Tritoxa cuneata 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 : 362-365

publication ID 10.11646/zootaxa.4920.3.3

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Tritoxa cuneata Loew


Tritoxa cuneata Loew View in CoL

( Figs 7 View FIGURES 6–13 , 16 View FIGURES 14–17 , 26 View FIGURES 24–26 )

Tritoxa cuneata Loew, 1873: 107 View in CoL . Type locality: Nebraska, USA.

Type material examined. LECTOTYPE ♂ [ MCZ:Ent:13246], labelled: “Neb[raska]. [41°29′33″N 99°54′06″W]”; “cuneata/ m.”; “Loew/ Coll.”; “Type/ 13246 [red label]”; “ Lectotype / Tritoxa cuneata / Loew/ Steyskal 1971”; “MCZ-ENT/ 00013246/ data matrix code”; “ LECTOTYPE / Tritoxa / cuneata Loew / des. B.J. Sinclair 2020 [red label]” ( MCZ). PARALECTOTYPE: same data as lectotype (1 ♂, dissected, MCZ).

Taxonomic notes. Loew based this species on an unspecified number of male and female specimens. Steyskal attached his lectotype label to a male syntype, but this designation was never published. Our lectotype label is now attached to this specimen in order to fix the identity of the species.

Additional material examined. CANADA. Alberta: Elkwater Park [49°39′39″N 110°16′54″W],, A. R. Brooks (1♂, CNC) GoogleMaps ; Empress [50°57′0″N 110°00′22″W],, Brooks & MacNay (1♂, 1♀, CNC) GoogleMaps ; Irvine [49.9553°N 110.2767°W],, L.A. Konotopetz (1♂, CNC) GoogleMaps ; Medicine Hat [50°02′30″N 110°40′39″W], 28.vii.1927, F.S. Carr (1♂, CNC) GoogleMaps ; Onefour Heritage Range Land, nr Rte 41, Sage Ck , 49.15666° -110.2036°, 4.vii.2012, S. Rochefort (1♂, 1♀, CNC) ; Pinhorn Grazing Reserve , 33 km SSW Manyberries, 49°7′51″N 110°53′23″W, 7.vii.2009, J.H. Kits (1♂, DEBU) GoogleMaps . Saskatchewan: Grasslands NP, Butte trail, grass/sage brush plains, 49.198° -107.634°, 15.vii. 2008, 814 m, J. Straka, N. Jeffery, 08BBDIP-0174, 08BBDIP-0173 (2♂, barcoded, CBG) ; Saskatoon [52°08′N 106°41′W],, L.A. Konotopetz (1♂, 1♀, CNC) GoogleMaps ; Val Marie [49°13′59″N 107°44′05″W],, A. R. Brooks (1♂, CNC) GoogleMaps ; same data except, 8.viii.1955 (4♂, CNC) GoogleMaps ; 15 km E Val Marie , hilltop,, M. Polak & M. Wood (1♂, CNC) ; Wood Mountain [49°13′18″N 106°13′32″W],, A. R. Brooks (2♂, CNC) GoogleMaps . USA. Arizona: Apache Co., Big Lake , 33°53′N, 109°26′W, 14.vii.1992, G.F. Hevel (1♂, USNM) GoogleMaps . California: Callahan [41°18′35″N 122°48′05″W],, T. G.H. Aitken (1♀, CAS) GoogleMaps ; Glen Co., Plaskett Meadows [39°43′40″N 122°50′42″W], 11.x.1964, J.D. Birchim (1♂, CAS) GoogleMaps ; Inyo Co., Sage Flat [37.130241° -118.413617°], 15.viii.1966, E.L. Sleeper (1♂, CAS) ; Inyo Co., White Mts , 2 mi S Schulman Grove [37.385° -118.178°], 28.viii.1984 –, 9200 ft, D. Giuliani (1♂, CSCA) ; same data except, 6.5 mi N, 7.5 mi E Big Pine , 7000 ft, 27.ii.–28.viii.1984 (2♂, 1♀, CSCA) ; Lake Tahoe [39°05.5′N 120°02.5′W], 2.vii.1915, E.C. Van Dyke (1♂, CAS) GoogleMaps ; Mendocino Co., Anthony Peak [39.84624°N 122.96457°W], 6.ix.1961, M. Poyner (1♂, CAS) GoogleMaps ; Mt. Shasta [41°24′33″N 122°11′42″W], 1.viii.1909, 7000 ft, L. Eighme (1♂, CSCA) GoogleMaps ; Obispo Co., San Luis, Cerro Alto [35°25′27.37″N 120°44′20.35″W], 4.iv.1966, E.L. Sleeper (2♂, 2♀, CAS) GoogleMaps . Colorado: Buckhorn Ck [40.4208169° -105.1752614°], 11.vii.1937, C.L. Johnston (2♂, USNM) ; Clark [40°42′26″N 106°55′08″W], 3.viii.1947, O. Bryant (1♂, CAS) GoogleMaps ; Estes Park [40°22′N 105°31′W], 7500 ft, 2.vii.1961, W. R. M. Mason (1♂, CNC) GoogleMaps ; 4.5 mi N Boulder [40°00′N 105°16′W], 5500 ft,, W. R.M. Mason (1♂, CNC) GoogleMaps ; Jefferson [39°22′N 105°48′W], 9400 ft, 14.vii.1961, W. R. M. Mason (1♂, CNC) GoogleMaps . Idaho: Blaine Co., Galena Summit [43°52′N 114°42′W], 8600 ft, dry hillside, 15.vii.1961, J.G. Chillcott (1♂, CNC) GoogleMaps ; Waha [46°12′N 116°49′W], 12.viii.1923, A.L. Melander (1♂, USNM) GoogleMaps . Montana: Petroleum Co., 1.5 mi S, 5 mi W Winnett [47°0′N 108°21′W], 30.vii.1969, G.B. Hewitt (1♀, USNM) GoogleMaps ; Petroleum Co., 3 mi NW Winnett ,, G.B. Hewitt (1♂, USNM) . Nevada: Elko Co., Wells [41°6′34″N 114°58′8″W], 13.viii.1981, P.H. Arnaud (1♂, CAS) GoogleMaps ; White Pine Co. [39°26′N 114°54′W], Lehman Ck, 10.vii.1966, R. P. Allen (1♂, 2♀, CSCA) GoogleMaps . New Mexico: Otero Co., Lincoln NF, Sacramento Mtns , Bailey Ck nr Cloudcroft , 1642 m, 32°58′56.1″N 105°45′13.4″W,, S.D. Gaimari (1♂, CSCA) GoogleMaps . Oregon: McMinnville [45°12′42″N 123°11′50″W], 28.vii.1930 (2♂, USNM) GoogleMaps . Texas: NW Blanco Co. [30°16′N 98°24′W], Davis Ranch, 12.iv.1959, J.F. McAlpine (2♂, CNC) GoogleMaps ; Dallas Co. [32°46′N 96°47′W], vii.1931, J.K.G. Silvey (1♀, USNM) GoogleMaps ; Garza Co., 2 mi N Justiceburg [33°2′31″N 101°12′11″W], collected on Xanthocephalum sarothrae , 4.viii.1976, D.E. Foster (1♂, USNM) GoogleMaps ; Hondo [29°20′49″N 99°8′44″W], 25.iv.1942, A.L. Melander (1♀, USNM) GoogleMaps ; Kerrville [30°2′51″N 99°8′26.1″W], swept meadow, 18–20.iv.1959, J.F. McAlpine (3♂, 2♀, CNC) GoogleMaps ; same data except, 16.iv.1959, W. R.M. Mason (1♂, CNC) GoogleMaps ; Maverick Co., Texas A&M Ranch , 15 mi WSW Uvalde [29°12′N 99°47′W], sweeping Xanthocehalum sarothrae , 13.x.1976, Robbins & Seedle (1♀, USNM) GoogleMaps ; Maverick Co., 35 mi SE Del Rio [29°21′N 100°54′W], 4.ix.1982, Huber, Gonzalez (1♀, CSCA) GoogleMaps ; San Antonio [29°25′N 98°29′W], 3.iv.1942, A.L. Melander (1♂, USNM) GoogleMaps ; same data except, 16.iv.1942 (1♀, USNM) GoogleMaps ; San Antonio , ii.1928, F.C. Pratt (1♀, USNM) ; Texas 281 RV Park Meadow , Bulverde, 29.7875°N 98.4191°W, 340 m, 12.iv.2010, Biobus 2010, 10BBDIP-0308, 10BBDIP-0309, 10BBDIP-1818 (1♂, 2♀, barcoded, CBG) GoogleMaps ; same data, 29.7898° -98.4202°, 11.iv. 2010, 378 m, Treed Nature Trail, 10BBDIP-1821 (1♂, barcoded, CBG) GoogleMaps ; Travis Co., Austin [30°16′N 97°44′W], Gutierrezia glutinosa , 20.ix.1978, P.D. Hurd (1♂, USNM) GoogleMaps ; Uvalde Co., 3 mi NW Uvlade [29°12′52″N 99°47′23″W], MT, 4–6.v.1977, T. Eichlin, M. Washbauer (2♀, CSCA) GoogleMaps ; Val Verde Co., Langtry [29°48′N 101°33′W], 4.ix.1982, Huber & Gonzalez (1♀, CSCA) GoogleMaps . Utah: 9 mi E Oak City [39°22′N 112°20′W], Oak Ck Camp, MT, 1.ix.1963, D.C. Rentz (5♂, 2♀, CAS) GoogleMaps . Washington: Blue Mtns, Godman’s Springs RS [46.1007217° -117.7868657°], 6000 ft, 28.vii.1940, M.C. Lane (1♂, USNM) ; Pullman [46°44′N 117°10′W], 25.viii.1897, R. W. Doane (1♂, 1♀, USNM) GoogleMaps . Wyoming: Cheyenne Co. [38°49′N 102°35′W],, E.L. Sleeper (1♂, CAS) GoogleMaps ; Sheridan [44°47′N 106°57′W], no date, Metz (1♂, USNM) GoogleMaps .

