Microdon

Hover flies (family Syrphidae) of the genus Microdon are unusual among the Diptera. Like other members of the subfamily, they are myrmecophiles, meaning they inhabit the nests of ants.

There are 249 species known worldwide, with the greatest diversity being from the tropics; 30 species are known from North America, though it is expected that many of these species will be placed in other genera in time, as Microdon has been used as a catch-all for various unrelated species not placed in other genera.

Appearance
Microdon adults look more or less like typical flies. Like some other hoverflies, they are generally robust and very hairy, often closely resembling bees. They are between 8 and 15 mm long. The antennae are rather long, with the last (third) segment nearly as long as, or sometimes significantly longer than, the first segment; the antennae are nearly as long as the fly's face. These flies are covered in black or pale (white or golden) hairs, and are themselves either black or metallic green or blue. The scutellum is with apical calcars and wing vein R4+5 with an appendix. They have simple legs and abdomens.

The real oddity of the genus Microdon is in its larvae and pupae. These are dome-shaped and look like stout little slugs. Their appearance originally led scientists to describe them as mollusks and scale insects. They are slow-moving.  Most have the spiracles on a peg-like protuberance extending from the end of their abdomens.

Behaviour
Adult Microdon flies do not behave like other syrphid flies; they do not hover around flowers, but instead remain very near the ant colonies which serve as larval hosts.

Larvae may be found very deep in ant colonies. Some species actively feed on ant larvae in the colony, others are speculated to be scavengers. Microdon larvae are more or less restricted in their ant host species. Some Microdon species have only ever been found in the colonies of a single ant species, while others are restricted to related ant species or genera.  Because these flies have such cryptic life cycles, biological information on most species is limited.

Species
Microdon is divided into six subgenera (including Microdon s.s.), plus five species groups and some unplaced species in "Microdon s.l.".

Subgenus Chymophila

Subgenus Dimeraspis

Subgenus Megodon

Subgenus Microdon s.s.
Nearctic:
 Microdon abstrusus Thompson, 1981
 Microdon albicomatus Novak, 1977
 Microdon aurulentus (Fabricius, 1805)
 Microdon cothurnatus Bigot, 1883
= Microdon cockerelli Jones, 1922
 Microdon lanceolatus Adams, 1903
= Microdon coloradensis Cockerell & Andrews, 1916
= Microdon modestus Knab, 1917
= Microdon senilis Knab, 1917
= Microdon similis Jones, 1917
 Microdon manitobensis Curran, 1924
 Microdon megalogaster Snow, 1892
= Microdon bombiformis Townsend, 1895
 Microdon newcomeri Mann, 1924
 Microdon ocellaris Curran, 1924
 Microdon piperi Knab, 1917
 Microdon ruficrus Williston, 1887
= Microdon basicornis Curran, 1925
= Microdon champlaini Curran, 1925
 Microdon tristis Loew, 1864
= Microdon robusta Telford, 1939
 Microdon xanthopilis Townsend, 1895

Neotropical:
 Microdon aureopilis Marinoni, 2004
 Microdon barbouri Hull, 1942
 Microdon bassleri Curran, 1940
 Microdon bonariensis Lynch Arribalzaga, 1891
 Microdon brutus Hull, 1944
 Microdon caesar Curran, 1940
 Microdon colakriki Reemer, 2014
 Microdon crassitarsis (Macquart, 1848)
 Microdon eutristis Curran, 1925
 Microdon macquartii Lynch Arribalzaga, 1891
= Aphritis angustus Macquart, 1848 (nec Macquart, 1846)
= Microdon angustatus Fluke, 1957 (misspelling)
 Microdon mourei Marinoni, 2004
 Microdon remus Curran, 1941
 Microdon rufiventris (Rondani, 1848)
 Microdon violaceus (Macquart, 1842)
 Microdon virgo Curran, 1940

Oriental:
 Microdon aeneus Keiser, 1952
 Microdon alboscutatus Curran, 1931
 Microdon bellus Brunetti, 1923
 Microdon formosanus Shiraki, 1930
 Microdon fulvopubescens Brunetti, 1923
 Microdon fumipennis Hull, 1944
 Microdon metallicus Meijere, 1904
 Microdon sumatranus Wulp, 1892
 Microdon sumbanus Keiser, 1952

