Canacidae

Distinguished from similar small coastal Diptera by the combination of: large head with small antennae and prominent arista; large oval mouth opening; three to four pairs of outward-directed orbital bristles; absence of postvertical bristles with presence of diverging pseudopostocellar bristles; wing with subcostal break where subcosta parallels and merges with R1; and tibiae lacking dorsal preapical bristle. The unmarked wings and pruinose grey-brown to yellow body coloration separate them from many other minute shore-dwelling flies. Tethininae (now subfamily) can be distinguished from Canacinae by subtle chaetotactic differences and male terminalia structure requiring microscopic examination.

Minute flies ranging 1.6–5 mm in length. Body coloration yellow, grey, or grey-brown with pruinose (powdery) coating and whitish to greyish markings. Head disproportionately large with small antennae bearing bare to pubescent arista. Mouth opening large and oval. Three or four pairs of orbital bristles directed outward (inset upswept). Postvertical bristles absent; diverging pseudopostocellar bristles present. Additional head bristles include ocellar bristles, 2–5 pairs of frontal bristles curving outward, interfrontal bristles, and vibrissae. Genae high with one or more upcurving bristles. Wings unmarked in nearly all species. Costa with subcostal break; subcosta parallels vein R1 and merges with it just before the costa. Tibiae lack dorsal preapical bristle.

Strictly intertidal zone along sea coasts. Found on surfaces of small water bodies, both saline and fresh, in locations protected from wind. Rocky shore habitats appear essential for many species; absence of such habitats correlates with absence of surf flies (e.g., Rodrigues Island). Some populations occur in subantarctic regions including the Kerguelen Biogeographical Province.

Worldwide distribution in coastal intertidal zones. Documented from: Mascarene Islands (La Réunion, Mauritius, Rodrigues), Seychelles, Madagascar, Aldabra, Philippines, Marshall Islands, Hawaiian Islands (Kauai, Oahu, Molokai, Maui, Hawaii, Kahoolawe), East Africa, southern Arabian Peninsula, Macquarie Island, and subantarctic islands of the Kerguelen Biogeographical Province. Scandinavian records (Denmark, Norway, Sweden) present in GBIF.

Feeds on Infusoria and other minute organisms.

Adults restricted to intertidal surfaces and protected coastal water bodies. Strong association with rocky shore microhabitats.

• Tethinidae (sensu stricto, now Tethininae)Previously treated as separate family; now included within Canacidae as subfamily. Distinguished by subtle chaetotactic differences and male terminalia morphology.
• AcartophthalmidaeSmall coastal Diptera family with dark flies and hyaline or infuscate wings; adults associated with decaying wood, fungi, carrion, excrement, and rotten meat in forest habitats rather than intertidal zones. Distinguished by habitat preference and wing infuscation.
• CarnidaeSmall Diptera family with saprophagous or coprophagous larvae in bird nest litter; distinguished by larval habitat and association with bird nests rather than intertidal zones.
• Ephydridae (shore flies)Common intertidal Diptera family with superficially similar habitat preference; distinguished by wing venation patterns, presence of distinct facial structures, and different chaetotaxy.

• intertidal
• marine
• coastal
• minute flies
• Diptera

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• The beach flies of the Mascarene Islands (Diptera: Canacidae: Tethininae)
• A new species of Procanace Hendel from the Philippines (Diptera: Canacidae: Canacinae)
• Taxonomic and distributional notes on two species groups of the genus Dasyrhicnoessa Hendel (Diptera: Canacidae: Tethininae)
• Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace
• World Catalog of the Family Canacidae (including Tethinidae) (Diptera), with keys to the supraspecific taxa
• The surf flies of the Mascarene Islands (Diptera: Canacidae: Canacinae), with the description of a new species
• Survey of conceptual and taxonomic characteristics of the Families Acartophthalmidae, Canacidae and Carnidae (Insecta: Diptera)
• Studies on the Canacidae (Diptera), subfamily Apetaeninae. I.  Apetaenus enderleini, nomen novum for Listriomastax litorea Enderlein, 1909, with remarks on the chaetotaxy, morphology, and habitats of the Apetaeninae  from the Kerguelen Biogeographical Province
• Figure 3 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611
• Figure 7 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611
• Figure 14 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611
• Figure 11 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611
• Figure 12 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611
• Figure 1 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611
• Figure 13 from: O'Grady P, Pak N (2016) Studies in Hawaiian Diptera III: New Distributional Records for Canacidae and a New Endemic Species of Procanace. Biodiversity Data Journal 4: e5611. https://doi.org/10.3897/BDJ.4.e5611