Key to Australian Families of Bibionomorpha
This key is principally for the identification of the adults of Australian Fungus Gnat families (Sciaroidea – Sciaridae, Rangomaramidae, Ditomyiidae, Keroplatidae, Diadocidiidae, Lygistorrhinidae, and Mycetophilidae) following the keys of Tonnoir (1929) and Colless (1970). As a generalisation fungus gnats have reasonably long legs with elongate foreleg coxae, the thorax and legs often with strong bristles, and tibiae usually with strong apical spurs. Bibionomorpha families outside the fungus gnats are, with the exception of the Wood Gnats (Anisopodidae), quite different in look and will key out early – they are included to present some easy key differences between some that are superficially similar to each other (e.g. Bibionidae and Scatopsidae), but also to present families that are not so popularly known (Perissommatidae, Diadocidiidae, Lygistorrhinidae, and Rangomaramidae) and are also extremely rare (Valeseguyidae).
Key to Adults of Australian Families of Bibionomorpha
| 1. | Antennae short with less than 13 segments, most segments wider than long (Figs 1, 2); body blackish, or black with red/yellow, or largely reddish; generally robust bodied (Figs 3, 4) …………………………………..2 | →couplet_2 |
| Not with above combination …………………………………..3 | →couplet_3 | |
| 2. | Head with antennae inserted mid eye height, the eyes in both sexes kidney-shaped and typically meeting above, and palpi single segmented (Figs 1, 3); wing with dark pigmented veins restricted to anterior section and ending far from wing apex (Fig. 5) …………………………………..Scatopsidae (Minute Black Scavenger Flies) | Scatopsidae |
| Head with antennae typically inserted low on head, the eyes either well separated and rounded (female) or holoptic (male), and palpi 5-segmented (Figs 2, 4); wing with dark pigmented veins reaching, or nearly reaching, wing apex (Fig. 6) …………………………………..Bibionidae (Lovebugs) | Bibionidae |
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| 3. | Mid and hind tibiae without spur or strong seta at apex; legs lacking strong spines (Fig. 7) …………………………………..4 | →couplet_4 |
| Mid and hind tibiae with at least a single spur or strong seta at apex (can be missed depending on angle) (Fig. 8); legs sometimes with strong spines (e.g. Fig. 8b) …………………………………..6 | →couplet_6 |
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| 4. | Wing membrane distinctly haired (macrotrichia) (Figs 10, 12); wing either with reduced venation (Fig. 9) or more extensive (e.g. Fig. 11); eyes holoptic (Fig. 10) or with narrow dorsal bridge (similar to Sciaridae) (Fig. 12); antennae segments typically monoliform (bead-like), or bead-like with long necks, or cylindrical; ocelli absent or present …………………………………..Cecidomyiidae (Gall Midges, Wood Midges) | Cecidomyiidae |
| Wing membrane without macrotrichia; eyes not meeting above or with dorsal bridge; antennae segments not monoliform or cyclindrical; ocelli present (see Figs 14, 16 for flies in couplet 5) …………………………………..5 | →couplet_5 |
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| 5. | Wing venation characteristic, including the disc with an incomplete (not closed) cell and R2+3 forked (i.e. R2 and R3 running separately to wing costa) (Fig. 13); …………………………………..Perissommatidae (Four-eyed Flies) [Only the single genus Perissomma. These are small winter loving flies with characteristic habitus including possessing four compound eyes, each side of the head with an upper and lower section (Fig. 14), earning the common name Four-eyed Flies. Perissomma is known to be present in Tasmania but is not recorded here.] | Perissommatidae |
| Wing venation also characteristic, of note veins R1, M branches and CuA not reaching wing margin (Fig. 15); eyes normal, rounded; habitus as in Fig. 16 …………………………………..Valeseguyidae [One extant species Valeseguya reiki – known only from the single male type specimen collected in Victoria in 1970.] | Valeseguyidae |
