Diastata Meigen, 1830

Costa, Sávio Cunha, Pirani, Gabriela & Mathis, Wayne N., 2023, First record of Diastatidae (Diptera: Ephydroidea) from Brazil, with the description of a new species, Zootaxa 5278 (2), pp. 378-386 : 379-385

Genus Diastata Meigen

Diastata Meigen, 1830: 94 . Type species: Geomyza obscurella of Meigen, not Fallén, by designation of Thon (1833: 487) [misidentification = Diastata vagans Loew ; formally fixed as the type species by Mathis and Barraclough 2011: 243 as authorized by ICZN (Art. 70.3)]. Westwood 1840: 152 [type designation].─ Loew 1864: 356-368 [revision].─ Hennig 1956: 150 [Neotropical fauna].─ McAlpine 1965: 772 [Nearctic catalog].─ Cole 1969: 411 [fauna, western North America].─ Prado 1984: 1 [Neotropical catalog].─ Chandler 1987: 10-41 [revision].─ Sabrosky 1999: 112 [discussion of nomenclature, “True obscurella Fallén is a Trixoscelis , and it is agreed that Meigen’s identification of obscurella Fallén was an error for D. vagans Loew. [Thon’s and] Westwood’s designation confused the nomenclature of two families for years. However, for some years, authors have recognized vagans as the type of Diastata , thus accepting what Meigen had before him rather than his identification of it. Thus the genera Diastata and Trixoscelis and the family-group taxa based on them, family or subfamily, have coexisted for over a half century without formal action by the Commission.”].─ Mathis and Barraclough 2011: 242-251 [world catalog, fixation of type species].

Trichoptera Lioy, 1864: 1109 . Preoccupied Meigen 1803. Type species: Diastata adusta Meigen , by subsequent designation [ Coquillett 1910: 616].

Calopterella Coquillett, 1910: 517 . Type species: Diastata vagans Loew , by original designation [as first revisers, we select this nomenclatural act (a new genus) over the replacement name on page 616 (ICZN Article 24)].

Calopterella Coquillett, 1910: 616 . Replacement name for Trichoptera Lioy , not Meigen. Type species: Diastata adusta Meigen , automatic.

Diagnosis. Head: frons yellow, dull; fronto-orbits, vertex, and occiput gray microtomentose; large reclinate fronto-orbital seta inserted close to anterior margin of fronto-orbital plate, lacking shorter reclinate fronto-orbital seta anterior to it, but usually with much smaller, posterior setula; length of large proclinate fronto-orbital seta slightly less than reclinate seta. Postpedicel with length greater than height, parallel sided, rounded apically; arista longer than length of other antennal segments, plumose with longer branches dorsally. Face and gena with silvery white to grayish sheen; gena short, ca half height of postpedicel. Eye oval, higher than wide; palpus yellow, often with dusting of whitish microtomentum.

Thorax: apical scutellar setae distinctly dorsoclinate and cruciate; anepisternum setulose, setulae stronger along posterior margin; katepisternum with 2 setae, posterior seta more strongly developed than anterodorsal seta. Wing membrane hyaline to conspicuously patterned; costa with humeral and subcostal breaks; costa bearing several longer, erect, more or less evenly spaced, setae; subcostal vein attenuated apically, closely approximate to vein R 1; crossvein r–m near or before mid length of cell dm; crossvein dm–m subequal to length of apical section of vein M4; cell cup small, angular apically; vein CuA+CuP short, not extended to posterior margin.

Abdomen: tergites varying from yellowish orange at base to mostly or entirely brownish black to black; usually subshiny to mostly shiny. Male: 7 pregenital tergites; segments 1–5 well-developed, each represented by an entire tergite and sternite; tergite 6 narrow, band-like, sometimes weakened medially or divided; sternite 6 developed as 2 elongate, triangular-shaped, lateral sclerites; tergite 7 wider than tergite 6 dorsally, but still much narrower than tergites 1–5; sternite 7 absent. Male terminalia: epandrium well-developed, bulbous, often somewhat projected; cercus lobe-like, small, setulose; 2 surstyli present; posterior surstylus more robustly developed than anterior surstylus, shape usually diagnostic of species; anterior surstylus usually simple, narrow, often clavate or spatulate, apically bearing moderately long to long setulae; pre and postgonites evident, pregonite usually with apical setulae; phallapodeme usually elongate, apical portion straight; phallus aedeagus usually entire, not divided into a basiphallus and distiphallus; ejaculatory apodeme evident, ovate, sclerotized medial portion linear, apically angled; internally a bacilliform sclerite or subepandrial plate or sclerite over the phallus; hypandrium developed as large, ventral sclerite, articulated with dorsal epandrium, often bearing paired lobes. Female: 8 segments plus epiproct, hypoproct, and cerci; segments 1–5 with separate tergites and sternites; segments 6–7 entire, as an annulus; segment 8 with sternite as paired egg guides and a sclerotized tergite; spermathecae atrophied; female ventral receptacle sclerotized, shape as a compressed hook or uneven and flattened U, associated with segment 6.

Higher elevational and cool-climate species of Diastata

There are few known species of Diastatidae (all Diastata ) from tropical regions. In South America, these species are essentially cool-climate species that usually occur at higher elevations. For example, D. dimidiata ( Hendel 1913) was collected from two high elevation sites: Sorata, Bolívia (2300 m) and Cuzco, Peru (3700 m) ( Mathis & Barraclough 2011).

The specimens of Diastata fachini sp. nov. were collected from two cities in the state of São Paulo, Brazil. The first city, Campos do Jordão, is considered the highest city in Brazil, with an elevation of 1662 m and an average temperature of the 14.8°C. Campos do Jordão is constantly visited by tourists who go there to enjoy the winter weather. The second city, Salesópolis, is where the Estação Biológica de Boraceia is located. This conservation station belongs to the Museu de Zoologia, Universidade de São Paulo (MZUSP) and has an average temperature of the 18°C and an elevation of 850 m ( INMET 2023; PMS 2023). Salesópolis and Campos do Jordão share similar temperature regimes, despite the former being lower in elevation.