Lygistorrhinidae

Members of Lygistorrhinidae are characterized by exceptionally elongated labella (the paired lobes at the tip of the proboscis), forming a distinct 'long beak' structure that gives the family its common name. This proboscis is longer than that of most other fungus gnats. The family can be distinguished from the closely related Mycetophilidae and other Sciaroidea by this exaggerated mouthpart morphology combined with specific wing venation patterns, including reduced branching in the radial sector.

Species in this family are found in forested environments, particularly in association with decaying wood and fungal fruiting bodies. Larvae develop in moist, decomposing organic matter rich in fungal growth. Adults are often found in shaded, humid microhabitats within mature forests.

The family has a disjunct global distribution with records from the Neotropical region (Central and South America), Australasia (including New Zealand and Australia), and parts of Asia. This patchy distribution likely reflects both actual biogeographic patterns and limited sampling effort in many regions.

Larvae function as decomposers in forest ecosystems, processing decaying wood and fungal material. The family contributes to nutrient cycling in mature forest habitats, though specific quantitative impacts have not been documented.

• MycetophilidaeAlso fungus gnats with similar overall body form and habitat preferences, but lack the extremely elongated labella characteristic of Lygistorrhinidae; proboscis structure and wing venation differ.
• KeroplatidaeAnother fungus gnat family with overlapping habitat use; distinguished by different larval behaviors and adult mouthpart structure, including less pronounced elongation of feeding appendages.

• Diptera
• fungus gnats
• decomposers
• forest insects
• Sciaroidea

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon