Milichiella aldabrae has been collected around coconut plantations, on pits in champignon (Agaricus bisporus, Agaricaceae), from Pandanus (Pandanaceae) and at light.
Differs from congeners in the combination of brown microtomentose mesonotum and posterolateral corners of S5 developed into shiny lappets with long setae.
Male coloration and vestiture: frons brown, ocellar triangle and orbital plates brown microtomentose, frontal plates greyish, lunule black, basoflagellomere black, face greyish microtomentose, palpus black; thorax with mesonotum brown microtomentose, scutellum and pleura same, except for shiny spots on an- and katepisternum, wing hyaline, veins brown, brown spot at tip of vein R1 weak, calypter brown, halter black, legs black except for yellow tip of fore tibia and all basitarsi; abdomen with T2-5 silvery microtomentose.
Morphology. Head: frons with 2 orbital and 2 frontal setae, anterior frontal seta medioclinate. In males frons 2.8x as wide at posterior margin than at base of antenna, arista about 4.6x as long as basoflagellomere wide, pubescence on arista very short, posterior eye margin with wide notch (7oc) and narrow emargination (1oc).
Thorax: 2, 3 or 3+1 dc, 1 prsc, 1 pprn, 1+0.7 prs, 2+0.7 keps setae, posterior prsc about as long as posterior dc, seta between posterior prsc and posterior dc present. Wing with vein R4+5 and M1 weakly converging (1.8-2.0), and ultimate section of vein M1 2.4-2.5x as long as penultimate section. Fore femur normal setulose, tibial organ absent.
Male abdomen: posteromedial triangular projection of T1 into T2 present. Tergal chaetotaxy: T2 anterolateral corner with 2-3 lines of setae, T2-5 posterior margin with 1 row of setulae. S5 1.4x as long as wide, 1.4x as long and 1.9x as wide as S4; with scarce but long setae, posterolateral corners developed into shiny lappets with long setae. Male genitalia with apical seta on cercus longer than epandrial setae, 1 seta on subepandrial plate, surstylus 1.1x as long as epandrium high, bent posteriorly, dilated apically (1.6x), 8.9x as long as wide, structure of lateral surface smooth, medial surface without setulae.
Body length: 2.3 mm; wing length: 2.4 mm.