ ( NMNH) ; nr. Madison, nr. Rte 80, [no GPS], 18 June 1965, S.W. Hitchcock, 1♂ ( NMNH) . Salem Co., Fraser Brook, Salem, Four Corners, [N 41.47291, W 72.26029], 15 June 1967, S. W. Hitchcock, 1♂ ( NMNH) . Tolland Co., Storrs, [N 41.80843, W 72.24952], 18 June 1954, J.A. Slater, 1♂, 1♀ ( NMNH) . Maryland, Frederick Co., Fishing Creek, Mountaindale, [N 39.51949, W 77.45114], 1 July 1958, P. Freytag, 3♂ ( INHS) . New York, Herkimer Co., Old Forge, [N 43.71007, W 74.97434], 18 July 1905, J.G. Needham, P.W. Claassen, 1♂, 1♀ ( NMNH, paratypes) North Carolina, Alleghany Co., Brush Creek, Blue Ridge Parkway, BLRI, N 36.46067, W 80.99979, 26 May 2016, C. Verdone, B.C. Kondratieff, 1♂ ( CSUIC) ; Stone Mountain Creek, Stone Mountain Rd., Stone Mountain State Park, N 36.39445, W 81.03341, B.C. Kondratieff, R.F. Kirchner, R.E. Zuellig, D. R. Lenat, 10♂, 3♀ ( CSUIC) . Ashe Co., tributary to Peak Creek, Peak Creek Rd., BLRI, N 36.38101, W 81.27936, 21 May 2017, [emerged 25 May 2017], C. Verdone, D. Fuller, 1♀ ( CSUIC) ; Same data, [emerged 26 May 2017], 1♀ ( CSUIC) ; Same data, [emerged 30 May 2017], 1♀ ( CSUIC) . Caldwell Co., Johns River, Old Johns River Rd., NE of Collettsville, N 35.94711, W 81.70472, 2 May 2005, B.C. Kondratieff, R.F. Kirchner, R.E. Zuellig, D. R. Lenat, 1L ( CSUIC) ; Johns River, St. Johns River Rd. just upstream of Franklin Branch NE of Collettsville, N 35.93361, W 81.69056, 17 May 2004, B.C. Kondratieff, R.F. Kirchner, R.E. Zuellig, D. R. Lenat, 1♂ ( CSUIC) ; Thunderhole Creek, Rte 1366, N 36.07324, W 81.69975, 14 May 2017, C. Verdone, B.C. Kondratieff, 3♀, 1L ( CSUIC) . Jackson Co., Balsam, [N 35.42667, W 83.08528], 24 April 1938, H.H. Ross, B.D. Burks, 6L ( INHS) . Macon Co., Big Creek, Lake Randall, [N 35.07861, W 83.20806], 20 June 1939, T. Howell, 1L ( INHS) ; Jarrett Creek, Arrowwood Glade, [N 35.15444, W 83.58616], 25 May 1993, B.C. Kondratieff, R.F. Kirchner, 1♂ ( CSUIC) . Swain Co., Ekaneetlee Creek, 75 m upstream confluence Eagle Creek nr. Camp 89, N 35.49810, W 83.76640, 10–11 June 2003, B.D. Heinold, 1♂ ( INHS) ; Skidder Branch, Straight Branch mi. 20, [N 35.59062, W 83.23494], 28 July 1982, B. Armitage, 1♀ ( CSUIC) ; Twentymile Creek, Twentymile Creek Trail, Camp 93, GRSM, N 35.47300, W 83.85240, 1 July 2004, R.E. DeWalt, 1♀ ( INHS) . Transylvania Co., Pigeon Branch of South Fork Mills River, NFR 1206 off Rte 276, [N 35.35815, W 82.77810], 8 July 1981, B.C. Kondratieff, 1♂, 1♀ ( CSUIC) . Watauga Co., Clear Branch Blue Ridge Parkway, BLRI, N 36.22954, W 81.54462, 21 May 2017, C. Verdone, D. Fuller, 1♀ ( CSUIC) . Wilkes Co., Betseys Rock Falls Creek, Walsh Rd. NW of Wilkesboro, N 36.28380, W 81.39729, 11 July 2008, B.C. Kondratieff, R.E. Zuellig, D. R. Lenat, 1♂ ( CSUIC) ; Garden Creek, Stone Mountain Rd., N 36.38905, W 81.06922, 29 May 2006, B.C. Kondratieff, R.F. Kirchner, R.E. Zuellig, D. R. Lenat, 3♂, 4♀, 7L ( CSUIC) . Pennsylvania, Chester Co., Wet Lab at Stroud Research Center, London Grove, [N 39.86911, W 75.77245], 27 May 1980, D.H. Funk, 7♂ ( INHS) ; Same location, 4 June 1980, D.H. Funk, 3♂, 3♀ ( INHS) . Mifflin Co., Honey Creek, Reeds Gap, St. Park, New Lancaster Valley Rd., [N 40.72150, W 77.47426], 7 June 2013, B.C. Kondratieff, J. Sandberg, 2♂ ( CSUIC) ; Little Poe Creek, Poe Valley, Little Poe Rd. 2 mi. E Poe Paddy State Park, [N 40.82977, W 77.44454], 8 June 2013, B.C. Kondratieff, J. Sandberg, 1♂ ( CSUIC) . South Carolina, Pickens Co., Wildcat Creek, 9 km SW Clemson, [N 34.75607, W 82.85767], 18 May 1976, P.H. Carlson, 1♂ ( CSUIC) ; Wildcat Creek, Clemson Experimental Forest, [N 34.75607, W 82.85767], 5 May 1985, K.W. Stewart, B.C. Kondratieff, R.F. Kirchner, 1L ( INHS) . Tennessee, Blount Co., Abrams Creek, Cades Cove, Old Field ATBI Plot, [N 35.60470, W 83.77570], 9 May–3 June 2002, J. Burbank, 1♂ ( CSUIC) ; Abrams Creek, Cades Cove, Sparks Lane, GRSM, N 35.60400, W 83.79390, 7 June 2001, B.D. Heinold, 1♂ ( INHS) ; Abrams Creek, Cades Cove, GRSM, [N 35.60494, W 83.77653], 1–12 June 2003, C. R. Parker, 4♂ ( CSUIC) ; Same location, 18–25 June 2003, C. R. Parker, ♂ ( CSUIC) ; Cades Cove, GRSM, [N 35.60840, W 83.82700], 13 June 1940, T.H. Frison, 1♂, 1 exuvia ( INHS) ; Cattail Branch, GRSM, N 35.51490, W 83.97630, 21–22 May 2003, R.E. DeWalt, B.D. Heinold 3L ( INHS) ; Tabcat Creek, at first jeep trail crossing, GRSM, N 35.51956, W 83.97927, 21 May 2003, R.E. DeWalt, 4L ( INHS) . Sevier Co., Le Conte Creek, Gatlinburg, [N 35.70164, W 83.51361], 4 May 1939, T.H. Frison, 7L ( INHS) . Virginia, Albemarle Co., Blackrock Spring, Fire Rd. off Skyline Dr. ( SHEN) , N 38.20504, W 78.74916, 3 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 8♂, 2♀ ( CSUIC) ; South Fork Moormans River, Fire Rd. of Skyline Dr. ( SHEN) , N 38.09850, W 78.77815, 3 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 1♀ ( CSUIC) . Alleghany Co., Hays Creek, Rte 619, N 37.73125, W 80.00259, 10 June 2016, C. Verdone, B.C, Kondratieff, 2♂, 2♀ ( CSUIC) . Amherst Co., Dancing Creek, Blue Ridge Parkway, Dancing Creek Overlook Parking, BLRI, N 37.63430, W 79.33258, 18 June 2016, C. Verdone, 1♂ ( CSUIC) . Augusta Co., Calfpasture River, Jct. Hwy 250 and Rte 715, [N 38.27356, W 79.30068], 8 June 2017, B.C. Kondratieff, 5♂, 3♀ ( CSUIC) ; Love bog Blue Ridge Parkway, mile 15.61, BLRI, [N 37.88348, W 79.01054], 16-17 July 2007, C. R. Parker, 1♂ ( CSUIC) ; Paine Run, Jct 661 and 614, [N 38.19880, W 78.79340], 19 July 1975, O.S., C.M Flint 1♂ ( NMNH) ; tributary to Braley Pond, NW Rte 715, [N 38.28963, W 79.30448], 9 June 2017, B.C. Kondratieff, 1♂ ( CSUIC) . Bedford Co., Battery Creek, FR 951, N 37.55194, W 79.44059. 