Oemopteryx vanduzeea ( Claassen, 1937 )

Verdone, Chris J., Williams, Bronwyn W., Beaty, Steven R., Holland, Victor B., Grubbs, Scott A. & Dewalt, Edward, 2025, The adults, larvae, and systematics of the Nearctic Oemopteryx Klapálek, 1902 (Plecoptera: Taeniopterygidae), Zootaxa 5595 (1), pp. 1-94 : 73-86

Oemopteryx vanduzeea ( Claassen, 1937)

( Figs 45–49 )

Seep Willowfly

Taeniopteryx vanduzeea Claassen, 1937: 46 . Holotype male (CUIC), [Glen Alpine Creek, El dorado Co.,] California, USA. Oemopteryx vanduzeea : Illies 1966: 64.

Taenionema vanduzeea : Zwick 1973: 317.

Oemopteryx vanduzeea : Ricker & Ross 1975: 141.

Taenionema vanduzeeum : Steyskal 1976: 410.

Oemopteryx vanduzeea : Baumann & Kondratieff 2009a: 197.

Distribution. USA.—CA ( DeWalt et al. 2024) ( Fig. 39 )

Material examined. USA.— California: Butte Co., Oregon Gulch, Oregon Gulch Rd. at [Castleberry] Covered Bridge , [39.59369, -121.52996], April 2010, B. Kondratieff, R . Baumann 5F; UT to Campbell Creek , 5.6 mi. S of Cherokee, [39.59779, -121.54646], April 2008, J. Sandberg, 2M, 8F ( CSUIC); same location, 27 April 2010, B. Kondratieff, R . Baumann, 5F ( CSUIC) . El Dorado Co., Blue Tent Creek, Hwy 49, [38.82974, -120.98256], 29 April 2010, B. Kondratieff, R . Baumann, 1L ( CSUIC); Deadman Creek, Church Mine Rd. , [38.65164, -120.82598], 28 April 2010, B. Kondratieff, R . Baumann, 1M, 3F, 1L ( CSUIC); unnamed tributary seep to American River, FR 7 at Silver Fork [Campground], [38.69914, -120.20783], B. Kondratieff, R . Baumann, 19 June 2009, 1M ( CSUIC); unnamed tributary seep to North Fork Cosumnes River, Capps Crossing , E Grizzly Flats , [38.64608, -120.40967], 5 June 1983, R . L. Bottorff, 5M, 5F ( CSUIC); unnamed tributary, Long Canyon, NE Grizzly Flats , [38.63858, - 120.4861], B. Kondratieff, R . Baumann, 5M, 20F, 12L ( CSUIC); unnamed tributary off Church Mine Rd. , [unable to approximate coordinates], 29 April 2010, B. Kondratieff, R . Baumann, 1M, 3F ( CSUIC); unnamed tributary to [South Fork] Silver Creek , [38.84474, -120.235893], 19 June 2009, B. Kondratieff, R . Baumann, 1M, 4F ( CSUIC) . Modoc Co., Johnson Creek, 3 mi. off Hwy 299/139, [41.3359, -120.87647], 24 May 2007, B. Kondratieff, R . Baumann, 2M ( CSUIC) . Nevada Co., French Corral Creek, Pleasant Valley Rd. , [39.30166, -121.17894], 28 April 2010, B. Kondratieff, R . Baumann, 1M, 2F ( CSUIC); [unnamed tributary to South Yuba River], Indian Springs [Campground], Indian Springs Trailhead , [39.32934, -120.56943], 22 June 2009, B. Kondratieff, R . Baumann, 1M, 3F ( CSUIC); Rattlesnake Creek, Woodchuck Flat Campground , [39.33283, -120.51916], 22 June 2009, B. Kondratieff, R . Baumann, 1M ( CSUIC); South Yuba River, Indian Springs [Campground], [39.32817, -120.57132], 22 June 2009, B. Kondratieff, R . Baumann, 1M ( CSUIC); Sweetland Creek, nr. Jct. Hwy 49 & Pleasant Valley Rd. , Sweetland , [39.34306, -121.12472], 28 April 2010, B. Kondratieff, R . Baumann, 2M, 2F ( CSUIC) . Placer Co., Soda Springs, Tahoe National Forest , [39.24740, -120.32631], 5 June 1998, E. Riley, 2M ( CSUIC) . Plumas Co., Middle Fork Feather River, above Two Rivers Rd. , 39.82321, -120.66591, 25 May 2019, B. Kondratieff, E. South, 1M ( CSUIC) . Sonoma Co., Mark [West] Creek, St. Helena Rd. , 38.52070, -122.56070, 24 April 2010, D.E. Ruiter, 1M ( CSUIC) . Tehama Co., UT Mill Creek, Hole in the Ground Campground , 40.30962, -121.56105, 28 May 2019, B. Kondratieff, E. South, J. Sandberg, 8M, 3F ( CSUIC); UT Mill Creek, Hole in the Ground Campground , 28N06A, 3.5 SW Mill Creek , 40.309357, -121.56932, 21 May 2024, J.B. Sandberg, 13M, 10F, 6L, 10E ( NCDWR) . Tuolumne Co., unnamed tributary to South Fork Tuolumne River, Hwy 120, [unable to approximate coordinates], 22 June 2006, R . Baumann, B. Kondratieff, 19M ( CSUIC); unnamed tributary to South Fork Tuolumne River , [unable to approximate coordinates], 22 June 2006, B. Kondratieff, R . Baumann, 9M ( CSUIC) .

