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- Ditrichophora tacoma Cresson 1924: 160; 1942: 119 [review]. Strickland 1946: 167 [list Alberta]. Wirth 1965: 739 [Nearctic catalog]. Cole 1969: 398 [fauna, western North America].
- Gymnoclasiopa tacoma. Mathis and Zatwarnicki 1995: 178 [generic combination; world catalog].
This species is distinguished from congeners by the following combination of characters: Small to moderately small shore flies, body length 1.95–2.85 mm; generally black dorsally with moderately to sparse microtomentum . Head: Frons grayish black, moderately to sparsely microtomentose, subshiny. Scape black; pedicel black basally, apicoventrally yellow; basal flagellomere slightly darkened dorsally, otherwise yellow to reddish yellow, sometimes wholly so; arista bearing 5 dorsal rays. Facial microtomentum generally yellow to slightly brownish yellow; parafacial and gena grayish microtomentose, contrasted with gold-yellow color of face; gena moderately high, gena-to-eye ratio 0.13–0.18. Maxillary palpus yellow to red. Thorax: Mesonotum slightly grayish black to black, sparsely microtomentose, subshiny to shiny; pleural area largely like mesonotum, sometimes more grayish to tannish black. Wing hyaline; costal vein ratio 0.37–0.45; M vein ratio 0.55–0.60. Coxae, femora, and tibia grayish black to black; tarsi yellow, apical tarsomeres becoming darker, brownish yellow. Abdomen: Tergites Partially subshiny to mostly shiny black, very sparsely microtomentose. Male terminalia (Figs 53–55): Epandrium in posterior view (Fig. 54) as a broadly formed, inverted U with the base more narrowly formed, dorsal portion more thinly developed than lateral arms, lateral arms shallowly arched, enlarged ventrally, broadly rounded, setulae more clustered at ventral margin; cercus in posterior view (Fig. 53) elongate,semilunate, lateral margins arched, medial margins irregularly straight, setulae more clustered at ventral margin; aedeagus in lateral view (Fig. 55) slipper-like, base shallowly emarginate, tapered very gradually toward apex, apical half nearly parallel sided, apex moderately broadly rounded, in ventral view (Fig. 54) expanded laterally from narrow base on basal 1/3, thereafter to apex almost parallel sided, slightly tapered, apical margin shallowly incised medially, bilobed; phallapodeme in lateral view (Fig. 55) more or less irregularly triangular, extension toward hypandrium more elongate than angle towards aedeagal base, in ventral view (Fig. 54) I-shaped, apical crossbar robust, wider than basal crossbar, apical margin very shallowly emarginate; ejaculatory apodeme in lateral view shallowly comma-shaped, in ventral view L-shaped; postgonite in lateral view (Fig. 55) bar-like, only slightly tapered from base to apex, bearing 2-3 setulae along posterior margin and 1 setula subapically along anterior margin, in ventral view (Fig. 54) as an elongate triangle, wide basally, tapered to narrowly rounded apex, lateral margins shallowly emarginate laterally, arched medially; pregonite in lateral view (Fig. 55) moderately elongate, straight, expanded slightly aedeagal base, in ventral view (Fig. 54) lunate with apices pointed; hypandrium in ventral view (Fig. 54) robustly V-shaped, lateral margins shallowly curved, anterior margin rounded, posterior margin emarginate, widely V-shaped, in lateral view (Fig. 55) narrowly elongate, shallowly curved.
Type material. The neotype male of Ditrichophora tacoma Cresson, here designated, is labeled “WASH[INGTON].PierceCo. 3 mi. W.S.W. DuPont [47°05.6'N, 122°40'W], 9 Jun [handwritten] 1971[,] Wayne N. Mathis/NEOTYPE ♂ Ditrichophora tacoma Cresson, designated by Mathis & Zatwarnicki 2012 - USNM [red].” The neotype is double mounted (glued to a paper triangle), is in excellent condition, and is deposited in the USNM. There are also 46 specimens (24♂, 22♀; USNM) from the type locality, some with varying dates of collection (13 Apr-9 Jun 1971). DuPont is near the original type locality (Tacoma).
