Milichiella frontalis
Content
Description
Body length: 2.5 mm; wing length: 2.8 mm.
Male coloration and vestiture: frons black, ocellar triangle and orbital plates brown microtomentose, lunule black, basoflagellomere black, face black microtomentose, palpus black; thorax with mesonotum slightly to normally brown microtomentose with shiny hue, scutellum and pleura same except for polished spot on anepisternum, wing hyaline, veins brown, brown spot at tip of vein R1 absent, calypter light brown with dark margin, halter black, legs black; abdomen with T2-5 brown microtomentose except for silvery microtomentose posterolateral margin of T2 and narrow to broad anterior margins of T3-5, which get broader laterally to build silvery lateral margin; tip of T5 blueish silvery. Female coloration and vestiture: halter brown, abdomen with T2-5 subshiny, slighly brown microtomentose.
Morphology. Head: frons with 3 orbital and 2 frontal setae, anterior frontal seta medioclinate. In males frons 2.3-2.5x as wide at posterior margin than at base of antenna, arista about 6.0x as long as basoflagellomere wide, pubescence on arista very short, posterior eye margin with narrow notch (3-4oc) and emargination (2oc).
Thorax: 3+1 dc, 3 (female:1) prsc, 1 pprn, 1 prs and row of short setae, 2+0.8 keps setae, posterior prsc about as long as posterior dc, seta between posterior prsc and posterior dc small. Wing with vein R4+5 and M1 weakly converging (1.5), and ultimate section of vein M1 3.2x as long as penultimate section. Fore femur slightly 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, T1 setulose, T2-5 silvery parts bare, black parts setulose, lateral margins with long setae, T5 with row of setae anterior to silvery tip. S5 about 1.2x as wide as long, about 3.1x as wide and 1.3x as long as S4, crescent shaped, setulose,. Male genitalia with apical seta on cercus not longer than epandrial setae, 1 seta on subepandrial plate, surstylus (0.2-)0.3x as long as epandrium high, slightly bent anteriorly, about as long as wide, not dilated apically, structure of lateral surface smooth, medial surface without setulae.
Special characters: orbital plate extends into frons as acute medioventral tip; setae much shorter in female.
Male coloration and vestiture: frons black, ocellar triangle and orbital plates brown microtomentose, lunule black, basoflagellomere black, face black microtomentose, palpus black; thorax with mesonotum slightly to normally brown microtomentose with shiny hue, scutellum and pleura same except for polished spot on anepisternum, wing hyaline, veins brown, brown spot at tip of vein R1 absent, calypter light brown with dark margin, halter black, legs black; abdomen with T2-5 brown microtomentose except for silvery microtomentose posterolateral margin of T2 and narrow to broad anterior margins of T3-5, which get broader laterally to build silvery lateral margin; tip of T5 blueish silvery. Female coloration and vestiture: halter brown, abdomen with T2-5 subshiny, slighly brown microtomentose.
Morphology. Head: frons with 3 orbital and 2 frontal setae, anterior frontal seta medioclinate. In males frons 2.3-2.5x as wide at posterior margin than at base of antenna, arista about 6.0x as long as basoflagellomere wide, pubescence on arista very short, posterior eye margin with narrow notch (3-4oc) and emargination (2oc).
Thorax: 3+1 dc, 3 (female:1) prsc, 1 pprn, 1 prs and row of short setae, 2+0.8 keps setae, posterior prsc about as long as posterior dc, seta between posterior prsc and posterior dc small. Wing with vein R4+5 and M1 weakly converging (1.5), and ultimate section of vein M1 3.2x as long as penultimate section. Fore femur slightly 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, T1 setulose, T2-5 silvery parts bare, black parts setulose, lateral margins with long setae, T5 with row of setae anterior to silvery tip. S5 about 1.2x as wide as long, about 3.1x as wide and 1.3x as long as S4, crescent shaped, setulose,. Male genitalia with apical seta on cercus not longer than epandrial setae, 1 seta on subepandrial plate, surstylus (0.2-)0.3x as long as epandrium high, slightly bent anteriorly, about as long as wide, not dilated apically, structure of lateral surface smooth, medial surface without setulae.
Special characters: orbital plate extends into frons as acute medioventral tip; setae much shorter in female.
Diagnosis
Differs from congeners in the brown microtomentose male T2-5 except for silvery microtomentose posterolateral margin of T2 and narrow to broad anterior margins of T3-5, which get broader laterally to build silvery lateral margin, and blueish silvery tip of T5.
Distribution
Southern America: Southern South America (Argentina South (Rio Negro present), Juan Fernández Is. present)
Citation
checklist, Chile (Ortiz 1946: Catalogo de los dipteros de Chile: 250pp: 142 (as Eccoptomma frontale))
variation in microtomentum on tergites, swarming, Argentina (AGS-RN), Chile (Malloch 1934: Acalyptrata (concluded), 393-489,pl.8,text-figs.69-84. – In: Malloch, Diptera of Patagonia and South Chile 6: 463 (as Eccoptomma frontale))
on Isle Juan Fernandez, Chile (JNF-OO) (Hennig 1957: Los insectos de las Islas Juan Fernandez. – Revta chil. Ent. 5: 409-412: 411 (as Eccoptomma frontale))
Neotropical catalog, Argentina (AGS-RN), Chile (Sabrosky 1973: Family Milichiidae 75: 12 pp: 4 (as Eccoptomma frontale))