17 June 2016, C. Verdone, 2♂, 1♀ ( CSUIC) ; Falling Rock Creek, Blue Ridge Parkway, BLRI, N 37.56403, W 79.40851, 27 May 2017, C. Verdone, D. Fuller, 2♂ ( CSUIC) ; Hunting Creek, Rte 602, N 37.53511, W 79.42025, 17 June 2016, C. Verdone, 1♂, 1♀ ( CSUIC) ; Little Stony Creek, Hwy 43, Peaks of Otter Picnic Area, BLRI, N 37.4454, W 79.59713, 17 June 2016, C. Verdone, 5♂, 6♀ ( CSUIC) . Bland Co., Laurel Creek, Rte 613, under Hwy 77, N 37.25547, W 81.12081, 8 June 2016, C. Verdone, B.C. Kondratieff, 1♂ ( CSUIC) ; Wolf Creek, Hwy 61, [No GPS], 10 June 1978, B.C. Kondratieff, 1♀ ( CSUIC) . Botetourt Co., spring fed stream, Blue Ridge Parkway, BLRI, N 37.39235, W 79.83864, 31 May 2016, C. Verdone, B.C. Kondratieff, 3♂, 2♀ ( CSUIC) ; Bearwallow Creek, Hwy 443, N of BLRI, Bearwallow Gap, N 37.4856, W 79.66866, 19 May 2017, C. Verdone, B.C. Kondratieff, 1♂, 1♀ ( CSUIC) . Carroll Co., Big Reed Island Creek Rd. between Rte 640 & Rte 645, N 36.67665, W 80.51019, 30 May 2016, C. Verdone, B.C. Kondratieff, 1♂ ( CSUIC) ; Crooked Creek, Rte 620, trout fishing trail, N 36.67296, W 80.80853, 29 May 2016, C. Verdone, B.C. Kondratieff, 20♂, 27♀ ( CSUIC) ; Stewarts Creek, Rte 896, N 36.58083, W 80.76437, 30 May 2016, C. Verdone, B.C. Kondratieff, 4♂ ( CSUIC) ; tributary to Crooked Creek, Rte 620 nr. abandoned barn, N 36.67318, W 80.81921, 30 May 2016, C. Verdone, B.C. Kondratieff, 1♀ ( CSUIC) . Craig Co., seeps into Barbours Creek, Rte 617, Potts Jeep Trail, N 37.63398, W 80.05481, 10 June 2016, C. Verdone, B.C. Kondratieff, 2♂ ( CSUIC) . Fauquier Co., Bartons Brook, Jackson Hollow, [no GPS], 15 July 1974, R.W. Baumann, O. Flint, 1♀ ( NMNH) ; Little Bull Run, Bull Run Mtn., Shurburg Home, Hopewell Rd., N 38.86665, W 77.703922, 1 June–10 July 2014, D. R. Smith, 7♂, 3♀ ( NMNH) ; tributary to Broad Run, Arlington Outdoor Lab, [N 38.80720, W 77.72170], 3–20 June 2016, D. R. Smith, 1♀ ( NMNH) ; tributary to Piney Branch, Roland Farm, N 38.843, W 77.8261, 23 May–6 June 2013, D. R. Smith, 3♂, 3♀ ( CSUIC) ; Same location, 7–25 June 2013, D. R. Smith, 5♂, 7♀ ( NMNH) . Floyd Co., Dodd Creek, Blue Ridge Parkway, BLRI, N 36.87178, W 80.27901, 31 May 2016, C. Verdone, B.C. Kondratieff, 1♂, 1♀ ( CSUIC) . Franklin Co., Grassy Fork, Rte 619, N 36.81097, W 79.74516, 7 June 2016, C. Verdone, B.C. Kondratieff, 1♀ ( CSUIC) ; Frederick Co., Cold Spring, 800 m S FR 93 Gate, N 38.80720, W 77.72170, 20 June 2007, A.C. Chazal, 1♂ ( NMNH) . Greene Co., Fork Hollow, Ranger Station, nr. Simmons Gap ( SHEN) , N 38.3007, W 78.61979, 3 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 11♂, 6♀ ( CSUIC) . Madison Co., Cedar Run, Rte. 600, White Oak Canyon Trailhead, SHEN, N 38.53907, W 78.34813, 2 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 6♂ ( CSUIC) ; Rapidan River, Rte 649 ( SHEN) , N 38.46256, W 78.36535, 2 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 1♂ ( CSUIC) ; Robinson River, Rte 600, N 38.52717, W 78.35015, 2 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 6♂, 4♀ ( CSUIC) ; tributary to Rapidan River, Rte 649 ( SHEN) , N 