Adult male ( Fig. 45A ). Macropterous. Length of forewings 6.9–8.7 mm (n = 10). Length of body 6.3–7.7 mm (n = 10). General body color light-brown to brown.

Head. ( Fig. 45A ). Dorsum of head mostly light-brown. Labrum pale anteriorly, brown posteriorly. Anterior frontoclypeus light-brown. Frons with a brown U-shaped marking. Antenna longer than body. Scape, pedicel, and flagella light-brown. Scape with a distal notch on anterior face. First flagellum subdivided at distal 1/4. Pale areas distal of lateral ocelli. Interocellar area uniformly light-brown and slightly depressed. Occiput with brown rugosities. Medial areas of the frons, interocellar surface, and occiput covered with fine, pale, clothing hairs.

Thorax ( Fig. 45A ). Pronotum subquadrate, wider than long (length 0.9X width) with posterior width slightly wider than anterior width; light-brown overall with darker rugosities and a pale medial triangular area that widens posteriorly. Disk with irregular dark rugosities. Prosternum lightly sclerotized. Meso- and metathorax dark-brown, heavily sclerotized dorsally and ventrally. Mesonotum with a pale anteromedial spot. Thoracic nota and coxae uniformly covered with sparse, short, fine clothing hairs. Legs mostly light-brown. Distal portion of femur with darker pigment. Tibia light-brown, darker brown on proximal and distal portions. Apex of tibiae with 2-stout apical spines. Tarsus brown. Legs uniformly covered with dark, short stout setae. Wings hyaline, amber; venation brown; mottling absent. Forewing without costal crossveins between humeral crossvein and apex of the subcostal vein which may be forked.

Abdomen. Abdominal segments 1–9 sparsely covered with short, fine clothing hairs. First abdominal tergite completely pale. Tergite-2 mostly brown. Terga 3–9 brown with a pale medial area that becomes progressively wider on posterior segments. Sterna 1–9 pale with a pair of sub-lateral brown spots. Sternum-9 with a lightly sclerotized clavate tab-like vesicle that is attached to sternum-9 at the anterior margin of the vesicle. ( Fig. 45C ). Sternum-9 elongated into a scooped plate ( Fig. 46D ), width narrowing from base to apex; apex with broadly rounded lateral margins ( Fig. 45C ). Dorso-apical margin of sternum-9 recurved anteriorly, broadly triangular with a minute, posterior medial protrusion (not visible in Fig. 45A ). Plate with numerous long setae on dorsal and ventral surfaces ( Figs 46A, 46D ). Plate covering sternum-10 ventrally and extending beyond.

