Setacera durani Cresson

Mathis, Wayne N. & Marinoni, Luciane, 2016, Revision of Ephydrini Zetterstedt (Diptera: Ephydridae) from the Americas south of the United States, Zootaxa 4116 (1), pp. 1-110 : 100-102

31. Setacera durani Cresson

Figs. 133–138 , Map 31

Setacera durani Cresson 1935: 348 .— Sturtevant and Wheeler 1954: 202 –203 [review].— Wirth 1965: 755 [Nearctic catalog].— Mathis 1982b: 38 –40 [revision, Figs. of head, thorax, male terminalia].— Mathis and Zatwarnicki 1995: 253 [world catalog].

Diagnosis. Setacera durani is similar to S. needhami and S. trichoscelis but is distinguished by the following characters: interfoveal facial ridge more explanate; setation of male midfemur lacking conspicuous row of 4–7 larger setae along posteroventral surface; apical tufts of longer hairs of mid- and hindtibiae not as long; 3rd and 4th sternites of male with clump of stout setae at posteromedial edge; anal plate of female not as prominent, width greater than length; structures of male terminalia distinctive. Medium-sized to moderately large shore flies, body length 3.40–5.00 mm; coloration mostly gray to bluish green, generally microtomentose except dorsum which is subshiny to shiny with distinct metallic luster.

Head ( Fig. 133 ): Head ratio 0.61; frontal ratio 0.48; coloration of frons, fronto-orbital plates, and dorsum of interfoveal ridge concolorous, greenish blue with shiny metallic luster; frons gradually becoming narrower anteriorly, sparsely setose, setae small, generally inconspicuous; ocellar triangle microtomentose, brownish, microtomentose; ocelli in equilateral triangle. Antenna mostly unicolorous, brownish black, microtomentose; scape and pedicel with some grayish green coloration ventrally; arista thickened on basal 1/3; basal 2/3 with dorsal subpectinate branching, length of longer rays about twice greatest width of arista. Face bicolored; dorsum of interfoveal ridge bluish green, mostly shiny, becoming duller and brownish toward edge of facial ridge; lower portion of face silvery white, from some angles with slight brownish to olivaceous coloration; setae along anterior edge of ridge larger, stout, otherwise facial setae relatively small, generally inconspicuous, uniformly scattered; anterior margin of lower portion of face in profile receding slightly to oral margin. Eye ratio 0.80, orientation of eye at oblique angle to plane of epistoma. Gena-to-eye ratio 0.52; gena mostly concolorous with lower portion of face, posterior portion becoming duller, grayer, with some faint olivaceous coloration.

Thorax: Mesonotum dull, microtomentose along anterior margin, becoming progressively shinier posteriorly, posterior portion distinctly shiny with metallic, slightly brownish green luster; scutellum concolorous with posterior portion of mesonotum; setae other than larger setae reduced, generally inconspicuous. Pleural areas mostly dull, microtomentose to microtomentose; notopleuron with some subshiny to shiny areas like mesonotum above; coloration generally olivaceous to gray, becoming grayer ventrally and anteriorly. Femora mostly gray with some greenish or bluish coloration; tibiae mostly black; hindtarsi mostly concolorous with hindtibia; mid- and foretarsi more yellowish orange. Costal vein ratio of averaging 0.27; M vein ratio 0.79.

Abdomen: Dorsum generally subshiny, extreme anterior margin mostly dull gray, becoming subshiny posteriorly with metallic greenish luster; venter entirely dull, gray to olivaceous green. Tergite 5 of males almost as long as combined length of tergites 3 and 4, becoming narrower to subtruncate posterior edge. Epandrium of male terminalia ( Figs. 135–136 ) rounded dorsally, lateral margins expanding laterally, broadly truncate ventrally where surstyli attach; surstyli in posterior view ( Fig. 135 ) fused medially forming broadly U-shaped process with median, pointed process as long as either surstylar arm, each arm broadly rounded and densely setose; aedeagus ( Fig. 136 ) rather bulbous, broadly produced, rounded apically. Sternites 3 and 4 of males ( Fig. 134 ) with dense clusters of stout setae at posteromedial edge. Female terminalia, including female ventral receptacle, as in Figs. 137–138 .

MAP 31. Distribution map for Setacera durani Cresson.

Type material. The holotype male is labeled “Los Angeles R[iver]. Cal[ifornia]., Aug. 15, 1916, V. Duran, Coll/Ƌ/ TYPE No. 6515 Setacera DURANI E T Cresson, Jr. [red].” The holotype is in good condition and is deposited in the ANSP (6516). Cresson's original description lists a female paratopotype, also in the Academy.

Type locality. United States. California. Los Angeles: Los Angeles River (33°45'S, 118°11.3'W).

Additional specimens examined. MEXICO. Baja California: San Vicente (31°20'S, 116°15'W), 20 Sep 1941, E. S. Ross, G. Bohart (1♂; CAS); Santo Domingo (5.7 m E; Hamilton Ranch; 30°44'S, 115°58'W), 22 Apr 1963, H. B. Leech, P. H. Arnaud, Jr. (4♂, 1♀; CAS, USNM); Tijuana (60 km S; 32°02'S, 117°01'W), 26 Jun 1950, A. L. Melander (1♂; USNM).

Distribution ( Fig. 31 ). This species occurs in the Southwest of the United States (California, Arizona, Oregon, Nevada, Colorado) and extends into northern Mexico. We have examined many specimens from the three sites in Baja California noted previously.

Natural history. Practically nothing is known about the ecology or immatures of this species. Foote (1982) collected adults from an algal mat that had formed in a small, sewage-polluted stream near Patagonia, Arizona.

Remarks. This species and S. pacifica are sister species, as evidenced by the joint possession of a median, triangular projection between the surstyli. This species is distinguished externally from S. pacifica by the evenly rounded, supraspiracular convexity and by the distinct tuft of setae at the apex of the midtibia.

Figures

FIGURES 133 – 138. Setacera durani Cresson. (133) head, lateral view; (134) male sternites 3 and 4, ventral view; (135) surstyli, posterior view; (136) male terminalia, lateral view; (137) female terminalia, lateral view; (138) female ventral receptacle, lateral view (from Mathis 1982).

FIGURES 30 – 34. Structures of male and female terminalia of Paracoenia wirthi Mathis. (30) epandrium, cerci and surstyli, posterior view; (31) epandrium, cerci, surstyli and gonite, lateral view; (32) ventral apex of male tergite 5, ventral view; (33) female ventral receptacle, lateral view; (34) male sternite 5, ventral view (from Mathis 1980).