Isoperla dewalti Verdone & Kondratieff

Verdone, Chris J. & Kondratieff, Boris C., 2017, A New Species Of Isoperla Banks (Plecoptera: Perlodidae) From The Southern Appalachians, With Notes On The I. Montana Group, Illiesia 13 (12), pp. 111-126: 113-120

publication ID

http://doi.org/10.5281/zenodo.4757785

publication LSID

lsid:zoobank.org:pub:39554E35-3E42-4BC1-AF04-3DC5ABD92DAC

DOI

http://doi.org/10.5281/zenodo.4765429

persistent identifier

http://treatment.plazi.org/id/03FD141F-FF8F-FFD4-FCAF-2809FC21F9E1

treatment provided by

Felipe

scientific name

Isoperla dewalti Verdone & Kondratieff
status

sp. n.

Isoperla dewalti Verdone & Kondratieff   sp. n.

http://lsid.speciesfile.org/urn:lsid: Plecoptera   .speciesfile.org: TaxonName:501137

( Figs. 1–20 View Fig View Figs View Figs View Figs View Figs View Figs View Figs )

Material examined. Holotype ♂ U.S.A. – Virginia: Grayson Co., Helton Creek, Rte 783 at gated trail by pond , N 36.62816, W 81.56684, 13 May 2017, C. Verdone, B.C. Kondratieff ( INHS, Insect Collection 659585) GoogleMaps   . Paratypes: North Carolina: Avery Co., Shantee Creek, Adams Apple Dr., SW of Foscoe, N 36.12439, W 81.82068, 13 May 2010, B.C. Kondratieff, R.E. Zuellig, D. R. Lenat, R.F. Kirchner, ♂ ( CSUIC). Macon Co., Tellico Creek, Tellico Rd. ~ 0.5 mi. W of Sugar Cove Rd., N 35.27688, W 83.54347, 15 May 2017, C. Verdone, B.C. Kondratieff, ♂ ( CSUIC). Swain Co., Beech Flats Prong, GSMNP, Hwy 441, N 35.60227, W 83.41534, 16 May 2017, C. Verdone, B.C. Kondratieff, ♂ ( CSUIC). Watauga Co., Boone Fork, CR 1561, W of Boone Fork, [N 36.12310, W 81.77006], 2 May 2005, B.C. Kondratieff, R.E. Zuellig, D. R. Lenat, R.F. Kirchner, ♂, 2♀ ( CSUIC). Tennessee: Sevier Co., trib. to Le Conte Creek, GSMNP, Twin Creeks Uplands Research Lab, N 35.68706, W 83.50096, 16 May 2017, C. Verdone, B.C. Kondratieff, 2♂, 2♀ ( CSUIC). Virginia, Franklin Co., Grassy Fork, [Co. Rd. 619, 2 mi. SE Snow Creek Rd.], [N 36.81097, W 79.74516], 21 May 2012, B.C. Kondratieff, R.F. Kirchner, ♂ ( CSUIC). Grayson Co., Same location as holotype, 12 May 2017, C. Verdone, B.C. Kondratieff, J. Richards, R. Agbalog, 4♂, 17♀ ( USNM); Same location as holotype, 13 May 2017, C. Verdone, B.C. Kondratieff, 6♂, 71♀ ( CSUIC); Same location as holotype, 17 May 2017, C. Verdone, B.C. Kondratieff, ♀ ( INHS, Insect Collection 659584).

Distribution. U.S.A. – NC, TN, VA ( Fig. 22 View Fig ).

Etymology. The new species is named in honor of Dr. R. Edward DeWalt, Illinois Natural History Survey, Champaign, Illinois, for his dedication and numerous contributions to the study of stoneflies. The proposed common name is the “DeWalt Stripetail”.

