Grubbs, Scott A. & Dewalt, R. Edward, 2018, Perlesta armitagei n. sp. (Plecoptera: Perlidae): More cryptic diversity in darkly pigmented Perlesta from the eastern Nearctic, Zootaxa 4442 (1), pp. 83-100: 89-96
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Perlesta armitagei sp. nov.
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Description. Male forewing length 8.0‒10.0 mm (n = 29). Head pale yellow with a dark brown subquadrate ocellar patch and a small, light brown triangular patch anterior to the median ocellus, usually separated by a pale M-line; epicranial suture extends laterally, slightly beyond lateral ocelli ( Figs. 6a, 6c, 6e, 6g View Figure ). Pronotum brown with a faint yellow medial stripe ( Figs. 6a, 6c, 6e, 6g View Figure ). Female forewing length 10.0‒ 11.5 mm (n = 25). Color pattern similar to male but typically lighter and with less ocellar and epicranial suture pigmentation ( Figs. 6b, 6d, 6f, 6h View Figure ). Wing membrane and veins amber except for pale white costal region. Femora brown dorsally extending to articulation with tibiae ( Figs. 6a‒6h View Figure ), dorsum of tibiae brown.
Abdominal terga brown, sterna yellow. Cerci pale yellow proximally, brown distally. Tergum 10 mesal sclerites brown, sensilla basiconica restricted to posterolateral margins with interspersed long hairs ( Figs. 7d‒7e View Figure ). Paraprocts long and slender, bearing a prominent mesoapical tooth in lateral aspect and directed anteriorly, rounded apically ( Figs. 7a, 7c‒7d View Figure ), not visible in caudal aspect ( Fig. 7b, 7e View Figure ). Penis tube + sac long, caecum prominent and thumb-like ( Figs. 8a‒8c View Figure ), sac nearly as long as tube ( Figs. 8a‒8b, 8e View Figure ), lateral sclerite often lightly sclerotized, located in proximal ¼ of tube ( Fig. 8a View Figure ), dorsal patch broad basally, narrowing apically throughout length of sac, completely covering caecum ( Figs. 8d‒8f View Figure ).
Female ( Figs. 6 View Figure , 9 View Figure ). Subgenital plate, ca. 1/2 width of 8th abdominal sternum ( Fig. 9a View Figure ), lacking pigmentation; lobes subtruncate and rounded both medially and laterally ( Figs. 9b‒9d View Figure ), with some populations with a slight concavity near medial corners ( Figs. 9b, 9d View Figure ); lobes bordered posteriorly by a diffuse row of stiff bristle-like hairs; separated by an oval-shaped notch that is expanded medially ( Figs. 9b‒9d View Figure ).
Egg ( Fig. 10 View Figure ). Oval. Collar distinctly stalked, wide, ribbed, and flanged at apex ( Figs. 10a‒10c View Figure ). Chorion smooth with very fine shallow impressions visible only under high magnification ( Figs. 10a, 10d View Figure ). Micropyles located ca. ¼ from anterior pole ( Fig. 10d View Figure ).
Type material. Holotype male ( INHSAbout INHS): USA, Ohio, Ross Co., Deer Creek , 15 km NNE Chillicothe, 39.46120, -83.02120, 28 June 2010, S.A. Grubbs . Paratypes: USA, Indiana, Bartholomew Co., East Fork White River, Azalia Bridge , 1.5 km SW Azalia, 39.0849, -85.8598, 11 June 2000, S.A. Grubbs, 3 males, 3 females ( WKUC) ; Daviess Co., East Fork White River , 14 km S Washington, 38.5447, -87.2138, 7 June 2009, S.A. Grubbs, 8 males, 1 female ( WKUC) ; Greene Co., West Fork White River, Rte. 157, 2 km SE Worthington , 39.1109, -86.9632, 7 June 2009, S.A. Grubbs, 3 males, 16 females ( WKUC) ; Harrison Co., Blue River, 6 km NE Leavenworth, Stagestop Canoe Access Site , Harrison-Crawford State Forest , 38.2153, -86.2718, 18 May 2000, S.A. Grubbs, 15 males, 7 females ( WKUC); same but 9 June 2000, S.A. Grubbs, 2 males, 1 female ( WKUC) ; Ohio River, Leavenworth , 38.1966, -86.3504, 28 June 2002, S.A. Grubbs, 3 males ( WKUC) ; Jackson Co., Little Salt River, Houston , 39.0342, -86.1679, 22 June 2008, R.E. DeWalt, 1 male ( INHSAbout INHS) ; Martin Co., East Fork White River, 2 km NNE Shoals , 38.7013, -86.7674, 7 June 2009, S.A. Grubbs, 2 males, 4 females ( WKUC) ; Washington Co., Blue River, Rte. 150, Fredericksburg , 38.4338, -86.1918, 28 June 2010, S.A. Grubbs, 3 males, 3 females ( WKUC) . Kentucky, Adair Co., Russell Creek, nr. Rte. 768, Milltown , 37.1235, -85.4046, 19 June 2008, S.A. Grubbs, 2 males, 5 females ( WKUC) ; Green Co., Green River, at mouth of Big Pitman Creek , 7.5 km SE Summersville , 37.2851, -85.5819, 22 May 2002, S.A. Grubbs, 4 males, 1 female ( WKUC) ; Big Pitman Creek, Narrows of Pitman, 5 km WNW Greensburg , 37.2833, -85.5576, 21 May 2002, S.A. Grubbs, 4 males, 5 females ( WKUC) . Ohio, Ross Co., same as holotype but 1 July 2007, S.A. Grubbs, 1 female ( WKUC); same but 28 June 2010, S.A. Grubbs, 7 males, 9 females ( WKUC) . Pennsylvania, Crawford Co., French Creek, Meadville Access Site , 3 mi SE Meadville, 41.5914, -80.1449, 10 June 1998, S.A. Grubbs, 14 males, 9 females ( WKUC); same but 1 July 1998, S.A. Grubbs, 1 male ( WKUC).
