Ditomyiids form a small family of 8 genera and about 90 species. Distributed
worldwide (except in the Afrotropical Region), most species are found in
the Australasian and Neotropical regions. The earliest fossil dates from
the European Eocene/Oligocene (in Baltic amber). It belongs to Symmerus Walker, a genus still extant in the Holarctic. Centrocnemis imperfecta Riek, described from the Tertiary Redbank Plains series of Queensland, probably
belongs to Australosymmerus, still present in Australia (see Appendix
I). Biogeographical data imply a much greater antiquity for these genera.
Two genera, with 36 species, are known from the Australasian Region. All
of these species are more or less closely related to groups with a Chilean
center of endemism. Colless (1970b) noted that the Australian Australosymmerus seemed more closely allied to the Patagonian species than to the New Zealand
species. That conclusion was also reached by Munroe (1974), who noted that
both Australian and New Zealand species of this genus have a sister-group
relationship with Chilean species instead of with one another. These Transantarctic
tracks imply that the Southern Hemisphere ditomyiids must have a common
ancestor dating as far back as the Lower Cretaceous.
Larvae of species belonging to 2 Holarctic genera (Symmerus and Ditomyia Winnertz) and 1 Chilean Australasian genus (Australosymmerus) are
known. They live either in ligneous Polyporaceae (bracket fungi) or in dead
but unrotten wood, where they bore galleries. Like other Mycetophiloidea,
the adults are mainly sylvan. They can be swept in low vegetation or collected
in Malaise traps.
Refs.: Tonnoir & Edwards (1927, rev. NZ spp.), Colless (1970b,
rev. Australian spp.), Munroe (1974, rev. phylog., zoogeogr. Australosymmerus, Symmerus)
CENTROCNEMIS Philippi, 1865: 619. Type species: Centrocnemis
stigmatica Philippi, 1865, mon. [Preocc. Signoret, 1852.]
AUSTRALOMYIA Freeman, 1951b: 7 (n. n. for Centrocnemis). [Preocc.
Schmid, 1950.]
AUSTRALOSYMMERUS Freeman, 1954b: 39 (n. n. for Australomyia).
CENTROCNEMIS Philippi, 1865: 619 (as gen.). Type species: Centrocnemis
stigmatica Philippi, 1865, mon. [Preocc. Signoret, 1852.]
AUSTRALOMYIA Freeman, 1951b: 7 (n. n. for Centrocnemis). [Preocc.
Schmid, 1950.]
AUSTRALOSYMMERUS Freeman, 1954b: 39 (n. n. for Australomyia).
basalis Tonnoir in Tonnoir & Edwards, 1927: 759 (Centrocnemis).
NZ (NZ).
nitidus Tonnoir in Tonnoir & Edwards, 1927: 759 (Centrocnemis).
NZ (NZ).
tillyardi Tonnoir in Tonnoir & Edwards, 1927: 758 (Centrocnemis).
NZ (NZ).
CRIONISCA Colless, 1970b: 95 (as gen.). Type species: Crionisca
rieki Colless, 1970, orig. des.
aculeatus Edwards, 1921a: 434 (Centrocnemis). Australia (Tas).
rieki Colless, 1970b: 95 (Crionisca). Australia (Vic); Australia
(ACT, Tas).
VENTRILOBUS Munroe, 1974: 45. Type species: Centrocnemis fuscinervis Edwards, 1921, orig. des.
anthostylus Colless, 1970b: 90. Australia (Tas).
cornutus Colless, 1970b: 95. Australia (NSW); Australia (Vic).
fuscinervis Edwards, 1921a: 434 (Centrocnemis). Australia
(Tas); Australia (NSW).
nebulosus Colless, 1970b: 92. Australia (Tas).
propinquus Colless, 1970b: 90. Australia (Tas).
fumipennis Tonnoir in Tonnoir & Edwards, 1927: 758
(Centrocnemis). NZ (NZ).
naevius Colless, 1970b: 94. Australia (NSW); Australia (Vic).
tonnoiri Colless, 1970b: 92. Australia (Tas).
trivittatus Edwards in Tonnoir & Edwards, 1927: 759 (Centrocnemis).
NZ (NZ).
CYRTONEURA Marshall, 1896b: 262. Type species: Cyrtoneura hudsoni Marshall, 1896, mon. [Preocc. Agassiz, 1846.]
NERVIJUNCTA Marshall, 1896b: 265. Type species: Nervijuncta nigrescens Marshall, 1896, mon.
HUTTONIA Marshall, 1896b: 267. Type species: Platyura tridens Hutton, 1881, mon. [Preocc. Pickard Cambridge, 1880.]
ARCTONEURA Hutton, 1904a: 133 (n. n. for Cyrtoneura).
CASA Hutton, 1904a: 133 (n. n. for Huttonia).
CYCLONEURA, error for Cyrtoneura.
bicolor Edwards in Tonnoir & Edwards, 1927: 770. NZ (NZ).
concinna Matile, 1988d: 139. New Caledonia (New Caledonia).
evenhuisi Matile, 1988d: 140. New Caledonia (New Caledonia).
flavoscutellata Tonnoir in Tonnoir & Edwards, 1927: 765.
NZ (NZ).
harrisi Edwards in Tonnoir & Edwards, 1927: 766. NZ (NZ).
hexachaeta Edwards in Tonnoir & Edwards, 1927: 766. NZ
(NZ).
hudsoni Marshall, 1896b: 263 (Cyrtoneura). NZ (NZ).
longicauda Edwards in Tonnoir & Edwards, 1927: 765. NZ
(NZ).
marshalli Edwards in Tonnoir & Edwards, 1927: 769. NZ
(NZ).
nigrescens Marshall, 1896b: 266. NZ (NZ).
nigricornis Tonnoir in Tonnoir & Edwards, 1927: 767. NZ
(NZ).
nigricoxa Edwards in Tonnoir & Edwards, 1927: 770. NZ
(NZ).
ostensackeni Tonnoir in Tonnoir & Edwards, 1927: 767.
NZ (NZ).
parvicauda Edwards in Tonnoir & Edwards, 1927: 763. NZ
(NZ).
pilicornis Edwards in Tonnoir & Edwards, 1927: 764. NZ
(NZ).
pulchella Edwards in Tonnoir & Edwards, 1927: 768. NZ
(NZ).
punctata Tonnoir in Tonnoir & Edwards, 1927: 768. NZ (NZ).
ssp. punctata s. str. NZ (NZ).
ssp. robusta Tonnoir in Tonnoir & Edwards, 1927: 769
(punctata var.). NZ (NZ).
ruficeps Edwards in Tonnoir & Edwards, 1927: 762. NZ (NZ).
tridens Hutton, 1881: 12 (Platyura). NZ (NZ).
vicina Matile, 1988b: 139. New Caledonia (New Caledonia).
wakefieldi Edwards, 1921a: 435 (Arctoneura). NZ (NZ).
ssp. abbreviata Edwards in Tonnoir & Edwards, 1927: 762
(wakefieldi var.). NZ (NZ).
ssp. wakefieldi s.str. NZ (NZ).