Achoanus hulleyi (Munro, 1924):87

Adapted from Munro (1924).

Very like Asarkina, particularly the ericetorum group, but may be distinguished by the absence of a well-defined "collar" of pile on the anterior margin of the dorsum of the thorax. It differs from any form of Asarkina yet recorded by the following features: (a) enlargement of the upper ommatidia of the eyes of the male. The dorsal part of each eye is so inflated anteriorly that, the two organs being contiguous for a considerable length, the frontal triangle is much reduced; (b) by the longer vertical triangle, which is, in the type, three times as long as its base; (c) from known Ethiopian forms, at least, by the vein R4+5 being only gently curved downwards, and not making a decided bend into the cell R4+5. Achoanus resembles Asarkina in the following characters: the frons in the female is narrowed gradually; the buccal cavity is long and narrow; the lateral median sinuosity of the posterior border of the eye is clothed with silvery squamous pile; the abdomen is flat, margined, yellow and transparent, with transverse black bands; the hypopygium in the male is small and asymmetrical.

Adapted from original description (Munro 1924).

MALE.

Head: hemispherical, wider than thorax, face not conically produced, anterior margin of buccal cavity retreating; oral opening long and narrow. Face saffron yellow, sides paler and clothed with pale yellow pile, golden pollinose above, and white below; facial tubercle cariniform. Gena black with white pollinosity. Frons tuberculate, small, shining black, clothed on sides and above with long, black pile and rather sparse, golden pollinose. Lunule yellow. Antennae approximated at base; scape and pedicel of equal length, rufous and clothed with short black bristles; basoflagellomere oval, rufous with a blackish infuscation except on a narrow margin where it meets the pedicel; darker above. (The infuscation is less pronounced in the specimen from the Transvaal.) Arista black, with minute pile on the proximal thickened two-thirds. Proboscis short. Vertical triangle very long and narrow, three times as long as its base; clothed with black pile except on the apex in front of the anterior ocellus. Ocelli far forward; posterior ocelli at middle of triangle, anterior ocellus half as far again from them as they are from each other. Eyes bare, inflated anteriorly above; contiguous for a distance one and a half times the length of the vertical triangle and for twice the length of the frontal triangle. Dorsal facettes greatly enlarged. Occiput deeply excavated above, so that the posterior dorsal margin of the eyes and vertex forms a sharp edge on which is a row of short yellowish pile. Laterally, in the posterior median sinuosity of the eye the occiput widens out and is clothed with a very thick silvery tomentum and long silvery squamous pile; the latter extend down to t.he lowest corner of the eye where they merge into the long white pile on the lower part of the occiput.

Thorax: dorsum dull black, shining, clothed with yellow hair which does not form a well-defined collar anteriorly; sides of dorsum and pleura yellowish; clothed with long yellow pile and yellow pollinosity as in Asarkina. Scutum blackish in front and on sides, yellowish behind. Legs slender, yellow, first two pairs clothed with yellow, last pair with black pile; tarsi black above. Wings as long as abdomen and thorax together, hyaline with a slight greyish infuscation, and a few yellowish marks towards the base; stigma yellow; veins brown; vein R4+5 with only a gentle curve downwards. Calypter rather small; yellow; margin thickened, inner lobe fringed with short yellow pile, outer with long, yellow, branched pile. Halter pale lemon yellow. Scutellum yellowish translucent; clothed with black hair above, except at base where it is yellowish; hair yellow beneath. Subscutellum shining black.

Abdomen: ovate, wider than thorax; dorsum saffron yellow, clothed with short black hair except longer yellow pile on basal angles. Tergum 1 entirely yellow; on the posterior margins of the second to fourth terga is a rather narrow blackish or very dark brown transverse fascia; the fasciae become somewhat
broader backwards; on the fifth tergum the fascia is reduced and does not reach the outer margins of the tergum. The anterior edge of each fascia is not very clearly defined (in the Transvaal specimen the fasciae are much narrower; the abdomen is badly discoloured, but as far as may be observed, the fascia on the second tergum seems to be almost absent). Hypopygium: small, spherical, concealed and asymmetrical.

FEMALE.

The infuscation on the basoflagellomere is not as deep as in the male, but in two specimens it is even more so. Eyes not inflated above. Frons narrowed gradually; clothed with hair laterally and above, and golden pollinosity laterally, leaving a broad shining black, median vitta from the tubercle to the dorsal shining black portion of the frons. Vertex black, with azure blue reflections (this is more pronounced in some specimens than others); clothed with black pile. Ocelli equidistant. Occiput with a narrow margin visible above, clothed with fine yellowish tomentum. The transverse abdominal fasciae are blacker, rather wider, and better defined than in the male. Ovipositor short, yellow. In other respects the female is similar to the male.

Munro (1924) dscribed his new genus Achoanus based on hulleyi, but Hull (1949) did not recognized it as a valid genus. Vockeroth (1969) considered Achoanus as a subgenus of Asarkina and wrote that hulleyi differs from all the other species in many external characters and the male genitalia. Smith and Vockeroth (1980) followed Vockeroth (1969), but not Dirickx (1998), who used Asarkina hulleyi.

Asarkina (Achoanus) hulleyi (Munro, 1924).

Munro, H.K. (1924) A new genus and species of Syrphidae (Diptera) from South Africa. Annals of the Transvaal Museum 10, 87-88.

MALE.

Body length 13.8 mm.; Head: length, 2.8 mm., width, 4.3 mm.; Wing, length, 11 mm.; Abdomen, maximum width, 4.5 mm (Munro 1924).

FEMALE.

Body length 11-14 mm.; Head, length, 2.1-2.7 mm., width, 3.4-4 mm.; Wing, length, 10-10.5 mm.; Abdomen, maximum width, 4.2-4.9 mm (Munro 1924).

Species only known from South Africa.

As far as has been observed by the author, this species frequents the same haunts as do most of the species of Asarkina. Like these, it seems averse to bright sunlight, and is found among the undergrowth below trees, hovering in the air, and occasionally resting on leaves or twigs (Munro 1924).