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| 6. | Wing with closed discal cell, with three branches of M emitting from this cell (Fig. 17) …………………………………..Anisopodidae (Wood Gnats) [All Australian mainland and Tasmanian species with banded wings; female with eyes separated, males holoptic – Sylvicola spp. (Fig. 18).] | Anisopodidae |
| Wing without closed cell in the center of the wing (see all wings from couplet 7 onward); males not holoptic …………………………………..7 [Couplet 7 begins Sciaroidea (Fungus Gnats)] | →couplet_7 |
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| 7. | Crossvein, ‘basal transversal’ (tb), connecting M1+2 with M4 present (Figs 19, 21, 23, 25) …………………………………..8 | →couplet_8 |
| M1+2 not connected to M4 by crossvein tb (Figs 27, 29, 31, 32, 33, 34, 35, 37) …………………………………..11 | →couplet_11 | |
| 8. | R4 present and long, about half or more the length of R5; Australian genera with Rs arising at about level of crossvein r-m (Fig. 19) …………………………………..Ditomyiidae (Ditomyiid Fungus Gnats) [All Australian species belong to genus Australosymmerus (Fig. 20).] | Ditomyiidae |
| R4 absent (Figs 23, 25), or if present shorter than half length of R5 (Fig. 21); Rs arising well before crossvein r-m (Figs 23, 25) or r-m not present as crossvein (Fig. 21) …………………………………..9 | →couplet_9 |
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| 9. | Crossvein form of r-m absent, r-m instead represented by the fusion of M1+2 and Rs over a short distance (Fig. 21) ………………………………Keroplatidae: Macrocerinae and Keroplatinae (Predaceous Fungus Gnats) [Macrocerinae and Keroplatinae have consistent, and similar, wing venation. Antennae are variable, ranging from short, unremarkable to very long (e.g. Macrocera) to segments produced (e.g. Mallochinus) (Fig. 22) or even pectinate. Includes some brightly coloured wasp mimics.] | Keroplatidae (Macrocerinae & Keroplatinae) |
| Crossvein r-m distinct; M1+2 and Rs not fused (Figs 23, 25) …………………………………..10 | →couplet_10 |
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| 10. | Basal part of M present (i.e. M vein (stem of M1 and M2) runs from wing base to the fork of M1 and M2); crossveins tb and r-m distant from each other and thus not aligned (Fig. 23) …………………………………..Keroplatidae: Arachnocampinae (Predaceous Fungus Gnats; Glow-worms) [The genus Arachnocampa is well known for their bioluminescent larva that inhabit caves. Adults have characteristic ‘tiger’ banding on the abdomen (Fig. 24).] | Keroplatidae (Arachnocampinae) |
| Basal part of M absent (i.e. M vein (stem of M1 and M2) appearing evanescent in basal third of wing); crossveins tb and r-m in line with each other (Fig. 25); eyes reniform with a more or less incomplete dorsal eye bridge (Fig. 26) …………………………………..Diadocidiidae (Diadocidiid Fungus Gnats) [Only the single genus Diadocidia in this family. The genus is known to be present across Tasmania (at least one undescribed species) but is not recorded here.] | Diadocidiidae |
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| 11. | Rs running separately, not connecting R1 with R5; branches of M veins free at wing margin (Fig. 27); proboscis greatly elongated (Fig. 28) …………………………………..Lygistorrhinidae (Long-beaked Fungus Gnats) [Only the single Australian species, Lygistorrhina insignis, has been described. The species has not been recorded for Tasmania.] | Lygistorrhinidae |
| Rs connecting R1 with lower R vein (Figs 29, 31, 32, 33, 34, 35, 37); proboscis usually otherwise …………………………………..12 | →couplet_12 |
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| 12. | Eyes usually nearly or quite connected above antennae by a dorsal bridge (Fig. 36); if eyes rounded then the male wingless or both sexes wingless; tibiae without strong spines; fully formed wing with characteristic venation, M1+2 as long as M1 and M2 fork, the M1 and M2 fork bellied (Figs 35, 37) (Dark-winged Fungus Gnats and most similar)…………………………………..13 | →couplet_13 |