Terminalia ( Figs 46A–E ).Abdominal segment-10 nested within segment-9; anterior margin unsclerotized.Tergal sclerite-10 well sclerotized with a medial cleft, paired anterior processes absent ( Fig. 46C ). Cercus 5-segmented, excluding vestigial apical segment ( Fig. 46A ), and with a long basal-cercal process covered dorsally with long socketed setae; basal-cercal process about as long cercus, bent at midlength anteriorly ( Figs 46A, 46D–E ). Basal plate of tergum-10 bulbous with 2-hemispherical lobes divided by a median furrow and bearing, long socketed setae ( Figs 46A–E ). Lateral struts present, median strut present ( Fig. 46C ). Basal bulb ( Figs 46A–B ), glabrous, oval, bulbous, moderately sclerotized and with an inner bulb bearing a small hollow stalk, which terminates at a pore at the mid-length on the ventral face of the anterior epiproct. Anterior epiproct prong fused to basal bulb, heavily sclerotized, broadly spatulate and depressed medially ( Figs 46A–B ). Posterior epiproct prong closely appressed to anterior prong, lightly sclerotized, divided near apex with dorsal and processes armed with posteriorly direct scale-like setae ( Figs 46A–B, 46D–E ); ventral process sclerotized basally and ventrally, length exceeds dorsal process ( Figs 46A–B, 46D–E ); Dorsal process pouch-like, armed with posteriorly directed spine-like setae with an apical sleeve containing a single, eversible internal filament ( Figs 46A–B, 46D–E ); filament visible inside basal bulb. Paraprocts subdivided into 2-parts, symmetrical anterior paraprocts and asymmetrical multi-lobed posterior paraprocts. Anterior paraproct ( Fig. 46D ) posterior to cercus, base pentagonal, well sclerotized with a minute, membranous finger-like mediodorsal projection. Posterior paraprocts ( Figs 46A, D ) with 4-prongs, variously fused; left outer prong flattened with a sclerotized clavate apex; outer and inner middle prongs both flattened, twisted, apices spatulate; inner prong moderately sclerotized with a scoop-shaped apex; right outer prong lightly sclerotized, flattened, concave posteriorly with a sclerotized clavate apex; right outer middle prong flat sclerotized with a truncate apex; right inner middle prong twisted with a membranous filamentous apex; right inner prong light sclerotized, apex truncate and bearing 2-stout spines.

Adult female ( Fig. 45B ). Macropterous. Length of forewings 7.6–10.5 mm (n = 10). Length of body 5.7–9.7 mm (n = 10). General body color brown. Overall appearance similar to male. Wings hyaline, amber; venation brown; mottling absent. Forewing without costal crossveins between humeral crossvein and apex of the subcostal vein which may be forked ( Fig. 45D ). AA1 vein of forewing with short fine setae ( Fig. 45F ). Dorsum of abdomen lightly sclerotized, uniform. Venter of abdomen similar to male. Sternum-8 lightly sclerotized anteriorly ( Fig. 45E ). Subgenital plate entire, at most with a subtle medial depression posteriorly ( Figs 45E , 47A–B ), moderately sclerotized ( Fig. 45E ). Sternum-9 moderately sclerotized anterolaterally, plate parabolic, produced just beyond the apex of abdominal segment-10; length of free portion of sternum 0.7X basal width; uniformly covered with long setae that become longer posteriorly; lateral margins moderately narrowing to a rounded apex ( Figs 45E , 47A ). Cercus 5-segmented, excluding vestigial apical segment ( Figs 45E , 47A ).

Ovum. Unknown.

Mature larva ( Fig. 48A ). Length of male body 6.8 mm (n = 1), female body 6.9–7.5 mm (n = 10). General color light-brown to brown. Integument glossy, much of the body with sparse, fine, hair-like sensillae and socketed stout setae, observable at>100X magnification. Specimens generally preserve in a curled posture with the head touching or approaching the abdomen apex, similar to other Taeniopterygidae .