38.46519, W 78.36990, 2 June 2016, C. Verdone, B.C, Kondratieff, S. Roble, 4♂, 1♀ ( CSUIC) . Montgomery Co., spring flowing into Craig Creek, 2.7 km off 460 on Rte 621, [No GPS], 17 June 1980, B.C. Kondratieff, 1♂ ( CSUIC) ; spring tributary to Poverty Creek, Rte 708, N 37.26314, W 80.49781, 15 June 2016, C. Verdone, 8♂, 5♀ ( CSUIC) . Toms Creek, Rte 655, [N 37.238054, W 80.47339], 29 May 1978, B.C. Kondratieff, 1♂ 1 exuvia. Patrick Co., Little Rock Castle Creek, of milepost 165, Rt. 8, BLRI, [N 36.82747, W 80.32460], 18–19 May 2007, C. R. Parker, 3♂, 2♀ ( CSUIC) . Prince William Co., Bull Run Mtn., Mountain House, N 38.82500, W 77.70500, 26 May–11 June 2012, D. R. Smith, 2♂, 1♀ ( NMNH) ; Catharpin Creek., Jackson Hollow Campground, N 38.876667, W 77.68900, 11–24 June 2011, D. R. Smith, 5♂, 1♀ ( CSUIC) ; Same location, 26 May–11 June 2012, D. R. Smith, 2♂, 2♀ ( CSUIC) ; Same location, 26 May–11 June 2012, D. R. Smith, 12♂, 5♀ ( NMNH) ; Same location, 12–27 June 2012, D. R. Smith, 2♂, 1♀ ( CSUIC) ; Same location, 21 June– 10 July 2014, D. R. Smith, 2♂ ( CSUIC) ; Same location, 20 May–2 June 2016, D. R. Smith, 3♂ ( NMNH) ; tributary to North Fork Broad Run, Bull Run Mtn. Natural Area above rd., N 38.84700, W 77.70072, 21 May–5 June 2014, D. R. Smith, 1♂ ( NMNH) . Rockbridge Co., Back Run, Cave Mtn. Rec. Area, N 37.56891, W 79.54088, 17 June 2016, C. Verdone, 5♀ ( CSUIC) . Rockingham Co., Deep Run, Rte 708, N 38.27972, W 78.76374, 3 June 2016, C. Verdone, B.C. Kondratieff, S. Roble, 1♂ ( CSUIC) . Tazewell Co., Cove Creek, Rte 662, off Hwy 61, N 37.17837, 81.29900, 6 June 2016, C. Verdone, B.C. Kondratieff, 9♂, 9♀ ( CSUIC) ; East Fork Cove Creek, Rte 662, [N 37.19464, W 81.30068], 12 June 1983, B.C. Kondratieff, 1♂ ( CSUIC) . Washington Co., Detroit Cove, Jct. Brumley Gap Rd. & Rte 689, N 36.79664, W 82.05730, 24 May 2016, C. Verdone, B.C. Kondratieff, B. Evans, 9♂, 9♀ ( CSUIC) ; Detroit Cove, Rte 689, N 36.79664, W 82.05730, 4 May 2017, C. Verdone, B.C. Kondratieff, 1L ( CSUIC) ; Little Moccasin Creek, Rte 690 (below switchbacks) , N 36.83005, W 82.08855, 13 June 2016, C. Verdone, 1♂, 1♀ ( CSUIC) . Wythe Co., Gullion Fork, Rte 619, N 37.01228, W 81.25340, 27 May 2016, C. Verdone, B.C. Kondratieff, 2L ( CSUIC) . West Virginia, Hardy Co., Lower Cove Run, 3 mi. NE of Mathias, N 38.91938, W 78.81641, 10-24 July 2003, D. R. Smith, 1♂ ( CSUIC) ; Same location, 18 June–1 July 2004, D. R. Smith 6♂, 2♀ ( CSUIC) ; Same location, 12–15 July 2004, D. R. Smith, 4♂ ( NMNH) . Mingo Co., Laurel Branch of Laurel Fork, 2 mi. S Dingess at CR-3/07, [N 37.85006, W 82.20055], 17 June 1975, R.F. Kirchner, 1♂, 1 exuvia ( INHS) ; Laurel Fork of Pigeon Creek, 2 mi S Dingess at CR-3/07, [N 37.84891, W -82.20064], 8 May 1976, R.F. Kirchner, 2L ( INHS) ; Same location, 13 June 1975, R.F. Kirchner, 1♀, 1 exuvia ( INHS) ; Same location, 20 June 1975, R.F. Kirchner, 7N ( INHS) .

