Tritoxa pollinosa Cole, 1919

Sinclair, Bradley J., Macleod, Alyssa M. & Wheeler, Terry A., 2021, Revision of the Nearctic genus Tritoxa Loew (Diptera: Ulidiidae), Zootaxa 4920 (3), pp. 359-379 : 373-374

Tritoxa pollinosa Cole

( Figs 4 , 11 , 22 , 28 )

Tritoxa pollinosa Cole in Cole & Lovett, 1919: 252 . Type locality: Warm Springs , Oregon, USA.

Type material examined. HOLOTYPE ♀, labelled: “July 7”; “ ♀ ”; “Warm Springs V [alley] [44°45′N 121°16′W]/ 1906 Or[egon]”; “ ♀ ”; “ Holotype / pollinosa [red label]”; “ Tritoxa / pollinosa/ Type Cole”; “ California Academy/ of Sciences/ Type No. 511” ( CAS).

Additional material examined. USA. California: Alpine Co., Long Valley [38.490188° -119.6087828°], 30.viii.1964, G. Tawcan (1♂, CSCA) ; Cedarville [41°31′N 120°10′W], eastside Mid. Lake , 13.vi.1951, H.H. Keifer (3♂, CSCA) ; Inyo Co., Deep Springs [37°22′N 117°59′W], 16.vii.1953, R. M. Bohart (1♂, 1♀, USNM) ; same data except, E.I. Schlinger (1♀, USNM; 1♀, CSCA); Modoc Co., Lake City [41°38′N 120°13′W], Frick trap, xi.1959, L. White (1♂, CSCA) ; Peavine , 11.vii.1949 (1♀, CSCA) ; Siskiyou Co., Dorris [41°57′54″N 121°55′8″W], 17.vi.1961, J. Lambert (1♀, CSCA) . Colorado: Craig [40°31′N 107°33′W], 14.vi.1947, F.C. Harmston (1♂, USNM) . Nevada: Eureka Co., Hwy 80, Beowawe [40°35′N 116°28′W], rest area, swept tree trunk and tree foliage, 11.vi.2001, P.H. & M.M. Arnaud (1♂, CAS) ; Humboldt Co., 39 mi SE Denio [41°59′N 118°37′W], 23.vi.1971, G. Steyskal (1♀, USNM) ; Humboldt Co., 18 mi W Denio , 17.vi.1962, R. R. Snelling (1♀, CSCA) ; Elko [40°50′N 115°46′W], no date or collector (1♀, USNM) ; Humboldt Co., McDermitt [41°59′N 117°43′W], 26.vi.1968, G.J. & A.D. Keuter (1♀, CAS) ; Humboldt Co., Paradise Valley [41°29′35″N 117°31′59″W], 2.vi.1964, G.D. Cooney (1♂, CAS) ; Orovada [41°34′N 117°47′W], 28.vi.1953, A.B. Gurney (1♂, USNM) ; Reno [39°31′N 119°49′W], peach, Orient survey, 27–30.vi.1944 (1♀, USNM) ; Washoe Co., Winne Mucca Lk. [40°07′N 119°20′W], beehives, 17.v.1969, T.W. Davies (2♂, 1♀, CAS) . Oregon: Harney Co., Borax Lk. , 6 mi NE Fields [42.2643°N 118.6751°W], 24.vi.1991, J.L. Furnish, J. McIver (1♂, 1♀, USNM) ; Harney Co., Juniper Lake [42.917° -118.344°], 18.vi.1951, B. Malkin (1♂, CAS) . Utah: Delta [39°21′N 112°34′W], 15.vii.1941, G.F. Knowlton & F.C. Harmston (5♂, 3♀, USNM) ; Deseret [39°17′N 112°39′W], 27.vii.1957, G.F. Knowlton (1♀, CSCA) ; Manila [40°59′N 109°43′W], 13.vii.1938, G.F. Knowlton, F.C. Harmston (1♀, USNM) ; Vernal [40°27′N 109°32′W], 3.vi.1940, B.A. Haws (1♂, USNM) ; Millard Co. [39°03′N 113°06′W], 14.v.1940, R.W. Fautin (1♀, USNM) . Washington: Granger [46°20′N 120°11′W], peach, Orient survey, 20.vii.1944 (1♂, 1♀, USNM) ; same data except, 24.vii.1944 (2♀, USMN) ; Walla Walla [46°3′N 118°19′W], 7.v.1940, H.P. Lanchester (1♂, USNM) ; same data except, 23.v.1940 (2♀, USNM) ; same data except, 15.v.1940 (1♂, USNM) ; Walla Walla , 7.vii.1937, R.M. & G.E. Bohart (1♀, USNM) ; Ritzville , 9.vi.1923, M.C. Lane (1♂, USNM) ; Yakima [46°36′N 120°30′W], in insectary, 26.v.1919, WDW (1♀, USNM) . Wyoming: Red Gulch Rd. off Hwy. 14 nr. Shell [44°32′N 107°46′W], pans in barren area nr. cottonwoods, cow dung, 5–19.viii.1990, J.E. Swann (1♂, DEBU) .

