Tethina Haliday

Mathis, Wayne N. & Marinoni, Luciane, 2012, A conspectus on the Canacidae (Diptera) of Brazil, ZooKeys 162, pp. 59-92 : 78-79

Genus Tethina Haliday (77 species worldwide; 3 from Brazil)

Tethina Haliday, in Curtis 1837: 293 (as a subgenus of Opomyza ; published in synonymy; first made available by use in Haliday 1838: 188). Type species: Opomyza (Tethina) illota Haliday 1838, by subsequent monotypy ( Haliday 1838: 188). Sturtevant 1923: 5-7 [discussion of synonymy, listing of Nearctic species]. Thompson and Mathis 1981: 86 [citation, nomenclature]. Mathis and Munari 1996: 13-19 [world catalog]. Foster and Mathis 1998: 608-630 [revision of Caribbean and Gulf of Mexico species]. Sabrosky 1999: 32, 304 [citations, nomenclature]. Munari and Mathis 2010: 48-66 [world catalog].

Rhicnoessa Loew 1862: 174. Type species: Rhicnoessa cinerea Loew, by monotypy. Loew 1865: 34-39 [revision]. Williston 1908: 292, 296 [fig. of head, key]. Collin 1911: 234 [probable synonymy with Tethina ]. Malloch 1913: 147 [discussion, fig. of head]. Hendel 1917: 46 [synonymy in key]; 1934: 46 [references]. Munari 1990: 60-61 [status as a subgenus of Tethina ].

Phycomyza Melander 1952: 198. Type species: Rhicnoessa milichioides Melander, by original designation. Vockeroth 1965: 727 [Nearctic catalog]. Foster 1976a: 338 [synonymy].

Diagnosis.

Tethina is distinguished from other genera of the subfamily Tethininae by the following combination of characters: Head: Frons bearing some setulae in addition to larger setae; fronto-orbital and orbital setae usually with similar orientation, mostly reclinate or lateroclinate; fronto-orbital setae 3-4; postocellar setae more or less convergent (lacking in Tethina lusitanica ). Face with shiny tubercle above vibrissal pore. Eye appearing bare, setulae very sparse or lacking. Gena bare (except for Tethina pictipennis and Tethina lusitanica , which have scattered, inconspicuous setulae) except for a ventral or nearly ventral row of setulae; gena high in many species, height 0.50-0.75 that of eye height. Palpus and proboscis usually normally developed; clypeus small, if exposed not protruding anteriad beyond oral margin. Thorax: Scutum generally with more or less numerous rows of coarse setulae arising from punctures; scutellar disc bare; postpronotum with 3 or more setae, ventral seta curved upward; acrostichal setulae in two or more complete or nearly complete rows (lacking in Tethina lusitanica ); prescutellar acrostichal setae present (lacking in Tethina lusitanica ). Wing with costa not spinose; vein A1+CuA2 short, much shorter than discal cell; wing usually shorter, about twice as long as wide (less often 2.5-3.0 times); cell bm and discal cell distinct. Mid and hind tibiae evenly setulose, lacking anterodorsal or posterodorsal setae. Abdomen: Tergites wider than long; tergite 6 well differentiated from short syntergosternite 7+8, the latter forming a dorsal pregenital sclerite. Male terminalia: Surstylus positioned at ventral margin of epandrium, usually broadly articulated externally with epandrium, internally with subepandrial sclerite; aedeagus usually very long and sinuous, either thick and straplike or narrow and ribbonlike; aedeagus micropubescent dorsally.

Discussion.

Worldwide among genera of Tethininae , Tethina has more than half of the described species (77 of 115) ( Munari 2002). Two species occur in the study area and a third, Tethina albula (Loew), has been reported ( Prado and Tavares 1966) but not seen as part of this study. Since Tethina albula has been reported from Brazil, and as there is the possibility of its occurrence there, we have included it in the key to species. The included species of Tethina occur along maritime beaches of the littoral biotic region. Specimens are sometimes abundant, especially on fresh and decomposing wrack.

Key to Species of Tethina from Brazil