Additional records not examined. New York, Franklin Co., Dutton Brook, Rt. 3 nr. Saranac Lake , N 44.2495, W 74.23818, 4 August 2006, L. Myers, 3♀ ( LCRI) . Warren Co., seep to Lake George, Rt. 9 North , Basin Bay , N 43.52100, W 73.67410, 5 August 2009, L. Myers, 1♂, 5♀ ( LCRI) .

Distribution. USA – AL, CT, DE, GA, KY, MD, NC, NY, PA, SC, TN, VA, WV. ( Fig. 19 ).

Male. ( Fig 20 ). Macropterous; forewing length 10.0– 11.0 mm (n = 10) ( Fig. 21 ). Body length 8.1–10.6 mm (n = 10). General body color yellow-gold with light brown markings. Dorsum of head typical of genus ( Fig. 22 ). Pronotum light brown, covered in regularly spaced setae, with pale, glabrous rugosities mediolaterally ( Fig. 22 ); medial pale area widest posteriorly ( Fig. 22 ). Abdominal terga uniformly yellow-gold ( Fig. 23 ). Tergum 8 with mediolateral patches of <10 sensilla basiconica ( Fig. 23 ). Tergum 9 with a medial glabrous division that extends anteriorly ¾ tergum length and mediolateral patches of ~ 20 sensilla basiconica ( Fig. 23 ). Hemitergal lobes short, separated from 10 th tergum, with long trichoid sensilla and> 20 sensilla basiconica on each lobe ( Figs. 23–26 ). Epiproct length ~ 300–320 μm; width ~ 80–84 μm (n = 3); epiproct flattened laterally ( Figs. 23 , 26 ), with a ventral keel ( Figs. 24 , 27–28 ), and a mediodorsal sclerite that is broadest basally and greatly exceeds the epiproct apex terminating in a thread-like lash ( Figs. 23 , 26-27 ); complete lash length ~ 830 μm (n = 1); keel widest at mid-length ( Fig. 26 ), covered in dense, hair-like spinulae ( Fig. 28 ). Paragenital plates broadly triangular ( Figs. 23–24 , 26 ). Basal cowl clothed in dense golden-brown spinulae ( Figs. 23– 24 ).