Head ( Fig. 48A ). Dorsum of head light-brown with darker brown maculations variously developed.Antelabrum light-brown with 2-anterolateral pale spots; anterior margin of antelabrum with a dense brush of golden setae; postlabrum light-brown. Anterior frontoclypeus pale. Frons with a brown U-shaped marking with posterolateral extensions; light-brown rectangular markings near, but not touching the lateral ocelli, anterior to ecdysial suture. Interocellar area diffusely light-brown. Occipital area diffusely light-brown near ecdysial suture and with irregular brown rugosities. Eyes with pigmented ommatidia reaching eye margins. A single long seta both anterior and posterior to eyes. Antennal scape brown; scape and flagella light-brown; dorsobasal apically inserted setae absent ( Fig. 48C ); antenna slightly shorter than body ( Fig. 48A ).

Maxilla ( Figs 49A–B ). Lacinia triangular with a straight inner margin. Lacinia with 2-apical, cupped teeth with at least 1-large subapical denticle on ventral face; actual number difficult to discern due to wear. Apical teeth subequal in length; length of apical teeth relative to palm length difficult to discern due to wear. Inner palm margin with 12-stout socketed marginal setae below apical teeth; first setae below apical teeth robust. A patch of hair like acanthae absent below apical teeth; acutely pointed sensilla basiconica below apical teeth and on inner palm margin near the middle. Galea with a dense brush of curved setae on the distal apical margin, which transition to sparse peg-like setae at the apical 2/3. A thin marginal row of long setae below apical setae extends about 2/3 to base. Length of galea, including apical setae, 1.3X length of lacinia; width of galea 1.3X the lacinia width. Maxillary palp with 5-segments; 2.0X length of lacinia; palp with sensilla basiconica developed on the apical and lateral margins of each segment.

Mandible. Right mandible ( Fig. 49C ) bicuspid, outer cusp with 3-teeth, inner cusp with 1-tooth. Molar pad adorned with marginal rows of truncate peg-like acanthae (length 2.0X width). Palm dorsum with 8–9 dorsal sensillae adjacent to molar pad (requires focusing through the mandible) ( Fig. 49C circle inset); proximal basal corner with a marginal patch of 3-hair-like, branched setae. Ventro-apical setal patch extending from outer cusp to beyond the inner cusp basally (indicated by dotted line in Fig. 49C ). Left mandible ( Fig. 49D ) bicuspid, outer cusp with 5-teeth, inner cusp with 1-broad tooth. Molar pad with marginal rows of rounded acanthae and long pointed acanthae (length 3.0X width). Palm dorsum with 7–9 dorsal sensillae adjacent to molar pad (requires focusing through the mandible) ( Fig. 49D circle inset); the proximal basal corner with a marginal patch of 3-hair-like, branched setae. Ventro-apical setal patch extending from outer cusp to beyond the inner cusp basally (indicated by dotted line in Fig. 49D , square inset).

Thorax ( Fig. 48A ). Pronotum wider posteriorly; light-brown with faint rugosities; Length of forewing pad 3.2X width; length of hindwing pad 1.8X width. Venter of thorax pale. Prothoracic presternum mostly glabrous with light-brown spicules laterally and a pair of elongate lateral cervical sclerites. Prothoracic basisternum and furcasternum light-brown spicules dense medially and sporadic distally. Mesothorax with an oval prefurcasternal pit; light-brown spicules present both anterior and posterior to pit; lateral areas glabrous. Mesothoracic basisternum with light-brown spicules mostly concentrated medially. Furcasternal pit present between mesothoracic legs; furcasternum triangular, wider than long (length 0.8X width). Metathoracic basisterna with a medial patch of light-brown spicules and a pair of furcasternal pits. Femur and tibia generally light-brown ( Fig. 48D ) and with a sparse fringe of silky setae (not shown); length of femoral setae about 1/2 the width of the femur; length of tibial setae about equal to tibial width. Anterior and posterior faces of the femur with scattered short stout setae; anterior face usually with a thin, distal, longitudinal, brown stripe ( Fig. 48D ). Tibial callus darkened ( Fig. 48D ). Tarsus with a few sporadic setae; tarsus uniformly light-brown; venter of tibia and tarsus with scattered short stout setae.

