Allograpta alamacula is very distinct due to the dark apical wing maculae, which is atypical for Allograpta. Also it differs from all other Australian Allograpta species in having the metasternum bare. The New Zealand species, A. ventralis (Miller, 1921) also has a bare metasternum and a faint apical wing macula. However, A. ventralis is quite different, having dichoptic males and narrow petiolate abdomen (Carver and Thompson 2003).
Small flies, 6 mm or less, with face straight, not produced anteriorly, with a large tubercle; oral opening about 2 times as long as wide, with oral apex at level of antennal base; antennal pits confluent; male holoptic; plumula absent; subscutellar pile fringe absent; wing broadly bare basomedially, with apical dark macula; alula broad, as broad as cell BM; metasternum bare; abdomen elongate (Mengual et al. 2009).
Original description from Carver and Thompson (2003).
ADULT.
Head. Face not produced, with low tubercle, yellow except narrow brownish-black medial vitta which does not reach antennal bases, white pilose; tubercle distinct, convex; gena yellow; lunule black medially, yellow laterally; frontal triangle yellow laterally, brown medially, black pilose; frons black except narrowly yellow laterally, shiny on ventral 1/3, dull black pollinose dorsomedially; ventral triangle black, black pilose; vertex black, black pilose; occiput black, grayish-white pollinose, white pilose ventrally, yellow pollinose and brownish yellow pilose on dorsal 1/3; antenna orange except basoflagellomere brownish on dorsoapical 2/3, black pilose; arista brown; male holoptic.
Thorax. Postpronotum yellow; scutum shiny, black except yellow laterally, continuously yellow from postpronotum to scutellum, yellow pilose; postalar callus yellow, yellow pilose; scutellum convex apically, black except yellow base and margins, black pilose; subscutellar fringe absent; pleuron black except yellow dorsad to procoxa, posterior 1/3 anepisternum, dorsal half katepisternum, katepimeron, katatergum; pleuron yellow pilose; metasternum black, bare; plumula yellow, calypter yellow; halter orange. Wing: Hyaline except brown anteroapical macula and dark stigma; microtrichose except bare cells C, R, BM, CuP, basal half of cell R1, basal 1/3 of cell R2+3, base of cell DM and CuA1, base of anal lobe; alula broad, about as broad as cell BM, microtrichose. Legs: Coxae and trochanters brownish black, white pilose; pro and mesofemora yellow to brownish yellow, white pilose except black pilose dorsoapically; metafemur brown to black except yellow base, black pilose except pale pilose basally; pro and mesotibiae yellow, white pilose; metatibia black, black pilose; tarsi black, black pilose.
Abdomen. 1st tergum yellow basally and laterally, black posteromedially, white pilose; 2nd tergum black except basolateral corners yellow and with yellow oblique fasciate macula on medial 1/3, with maculae broadly separated medially, apical 1/5 shiny, basal 1/4 subshiny, elsewhere dull black pollinose, black pilose except yellowish-white pilose laterally; 3rd and 4th terga black except arcuate yellow fasciae, black pilose except pale pilose laterally; 5th tergum black except basomedial yellow vittate maculae, black pilose; 1st sternum black, shiny, white pilose; 2nd-4th sterna black medially, yellow laterally, white pilose; male genitalia black, black pilose.
Allograpta (Allograpta) alamacula Carver, 2003.
Carver, M. & Thompson, F.C. (2003) Two new species of Syrphidae (Diptera) from Australia. Studia Dipterologica 10, 37-41. [2003.12.15]
unless otherwise stated