Austrocoenia Wirth, 1970

Mathis, Wayne N. & Sepúlveda, Luciane Marinoni and Tatiana A., 2025, Phylogeny and taxonomy of the shore-fly tribe Ephydrini with comments on related tribes in Ephydrinae (Diptera: Ephydridae), Zoologia (e 24044) 42, pp. 1-42 : 11

Austrocoenia Wirth, 1970

Figs 3–9

Austrocoenia Wirth 1970: 3 (feminine; type species: Austrocoenia aczeli Wirth 1970 , original designation). – Mathis 1980: 4–7 [revision]. – Lizarralde de Grosso 1989: 59 [fauna of Argentina]. – Mathis and Zatwarnicki 1995: 235 [world catalog].

Diagnosis. Austrocoenia is distinguished from other genera of Ephydrini by the following combination of characters: Medium-sized to large shore flies, body length 3.65–5.10 mm; coloration generally gray; wing mostly hyaline; setae generally reduced.

Head: Mesofrons conspicuously setulose, completely microtomentose, dull, lacking large setae, cruciate or otherwise, parafrons more sparsely microtomentose; lateroclinate fronto-orbital setae 2; medial and lateral vertical setae both well developed; paravertical setae either reduced or lacking; antenna short; basal flagellomere lacking a lateral seta; basal flagellomere subequal in length to that of pedicel from dorsal view; arista short, only slightly longer than length of basal flagellomere, basal 2/3 thickened; antennal grooves deeply impressed; face long, distinctly protuberant anteriorly; facial setae small, setula-like; eye subspherical, slightly higher than wide; gena mostly bare, lacking a prominent seta, high, gena-to-eye ratio at least 0.60; maxillary palpus well developed.

Thorax: Acrostichal setae in two rows, these extended posteriorly to base of scutellum, a well-developed prescutellar pair, these inserted slightly laterad of alignment of anterior setulae, rows of setulae slightly more divergent posteriorly; dorsocentral setae 5 (1:4), 1 well-developed dorsocentral seta inserted near base of scutellum, with 3–4 larger setae along dorsocentral tract, anterior setae more weakly developed; postpronotal setae 1–2, these subequal in length to presutural supra-alar seta; postsutural supra-alar seta reduced or lacking; disc of scutellum bare; lateral scutellar setae 2; prosternum bare. Wing normally developed, mostly hyaline; costal margin with short spinelike setae between 2 nd costal break and the apex of vein R 2+3; costal vein long, extended to vein M 1; R stem vein bare dorsally; costal vein ratio 0.18, M 1 vein ratio 0.78. Pulvilli well developed; tarsal claws short and distinctly curved; hindfemur of male not differing markedly from fore- or midfemur, lacking stout, closely set setae; hindtibia of male lacking tuft of setulae; hindtarsi of male evenly cylindrical, normal.

Abdomen: Tergites generally setose, setae along margins larger. Males with five visible segments, with tergite 5 longest, trapezoidal, broadly truncate posteriorly; females with 7 segments, sternites narrow, bearing robust and long setae on subanal plate. Male terminalia: Cercus of male terminalia very elongate, length equal to width of epandrium at midheight, fused ventrolaterally with epandrium; surstylus evidently fused with ventral margin of epandrium; gonite plate-like; aedeagus greatly reduced. Female terminalia: Female ventral receptacle with operculum subtrapezoidal, asymmetrical, extended process more or less C-shaped.

Distribution. Neotropical: Austrocoenia is endemic to southern South America on the Atlantic Ocean side (Patagonia, between 49°– 52°S).

Remarks. Austrocoenia is a monotypic genus and is somewhat of an anomaly due to the autapomorphic condition of several of its characters.

In our morphological studies ( Wirth 1970, Mathis 1980) and in this phylogenetic analysis, Austrocoenia was recovered at the base of the cladogram of Ephydrini . We further highlight that the next node in Ephydrini after Austrocoenia is the lineage giving rise to Notiocoenia , a genus that is likewise found only in the southern latitudes of South America ( Chile).

Wirth (1970: 6–7) was perplexed by his new genus, noting that although Austrocoenia is clearly a member of the subfamily Ephydrinae , “...it is not closely allied with any known genus. It appears to be closest to Coenia Robineau-Desvoidy , a Holarctic genus, which it resembles to a slight extent in the presence of four pairs of dorsocentral setae and curved tarsal claws. Otherwise, its similarities are diverse and rather remote. Austrocoenia is doubtless an annectant form surviving and modified from a very early offshoot of the Ephydrinae .” The single included species, A. aczeli Wirth , is only known from the southern temperate regions of the Neotropics ( Argentina, Chile). Immature stages are unknown.

Figures

Figures 3–9. Austrocoenia aczeli. (3) male habitus; (4) head anterior; (5) head lateral; (6) thorax dorsal; (7) epandrium and cerci posterior; (8) male terminalia lateral; (9) ventral receptacle lateral.