Abdomen. Dorsum of abdomen uniformly light-brown ( Fig. 48E ). Posterior margins of terga with a single row of short, stout sensillae. Posterior margins of tergum-8 and tergum-9 with a pair of thin, erect, submedial setae. Venter of abdomen pale; sterna 1–8 light-brown. Female sternum-8 with developing subgenital plate visible, posterior edge notched medially. Sternum-9 with an elongate plate (male = length 1.7X width ( Fig. 48F ); female = length 1.6X width ( Fig. 48G ); plate width relative to sternal width (male = 0.7X; female = 0.8X). Both male and female with plate narrower basally, widest at posterior margin of sternum-9; posterolateral margins linear to convex, evenly narrowing towards apex; apex acutely pointed, nipple-like. Plates of both males and females with stout setae begin at basal 1/5, becoming denser towards apex. Cercus uniformly brown; dorsobasal apically inserted setae absent ( Fig. 48B ); cercus about as long as body ( Fig. 48A ).

Diagnosis. Oemopteryx vanduzeea is defined in the male by the anterior epiproct prong being broadly spatulate with a medial depression and having anteriorly directed basal cercal processes subequal in length to the cerci. The female is distinguished by having a subgenital plate that is moderately sclerotized throughout with an entire or minimally concave posterior margin. The larvae are unique in having a ninth sternum with an acute nipple-like projection at its apex.

Biological notes. Oemopteryx vanduzeea is presently known from four Level III ecoregions (Central California Foothills/Coastal Mountains, Sierra Nevada, Cascades , and Eastern Cascades Slopes and Foothills) in California. Elevations of collection locations range between 21 m to 3077 m ASL. Based on known records, O. vanduzeea appears to be allopatric with O. leei , which primarily occurs in the Coast Range, Klamath Mountains, though some range overlap could occur in the Cascades Level III ecoregion. Available records indicate adults are generally active from late January to mid-July. Larvae have been collected from streams with drainage areas ranging from 3.6 km 2 to 56.2 km 2. Nothing is known regarding this taxon’s life history. A conservation rank of G3 was calculated for this species indicating a moderate risk of extinction because of its relatively restricted range and few known populations (NatureServe 2020).

Genetic data results

We generated a total of 74 new COI sequences for seven Nearctic Oemopteryx species and the outgroup taxon Taenionema atlanticum ; an additional 11 sequences were obtained from BOLD ( Table 2). Intraspecific genetic distances varied between species. Maximum intraspecific distances were high for O. contorta (max p-dist. = 5.71%) and O. vanduzeea (max p-dist = 11.58%) ( Table 3). Specimens of O. contorta , formed clades representing the end boundaries of the species’ range in the Northeast and Southeast. Whereas, specimens of O. vanduzeea generally formed clades representing either the Sierra Nevada, or the Central California Foothills/Coastal Mountains, Cascades, and Eastern Cascades Slopes and Foothills, collectively. However, both clades included O. vanduzeea specimens from a site in Butte County, California. As a result, these groupings suggest possible gene flow between transitionary populations of the Sierra Nevada, Cascades , and Coastal Mountains. Maximum intraspecific distances were closer to expected values for the remaining species (max p-dist ≤ 2.28%) ( Table 3). Within the O. contorta Group, interspecific genetic distances between O. contorta and O. bimaculata sp. nov. (avg. p-dist. = 12.97%, min p-dist = 11.25%) and O. contorta and O. tuscarora sp. nov. (avg. p-dist = 16.04%, min p-dist = 13.22%) greatly exceeded the intraspecific distance for O. contorta (avg. p-dist = 2.43%, max p-dist = 5.71%) ( Table 3).

