Adapted from original description (Ferguson 1926).
MALE.
Head black, front black with faint green sheen, very broad, wider than the width of an eye, closely punctate, a triangular area around and in front ocelli, laevigate, with few punctures; pubescence mainly dark, but white in front and on vertex; face reddish-brown, subquadrate, moderately closely punctuate with rather dense white pubescence; gena black and with white pubescence; eyes bare. Antennae black, of extraordinary form, scape cylindrical, about two and a half times the length of the small pedicel; basoflagellomere very large, much longer than the other two segments together, biramate, the upper branch curving upwards and then forwards, the lower forwards and then upwards to end on a level with tip of upper branch, the junction of the two branches rounded, not angulate, both branches thick, but the lower considerably the thicker, the upward-turned portion thinner and somewhat rotated; arista stout, arising at base of fork, slightly to outer side and ending within the space enclosed by the branches; relative proportions of segments 5: 2: 30.
Thorax: Scutum black, punctate and finely strigose in places, giving an appearance of shagreen; pilosity mainly dark, some light pollen present on side as a feeble fascia along transverse suture, and as another fascia along posterior margin. Scutellum dark, punctate; pilosity mainly dark with some light hairs intermingled. Pleurae mainly black, with pale pilosity. Legs with coxae, trochanters, basal two-thirds of femora and tarsi black, the apical third of femora and all the tibiae yellowish-brown. Wings grey, more darkly suffused along the veins; venation normal, stump of R5 present. Calypters white; halteres brown with capitulum yellow.
Abdomen not markedly constricted at base, closely granulate, reddish-brown, darker at base, the first tergum black, pilosity mainly dark, white patches present along the apical margins of second and third terga in lateral half, extending on to adjacent laterobasal angles of third and fourth terga respectively, a small obscure pale fascia on each side of base of second, a pale patch on each side of mid-line at apex of fourth.
Originally, Ferguson placed this species in the genus Microdon arguing that: "The antennal structure is most extraordinary, but I do not think sufficient to justify the erection of a new genus, as in all other respects the species is in agreement with other Australian species of Microdon and the antennae are most variable in the genus".
Later, Hull (1945) created a new subgenus for this single species.
Microdon (Cervicorniphora) alcicornis (Ferguson, 1926).
Ferguson, E.W. (1926) Revision of Australian Syrphidae (Diptera). Part I. Proceedings of the Linnean Society of New South Wales 51, 137-183. [1926.07.01]
unless otherwise stated