Keroplatidae

Keroplatidae can be distinguished from the closely related Mycetophilidae s.str. and Sciaridae by a combination of characters: eyes separated (dichoptic) rather than meeting above the antennae (as in Sciaridae), and generally more elongate coxae. They differ from Bolitophilidae, Diadocidiidae, and Ditomyiidae by subtle characters of wing venation, genitalia structure, and larval morphology. Accurate family-level identification typically requires examination of adult genitalia or larval characters; family boundaries have been revised substantially in recent decades, and many historical records require re-evaluation. Bioluminescent larvae in three genera (Arachnocampa, Orfelia, Keroplatus) are distinctive but represent a minority of the family's diversity.

Primarily forest habitats, especially old-growth and mature forests with high humidity and abundant decaying wood. Strongly associated with damp microhabitats favored by fungi, including rotting logs, leaf litter, and soil rich in organic matter. Frequently recorded from caves and similar sheltered, wet environments such as rock overhangs and cavities. Some species occupy more open habitats, but mesic conditions appear essential for most.

Worldwide distribution with records from all major biogeographic regions. Documented from North America (including the Florida Keys), Central and South America (17 genera recorded from Colombia), Europe, Asia (extending to Sakhalin), Australia, and New Zealand. Fossil record extends to the Cretaceous (Barremian) with specimens from Lebanese, Spanish, Burmese, Bezonnais, Taimyr, and Canadian ambers; Eocene fossils known from Baltic and Green River deposits. The bioluminescent genus Arachnocampa is restricted to New Zealand and Australia; Orfelia occurs only in North America; Keroplatus is found in Eurasia.

Adult activity patterns are poorly documented for most species. Records from Finland indicate collections during 1997–1998, but specific seasonal timing is not reported. In temperate regions, activity likely peaks during warmer months when humidity is sufficient; cave-dwelling species may show reduced seasonality.

Larvae exhibit diverse feeding strategies: fungivory (consuming fungal hyphae and spores), predation on small invertebrates, or both. Predatory larvae spin webs using acid secretions to capture prey and kill smaller invertebrates; these webs also trap fungal spores for consumption. Cannibalism of conspecific pupae has been observed. Adult feeding habits are poorly known but likely involve nectar or not feeding at all.

Complete metamorphosis with egg, larva, pupa, and adult stages. Larval development occurs in damp, fungus-rich substrates. Larvae of some species construct silken webs. Pupation occurs within or near larval habitats. Specific developmental durations are unknown for most species.

Larvae of predatory species spin sticky webs using acid secretions to capture prey. Three genera (Arachnocampa, Orfelia, Keroplatus) possess bioluminescent larvae that produce blue-green light. In Arachnocampa and Orfelia, bioluminescence functions to lure prey into webs. In Keroplatus, bioluminescence is considered non-functional and possibly vestigial, as these larvae feed only on fungal spores. Some larvae cannibalize pupae of their own species. Adults are typically weak fliers and are often collected in Malaise traps or by hand searching in appropriate microhabitats.

Larvae function as decomposers through fungivory and as predators of small soil and litter invertebrates. Their role in nutrient cycling in forest ecosystems is likely significant but quantified only for the most conspicuous species. Bioluminescent species serve as notable examples of convergent evolution in arthropods. Some species are indicators of old-growth forest conditions.

Bioluminescent species, particularly Arachnocampa luminosa in New Zealand, are significant ecotourism attractions. The family has minor importance as nuisance pests in some contexts. Scientific interest focuses on the convergent evolution of bioluminescence and the unique predatory larval ecology. No major economic importance as agricultural pests or beneficial organisms has been documented.

• MycetophilidaeHistorically included many Keroplatidae genera; distinguished by subtle differences in wing venation and genitalia structure; recent taxonomic revisions have separated the families
• SciaridaeSimilar size and habitat preference; distinguished by contiguous eyes meeting above antennae and generally shorter coxae; often smaller (<5 mm) though size ranges overlap
• BolitophilidaeRecently separated family historically included in Mycetophilidae; distinguished by larval and adult morphological characters requiring expert evaluation
• DiadocidiidaeSmall family of fungus gnats with reduced wing venation; distinguished by specific wing vein reductions and larval characters
• DitomyiidaeAnother segregate family from historical Mycetophilidae; distinguished by combination of adult and larval features

The common name "fungus gnats" is applied to multiple families (Keroplatidae, Mycetophilidae, Sciaridae, and others), causing confusion. Not all Keroplatidae are predatory—larval ecology varies substantially, and some feed primarily on fungi. The three bioluminescent genera are often assumed to be closely related, but their bioluminescent systems are not homologous and evolved independently.

• fungus gnats
• bioluminescence
• predatory larvae
• forest insects
• cave fauna
• old-growth forest indicators
• convergent evolution

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• An elegant Eocene fly | Beetles In The Bush
• A new species of Chetoneura Colless from Borneo (Diptera: Keroplatidae)
• New Distributional Records for Diptera (Ceratopogonidae, Keroplatidae, Drosophilidae) from the Florida Keys
• Fungus gnats (Diptera: Bolitophilidae, Diadocidiidae, Keroplatidae and Mycetophilidae) new to Finland
• Generic diversity of the predaceous fungus gnats (Diptera: Keroplatidae) from Colombia
• Eocene amber provides first fossil record and bridges distributional gap in the rare genus Robsonomyia (Diptera: Keroplatidae)
• Transcriptomic, proteomic and biochemical comparison of luminescent and non-luminescent Keroplatinae larvae (Diptera: Keroplatidae).
• A Review of the Newly Recorded Genus Proceroplatus Edwards, 1925 (Diptera: Keroplatidae) in China with Two New Species, and Its Characterization and Phylogenetic Implication of Mitogenomes.