Additional material examined. Indiana, Harrison Co., Blue River , White Cloud, 38.2290, -86.2254, 25 May 1949, W.E. Ricker, 1 male ( CNCIAbout CNCI) . Kentucky, Fayette Co., Lexington, 7‒9 June 1970, 1 male ( DCTC) . Ohio, Butler Co., Seven Mile Creek, Hwy 127 Collinsville, 39.5050, -84.5946, 28 May 1953, A.R. Gaufin, 1 male, 1 female (BYU); Seven Mile Creek, New Miami, 39.4316, -84.5441, 28 May 1953, A.R. Gaufin, 1 male (BYU); Coshocton Co., Beaver Run, 2 km NW Warsaw at Twp. 348 Bridge, 40.3495¸ -82.0134, 26 June 1999, S.W. Chordas III and J. Thompson, 1 male ( INHSAbout INHS); Mohawk Creek , 0.5 km E Mohawk Village at Co. Rd. 82 Bridge, 40.3205, -82.0741, 26 June 1999, S.W. Chordas III and J. Thompson, 2 males ( INHSAbout INHS); Killbuck Creek , 2 km NNW Randle at Co. Rd. 28 Bridge , 40.3338, -81.9457, 20 July 1999, S.W. Chordas III and J. Thompson, 1 male ( INHSAbout INHS); Miami Co., Stillwater River , Hwy 718, 40.0521, -84.3659, 3 June 1953, A.R. Gaufin, 1 male ( BYUAbout BYU); Warren Co. , Little Miami River , Morrow, 39.3568, -84.1288, 28 June 1952, A.R. Gaufin, 1 male ( BYUAbout BYU) . Pennsylvania, Crawford Co., French Creek, SR 1002 bridge, Venango, 41.7716, -80.1083, 10 June 1991, S.A. Grubbs, 16 females ( WKUC).
Etymology. This species is named in honor of Dr. Brian J. Armitage, former Director of the Ohio Biological Survey and now “retired” in Boquete, Panama. Brian tirelessly performed design, layout, and other production activities for several books through the Ohio Biological Survey and Caddis Press. He improved our understanding of the modern day composition and distribution of aquatic insects within Ohio and secured funding for statewide surveys of aquatic insects that trained several young entomologists. The common name “Brian’s Stone” is proposed for this species ( Stark et al. 2012).
Diagnosis. Males of P. armitagei possess a well-developed dorsal caecum ( Figs. 8a‒8c View Figure ), which initially takes this species to couplet 2 in Stark (2004, pg. 88). The first choice in couplet 2 reads “epicranial suture arms extend well beyond ocelli as a distinct dark line” ( Stark 2004). Couplet 2, however, can be problematic for specimens that are lightly pigmented either due to (a) bleaching following long-term wet storage, or (b) adults preserved while still teneral. Five midwestern and Interior Highland species exhibit this characteristic: P. adena , P. baumanni Stark, 1989 , P. cinctipes , P. fusca Poulton & Stewart, 1991 , and P. xube . Material of P. adena ( Figs. 1a, 1c, 1e View Figure ), P. cinctipes ( Figs. 5a, 5c View Figure ), and P. xube ( Figs. 2a, 2c, 2e View Figure ) examined in this study exhibit this characteristic. Perlesta armitagei ( Figs. 6a, 6c, 6e, 6g View Figure ) and P. browni ( Figs. 3a, 3c View Figure ), however, generally lack this feature.
