Microdon is the nominotypic group, hence, remains some what a catch all for various unrelated species not placed in other genera. The species related to the type, mutabilis Linnaeus, are restricted to the North Temperate region and are characterized by long antenna, scutellum with apical calcars, vein R4+5 with an appendix, simple legs and abdomen. The European species have been revised (Doczkal & Schmid 1999, Schmid 2004), Nearctic (Thompson 1981b) and Japanese (Maruyama & Hironaga 2004, Hironaga & Maruyama 2004) (from Cheng and Thompson 2008).
Microdon (Microdon) bidens (Fabricius, 1805).
Fabricius, J.C. (1805) Systema antliatorum secundum ordines, genera, species, adiectis synonymis, locis, observationibus, descriptionibus. xiv + 15-372 + [1] + 30 pp. C. Reichard, Brunsvigae [=Brunswick].
From original description (Fabricius 1805) in Latin.
M. feutello bidentato niger, abdomine rufo.
Habitat in America meridionali Dom. Smidt. Muf. Dom. Lund.
Magintudo M. bicincti. Antennae porrectae, cylindricae, bafi fetigerae. Caput atrum fub antennis argenteo tomentofum. Thorax niger, feutello cyaneo, dentibus duobus validis, albis. Abdomen rufum, immaculatum. Pedes rufi.
New description:
MALE.
Head: Face straight, without tubercle, slightly ventral produced, yellow with medial very broad reddish-brown vitta and reddish-brown lateroventrally, yellow pilose; gena reddish-brown; frontal triangle reddish-brown, pale pilose; dichoptic, eye bare; vertical triangle reddish-brown to dark, dark pilose; antenna brown, elongate, scape:pedicel:basoflagellomere ratio 3.5:1:6.3, arista subbasal, long; occiput black, white pilose ventrally, yellow pilose dorsally.
Thorax: Scutum black to dark brown, with appressed pile, yellow pile anteriorly and posteriorly, dark pile medially; postpronotum yellow pilose; scutellum black, yellow apically and laterally, with two apical calcars, black pilose, subscutellar fringe absent. Pleuron dark brown to orange, yellowish pilose. Anepisternum pilose anteriorly, dorsally and posteriorly, anepimeron pilose anteriorly, katepimeron with a pile patch on dorsal margin; metasternum bare; calypter brownish; plumula absent; halter brownish, capitulum black; spiracular fringes brownish. Wing: Wing membrane brown, lighter apically; entirely microtrichose. Vein R4+5 with an appendix; vein M1 recessive. Alula broad, bare medially and microtrichose apically. Legs: Entirely orange to brown, metafemur a bit lighter, pale pilose, more evident on tibiae. Metafemur broadened.
Abdomen: Subtriangular, posterior margin of tergum 2 with the maximum width, concave, unmargined. Dorsum orange except tergum 1 brown, pale pilose. Sterna orange.
Original text from www.archive.org and Biodiversity Heritage Library:
http://www.archive.org/stream/iohchristfabrich00fabr#page/185/mode/1up
unless otherwise stated