| Eyes without eye-bridges above; tibiae with or without strong spines (Fig. 30); M1+2 fork typically shorter than the fork, with fork not so bellied (e.g. Figs 29, 31, 32, 33, 34) …………………………………..Mycetophilidae (Fungus Gnats) [Mycetophilidae contains most of the numerous Fungus Gnat genera. Wing venation is quite varied (below wing figures only a snapshot). Typically these gnats are with strong body and leg bristles (Fig. 30).] | Mycetophilidae |
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| 13. | Wing membrane with microtrichia only, not covered with larger setae; abdomen broadly attached to thorax (Fig. 36); R1 generally not reaching mid length of wing and with crossvein Rs positioned in basal third (Fig. 35) …………………………………..Sciaridae (Dark-winged Fungus Gnats; Black Fungus Gnats) | Sciaridae |
| Wing membrane above and below with many noticeable large setae (Fig. 38); abdomen narrowly connected to thorax; the three described Australian species in this section with R1 reaching at least middle length of wing and crossvein Rs much closer to middle (Figs 37, 38) …………………………………..Rangomaramidae: Ohakuneinae [Both Colononymyia and Ohakunea have described species present in Tasmania but are not recorded here. The position of these, and related overseas, are in dispute and are often left unassigned in Sciaroidea in the Heterotricha Group.] | Rangomaramidae (Ohakuneinae) |
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References
Chandler, P. 2002. Heterotricha Loew and allied genera (Diptera : Sciaroidea): offshoots of the stem group of Mycetophilidae and/or Sciaridae ? Annales de la Société entomologique de France 38 (1-2): 101-144.
Colless, D. H. 1963. New species of Ohakunea Edwards and a related new genus with notes on the relationships of Heterotricha Loew (Diptera). Proceedings of the Linnean Society of New South Wales 87: 303-308.
Colless, D. H. 1970. The Mycetophilidae (Diptera) of Australia. Part 1. Introduction, key to subfamilies, and review of Ditomyiinae. Journal of the Australian Entomological Society 9: 83-99.
Colless, D.H. 1990. Valeseguya rieki, a new genus and species of dipteran from Australia (Nematocera: Anisopodidae). Annales de la Société Entomologique de France 26: 351-353.
Colless, D. H. & McAlpine, D. K. 1991. Diptera (Flies). In: The Insects of Australia Volume II. 2nd edn. Brown Prior Anderson Pty Ltd, Burwood, Victoria.
Evenhuis, N. L. 2011. Family Rangomaramidae. In: Evenhuis, N. L. (ed.), Catalog of the Diptera of the Australasian and Oceanian Regions. (online version). Available at: http://hbs.bishopmuseum.org/aocat/rangomaramidae.html . Last accessed: 20 July 2024.
Gatenby, J. B. 1960. The Australasian Mycetophilid Glowworms. Transactions of the Royal Society of New Zealand 88 (3): 577-593.
Matile, L. 2011. Family Keroplatidae. In: Evenhuis, N. L. (ed.), Catalog of the Diptera of the Australasian and Oceanian Regions. (online version). Available at: http://hbs.bishopmuseum.org/aocat/kero.html . Last accessed: 9 May 2021.
Matille, L. 2016. Family Mycetophilidae. In: Evenhuis, N. L. (ed.), Catalog of the Diptera of the Australasian and Oceanian Regions. (online version). Available at: http://hbs.bishopmuseum.org/aocat/myceto.html . Last accessed: 29 April 2022.
Skuse, F. A. A. 1888. Diptera of Australia. Part III. – The Mycetophilidae. Proceedings of the Linnean Society of New South Wales 2 3: 1123-1222.
Tonnoir, A. L. 1929. Australian Mycetophilidae. Synopsis of the genera. Proceedings of the Linnean Society of New South Wales 54: 584-614.
Tonnoir, A. L. & Edwards, F. W. 1927. New Zealand fungus gnats (Diptera, Mycetophilidae). Transactions of the New Zealand Institute 57: 747-878.