Male. Macropterous; forewing length 10.6–11.3 mm (n=5). Body length 9.6–10.0 mm (n=5). Head and pronotum pale yellow with contrasting pigmentation. General body color pale yellow with light brown to brown markings. ( Fig. 1 View Fig ). Dorsal background of head pale yellow with medium brown bands connecting ocelli; bands widest anteriorly; bands truncate at anterior ocellus; triangular dusky spot anterior to anterior ocellus ( Fig. 2 View Figs ). Antennal scape pale yellow with a diffuse diagonal brown stripe; flagellum segments 1–7 pale; remaining segments medium brown ( Figs. 1–2 View Fig View Figs ). Pronotum with a wide medial pale stripe; rugosities irregular, raised, medium brown; anterolateral margins medium brown; posterolateral margins pale ( Fig. 2 View Figs ). Femora light brown dorsally, covered with uniformly spaced, short, brown setae; femora pale ventrally; tibia light brown, covered with uniformly spaced, short brown setae; tarsi medium brown ( Fig. 1 View Fig ). Meso- and metanota light brown ( Fig. 1 View Fig ). Wings hyaline, veins of forewing light basally, brown distally ( Fig. 1 View Fig ). Terga light brown, posterior ⅓ medium brown; terga 1–8 with uniformly spaced brown setae. Sterna pale yellow to light brown; sternum 8 with a light brown recessed vesicle, 0.65X as wide as long; evenly rounded, extending to the posterior margin of sternum 8 ( Fig. 3 View Figs ). Paraprocts short, triangular, slightly incurved, moderately sclerotized; trichoid sensilla scattered over dorsal surface, absent on apex; apex heavily sclerotized; tips acutely pointed ( Fig. 4 View Figs ). Cerci brown, setose; cercal segments with a single, long, stout, ventral hair at posterior margin. Aedeagus with a long basal stalk, a highly reduced (vestigial) posteroventral membranous aedeagal tube, a posteroventral lobe, paired posterolateral lobes, a dorsal lobe, and an anterior lobe ( Figs. 5– 10 View Figs View Figs ); posteroventral membranous aedeagal tube highly reduced (vestigial), appearing only occasionally as a small lobe at the base of the basal stalk ( Fig. 5 View Figs ); aedeagus with a posteromedial rectangular patch of dense, stout, rust colored spines, and a single posterior sclerotized arrowhead shaped aedeagal spine plate with upturned distal stout spine ( Figs. 8–10 View Figs ); apex of structure upturned with approximately 10 large stout rust colored spines ( Fig. 11 View Figs ); base of plate with broad flat sclerotized plates with numerous small apical finger-like projections ( Fig. 11 View Figs ); basal stalk with short sharp spinulae ( Fig. 12 View Figs ); posterolateral lobes with sparse scale like plates medially; posteromedial area with shallow shelf-like scales with apical hair-like projections ( Fig. 13 View Figs ); lateral area with dense short sharp spinulae ( Fig. 14 View Figs ).

Female. Macropterous; forewing wing length 11.3– 12.6 mm (n=5). Body length 9.1–10.9 mm (n=5). Body coloration and morphology similar to male. Sternum 8 with variable subgenital plate extending approximately ⅓–½ over sternum 9; subgenital plate broadly rounded ( Fig. 15 View Figs ), or broadly triangular, truncate with shallow posteromedian emargination ( Fig. 16 View Figs ), or broadly triangular ( Fig. 17 View Figs ).

Ovum. Length 226.3–234.4 μm (n=2); width 184.9– 192.5 μm (n=2). General shape oblong; cross section triangular, distinct cross shaped ridges dividing anterior and posterior poles; anterior end concave ( Fig. 18 View Figs ). Color pale brown. Collar well-developed, flared apically with elevated longitudinal ridges; base not offset from egg body ( Fig. 19 View Figs ). Hexagonal follicle cell impressions well-developed with thickened ridges and with numerous small mounds between reticulations ( Figs. 18, 20 View Figs ). Eclosion line absent, micropyles arranged singularly or in threes, positioned on top of cross ridges near anterior ⅓ of egg ( Figs. 18, 20 View Figs ).

Larva. Unknown.

