Tritoxa, Loew, 1873

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: 374-377

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Tritoxa   ra Harriot

( Figs 5 View FIGURES 3–5 , 12 View FIGURES 6–13 , 23 View FIGURES 22–23 , 29 View FIGURES 27–29 )

Tritoxa   ra Harriot, 1942: 23. Type locality: Lone Pine , Inyo Co., California, USA   .

Type material examined. HOLOTYPE: not examined. PARATYPES: USA. California: Inyo Co., Owens Valley, Diaz Lake [36°33′34″N 118°03′17″W],, T. G. Aitken (1♂, CAS); GoogleMaps   Inyo Co. Lone Pine [36°36′N 118°03′W],, L.D. Phillips (allotype ♀, CAS) GoogleMaps   .

Additional material examined. USA. California: Inyo Co., Lone Pine [36°36′N 118°03′W],, N.W. Frazier (1♀, CAS) GoogleMaps   ; same data except, (1♂, CAS)   ; Inyo Co., Bishop [37°21′N 118°23′W], ex Chrysothamnus   nr alfalfa, 7.viii.1971, E. Paddock (1♂, CSCA) GoogleMaps   ; Kern Co., Bakersfield [35°22′N 119°1′W],, B. Nemmer (1♂, CSCA) GoogleMaps   ; Kern Co., Bakersfield ,, T. Gullion (1♂, CSCA)   ; Kings Co., Hanford [36°19′N 119°38′W], McPhail trap, 23.vii.1958, B. Vaughn (1♀, CSCA, 2♂, USNM) GoogleMaps   ; same data except,, B. Felleke (1♂, CSCA) GoogleMaps   ; Kings Co., Lemoore [36°18′N 119°46′W], McPhail trap,, L. Tickle (1♂, CSCA) GoogleMaps   , same data except, Jackson trap,, J. Dunicliff (1♂, CSCA) GoogleMaps   ; Mojave [35°03′N 118°10′W], 22.iv.1945, G.P. Mackenzie (1♀, USNM) GoogleMaps   ; San Luis Obispo Co., Shandon [35°39′N 120°22′W], 1.ix.1988, J. Welch (1♀, CSCA) GoogleMaps   ; San Luis Obispo Co., McPhail trap, residence garden, 1.x.2005, L.H. Iegit (1♂, CSCA)   ; Santa Barbara Co., Cuyama [34°55′N 119°36′W], Frick trap, 18.ix.1958, G. Beevor & J. Rowell (1♀, CSCA) GoogleMaps   . Nevada: Nye Co., Ash Meadows, Fairbanks Springs [36.425°, -116.291°],, T. Frantz (1♀, CAS)   ; Washoe Co., Winne Mucca Lk. [40°07′N 119°20′W], beehives, 17.v.1969, T. W. Davies (1♂, CAS) GoogleMaps   .

Diagnosis. Tritoxa   ra may be easily recognized by a relatively wide silvery band of parafrontal microtrichia, combined with a stump vein proceeding from an angulation on crossvein dm-m which points towards the wing margin. The inner surstylus is distinctive with two rows of numerous strong prensisetae at base and outer surstylus short, broad, with apex expanded.

Redescription. Entirely yellowish with abdomen brownish dorsally. Head: ocellar triangle reddish brown, pruinescent; frons yellow to yellowish brown; silvery parafrontal microtrichose stripe extending to bases from eye margin to orbital setae and setulae, extending roughly 1/4 to 1/3 distance from eye to midfrons ( Fig. 5 View FIGURES 3–5 ), continuous with broad microtrichose parafacial; gena dark brown below narrowest part of lower eye margin; postocular microtrichia as wide as parafrontal microtrichia in lateral view, extending from oral margin to middle of eye; face greyish-yellow laterally, with brown spot just under brown part of the gena; supracervical setulae yellow. Antenna with postpedicel mostly yellow. Proboscis with yellow palpus. Thorax: yellowish to brown; scutum with pair of dark, greyish microtrichose dorsocentral vittae, with yellow microtrichia to suture and medially to scutellum; often posterior portion of postpronotal lobe and postsutural scutum laterally shiny; scutellum with apical half to posterior margin shiny reddish yellow; mediotergite with brownish stripe; pleura shiny, yellow to reddish yellow, lightly clothed in whitish microtrichis when viewed obliquely; area surrounding katepisternal seta reddish brown; whitish microtrichose band above fore coxa; 2 anepisternal setae. Wing ( Fig. 12 View FIGURES 6–13 ) rounded apically, brown, especially along margins of hyaline crossbands, with some faded or paler regions; costal cell with narrow hyaline band at humeral break and at apical fourth in line with discal hyaline crossband; often hyaline area from apical region of Sc to R 1; oblique subbasal hyaline crossband reaching beyond mid-length of cell dm, fading prior to wing margin; discal hyaline crossband narrow, continuous from R 1, broader posteriorly, long, obliquely arched, extending to beyond distal corner of cell dm to wing margin along M 4; subapical hyaline crossband broad, strongly arched, broad, anterior end extending proximal to crossvein r-m; crossvein dm-m angulate at mid-length, with short stump vein; anal lobe well-developed; calypter with broad white margin. Abdomen: broad brown bands on anterior two-thirds of some tergites; sternites yellow; pleural membrane infuscate. Male terminalia ( Fig. 23 View FIGURES 22–23 ): inner surstylus with double row of 5–7 thick prensisetae along inner margin; outer surstylus shorter than inner surstylus, broad, expanded apically, strongly arched mesally with blunt tip; subepandrial sclerite with strong dark setae. Cercus with short apicolateral setae; apical margin tapered. Phallus long, with some 3 loops.

Distribution. This species is known from the southern half of California and two neighbouring counties in Nevada ( Fig. 29 View FIGURES 27–29 ).


Tavera, Department of Geology and Geophysics


California Academy of Sciences


California State Collection of Arthropods


Smithsonian Institution, National Museum of Natural History













Sinclair, Bradley J., Macleod, Alyssa M. & Wheeler, Terry A. 2021


Harriot, S. C. 1942: 23