Males of P. armitagei will key most closely to P. decipiens ( Walsh, 1862) in Stark (2004, see couplet 12) and Grubbs & DeWalt (2012, a modified couplet 12), with a paraproct spine visible in lateral view and directed forward ( Figs. 7a, 7c‒7d View Figure ). Although the dorsal aedeagal patch of P. armitagei ( Figs. 8d‒8e View Figure ) is similar to P. decipiens ( Stark 2004, his Fig. 7.306), the mesoapical paraproct tooth of P. armitagei ( Fig. 7a, 7c View Figure ) is easily contrasted from the antepical paraproct tooth of P. decipiens ( Stark 1989, his Figs. 35‒36, 38‒41).
The paraprocts of P. armitagei ( Fig. 7c View Figure ) more closely resemble those of P. cinctipes ( Figs. 5e‒5f View Figure ) and P. browni ( Figs. 4a‒4c View Figure ) but are not as tubular or elongate as either species. Perlesta armitagei is more readily distinguished from P. cinctipes and P. browni by aedeagal characteristics. The aedeagi of P. armitagei and P. cinctipes are similar in that both species have a long tube + sac and well-developed caecum. The dorsal patch of P. cinctipes is very narrow ( Stark 2004, his Fig. 300) whereas the dorsal patch of P. armitagei is markedly wider ( Figs. 8d‒8e View Figure ). Although the epicranial suture arms of P. browni extend little laterad of the ocelli ( Figs. 3a, 3c View Figure ), and similar to P. armitagei ( Figs. 6a, 6c, 6e, 6g View Figure ), the aedeagi of the two species are distinct. The aedeagal tube + sac of P. browni ( Stark 1989, his Fig. 80; Stark 2004, his Fig. 7.297) is much shorter than that of P. armitagei ( Figs. 8a‒8b View Figure ).
One additional male characteristic appears worthy of further study and may provide diagnostic information. On P. browni the posterolateral corners of the male 9th sternum are clothed by a dense matting of long hairs ( Fig. 4d View Figure ). These are visible under standard light microscopy and appear brush-like and denser than the remaining portions of the segment. In contrast, the male 9th sternum of P. armitagei is only sparsely clothed with long hairs ( Fig. 7f View Figure ).
The female of P. armitagei can be confidently identified if mature eggs are present and associated with a male with a fully extruded aedeagus. Females will key to couplet 14 in Stark (2004), a dichotomy with P. shubuta Stark, 1989 and P. decipiens . Perlesta ephelida Grubbs & DeWalt, 2012 also keys to couplet 14, but the subgenital plate of these three species are easily differentiated using standard light microscopy. The subgenital plate notch of P. armitagei is ovoid and expanded medially ( Figs. 9b‒9d View Figure ). In contrast, the subgenital plate notches of P. ephelida (Grubbs & DeWalt 2012, their Fig. 7 View Figure ), P. shubuta ( Stark 1989, his Fig. 91; Stark 2004, his Fig. 7.391), and P. decipiens ( Stark 1989, his Figs. 44, 46, 48; Stark 2004, his Fig. 7.379) are variable but typically v-shaped.
The egg is only partially diagnostic for P. armitagei . The egg of P. armitagei possesses a wide, well developed, and distally flanged collar ( Figs. 10a‒10c View Figure ), resembling P. decipiens ( Stark 1989, his Figs. 12‒13; Stark 2004, his Figs. 7.397‒7.398), P. ephelida (Grubbs & DeWalt 2012, their Figs. 14‒21), and P. mihucorum Kondratieff & Myers, 2011 (their Figs. 9 View Figure ‒14), but easily contrasted from the coarsely and near-completely punctate egg chorion (except for the eclosion line) of P. cinctipes ( Stark 1989, his Fig. 17; Stark 2004, his Figs. 7.394‒7.396).
Remarks. The type locality is in southern Ohio at the southern edge of EPA Level IV Ecoregion 55b (Loamy, High Lime Till Plains). All streams where P. armitagei has been collected are mid-order systems with partially- to fully-open canopies. Allocapnia granulata ( Claassen, 1924) , A. vivipara ( Claassen, 1924) , and Taeniopteryx burksi Ricker & Ross, 1968 were the only other stonefly species collected at the type locality.
The plotted distribution of P. armitagei ( Fig. 11b View Figure ) is conditional since it only includes the specimens examined in this study. This distribution, however, suggests an Ohio River basin species. We have not found this species during our extensive fieldwork and examination of museum material from Illinois (DeWalt & Grubbs 2011), Michigan (Grubbs et al. 2012), and Ontario (unpublished data). The plotted records from Indiana may represent the western edge the range.
The species reported as Perlesta sp. I-4 from Ohio in DeWalt et al. (2012, 2016) is now regarded as P. armitagei . The specimen determined as P. cinctipes from Kentucky (Fayette Co., Tarter et al. 2006), and subsequently carried forward in the updated state checklist ( Tarter et al. 2015), was reexamined and determined as P. armitagei . The specimens determined as P. cinctipes from West Virginia (Monongalia Co., Tarter & Nelson 2006) were not available for study but the location was still plotted ( Fig. 11b View Figure ) and the inclusion in this map should be considered conditional.
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