Female. Macropterous; forewing length 9.8–12.0 mm (n = 10). Body length 8.8–11.1 mm (n = 10). Body coloration and morphology similar to male. Sternum 8 with variable subgenital plate extending ~ ½ over sternum 9, or to the posterior margin of sternum 9; subgenital plate moderately sclerotized, broadly triangular ( Fig. 29 ) or broadly rounded ( Fig. 30 ); with regularly spaced setae; posterolateral margins convex; basolateral margins either parallel or convergent posteriorly; basolateral crease nearly straight or convex posteriorly, extending ~ ⅓ length anteriorly into sternum 8 ( Figs. 29–30 ).

Ovum. Shape typical of genus ( Figs. 31–34 ). Length 439–440 μm; width 348–361 μm (n = 3).

Larva. ( Fig. 35 ). Body length 9.0– 10.4 mm, (n = 5). Head ( Fig. 36 ), lacinia ( Fig. 37 ), mandibles ( Fig. 38 ), and pronotum ( Fig. 36 ) typical of genus. Mature male larva with an elongate terminal process with a constriction at the basal ⅓; apical ⅔ thin and tapered ( Fig. 39 ). Mature larva with paired medial and lateral spots on the abdominal terga. Basal cercal segments with whorls of both long and short setae ( Fig. 40 ).

Diagnosis. Remenus bilobatus , with its characteristic epiproct lash is easily separated from the other Remenus species. However, the lash is rarely complete and may become broken as a result of collection, eversion, preservation, or possibly the lash is naturally broken during development or on mated individuals. Even when incomplete the lash generally still greatly exceeds the epiproct apex. The only other species of Remenus with a dorsal sclerite on the epiproct is R. duffieldi , but it does not greatly exceed the epiproct apex as in this species. Males of R. bilobatus are further differentiated in that the epiproct is laterally flattened, the 9 th tergum has a medial glabrous division, both terga 8 and 9 have mediolateral patches of sensilla basiconica, and the basal cowl is clothed in dense golden-brown spinulae. Whereas in males of R. duffieldi , the epiproct is dorsoventrally flattened, tergum 9 is not divided and lacks sensilla basiconica, and the spinulae covering the basal cowl are pale.

In general, the female subgenital plate of R. bilobatus is broadly triangular or broadly rounded, with basolateral margins either parallel or convergent posteriorly and a basolateral crease that is nearly straight or convex posteriorly. The subgenital plate can be quite similar to the other species, but the nearly straight or convex basolateral crease is consistently different compared to the concave crease seen in R. daniellae sp. n., and R. kirchneri . Females of R. bilobatus differ from R. duffieldi by a generally shorter subgenital plate and in pronotal pigmentation. The pronotum of R. bilobatus is brown with pale rugosities, whereas in R. duffieldi , it is pale with brown rugosities. We still agree with Kondratieff & Nelson (1995) who asserted that females of Remenus should not routinely be identified in the absence of male specimens.

Mature larvae of R. bilobatus can be separated from R. kirchneri and R. duffieldi by the presence of long setae on the basal cercal segments. However, this character is shared by R. daniellae sp. n. which is sympatric in several locations. Rearing of larvae is still the best hope for species level identification.

Biological notes. No life history or biological studies have been conducted on this species. Anecdotal evidence suggests that this predaceous perlodine has a univoltine life cycle and inhabits leaf packs in areas with swift current ( Beaty 2015).

Based on the examined material, emergence begins in early May and continues into late July. In the northern part its range emergence can continue into early August. Remenus bilobatus inhabits springs to 6 th order rivers ( Kondratieff & Voshell 1982) with drainage areas ranging from 0.26–165.2 km 2 and has been recorded from six eastern Nearctic physiographic provinces (Adirondack, Appalachian Plateau, Blue Ridge, New England, Piedmont Plateau, and Ridge and Valley). The average elevation of occurrence localities is 503.4 m (SD ± 219.1 m). The relatively large range of this species may be explained in part by the wide range of stream sizes it inhabits, providing it with greater habitat connectivity. Although this species is widely distributed, adults are seldom collected in large numbers. Of the 88 adult records presented only 13.6% (n = 12) were represented by more than 10 individuals, 43.2% (n = 38) were represented by a single specimen.

Figures

Figs. 3–6. Remenus bilobatus, adult male. 3. Head and pronotum, AO = anterior ocellus, AS = antennal scape, ES = epicranial suture, Fr = frons, IoA = interocellular area, LO = lateral ocelli, MPA = medial pale area, Ro = rugosities, Th1 = pronotum. 4. Right forewing, A = anal vein, ACS, apical costal space, C = Costal vein, Cu = cubital vein, M = median vein, R = radial vein, Rs = radial sector vein, Sc = subcostal vein. 5. Male abdominal sterna 7–10, A = posterodorsal lobes, Ae = aedeagus, Ab = abdominal segment, B = lateral lobes, SL = sternal lobe. 6. Male abdominal terga 8–10, A = posterodorsal lobes, Ae = aedeagus, Ab = abdominal segment, B = lateral lobes, BA = basal anchor, HL = hemitergal lobe, PP = paragenital plate, SB = sensilla basiconica.

