Austrocoenia aczeli Wirth

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 : 10-14

1. Austrocoenia aczeli Wirth

Figs. 2–8 , Map 1

Austrocoenia aczeli Wirth 1970: 8 .— Mathis 1980: 5 –7 [revision].—Lizarralde de Grosso 1989: 59 [list, Argentina].— Mathis and Zatwarnicki 1995: 235 [world catalog].

Diagnosis. Generally microtomentose, whitish gray to gray but with some brown coloration dorsally; ocelli arranged in equilateral triangle; tarsi with venter yellowish, hindbasitarsus mostly yellowish except for thin, linear, dorsal, gray stripe; wing mostly hyaline, veins brown except for yellowish costa, subcosta, and basal portions of other veins; structures of male terminalia as in Figs. 6–7 . Medium-sized to large shore flies, body length 3.65–5.10 mm; generally gray.

Head ( Figs. 3–4 ): Head width-to-height ratio 0.73. Frons mostly dull, microtomentose, mostly flat; mesofrons subtriangular, anterior angle produced anteriorly, rounded, and broadly reaching ptilinal suture, lateral margins bearing scattered but conspicuous setulae, approximately 8–10 on each side, but lacking large setae, cruciate or otherwise; mesofrons generally tan, but frequently with some bluish, greenish, or charcoalish coloration, especially around ocelli; parafrons generally darker in coloration than mesofrons, more grayish but with some bluish to charcoal color; ocellar triangle and fronto-orbits slightly raised in relief from parafrons; fronto-orbits nearly concolorous with mesofrons but more grayish; well-developed, lateroclinate, fronto-orbital setae 2, plus 8–11 setulae, frequently 1 proclinate to lateroclinate setula anterior of larger seta; ocellar seta 1, divergent, 3–4 smaller setulae posterior of larger seta; ocelli arranged in equilateral triangle; postocular setae becoming slightly larger toward vertex. Antenna mostly gray but with small patches blackish gray or whitish gray; arista shorter than combined length of 1st 3 segments, thickened along basal 3/4, apical 1/4 style-like; pedicel bearing small setae, generally inconspicuous, except for 1 larger, erect seta inserted dorsally. Facial unicolorous, whitish gray, becoming slightly darker dorsally. Eye nearly round, bare. Parafacials bearing 3–5 prominent setae. Gena high, gena-to-eye ratio 0.65, concolorous with face. Maxillary palpus blackish gray.

Thorax ( Fig. 5 ): Relatively long and narrow; rather densely microtomentose, appearing dull. Mesonotum dark bluish gray to whitish gray but mostly grayish brown to brown; 2 darker stripes on either side of acrostichal setae extended posteriorly no further than level of transverse suture; acrostichal track mostly brownish, frequently with whitish stripe between; scutellum with disc mostly grayish brown to brown; pleural areas distinctly paler in color than mesonotum, becoming whitish gray to white ventrally. Chaetotaxy as follows: Acrostichal setae becoming larger and rows slightly more divergent posteriorly, 1 pair of larger prescutellar setae, these slightly displaced laterally from track of other acrostichal setae; well-developed dorsocentral setae 2–5, but only posterior 1–2 obviously larger, posteriormost seta distinctly larger and slightly displaced laterally from alignment of other setae; interalar setae in a row, posteriormost seta largest; postpronotal setae 2–4, usually 1 seta largest; presutural, supraalar seta 1, this not much larger than surrounding setae; a row of supra-alar setae, 2 posterior setae larger but neither greater than 1/2 length of postalar seta, which is well developed; lateral scutellar setae 2, otherwise scutellum bare except for an apical pair of setae, these frequently cruciate; notopleural setae 2, each near ventral angle, remainder of notopleuron bare; anepisternal seta 1, inserted near middle along posterior margin, several scattered setulae, particularly toward dorsal and posterior margins; katepisternal seta 1, and a small row of setae just anterior of larger seta; prosternum bare. Wing ( Fig. 2 ) veins yellowish brown to yellowish anterobasally, otherwise brownish; membrane mostly hyaline, occasionally palely infuscate, brownish, or slightly milky; costal vein ratio 0.18; M vein ratio 0.88. Halter yellowish. Femora and tibiae concolorous, whitish gray; basal 2 tarsomeres pale, rufous to yellowish orange; apical tarsomeres becoming darker, grayer.

MAP 1. Distribution map for Austrocoenia aczeli Wirth.

Abdomen: Generally unicolorous, gray. Male terminalia ( Figs. 6–7 ): Epandrium in posterior view ( Fig. 6 ) as an inverted U, dorsal arch of U, less well developed, thinner, in lateral view ( Fig. 7 ) dorsal 2/3 nearly parallel sided although dorsal portion thinner, ventral 1/3 becoming wider, with anteriorly oriented, short projection; cercus elongate, in posterior view with dorsal hald triangular, fused ventrolaterally with epandrium; surstylus evidently fused with ventral margin of epandrium, in posterior view ( Fig. 6 ) oriented ventromedially, somewhat pointed apically; gonite plate-like; aedeagus greatly reduced. Female ventral receptacle ( Fig. 8 ) with operculum subtrapezoidal, asymmetrical, extended process more or less C-shaped.

Type material. The holotype male is labeled “R[epublica] A[rgentina]. SANTA CRUZ Cabo Buen Tiempo Gallegos 29-II- [1]953 Coll: Biraben [handwritten; black border].” The holotype specimen is double mounted (minute nadel in cork base), is in good condition, and is deposited in FML. Allotype female and 31 paratypes (7Ƌ, 24♀; BMNH, FML, USNM) bear the same locality label data as the holotype.

Type locality. Argentina. Santa Cruz: Cabo Buen Tiempo Gallegos (51°34'S, 69°05'W).

Other specimens examined. ARGENTINA: Santa Cruz: Piedrabuena (5 km NW; 49°59'S, 68°54'W; 130 m), 25 Nov 1966, M. E. Irwin, E. I. Schlinger (11♂, 4♀; USNM).

CHILE: Magallanes: Laguna Amarga (4 km W; 51°S, 72°48'W; 300 m), 7 Dec 1966, M. E. Irwin, E. I. Schlinger (1♀; USNM).

Distribution (Map 1): Neotropical: Argentina (Santa Cruz), Chile ( Magallanes ).

Figures

FIGURE 2. Habitus of Austrocoenia aczeli Wirth, lateral view (from Wirth 1970).

FIGURES 3 – 5. Austrocoenia aczeli Wirth. (3) head, anterior view; (4) same, lateral view; (5) mesonotum, dorsal view (from Wirth 1970).

FIGURES 6 – 8. Structures of male and female terminalia of Austrocoenia aczeli Wirth. (6) epandrium, cerci, and presurstyli, posterior view; (7) same, lateral view; (8) female ventral receptacle, lateral view. Scale bar = 0.1 mm (from Mathis 1980).