Diagnosis. Isoperla dewalti   is placed in the I. montana   Group based on the presence of a single posterior sclerotized arrowhead shaped aedeagal spine plate with an upturned distal stout spine, dark brown bars connecting the ocelli, and–albeit vestigial–a posteroventral membranous aedeagal tube. The new species is easily distinguished from I. montana   and I. nelsoni   by the lack of a well-developed posteroventral membranous aedeagal tube.

Several paratype specimens of I. dewalti   that are deposited in the C. P. Gillette Museum of Arthropod Diversity had previously been identified as I. montana   . The two species are superficially similar and it was likely thought that the posteroventral membranous aedeagal tube did not evert. However, it is the experience of the authors that when a welldeveloped aedeagal tube is present it is the first structure to evert. Additionally, differences in the posteromedial patch of spines distinguish the two species. In I. dewalti   the posteromedial patch of spines is broad, appearing as a uniform rectangular patch ( Figs. 8–10 View Figs ). Whereas, in I. montana   the posteromedial patch of spines is narrow, appearing as a thin ridge (figs. 33.15–33.16, Szczytko & Kondratieff 2015). Furthermore, I. montana   possesses a dorsal rounded mound of dense, long, stout, rust colored spines above the posteromedial patch of spines (figs. 33.15–33.16, Szczytko & Kondratieff 2015), which the new species lacks.

Females of the new species are most similar to I. montana   and I. kirchneri Szczytko & Kondratieff, 2015   . Females of the new species have a subgenital plate that extends approximately ⅓–½ over sternum 9 and appears broadly rounded ( Fig. 15 View Figs ), or broadly triangular, truncate with shallow posteromedian emargination ( Fig. 16 View Figs ), or broadly triangular ( Fig. 17 View Figs ), and have a dorsal head pattern with brown bands connecting the ocelli that are truncate at the anterior ocellus with a triangular dusky spot anterior to the anterior ocellus ( Fig. 2 View Figs ). Females of I. montana   and I. kirchneri   also have a subgenital plate that is variable, appearing broadly triangular usually with a shallow posteromedian emargination or pointed (figs. 25.5, 33.7, Szczytko & Kondratieff 2015) and have dorsal head patterns with brown bands connecting the ocelli. In I. montana   the bands extend anteriorly to near the frons (occasionally pale brown or faint), and without a medium brown anterior patch near the frons (fig. 33.1, Szczytko & Kondratieff 2015). In I. kirchneri   the bands sometimes extend anteriorly from the anterior ocellus, with a well-defined to diffuse spot on frons (fig. 25.1, Szczytko & Kondratieff 2015). The variation in subgenital plate morphology and dorsal head pattern exhibited by these species make the separation of isolated females very difficult.

Ova of the new species are similar to I. kirchneri   , I. montana   , I. nelsoni   , and I. signata (Banks, 1902)   , all of which are oblong and triangular in cross section with distinct cross shaped ridges dividing anterior and posterior poles. Ova of the new species are distinguished from other similar ova by the interreticulate follicle cell impressions, which are developed as mounds in the new species ( Figs. 18, 20 View Figs ) and punctations in the other similar species (figs. 25.19–25.22, 33.25–33.28, 36.9–36.11, 50.20–50.23, Szczytko & Kondratieff 2015).

Biological notes. There is no information about the biology or life cycle of I. dewalti   . Based on the above records, the emergence period appears to be in early to mid-May, and as with most eastern Isoperla   , a univoltine life cycle is presumed. The type locality, Helton Creek, has a unique stonefly fauna, species with generally northern distributions (e.g. Alloperla concolor Ricker, 1936   ) and species with generally southern distributions (e.g. Haploperla parkeri Kirchner & Kondratieff, 2005   ) have been documented from this location. From the limited records available it is inferred that the new species also has a generally southern distribution, occurring in 1 st –3 rd order streams in the Piedmont Plateau and the southern Blue Ridge physiographic provinces ( Fig. 22 View Fig ).

INHS

Illinois Natural History Survey

R

Departamento de Geologia, Universidad de Chile

USNM

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Plecoptera

Family

Perlodidae

Genus

Isoperla