Palaearctic:
 Microdon analis (Macquart, 1842)
= Scutelligera? ammerlandia Spix, 1824
= Microdon brevicornis Egger, 1862 (nec Loew, 1857)
= Microdon eggeri Mik, 1897
= Microdon fuscitarsis Schummel, 1842
= Microdon latifrons Loew, 1856
= Buchanania? reticulata Torrez Minguez, 1924
 Microdon auricomus Coquillett, 1898
 Microdon dentigiganteum Tian, Huo & Zhang, 2019
 Microdon devius (Linnaeus, 1761)
= Microdon anthinus Meigen, 1822
= Stratiomys conica Panzer, 1793
= Microdon micans Wiedemann in Meigen, 1822
= Microdon picticornis Mik, 1897
= Stratiomys pigra Schrank, 1803
= Musca viridescens Villers, 1789
 Microdon hauseri Reemer, 2013
 Microdon ignotus Violovitsh, 1976
 Microdon japonicus Yano, 1915
= Microdon jezoensis Matsumura, 1916
 Microdon kidai Hironaga & Maruyama, 2004
 Microdon lateus Violovitsh, 1976
 Microdon lehri Mutin, 1999
 Microdon macrocerus Hironaga & Maruyama, 2004
 Microdon major Andries, 1912
 Microdon mandarinus Reemer, 2013
 Microdon maritimus Violovitsh, 1976
 Microdon miki Doczkal & Schmid, 1999
 Microdon murayamai Hironaga & Maruyama, 2004
 Microdon mutabilis (Linnaeus, 1758)
= Mulio apiarius Fabricius, 1805
= Musca apiformis De Geer, 1776
= Aphritis auropubescens Latreille, 1805
= Parmula? cocciformis von Heyden, 1825
= Microdon rhenanus Andries, 1912
= Microdon scutellatus Schummel, 1842
 Microdon myrmicae Schönrogge, Barr, Wardlaw, Napper, Gardner, Breen, Elmes & Thomas, 2002
 Microdon mysa Violovitsh, 1971
 Microdon nigripes Shiraki, 1930
 Microdon nigrodorsatum Mutin, 2011
 Microdon novus (Schrank, 1776)
 Microdon oitanus Shiraki, 1930
 Microdon podomelainum Huo, Ren & Zheng, 2007
 Microdon ursitarsis Stackelberg, 1926
 Microdon yokohamai Hironaga & Maruyama, 2004
 Microdon yunnanensis Reemer, 2013

Subgenus Myiacerapis

Subgenus Syrphipogon

Microdon s.l. species groups

craigheadii-group
Nearctic:
 Microdon craigheadii Walton, 1912

erythros-group
Afrotropical:
 Microdon erythros Bezzi, 1908
= Microdon erytherus Bezzi, 1921 (misspelling)
 Microdon luteiventris Bezzi, 1915

mirabilis-group
Neotropical:
 Microdon bertonii Bezzi, 1910
= Microdon arcuata Curran, 1941
 Microdon iheringi Bezzi, 1910
 Microdon mirabilis Williston, 1888

tarsalis-group
Afrotropical:
 Microdon tarsalis Hervé-Bazin, 1913
= Microdon bequaerti Curran, 1929

Unplaced species
Afrotropical:
 Microdon tsara Keiser, 1971

Australian / Oceanian:
 Microdon amabilis Ferguson, 1926
 Microdon macquariensis Ferguson, 1926
 Microdon nigromarginalis Curran & Bryan, 1926
 Microdon pictipennis (Macquart, 1850)
= Microdon pictulipennis Hull, 1944
 Microdon rieki Paramonov, 1957
 Microdon waterhousei Ferguson, 1926

Oriental:
 Microdon carbonarius Brunetti, 1923
 Microdon pagdeni Curran, 1942
 Microdon trimacula Curran, 1928
 Microdon unicolor Brunetti, 1915

References

Category:Hoverfly genera
Category:Myrmecology
Category:Taxa named by Johann Wilhelm Meigen