......continued on the next page ......continued on the next page ......continued on the next page

1 2 3 4 5 6 7 1. Oemopteryx 0.36 | 0.95 11.25 17.59 14.30 18.24 14.10 18.09 bimaculata sp. nov. | n=12

2. Oemopteryx contorta 12.97 2.43 | 5.71 18.35 16.99 16.87 13.22 16.11

| n=16

3. Oemopteryx fosketti 18.25 20.56 1.11 | 2.28 | 15.90 18.65 15.98 12.39

n=5

4. Oemopteryx glacialis 18.21 18.09 18.01 0.76 | 2.22 18.24 17.17 15.00

| n=16

5. Oemopteryx leei 20.63 19.71 18.85 19.85 0.21 | 0.95 | 17.78 15.44

n=11

6. Oemopteryx tuscarora 14.73 16.04 17.33 18.36 20.02 0.67 | 1.76 | 17.70

sp. nov. n =7

7. Oemopteryx 21.08 18.89 16.53 17.60 17.57 20.23 5.95 | 11.58 | vanduzeea n=12

Maximum likelihood phylogenetic reconstruction recovered all species clades with high nodal support, bootstrap value (bs) = 96% for O. contorta and 99% for all other taxa ( Fig. 50 ). Oemopteryx bimaculata sp. nov., O. tuscarora sp. nov., and O. contorta formed a distinct well-supported clade, bs = 99%. The O. glacialis Group was not supported in the phylogenetic reconstruction. The O. glacialis Group ( O. fosketti and O. glacialis ) was paraphyletic ( Fig. 50 ) with both species being closer to O. vanduzeea (avg. p-dist = 16.53%, min p-dist = 12.39% and avg. p-dist = 17.60%, min p-dist = 15.00%, respectively) than they were to each other (avg. p-dist = 18.1%, min p-dist = 15.90%) despite numerous morphological similarities ( Table 3). The Taeniopterygidae are believed to be an early diverging lineage ( Ricker 1949). Low bootstrap support for the O. glacialis Group and deeper nodes possibly suggest that COI data may be insufficient for resolving deeper relationships between Oemopteryx species ( Ballard & Whitlock 2004). Future work may employ nuclear genes, RNA ( South et al. 2021), or genomic methods to better resolve deep-level relationships between species of Taeniopterygidae .

Figures

FIGURE 39. Distribution map of Oemopteryx leei and the Oemopteryx vanduzeea Group. Records include examined material, georeferenced data from Baumann & Kondratieff (2009a) and unpublished data from the CNCI.

FIGURE 45. Oemopteryx vanduzeea, UT Long Canyon, El Dorado Co., California, adults. A. Male habitus, dorsal. B. Female habitus, dorsal. C. Male sterna, ventral. D. Female wings. E. Female sterna, ventral. F. Female forewing, lateral. [morphological abbreviations: see Table 1].

FIGURE 46. Oemopteryx vanduzeea, adult male. A–B, D–E. UT Tuolumne River., Tuolumne Co., California. A. Terminalia, dorsal. B. Terminalia, close, dorsal. C. UT Mill Creek, Tehama Co., California, abdominal terga, dorsal. D. Terminalia, lateral. E. Epiproct, lateral. [morphological abbreviations: see Table 1].

FIGURE 47. Oemopteryx vanduzeea, UT Long Canyon, El Dorado Co., California, adult female. A. Abdominal sterna, ventral. B. Subgenital plate. [morphological abbreviations: see Table 1].

FIGURE 48. Oemopteryx vanduzeea, UT Long Canyon, El Dorado Co., California, larva. A. Habitus, dorsal. B. Right cercus, lateral. C. Right antenna, lateral. D. Legs, anterior. E. Abdomen, dorsal. F. Male sterna, ventral. G. Female sterna, ventral. [morphological abbreviations: see Table 1].

FIGURE 49. Oemopteryx vanduzeea, UT Long Canyon, El Dorado Co., California, larval mouthparts, ventral. A. Right lacinia, galea and maxillary palp. B. Left lacinia, galea and maxillary palp. C. Right mandible; dorsal sensillae (circle inset). D. Left mandible; ventro-apical setal patch (square inset); dorsal sensillae (circle inset). [morphological abbreviations: see Table 1].

FIGURE 50. Phylogenetic representation of the IQTREE-estimated maximum likelihood tree of cytochrome c oxidase I (COI) sequences. Bootstrap values of>50 are shown at associated nodes; values are not provided for short internodes within species clades. Tips are labeled with species name, accession number, and county and state. The scale bar represents estimated number of nucleotide substitutions per site.