Genus Rachicerus Walker, 1854

Rachicerus . Nomen nudum. Walker, 1848: 124. Attributed to Haliday.

Rachicerus Walker, 1854: 103 . Type species, Rachicerus fulvicollis Walker, 1854, by monotypy.

Rhyphomorpha Walker, 1861: 275 . Type species, Rhyphomorpha bilinea Walker, 1861, by monotypy.

Antidoxion Snellen van Vollenhoven, 1863: 6 . Type species, Antidoxion fulvicorne Snellen van Vollenhoven, 1863, by monotypy. Syn. by Osten Sacken, 1881: 409.

Rhachicerus . Unjustified emendation of Rachicerus Walker. Loew, 1872: 114 .

Antidoxia. Incorrect subsequent spelling. Marschall, 1873: 321.

Rhacicerus . Incorrect subsequent spelling. Malloch, 1917: 346.

Rhachicerella Enderlein, 1921: 167 . Type species, Rachicerus honestus Osten Sacken, 1877, by original designation. Syn. by Nagatomi, 1970: 418.

Rachicerella . Incorrect subsequent spelling. Carrera, 1945: 120.

Gymnorhachicerus Frey, 1954: 7 . Type species, Gymnorhachicerus pilosus Frey, 1954, by original designation. Syn. by Woodley, 2011: 476.

Diagnosis. Small to medium-sized flies; head hemispherical; frontal plate large, strongly depressed; compound eyes dichoptic and bare in males and females; the upper inner margin of the compound eyes, above the insertion of the antennae, with a triangular orbital area, without ommatidia or pilosity, adjacent to the fronto-orbital plate; antennal flagellum highly modified slightly to strongly pectinate, or bipectinate, composed of 15 up to 35 flagellomeres. Thorax with mesonotum (scutum) and scutellum unmodified; postpronotal lobe and laterotergites bare. Wings hyaline to infuscate, mainly around the longitudinal veins; between Sc and R 1 sometimes, there is an inconspicuous dark macula pterostigma-like; between veins R 1 and R 2+3 there is a small and inconspicuous hyaline spot; R S stem vein curved upwards before the bifurcation of the radial sector; distal end of M vein transparent or whitish, covered by a dense microtrichia; cell m 3 closed at wing margin. Legs unmodified, long and slender, tibial spurs 1:2:2. Abdomen slender, with seven to nine visible segments; about as wide as thorax, only slightly tapered posteriorly in males, whereas in females the apical segments are moderately elongate and strongly narrowed posteriorly (ovipositor-like).