Stenotothorax winnemucca Skelley and McPeak, 2018

Skelley, Paul E. & McPeak, Ron H., 2018, New species of Stenotothorax Schmidt from the northwestern United States (Coleoptera: Scarabaeidae: Aphodiinae), Insecta Mundi 681, pp. 1-31 : 23-25

Stenotothorax winnemucca Skelley and McPeak , new species

Figures 7 , 13 , 19, 23 , 29 , 54–59

Diagnosis. Stenotothorax winnemucca is distinguished from other members of the genus by the following combination of characters: protibia with dorsal secondary setal row and ventral surface with coarse punctures, pronotal basal groove and bead reduced, clypeus with 2 teeth and setal fringe, elytral striae wider and sharply edged at base, elytra epipleuron with short sparse lateral fringe of setae, and legs not robust. Stenotothorax winnemucca appears to be restricted to the northern Great Basin, from the southern end of Lake Winnemucca, Nevada, to the Alvord Desert in southeastern Oregon.

Description. Holotype male length 6.4 mm, width 2.8 mm. Body somewhat hourglass shaped, widest at apical third of elytra; color nearly dark red-brown, glossy. Head with clypeus narrow, distance between anterior most point of clypeal margin less than distance from teeth to frontoclypeal suture; clypeus anterior margin spiniformly dentate, with 2 primary teeth, and lateral crenulations toward the frontal lobes, with short setal fringe; clypeal surface rugosely granulate on apical half, reducing in intensity towards the frontoclypeal suture, where it is weakly granulate, extreme anterior clypeal surface with few short indistinct setae; punctation of head distinct, fine, dense, evenly distributed from clypeus to vertex; frontal lobe projecting, angulate. Epipharynx with apical margin sinuate, tylus projecting; chaetopedia few and stout; epitorma broad ( Fig. 58 ). Pronotum posteriorly hemispherical in shape, widest anteriorly, constricted in basal half; surface near anterior angles not explanate; disc punctation two sizes, fine punctures evenly distributed, coarse 4–5× larger than fine punctures evenly widely scattered, separated by 3 or more diameters; lateral margins with short setal fringe along anterior half, evenly arcuate from anterior angles to middle of base, posterior angles obliterated; basal margin evenly rounded, with fine marginal groove and bead only at middle, groove and bead absent on either side. Scutellum triangular, coarsely punctate basally, impunctate apically. Elytra fused, oval; each humerus reduced, humeral denticle minute; striae distinct, strial sides not crenated; striae I–VI sharply edged and wider at base; strial punctures fine; interval punctation fine, arranged in two vague rows, surface weakly convex; epipleural fold with short setae along ventral surface in addition to those at base. Appendages with hind wing vestigial, strap-like. Profemur with few indistinct coarse punctures on ventral surface. Protibia elongate, dorsal surface with primary setal row situated along midline; with a secondary row of setae ventral surface with groups of coarse punctures, lacking ventral projections at medial apex beneath spur and along medial basal margin; protibial spur evenly curved inwardly. Meso- and metafemur finely punctate on ventral surface, few coarse punctures less distinct than profemur; femora of similar shape, elongate. Meso- and metatibia gradually widening before abruptly dilated apex. Meso- and metatibial spurs narrowed, saber-like; lower mesotibial spur respectively 1/2–3/4 length of upper spur, bent inward at apex. Meso- and metatarsomere I length = length of upper spur. Venter with metasternum short; laterally punctures not evident only seta present, surface alutaceous, densely finely punctate medially. Abdomen with basal sternite setose and rugose across surface; medial and apical sternite surfaces as basal sternite laterally, smooth and setose medially. Male genitalia with parameres shorter than basal piece; sharply angled ventrally at apical third to acutely pointed apex in lateral view ( Fig. 59 ).

Sexual dimorphism. Female mesotibial lower spur unmodified. Males with a denser row of setae along the anterior part of the inner protibial margin.

Variation. Length 5.4–6.9 mm, width 2.5–3.1 mm. Older specimens show typical signs of wear on protibial and clypeal teeth. Pronotal punctation varies in number and density of coarse punctures. Some specimens the coarse punctures make surface appear rough. The number of coarse punctures on the ventral surface of the protibia varies from a few (approximately 6) to many that make entire surface rough. Color varies from red-brown (teneral) to nearly black. Setal fringes can be matted or worn, thus not visible.

