Diastatidae

Distinguished from similar small Diptera families by the combination of cruciate postvertical bristles, presence of vibrissae, and distinctive wing venation including interrupted costa and incomplete subcosta. Historically confused with Ephydridae, from which they differ in wing venation and bristle arrangement. Campichoetidae, when treated as separate, differs in genital structure and other morphological features. Identification keys for Palaearctic species exist in Duda (1934) and Shtakel'berg (1988), though these require revision.

Minute flies with grey or brown-grey body coloration. Wings usually bear dark spots or markings (maculate). Head possesses cruciate postvertical bristles and vibrissae. Front orbital bristles are inset and directed upward (upswept). Wing venation distinctive: costa interrupted near end of R1 and sometimes near humeral crossvein; subcosta incomplete, fusing with R1 before apex; posterior basal cell and discoidal cell separate; anal cell and anal vein both present.

Adults have been observed along margins of bogs, marshes, and edges of moist woodlands. Specific microhabitat requirements are poorly documented.

Primarily Holarctic in distribution. Recorded from the Palearctic (Europe, including Denmark, Norway, Sweden; Nepal; Far East), Nearctic (Vermont, USA), and with some species extending into the Oriental, Neotropical, and Australasian regions. GBIF records confirm presence in Denmark, Norway, Sweden, and Vermont, USA.

Immature stages and biology are largely unknown. Hennig suggested that Campichoeta punctum may represent the immature form, though this remains uncertain.

• EphydridaeHistorically confused with Diastatidae; distinguished by differences in wing venation and bristle arrangement
• CampichoetidaeCampichoeta and related genera sometimes treated as separate family; differs in genital structure and other morphological features from Diastatidae sensu stricto

The family was once considered by some authors to be part of Ephydridae. The genus Campichoeta is sometimes treated as a separate family Campichoetidae rather than a subfamily of Diastatidae.

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• The families Diastatidae and Campichoetidae (Diptera, Drosophiloidea) with a revision of Palaearctic and Nepalese species of Diastata Meigen