When Cresson (1924) described this species, he noted that the holotype was deposited in the collection of the University of Washington (Seattle). We were unsuccessful in locating this holotype at the Burke Museum, University of Washington (Rodney L. Crawford) or at other collections in the Northwest or where Cresson worked: Oregon State University (Christopher J. Marshall), Washington State University (Richard S. Zack), Academy of Natural Sciences of Philadelphia (Jon K. Gelhaus, Jason D. Weintraub). We are thus designating a neotype for this species, especially given the likelihood of a junior synonym (in the Old World) and the need for a primary type to stabilize the nomenclature of this species.
United States. Washington. Pierce: DuPont (4.8 km WSW; 47°05.6'N, 122°40'W).
Other specimens examined
Nearctic. CANADA. ALBERTA. Edmonton (53°32.1'N, 113°29.4'W), 29 Apr 1924, O. Bryant (1♂; USNM).
BRITISH COLUMBIA. Spences Bridge (50°25'N, 121°21'W), 29 Aug 1951, A. H. Sturtevant (1♀; USNM). Vanderhoof (ca. 27.4 km E, Route 16; 53°53'N, 123°26'W; ditch), 7 Jun 1983, R. S. and V. L. Zack (1♂, 1♀; WSU).
ONTARIO. Ottawa (45°23.5'N, 75°38'W), 26 Apr 1922, C. H. Curran (1♀; ANSP).
QUEBEC. Hull (45°25.8'N, 75°42.8'W), 4 Jun 1923, C. H. Curran (2♂, 1♀; ANSP); Sainte-Anne-de-la-Pérade (46°35'N, 72°12'W), A. L. Melander (1♀; USNM).
UNITED STATES. ALASKA. Anchorage: Mirror Lake (61°25.7'N, 149°24.9'W), 5 Aug 2002, D. and W. N. Mathis (2♀; USNM). Fairbanks North Star: Chena Lake Recreation Area (64°47.6'N, 147°11.4'W), 10 Aug 2003, D. and W. N. Mathis (1♂, 2♀; USNM); Fairbanks (64°50.3'N, 147°43'W), 1 Jul 1921, J. M. Aldrich (4♀; ANSP, USNM); Fairbanks, Creamer’s Field (64°51.7'N, 147°44.3'W; 160 m), 3 Aug 2011, D. and W. N. Mathis (1♂; USNM). Juneau: Eagle Creek (58°31.6'N, 134°49'W), 21 Jul 2011, D. and W. N. Mathis (1♂; USNM). Kenai Peninsula: Homer (59°38.8'N, 151°31.5'W), 2 Aug 2002, D. and W. N. Mathis (1♀; USNM); Kasilof (11 km S; 60°14.8'N, 151°21.9'W), 2 Aug 2003, D. and W. N. Mathis (1♂; USNM); Kenai River, Jim’s Landing (60°28.9'N, 150°06.9'W), 3 Aug 2002, D. and W. N. Mathis (2♂, 1♀; USNM); Ninilchik (60°03'N, 151°40.2'W; beach), 2 Jul 2006, D. and W. N. Mathis (1♂, 3♀; USNM); Rainbow Lake (60°43.1'N, 150°49.1'W), 13 Aug 2012, D. and W. N. Mathis (1♀; USNM); Skilak Lake (60°26.3'N, 150°19.4'W), 3 Aug 2002, D. and W. N. Mathis (10♂, 2♀; USNM); Soldotna (6.5 km E; 60°30.5'N, 150°55.6'W), 1 Aug 2003, D. and W. N. Mathis (2♂, 1♀; USNM); Swanson River