Adapted from original description (Curran 1938).
FEMALE.
Black, the legs mostly reddish, the abdomen with reddish markings.
Head black in ground color, the front with a large, convex area immediately above the antennae reddish. Front shining, densely ochraceous pollinose below the middle and along the orbits opposite the antennal tubercle, metallic bluish immediately below the pollinose fascia, in front of the ocellar triangle with a large, prominent swelling extending almost from side to side; vertical tubercle distinctly swollen, the ocellar triangle wider than long. Occiput cinereous yellow pollinose, the gena pale. Face with thick ochraceous pollinosity, the tubercle round and shining black. Antennae brownish red, the arista black on the apical half; basoflagellomere brown, about three times as long as wide, somewhat longer than the pedicel. Pile very short, brassy yellow, black on the upper half of the front.
Thorax aeneous in ground color, the pleura whitish pollinose; scutum with a broad posterior band of dense ochraceous pollinosity, and with paler pollen laterally in front of the suture, in the middle in front of the suture with thin brownish-yellow pollen. Pile very short, brassy yellow dorsally, white on the pleura, a broad fascia behind the suture mixed black and yellow. Scutellum large, distinctly margined. Scutum and scutellum with tiny tubercles, those on the margin of the scutellum conspicuous. Calypter white, broadly yellow apically. Halter reddish yellow. Legs rusty reddish, the tarsi blackish above; basal half of anterior four tibiae yellow, the trochanters and immediate bases of the femora reddish yellow, the posterior tibiae reddish brown. Anterior tarsi distinctly broadened. Wing hyaline, the stigma luteous.
Abdomen black, the sides and apex shining. First tergum and a large, hemispherical macula on the second tergum that is produced broadly to the lateral margins basally, dull orange; third tergum middle and tapers to the rounded ends, narrowly separated from the base of the tergum and broadly so from the lateral margins. The black of the second and third terga is opaque, the fourth is subopaque although this tergum appears to be mostly shining in some lights. Pile very short and black, yellowish only on the
broad base of the abdomen. Sterna reddish.
The species was described by Curran (1938) from DR Congo based on a female. Kassebeer (2000) described a new genus, Afroxanthandrus, and designated Xanthandrus congensis as genotype. Thompson (2010), after studying some material including types, decided to consider Afroxanthandrus a subgenus of Xanthandrus.
Xanthandrus (Afroxanthandrus) congoensis Curran, 1938.
Curran, C.H. (1938) Records and descriptions of African Syrphidae. -II (Diptera). American Museum Novitates 1010: 1-20.
Mengual et al. (2008) included 2 species of Xanthandrus in their molecular analysis. Both were resolved together as sister group of the clade including Argentinomyia and Melanostoma.
Xanthandrus has been considered member of the tribe Bacchini sensu lato, although some phylogenetic analysis suggest that Baccha is the only memeber of Bacchini and the other genera commonly related to them should be included in the tribe Melanostomini. Rotheray and Gilbert (1989, 1999) included Melanostoma and Xanthandrus, which, in their analysis, were isolated from the other genera of the ‘‘traditional’’ Bacchini by the tribe Syrphini. These authors also suggested the tribe Melanostomini with only Melanostoma and Xanthandrus as Palaearctic members.
unless otherwise stated