Diagnosis. Tritoxa pollinosa , as the name suggests, is immediately recognized by its silvery microtrichia. This species has wide silvery parafrontal microtrichia stripes and notably microtrichose thorax, especially the yellow microtrichia of the anepisternum, crossvein dm-m is strongly angulate usually without a stump vein and the discal hyaline crossband is interrupted along vein R 2+3.

Redescription. Yellowish-brown with dense areas of pruinosity. Head: ocellar triangle reddish brown, grey microtrichose; frons yellow to yellowish brown; silvery parafrontal microtrichose stripe extending beyond eye margin to bases of orbital setae and setulae, extending roughly halfway distance from eye to midfrons ( Fig. 4 ), continuous with broad microtrichose parafacial; gena dark brown below narrowest part of lower eye margin; postocular microtrichia very wide in lateral view, extending from oral margin to nearly full eye height; face yellowish, often with brown medial stripe extending onto clypeus, with brown spot just under brown part of the gena; supracervical setulae yellow. Antenna with postpedicel greyish yellow, paler along inner and medially surfaces. Proboscis with yellow palpus with white pruinescence. Thorax: yellow to yellowish brown; scutum with pair of dark, greyish microtrichose dorsocentral vittae, with whitish microtrichia along lower margin of notopleuron; posterior portion of postpronotal lobe and postsutural scutum laterally shiny; scutellum with at least apical half shiny reddish brown, base paler often with lateral microtrichia; mediotergite shiny with brownish stripe; posterior half of pleura and upper margin of anepisternum shiny, reddish brown; prosternum to katepisternum and anepisternum with whitish to yellow microtrichia; 2 anepisternal setae. Wing ( Fig. 11 ) somewhat tapered apically, brown, especially along margins of hyaline crossbands, with some faded or paler regions; costal cell with narrow hyaline band at humeral break and broad band at apical fourth in line with discal hyaline crossband; oblique subbasal hyaline crossband reaching apical third of cell dm, fading prior to wing margin; discal hyaline crossband broad, long, obliquely arched, band broken at R 2+3, extending to beyond distal corner of cell dm to wing margin; subapical hyaline crossband broad, strongly arched, broad posteriorly, anterior end extending proximal to crossvein r-m; crossvein dm-m angulate, usually without stump vein; anal lobe well-developed; calypter with broad white margin. Abdomen: dark brown; tergites 3–5 with broad anterior band of white pruinescence; sternites dark brown with greyish pruinescence; pleural membrane infuscate. Male terminalia ( Fig. 22 ): inner surstylus with some 8 thick prensisetae in rough row along straight inner margin; outer surstylus shorter than base, broad, strongly arched medially, with rounded apex; subepandrial sclerite with numerous dark setae. Cercus with long apicolateral setae; apical margin tapered. Phallus long, with some 4 loops.

Distribution. This species is rather widespread in western USA, from California to Colorado and north to Washington ( Fig. 28 ).

Figures

FIGURES 3–5. Heads of Tritoxa species, anterior view. 3. T. incurva; 4. T. pollinosa; 5. T. ra. Abbreviation: orb s—orbital setae.

FIGURES 6–13. Wings of Tritoxa species. 6. T. californica sp. nov.; 7. T. cuneata; 8. T. decipiens sp. nov.; 9. T. flexa; 10. T. incurva; 11. T. pollinosa; 12. T. ra; 13. Tritoxa sp. Abbreviations: d bd—discal band; dm—discal medial cell; dm-m—discal medial crossvein; r-m—radial medial crossvein; sbap bd—subapical band; sbb bd—subbasal band.

FIGURES 22–23. Male terminalia of Tritoxa species, posterior view. 22. T. pollinosa; 23. T. ra.

FIGURES 27–29. Distribution of Tritoxa species. 27. T. incurva; 28. T. pollinosa; 29. T. ra.