Landing (60°44.7'N, 150°48'W), 13 Aug 2012, D. and W. N. Mathis (8♂, 10♀; USNM). Peninsula: Savonoski, Naknek Lake (58°30.9'N, 155°31.8'W), 9-20 Jul 1919, A. J. Basinger (4♂, 3♀; USNM). Matanuska-Susitna: Eklutna (Knik Arm; 61°28.2'N, 149°21.4'W), 7 Aug 2002, D. and W. N. Mathis (3♂; USNM); Knik River (61°27.8'N, 148°51.6'W), 5 Aug 2002, D. and W. N. Mathis (4♂; USNM); Little Willow Creek (61°48.6'N, 150°05.8'W; 50 m), 25 Jul 2011, D. and W. N. Mathis (1♂; USNM); Lucile Lake (61°34.2'N, 149°28.6'W; 100 m), 15 Aug 2012, D. and W. N. Mathis (1♂, 1♀; USNM); Matanuska (61°32.5'N, 149°13.8'W; rotary trap), 28 Apr-21 May 1944, 1945, J. C. Chamberlin (1♂, 4♀; USNM); Palmer (Knik River; 61°31.2'N, 148°59.4'W), 6 Aug 2002, D. and W. N. Mathis (2♂; USNM); Pittman (61°35.5'N, 149°37.9'W), 14 Aug 2012, D. and W. N. Mathis (2♂; USNM); Sheep Creek (61°58.3'N, 150°05'W; 55 m), 10 Aug 2011, D. and W.N. Mathis (2♂, 2♀; USNM); Talkeetna (Susitna River; 61°19.4'N, 150°07.2'W; 120 m), 10 Aug 2011, D. and W.N. Mathis (♂, ♀; USNM); Willow Creek (61°46.1'N, 150°04.2'W; 50 m), 10 Jul-17 Aug 2006, 2011, 2012, D. and W. N. Mathis (22♂, 3♀; USNM). Valdez-Cordova (Census Area): Chitina (61°30.9'N, 144°26.2'W), 18 Jun 1953, W. C. Frohne (1♀; WSU); Gulkana River (19.3 km N Glennallen; 62°16.1'N, 145°23.1'W), 9 Jul-7 Aug 2006, 2011, 2012, D. and W. N. Mathis (22♂, 17♀; USNM); Klutina River (mile 101; 61°57.2'N, 145°19.3'W; 315 m), 7 Aug 2012, D. and W. N. Mathis (3♂, 2♀; USNM). Yukon-Koyukuk (Census Area): Yukon River at Dalton Highway (65°52.8'N, 149°43.2'W; 110 m), 4 Aug 2011, D. and W. N. Mathis (1♂; USNM).
COLORADO. Gunnison: Rocky Mountain Biological Laboratory (38°57.5'N, 106°59.4'W; 2900 m), 26 Aug 1961, D. L. Deonier (1♂, 4♀; USNM). Rio Grande: South Fork (37°40.2'N, 106°38.4'W; 2440 m), 20 Jun 1972, W. W. Wirth (2♂; USNM).
IDAHO. Latah: near Big Meadow Creek Recreation Area (11.25 km N Troy; 46°51'N, 116°44.7'W; 915 m; Malaise trap and sweeping), 13-31 Jul 1979, W. J. Turner (3♂, 2♀; WSU); Helmer (5 km S; 46°46.9'N, 116°28.2'W), 22 May 1971, W. J. Turner (1♂; USNM); Little Sand Creek, near Bonami Creek (25.75 km E Potlach; 46°54.9'N, 116°37.5'W; 884 m), 5 Aug 1979, W. Turner (1♀; WSU).
MICHIGAN. Presque Isle: (45°21.1'N, 83°29.3'W), 2 Jun 1951, R. R. Dreisbach (1♂; USNM).
OREGON. Benton: Corvallis (1.6 km SE, Willamette River; 44°31.7'N, 123°15.2'W), 4 Apr 1972, W. N. Mathis (1♀; USNM); Mary’s Peak (44°30.3'N, 123°33.1'W), 1 Aug 1975, W. N. Mathis (2♀; USNM).