Type material. Holotype: “/ NEVADA: Humboldt Co., Winnemucca Dunes , 4310 ft., ~ 7 mi. W. US-95, 0.6 mi. S. off Sand Pass Road, N41°07.543′ W117°49.649′ / 10-NOV-2011; P. Skelley, M.J. Paulsen, R. McPeak, walking on dunes at night / [red paper] HOLOTYPE Stenotothorax winnemucca Skelley&McPeak /”. Deposited in the FSCA.

Allotype and paratypes (n = 768): IDAHO: Owyhee Co.: Given Hot Springs , 43°24.928′N, 116°42.388′W, 2252 ft, 30-IX-2015 to 15-III-2016, R.H. McPeak [2 FSCA, 1 RMPC] ; Road to Silver City from Hwy 78, 43°05.443′N, 116°36.178′W, 4044 ft, 30-IX-2015 to 16-III-2016, R.H. McPeak [17 FSCA, 15 RMPC] ;

NEVADA: Humboldt Co.: Silver St. Vall., BFW Farms Dunes , 27-II-1974, D. Giuliani [2 CASC] ; Winnemucca Dunes , 41.100°, −117.767°, 1425 m, 10-XI-2011, M.J. Paulsen [49 MJPC, 27 UNSM] ; same data as holotype [allotype and 120 FSCA, 4 CNCI, 12 CMNC, 4 WFBM] ; same locality, 9-10-XI-2011, R.H. McPeak [10 WSU] ; same locality, 41°08.436′N, 117°50.124′W, 4298 ft, 10-XI-2011 to 19-I-2012, P. Skelley, M.J. Paulsen, R.H. McPeak, [4 DCGC, 46 FSCA, 4 NHML, 4 USNM, 10 WBWC] ; Winnemucca Dunes , 41°07.543′N, 117°49.649′W, 4313 ft, 9-10-XI-2011, R.H. McPeak [27 RMPC] ; Winnemucca Dunes , 41°08.025′N, 117°50.073′W, 4313 ft, 9-XI-2011 to 29-I-2012, R.H. McPeak [229 RMPC] ; Winnemucca Dunes, E. end, 2.6 mi. W. US-95, 1.7 mi. S. of Sand Pass Rd. , 41°06.258′N, 117°45.747′W, 10-XI-2011, P. Skelley, M.J. Paulsen, R.H. McPeak [1 FSCA] ; Winnemucca , 10 mi. N., 5 mi. W., sand dunes, 26-II- 1974, D. Giuliani [1 CASC] ; same locality, 27-II-1975, D. Giuliani [1 CASC] ; Winnemucca , 10 mi. N., sand dunes, 8-I-1982, William H. Clark, Paul E. Bloom [27 OJSM] ; Winnemucca , 10 mi. N., 7 mi. W., sand dunes, 27-II-1975, D. Giuliani [13 CSCA, 1 FSCA] ; Winnemucca , 20 mi. N., 10 mi. W., 26-II-1974, D. Giuliani [8 CASC] ; Pershing Co.: Rye Patch Dune, [3 OJSM] ; Rye Patch St. Pk., Pitt-Taylor St. Rec. Area (Humboldt Dunes), 40°36.178′N, 118°18.807′W, 4158 ft, 11-XI-2011, P. Skelley, R.H. McPeak [23 FSCA, 7 RMPC] ; Washoe Co.: Nixon , 5.5 mi. N. on Rt. 147, 39°52′51″N, 119°23′40″W, 18-XI-2008, P. Skelley and R.H. McPeak [17 FSCA] ; 6 mi. N, 3 mi. W. Nixon, 14-II-1973, D. Giuliani [4 CSCA] .

OREGON: Harney Co.: Fields, 42°15′48.8″N, 118°40′33.1″W, 4100 ft, 7-XI-2011, P. Skelley , M.J. Paulsen, R.H. McPeak [28 FSCA, 1 RMPC] ; Fields Station , 42.263°, -118.676°, 1300 m, 7-XI-2011, M.J. Paulsen [14 MJPC, 8 UNSM] ; Fields , 11.5 mi. N., 42°26′02.5”, 118°37′16.1″W, 7-XI-2011 to 14-IV-2012, P. Skelley, R.H. McPeak [2 FSCA] ; Fields , 12.2 mi. N., 42°26.097′N, 118°37.199′W, 4150 ft, 8-XI-2011 to 29-I-2012, P. Skelley, M.J. Paulsen, R.H. McPeak [17 FSCA] ; Malheur , 28-IV-1974, L. Russell [1 USNM] ; Malheur W [ildlife]. Ref [uge]., Sod House Sch., 20-VI-1974, Gordon & Carlson [1 USNM] ; Lake Co.: Hwy 140 between mileposts 21 & 22, 42°11.995′N, 120°00.621′W, 5162 ft, 14-X-2013 to 15-IV-2014, R.H. McPeak [1 FSCA] .