Diagnosis. This species can be recognized by the long discal hyaline crossband, extending to opposite crossvein r-m, inner surstylus with 3–4 strong, separated prensisetae and outer surstylus straight.

Redescription. Entirely reddish brown to black, abdomen darker. Head: ocellar triangle shiny black; frons reddish-brown to brown; silvery parafrontal microtrichose stripe very narrow, continuous with very narrow microtrichose parafacial; gena dark brown below narrowest part of lower eye margin; postocular microtrichia wider than parafrontal microtrichia in lateral view, extending from oral margin to middle of eye; face yellowish-brown to brown; supracervical setulae usually yellow. Antenna with postpedicel greyish brown, yellowish brown on ventral and basal surfaces. Proboscis with palpus concolourous with face. Thorax: yellowish-brown to brown; scutum mostly thinly pruinescent with pair of whitish pruinescent vittae; lateral margin of scutum and postpronotal lobe broadly shiny; scutellum concolourous with scutum; mediotergite without distinct stripe; pleura shiny, posterior portion of anepisternum and katepisternum lightly clothed in whitish microtrichia when viewed obliquely; whitish microtrichia above fore coxa; 1 rarely 2 anepisternal setae. Wing ( Fig. 7 View FIGURES 6–13 ) rounded apically, brown, especially along margins of hyaline crossbands, with some faded or paler regions; costal cell without narrow hyaline band at humeral break, with or without hyaline band 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 basal third of cell dm; discal hyaline crossband oblique, short, continuous from R 1, broader posteriorly, long, obliquely arched, extending to level of crossvein r-m in cell dm, often somewhat displaced at R 4+5; subapical hyaline crossband broad, nearly straight to arched, anterior end not extending proximal to crossvein r-m; crossvein dm-m straight; anal lobe well-developed; calypter usually with broad white margin. Abdomen: brown bands on anterior portion of some tergites in paler forms; sternites dark to yellow; pleural membrane infuscate. Male terminalia ( Fig. 16 View FIGURES 14–17 ): inner surstylus with 3–4 separated, thick prensisetae, inner margin straight; outer surstylus slender, longer than inner surstylus, slight tapered and straight with rounded apex; subepandrial sclerite with scattered dark setae. Cercus with long, strong apicolateral setae; apical margin straight. Phallus long, with some 4–5 loops.

Distribution. Tritoxa cuneata is widespread in western North America, from southeastern Alberta and southern Saskatchewan to Texas and west to California ( Fig. 26 View FIGURES 24–26 ).

Remarks. Tritoxa cuneata is very similar to T. decipiens and where the distribution of the two species overlap (e.g., Rocky Mtns), care should be taken for identification and examination of the male terminalia is recommended to confirm. In California, T. cuneata is also sympatric with T. californica and again, dissection and examination of the male terminalia is required to confirm identification.

A single male from Cochise County, Arizona (AZ: Cochise Co., Dragoon Mtns , Cochise Stronghold , 1219 m, 30.viii.1982, E.S. Ross ( CAS)) is possibly conspecific based on the wing pattern, but the male terminalia suggests T. decipiens . Specimens from this locality should be further investigated .


Museum of Comparative Zoology


Departamento de Geologia, Universidad de Chile


Canadian National Collection of Insects, Arachnids, and Nematodes


Ontario Insect Collection, University of Guelph


Australian National Botanic Gardens, specimens pre-1993


Smithsonian Institution, National Museum of Natural History


Tavera, Department of Geology and Geophysics


California Academy of Sciences


California State Collection of Arthropods


Collection of Leptospira Strains


Mus. Tinro, Vladyvostok














Tritoxa cuneata Loew

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

Tritoxa cuneata

Loew, H. 1873: 107
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