Figs. 7–10. Remenus bilobatus adult and ovum. 7. Male terminalia, lateral, A = posterodorsal lobes, Ae = aedeagus, Ab = abdominal segment, B = lateral lobes, Co = Cowl, DS = dorsal sclerite, Ep = epiproct, HL = hemitergal lobe, PP = paragenital plate. 8. Female abdominal sterna 8–10, Ab = abdominal segment, BC = basolateral crease, SP = subgenital plate. 9. Ovum, dorsal, A = globules, B = diamond-shaped follicle cell impressions, C = collar, D = dorsal keel. 10. Ovum, ventral, A = Collar, B = diamond-shaped follicle cell impressions, C = micropyles.

Figs. 11–14. Remenus bilobatus, larva, 11. Head and pronotum, A = pale M-shaped mark, B = pale enclosed anterolateral oval spot, C = postocular setae, D = large enclosed posterolateral oval spot, E = long erect marginal setae, ES = epicranial suture, Lb = labrum, Mp = maxillary palp, Th1 = pronotum. 12. Left lacinia, dorsal, A = minute irregularly spaced setae, B = minute submarginal setae, BK = basal knob. 13. Left mandible, dorsal, A = Middle three teeth with proximal margins lightly serrated. 14. Head, ventral, Gl = glossa, La = lacinia, Lb = labrum, LP = labial palp, Ma = mandible, MP = maxillary palp, Pg = paraglossa, PM = prementum.

Figs. 15–18. Remenus bilobatus, larva. 15. Meso- Meta-nota, A = mesonotal anterolateral setae, B = metanotal anterolateral setae, C = mediolateral seta, D = marginal setae, Th2 = mesonotum, Th3 = metanotum. 16. Male abdominal terga 6–10, A = posterior setal fringe, Ab = abdominal segment, B = intercalary setae, C = basal cercal segments, Ep = male terminal process (developing epiproct). 17. Female sterna 7–10, A = posterior setal fringe, Ab = abdominal segment, B = darkened posteromedially strip, C = intercalary setae. 18. Male sterna 8–10, A = basal cercal segments, Ab = abdominal segment, B = intersegmental setae, C = intersegmental setae, Ep = male terminal process (developing epiproct).

Fig. 20. Adult male habitus of Remenus bilobatus, Calfpasture River, Augusta County, Virginia.

Figs. 21–24. Remenus bilobatus, adult male. 21. Right forewing, Crooked Creek, Carroll County, Virginia. 22. Head and pronotum, Calfpasture River, Augusta County, Virginia. 23–24. Blackrock Spring, SHEN, Albemarle County, Virginia. 23. Terminalia, dorsal, 24. Terminalia, lateral.

Figs. 25–28. Remenus bilobatus, adult male, Blackrock Spring, Albemarle County, Virginia. 25. Male hemitergal lobe. 26. Male terminalia, dorsal. 27. Male epiproct, dorsolateral. 28. Male epiproct, hair-like setae, dorsolateral.

Figs. 29–30. Remenus bilobatus, adult female subgenital plate variation. 29. Crooked Creek, Carroll County, Virginia. 30. Calfpasture River, Augusta County, Virginia.

Figs. 31–34. Remenus bilobatus ovum, Blackrock Spring, Albemarle County, Virginia. 31. Ovum with membranous covering, dorsal. 32. Ovum, bare, dorsal. 33. Collar, ventral. 34. Micropyles, ventral.

Fig. 35. Larval habitus of Remenus bilobatus, Stone Mountain Creek, Alleghany County, North Carolina.

Figs. 36–39. Remenus bilobatus, larva. 36. Head and pronotum, Stone Mountain Creek, Alleghany County, North Carolina. 37–38. Toms Creek, Montgomery County, Virginia. 37. Left lacinia, dorsal. 38. Left mandible, dorsal. 39. Male terminal process (developing epiproct), ventral, Gullion Fork, Wythe County, Virginia.

Fig. 40. Remenus bilobatus, larval cercus, dorsal, Gullion Fork, Wythe County, Virginia.

Fig. 19. Remenus bilobatus, distribution of examined material and published records.