Gordon and Skelley (2007) report data for S. nevadensis from Nevada: Humboldt Co., BFW Fars Dunes. Specimens from this locality were not available for confirmation. However, they are expected to be S. winnemucca .

Observed habits. Most specimens of S. winnemucca were collected in different dunes or sandy soils across the range. Some were collected from Thomomys burrows in these soils, burrows of Spermophilus beldingi , sifted from the sands, walking on the dune surface on near freezing nights, and in rich sandy organic soils at the edge of a field. The holotype came from a large series (140 specimens) collected walking on dunes at night. Others collected in the same area and at the same time were from 5 barrier pitfall traps (235 specimens) and 30 Thomomys burrows (68 specimens). Based on these numbers and other observations, S. winnemucca are only opportunistically using rodent burrows. They are primarily associated with other organic deposits in sandy soils.

Remarks. Although considered to belong to different species complexes, S. winnemucca is most similar superficially to S. nevadensis , with which it has historically been attributed. Gordon and Skelley’s (2007) habitus photograph of S. nevadensis is actually S. winnemucca . The species differ in that S. nevadensis has the pronotum less constricted basally, basal margin nearly straight, lacks the visible clypeal fringe of setae, has more elongate elytra, and lacks wider elytral striae at the base. In addition, S. winnemucca and S. comosus differ from species in the pyriformis and nevadensis complexes by having coarse punctures on the ventral surface of the protibia, and from those in the pyriformis complex by having two distinct clypeal teeth and visible sexual dimorphisms. Stenotothorax comosus also differs from all other species of these complexes in having more robust legs and in being found only on two small isolated dunes east of Fallon, Nevada.

Etymology. This species is named after Winnemucca, an important Native American (Paiute) leader who had several regional places named after him; Lake Winnemucca, Winnemucca Dunes, the town Winnemucca, the Winnemucca Indian Colony, etc. It is fitting a beetle found in this area be named after him also (noun in apposition).

Figures

Figures 1–9. Stenotothorax spp. characters. 1–2) Extreme age-related wear on Stenotothorax spp.; note lack of clypeal teeth, smoothing and dulling of clypeal surface granulations, and reduction of protibiae. 1) S. wintoni. 2) S. schneppi. 3) Deformity on a S. woodleyi, note apparent tubercle is not centered on head. 4–9) Stenotothorax species heads. 4) S. niviviator. 5) S. odontomonteus. 6) S. nevadensis (Nevada, Washoe Co., Washoe Lake). 7) S. winnemucca. 8) S. lahontanensis, narrow head. 9) S. wintoni, broad head.

Figures 10–15. Stenotothorax spp. characters. 10–14) Stenotothorax pronotal and elytral bases. 10) S. niviviator, complete pronotal marginal bead, rounded strial margin. 11) S. odontomonteus, reduced pronotal marginal bead, rounded strial margin (inset shows cross section of rounded margin). 12) S. lahontanensis, pronotal marginal bead absent, sharply edged strial margin. 13) S. winnemucca, pronotal marginal bead absent, sharply edged strial margin. 14) S. wintoni, pronotal marginal bead absent, sharply edged strial margin, note striae also wider towards base (inset shows cross section of sharp edge). 15) S. wintoni, fused elytra removed exposing strap-like hind wings.

Figures 16–23. Stenotothorax protibiae dorsal (top) and ventral (bottom) surfaces. Note abrasions on ventral surfaces. 16, 20) S. ovipennis, lacking secondary dorsal row of setae. 17, 21) S. wintoni, with secondary dorsal row of setae proximal of basal tooth. 18, 22) S. comosus, with coarse setose punctures on ventral surface, female with sparse setae on medial margin. 19, 23) S. winnemucca, with coarse setose punctures on ventral surface, male with denser setae on medial margin. Arrow points to secondary row of setae.

Figures 24–29. Stenotothorax species, head and pronotum. 24) S. lanei. 25) S. mcpeaki. 26) S. washtucna. 27) S. woodleyi, typical pronotum. 28) S. woodleyi, from Rufus, OR. 29) S. winnemucca, ventral protibia, female paratype from type locality.

Figures 54–59. Stenotothorax winnemucca, n. sp. 54) Dorsal habitus. 55) Ventral habitus. 56) Lateral habitus. 57) Oblique anterior view head to elytral base. 58) Epipharynx. 59) Male genitalia, lateral view.