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- Ditrichophora cana Cresson 1940: 7; 1942: 121 [review]. Wirth and Stone 1956: 467 [key, California]. Wirth 1965: 739 [Nearctic catalog]. Cole 1969: 398 [fauna, western North America].
- Gymnoclasiopa cana. Mathis and Zatwarnicki 1995: 175 [generic combination; world catalog].
This species is distinguished from congeners by the following combination of characters: Moderately small to medium-sized shore flies, body length 2.40–3.60 mm; head and thorax generally microtomentose gray dorsally, abdomen subshiny to shiny black. Head: Frons moderately microtomentose, cinereous to whitish; proclinate fronto-orbital setae 2, length of anterior seta about 1/2 that of posterior seta, inserted far anteriad, distance between proclinate setae subequal to that between posterior seta and medial vertical seta. Antenna generally black, especially scape and pedicel; arista bearing 6–7 dorsal rays. Face rather flat; antennal grooves, especially ventral margins, poorly defined, not conspicuous; face slightly whitish gray dorsally, dorsal portion shallowly carinate between shallow antennal grooves, thinly, microtomentose, becoming blackish, less microtomentose ventrally; facial setae inserted close to parafacials, aligned vertically; gena short, less than height of basal flagellomere; gena-to-eye ratio 0.15–0.16. Maxillary palpus black. Thorax: Mesonotum moderately microtomentose, cinereous, similar to frons, not shiny; pleural areas from ventral notopleural suture ventrad black, contrasted with whitish gray mesonotum, similar to black abdominal tergites. Wing lacteous, more so in males; costal section II conspicuously longer than costal section III; costal vein ratio 0.47–0.51; M vein ratio 0.52–0.56; halter stem yellowish; knob white to whitish yellow. Femora black; tibiae black, including basal and apical extremities black; foretarsus black dorsally, yellowish ventrally; mid- and hindtarsi mostly yellowish orange. Abdomen: Tergites subshiny to shiny, black. Male terminalia: Epandrium in posterior view as an inverted U, narrowed dorsally, abruptly so medially with moderately deep incision, in lateral view widest subventrally with ventral margin rounded and bearing cluster of longer setulae, these becoming longer toward posteroventral angle; cercus in posterior view uniformly semilunate with dorsomedial margin more narrowly pointed; aedeagus in lateral view longer than wide, as anterior and posterior structures, anterior portion longer than posterior portion and with a long flap folded back on itself (as in Pectinifer aeneus (Cresson)), in ventral view robust, narrow ventrally; phallapodeme in lateral view with elongate, irregularly triangular keep, processes at either end about equal in length, in ventral view robustly T-shaped with thick stem, base as wide as cross bar; gonite (probably the postgonite) elongate, wide basally, narrowed to elongate, narrow, apically curved process, at midlength with a digitiform, pointed perpendicular to plane of gonite; hypandrium in lateral view bowl shaped, posterior portion slightly more extended, in ventral view with anterior margin broadly curved and deeply emarginate.
The holotype male of Ditrichophora cana Cresson is labeled “Ilwaco WASH July 1917 ALMelander/TYPE Ditrichophora CANA E. T. Cresson, Jr. [red; species number and name handwritten].” The holotype is double mounted (minuten pin in a rectangular card), is in fair condition (head dislodged and in an attached microvial), and is deposited in the ANSP (6552).
United States. Washington. Pacific: Ilwaco (46°18.5'N, 124°02.6'W).
Other Specimens Examined. CALIFORNIA. Humboldt: Orick (41°17.2'N, 124°03.6'W), 21 Jun 1935, A. L. Melander (1♂, 1♀; ANSP).
OREGON. Curry: Gold Beach (42°24.4'N, 124°25.3'W), 27 Jul 1951, A. H. Sturtevant (1♂, 2♀; USNM). Douglas: Elkton (43°38.2'N, 123°33.9'W), 28 Jul 1951, A. H. Sturtevant (1♂; USNM). Multnomah: Benson Park (45°34.5'N, 122°07.7'W), 24 Jun 1935, A. L. Melander (1♂; ANSP).
WASHINGTON. Clallam: Bogachiel Way, Forks (47°56.3'N, 124°24.6'W), 1 Aug 1951, A. H. Sturtevant (4♂, 3♀; USNM; Sequim (48°04.8'N, 123°06.1'W), 2 Aug 1951, A. H. Sturtevant (8♂, 2♀; USNM). Lewis: Toledo (46°26.4'N, 122°50.8'W), 27 Jun 1935, A. L. Melander (1♂, 1♀; ANSP). Pacific: Ilwaco (46°18.5'N, 124°02.6'W), 8 Jun-Jul 1917, 1925, A. L. Melander (4♂, 3♀; ANSP, USNM); Seaview (46°20.1'N, 124°03.3'W), A. Spuler (2♂; USNM). Pierce: Tacoma (47°15.2'N, 122°26.7'W), 23 Jul 1915, A. L. Melander (1♀; ANSP). Snohomish: Everett (47°58.7'N, 122°12'W), 4-6 Jul 1924, A. L. Melander (7♂, 3♀; ANSP; USNM).
(Fig. 57). Nearctic: United States (California, Oregon, Washington).
Although similar externally to Ditrichophora canifrons, the structures of the male terminalia of this species are remarkably different and appear to be more similar to Pectinifer aeneus (Cresson) (Zatwarnicki and Mathis 2001: 44), especially the elongated and robust aedeagus with an apical flap that folds back on itself. From Ditrichophora canifrons, this species is distinguished by the blackish antenna and entirely black foretibia.
- Mathis, W; Zatwarnicki, T; 2012: A revision of the New World species of Gymnoclasiopa Hendel (Diptera, Ephydridae) ZooKeys, 248: 1-69. doi
- Cresson E (1940) Descriptions of new genera and species of the dipterous family Ephydridae. Paper XII. Notulae Naturae. The Academy of Natural Sciences of Philadelphia 38: 1-10.
- 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.
- Wirth W, Stone A (1956) Chapter 14. Aquatic Diptera. In: Usinger R (Ed) Aquatic Insects of California. University of California Press, Berkeley, 372–482.
- 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.
- Zatwarnicki T, Mathis W (2001) A generic classification of the tribe Discocerinini (Diptera: Ephydridae). Annales Zoologici 51 (1): 5-51.