Mascaromyia grandicaudata
Male. Body length: 3.3 - 3.7 mm; wing length: 2.6 - 2.7 mm.
Head. Vertex shallowly excavated. Vertex and frons shining dark metallic green. Face greenish black, with a brownish yellow dusting, very narrow; eyes nearly touching each other. Clypeus small, heavily dusted pale yellowish grey, hardly protruding. Palpus small, yellow, with yellow hairs and a weak, black apical bristle. Rostrum rather large, pale yellow. [Ocellar bristles broken off in all specimens]. At either side 1 rather weak postvertical bristle. Lower postocular cilia very short, pale. Occiput greenish black, with a metallic shine.
Antenna yellow, short. Second segment with a circle of short marginal bristlets, the longest of which are a little shorter than third antennal segment. Third segment short, rounded triangular, blunt-tipped, about as long as deep. Arista dorsal, short (about 0.6 mm), brownish.
Thorax. Mesoscutum and scutellum entirely shining dark metallic green, with coppery and violet reflections; pleurae yellow; postnotum dark brown. 4 pairs of dc; no acr. Scutellum without laterals. A very small, hairlike, black propleural bristle.
Legs.Coxae and legs yellow, but hind leg distinctly more brownish; mid leg brownish from about middle of tibia; fore tarsus very feebly browned. Fore leg. Coxa anteriorly with very short, scattered pale hairs; at apex 3 rather weak, bent, black bristles. Femur antero- and posteroventrally with rows of hairlike bristles, longest on basal half of femur (there hardly longer than greatest depth of femur). Tibia about as long as femur, without bristles. First segment of tarsus ventrally on basal half dense rows of very short, black hairs. Length of tibia and tarsal segments (in mm): 1.0 : 0.75 : 0.4 : 0.3 : 0.2 : 0.1. Mid leg. Coxa with 2 weak, black exterior bristles. Femur without bristles; ventral (especially anteroventral) hairs slightly lengthened. Tibia much longer than femur (about 8 : 5); 1 ad near base, and 1 or 2 very small ad on apical half; 3 very small pd; some tiny pv. Length of tibia and tarsal segments (in mm): 1.6 : 1.0 : 0.4 : 0.3 : 0.2 : 0.1. Hind leg. Coxa with a black exterior bristle. Femur on basal two thirds anteroventrally with a row of about 7 strong, but rather short bristles (the longest of them are a little longer than greatest depth of femur). Tibia much longer than femur (about 3 : 2); 1short ad near base; 4 - 5 very short d. Length of tibia and tarsal segments (in mm): 1.9 : 0.55 : 0.45 : 0.3 : 0.2 : 0.1.
Wing narrow, without axillary lobe, hyaline, very feebly browned, with dark brown veins; costa with short spinules. m1 rises from m1+2 with an angle of about 90º, and runs towards tip of wing after a rounded rectangular curve; m2 short, faded away before reaching wing margin. Tp straight, about as long as apical part of m3+4. No anal vein. Halter yellow. Squama yellow, with a narrow black margin, and brown cilia.
Abdomen. Terga brown to dark brown; first tergum partly yellow; second tergum with a rather broad basal yellow border; sterna brownish yellow. Hairs and bristles on terga very short, black; longer bristles only on first tergum. Segment 7 forms a stalk to the hypopygium. Hypopygium very large, more or less rounded triangular, yellow on ventral half, dark brown on dorsal half; cerci small, brownish yellow, apically with a tuft of pale, wrinkled hairs (see Lamb, 1922, pl. 28, fig. 7).
Remarks: Answers well to the description and figures given by Lamb (1922). The only feature that does not fit in well is his remark 'The pleura is rather blackened'.
Mahé (above Port Gland, Morne Blanc, Cascade,
mare aux Cochons 1908-9, Silhouette (Mare aux Cochons and above, Jardin Marron,
1908, 2000-1), Praslin (Côte d'Or 1908).