WASHINGTON. Ferry: Colville National Forest, Republic (29 km E; 48°38.9'N, 118°42'W), 19 Jul 1970, P. W. Oman (1♀; USNM). Okanogan: Okanogan National Forest, Wauconda (11.25 km SE, Highway 30; 48°43.7'N, 118°57.9'W), 28 Jul 1973, W. J. Turner (2♂; WSU). Pierce: Mount Rainier National Park, Christine Falls (above; 46°46.9'N, 121°46.8'W; 1125 m), 11–13 Aug 1977, R. S. Zack (2♂; USNM, WSU); Mount Rainier National Park, Comet Falls Trail above Van Trump Creek (46°46.4'N, 121°46.8'W; 1370 m), 11 Aug 1977, R. S. Zack (1♂; WSU); Mount Rainier National Park, Ramparts (46°45.5'N, 121°48.9'W), 1 Aug 1922, A. L. Melander (1♀; WSU); Mount Rainier National Park, Shadow Lake near Sunrise (46°54.7'N, 121°39.4'W), 10 Aug 1977, R. S. Zack (2♂, 7♀; WSU); Mount Rainier National Park, St. Andrews Creek (19.3 km NE Sunshine Point campground; 46°50'N, 121°53'W), 26 Jun 1979, R. S. Zack (2♀; WSU); Mount Rainier National Park, Sunshine Point (6 km NE; 46°44.6'N, 121°55.6'W; 914 m; campground), 18 Jun-8 Aug 1979, R. S. Zack (5♂, 10♀; WSU); Mount Rainier National Park, Westside Road (5 km N; 46°51'N, 121°54.9'W), 12 Aug 1977, R. S. and V. L. Zack (1♂; USNM); Mount Rainier National Park NP, Westside Road, near Puyallup River (46°56'N, 121°35'W; 1066 m), 12 Aug 1977, R. S. Zack (1♀; WSU); Mount Rainier National Park, White River (46°59.6'N, 121°42.6'W), 28 Aug 1934, A. L. Melander (1♂; ANSP); Mount Rainier National Park, White River Campground (46°54.1'N, 121°38.5'W; 1340 m), 9-10 Aug 1977, W. J. Turner, R. S. Zack (1♂, 3♀; WSU); Tacoma (47°15.2'N, 122°26.7'W), 27 Aug 1911 (1♀; paratype; ANSP). Snohomish: Index (47°49.2'N, 121°33.3'W), 2 Aug 1917, A. L. Melander (1♂; ANSP); Verlot (48°05.4'N, 121°46.6'W), 3 Aug 1951, A. H. Sturtevant (2♂, 1♀; USNM).
WYOMING. Fremont: Lander (42°50'N, 108°43.8'W), 16 Aug 1950, A. H. Sturtevant (2♂; USNM).
(Fig. 56). Nearctic: Canada (Alberta, British Columbia, Ontario, Quebec), United States (Alaska, Colorado, Idaho, ?Maine [literature record, not confirmed; Cresson 1924: 160], Michigan, Oregon, Washington, Wyoming). Palearctic: Finland, Japan (Hokkaido), Mongolia (Töv).
This species is relatively widespread in the Nearctic Region and in the Old World, we have examined specimens from Finland, Japan, and Mongolia.
This species is distinguished from congeners by the yellowish to yellowish red antennae and maxillary palpi coupled with the black fore- and midtibiae, which are similar in color to the femora. Nearctic species excluded from Gymnoclasiopa In our world catalog (Mathis and Zatwarnicki 1995), we transferred two Nearctic species, Ditrichophora cana Cresson and Ditrichophora canifrons Cresson, from Ditrichophora to Gymnoclasiopa. This transfer was based on external characters. We have now examined structures of the male terminalia of these two species, and from this evidence, we suggest that their proper placement is in Ditrichophora. Like other species in Ditrichophora, these two species have a rounded epandrium, a single gonite (probably the postgonite) that is not divided into pre- and postgonites, and a phallapodeme that is somewhat Y-shaped in lateral view. Details concerning these two species, including diagnoses, follow.
- Mathis, W; Zatwarnicki, T; 2012: A revision of the New World species of Gymnoclasiopa Hendel (Diptera, Ephydridae) ZooKeys, 248: 1-69. doi
- Cresson E (1924) Descriptions of new genera and species of the dipterous family Ephydridae. Paper VI. Entomological News 35 (5): 159-164.
- Cresson E (1942) Synopses of North American Ephydridae (Diptera) I. The subfamily Psilopinae, with descriptions of new species. Transactions of the American Entomological Society 68: 101-128.
- Strickland E (1946) An annotated list of the Diptera (flies) of Alberta. Canadian Journal of Research, Zoological Sciences section D, 24 (5): 157-173.
- Wirth W (1965) Ephydridae. Pp. 734–759. In: Stone A, Sabrosky CW, Wirth WW, Foote RH, Coulson JR (Eds) A Catalog of the Diptera of America North of Mexico. Handbook 276, U. S. Department of Agriculture, Washington, D.C., 1696 pp.
- Cole F (1969) The flies of western North America. University of California Press, Berkeley, Los Angeles, and London, 693+xi pp.
- Mathis W, Zatwarnicki T (1995) A world catalog of the shore flies (Diptera: Ephydridae). Memoirs on Entomology, International 4: 1-423.