Platypezidae

Minute to medium-sized flies (1.5–6 mm), slender to robust in build. Sexual dimorphism in coloration is common: males often entirely black, while either sex may be partially or wholly grey or yellow with orange, grey, or silver markings; abdomen frequently bicolored. Males possess holoptic eyes. Antenna three-segmented with third segment largest, bearing long apical arista. Wing clear or tinged, with darkening along margin around veins Sc and R1 in some genera; large anal lobe present with anal vein reaching margin; cell cup acute and often elongate; vein M forked in most genera; crossvein DM-Cu present (absent in Microsania, which also lacks R-M). Legs short and robust: first tarsal segment swollen in males, slender in females; distal segments cylindrical (Callomyiina) or laterally compressed (Platypezinae, especially females). Hind leg first tarsal segment long and cylindrical in Callomyiina, short and laterally compressed in Platypezinae.

Primarily damp woodlands and forested areas. Larvae are xylobiont, developing in decaying wood and associated fungal substrates. Adults found in partially sunlit, dappled shade of forest understory, often on broad leaves of woody and herbaceous plants. Some species occupy cave habitats.

Worldwide distribution with greatest diversity in temperate regions. Documented from the Palaearctic (including Europe, Russia), Nearctic (North America, with some species transcontinental), Oriental, Australasian/Oceanian, and Ethiopian zoogeographic regions. Specific regional records include Slovakia, Romania, Japan, and Vermont (USA).

Adult activity bimodal within single day: morning feeding beginning at midmorning, ceasing before midday; afternoon feeding resuming when sun angle matches morning rest initiation angle. Midday rest period corresponds to peak activity of insectivorous birds. Specific seasonal patterns vary by latitude and species.

Larvae are obligate fungivores, feeding on fungal substrates in decaying wood. Adults feed on surface deposits on leaves, including honeydew and other exudates; feeding behavior involves rapid movement across leaf surfaces with brief pauses for ingestion.

Larva with poorly differentiated, weakly sclerotized head; short tubercle-like antennae above rudimentary palpi; 11 body segments. Amphipneustic respiratory system (anterior and posterior spiracle pairs only). Body form flattened or cylindrical; lateral marginal processes typically one pair per segment (multiple on segments 2 and 11); smaller dorsal processes on segments 3–10. Bristles present on segments 3–10, absent on 1, 2, and 11. Spiracles on wrinkled tube-like processes: anterior pair on segment 1, posterior on segment 11. Pupation and egg stages not described in available sources.

Adult males form aerial swarms prior to mating, using trees or bushes as swarm markers. Females approach swarms for mate selection; aerial coupling followed by settlement on low bushes with heads opposed until mating completion. Adults exhibit rapid, erratic running movements on leaves when not in flight. Some species of Microsania attracted to wood smoke and wood ash. Feeding and swarming activity timed to avoid avian predation peaks.

Larvae function as decomposers in woodland ecosystems through fungivory in decaying wood. Several species considered significant for conservation due to stenotopic habitat requirements and rarity; nine species in Slovak fauna noted as endangered, stenotopic, or generally rare.

• OpetiidaeFormerly included within Platypezidae; shares common name 'flat-footed flies' and superficially similar morphology, but now recognized as distinct family based on phylogenetic evidence
• AtelestidaeSome genera formerly placed in Platypezidae now recognized as unrelated asilomorphs and transferred to this family; distinguished by different phylogenetic affinities and morphological features

• Diptera
• Platypezoidea
• fungivore
• woodland
• swarming behavior
• sexual dimorphism
• Holarctic
• Palaearctic
• Nearctic
• xylobiont
• cave-dwelling
• conservation significance

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Figures 17–18 from: Tkoc M, Roháček J (2014) Diversity, distribution and biology of Romanian flat-footed flies (Diptera, Opetiidae and Platypezidae) with taxonomic notes on Callomyia saibhira Chandler. ZooKeys 459: 95-118. https://doi.org/10.3897/zookeys.459.8376
• The fauna of Opetiidae and Platypezidae (Diptera) in the Gemer region (Central Slovakia)
• The flat-footed fly genus Seri Kessel & Kessel (Diptera: Platypezidae)
• On biology of xylobiont platypezid larvae of the genus Callomyia (Diptera, Platypezidae)