The true A. callosus, as based on the material in the South African Museum, is here redescribed by Hesse (1969) as follows: Body in male with the front part mainly dark or black and abdomen mainly yellowish; antennae up to end of segment-3 brownish to dark blackish brown, the clubs for the greater part orange yellowish, but their apices dark; clypeus black; pleurae mainly black to blackish brown, the metasternal and often the posterior episternal parts more yellowish; tergite-1 often broadly darkened discally; sides of yellowish abdomen from sides of tergite-3 usually infused with reddish or reddish brownish, which almost occupy entire 6 and 7; venter paler yellowish, sometimes becoming darker posteriorly; bullae yellowish brownish to dark brownish, narrowly dark-margined, bean-shaped, but more pointed towards dorsum, separated by a space narrower than vertical length of a bulla; apical part of lobes of tergite 9, outer parts of anal lobes and bases of processes of sternite-9 darkened or blackened to a variable extent; legs, including coxae, mainly yellowish, though bases of latter darkened to a variable extent, and apices or apical parts of hind femora, and sometimes extreme bases of hind tibiae above also obscurely darkened, more brownish. Body in female entirely or mainly dark or black, the apical two-thirds or less of antennal clubs dark reddish; base of proboscis and palps more reddish brownish; two submedial discal streaks on thorax above, becoming fainter posteriorly and extending broadishly around inner side of humeral tubercles sometimes obscurely dark reddish to a variable extent; hind margins of tergites 1-3 obscurely dark reddish; bullae yellowish, much smaller than in male and farther apart; last tergite and sides of 7 also more or less showing through obscurely reddish; legs mainly dark or blackish brown, the apical parts of coxae, to a variable extent lower parts of trochanters, and extreme apices of femora, yellowish brownish, the front and middle tibiae sometimes also more yellowish brownish, extreme bases of hind ones of the same colour, and all the tarsi also yellowish brownish. Integument of middle parts of frons, clypeus, head below, pleurae and sides of metanotum, and in female also greater part of head in front, shining; that of thorax above duller, with three discal, dull, bare streaks, finely rugulose, the middle one finer, separated by streaks of fine separated granules or aciculated punctures, bearing the hairs, the postalar calli and scutellum smoother, more shining; abdomen above in male more or less shining, but covered with setiferous punctures and transversely 'nadelrissig' on tergites 2 and 3 and to a lesser extent on 4 and 5, and tergite-7, and to a certain extent sides of 6, slightly transversely wrinkled; abdomen in female more shining, with sparse puncturation, especially on tergites 3-8, becoming slightly denser posteriorly as well as on sides, and with tergites 7 and 8 transversely striated, more coarsely on 8; integument of femora, especially hind ones, rather transversely wrinkled. Vestiture relatively poorly developed, longer and denser in male, the female almost bare, with very much shorter and sparser hairs; longish hairs on head, extreme sides of thorax above, on propleural part, tuft in front of halteres, sides of tergite-1 and in part on sides of metasternum and hind coxae in male snow whitish; those at apex of palps in male fulvous reddish; those along two submedial streaks on thorax above and along inner margin of the white lateral ones in reddish fulvous to purplish brownish; shortish decumbent hairs on rest of abdomen above in male brownish or dark, appearing more brownish or reddish fulvous in certain lights; hairs on hypopygial parts and last two sternites dark, except for yellowish ones at apices of anal lobes and some on inner sides apically of processes of sternite-9. Vestiture in female not only very poorly developed, but to a certain extent also coloured differently, the sparse short ones on vertex and head in front black and longish sparse ones on head below and on occiput on sides behind eyes greyish whitish; short, sparse, decumbent ones along streaks on thorax above dark or blackish, those along the two submedial streaks however sometimes slightly dark fulvous brownish ; very short and sparse hairs in front of halteres and on abdomen above dark or black, and longer reversed ones on last two segments also black; fine, short, sparse ones on coxae fulvous brownish; hairs on legs shorter than in male, those on front and middle legs more dark fulvous brownish and not so yellowish as in and those on hind femora mainly dark; hairs on inner aspect of hind tibiae shorter than in where they are either yellowish or dark; spines and spicules on legs reddish in both sexes. Head with the antennae distinctly longer than thorax (excluding scutellum); segment-1 comparatively short, about 2.6–3.0 times length of 2; segment-3 slightly variable in length, relatively shorter in some males than in females, but in others longer than in females, its apical fourth or fifth slightly thickened ; club elongate, also variable in length, relatively and proportionally longer in female, more often slightly longer than segment-3, a little less than its basal third in female constricted bottle-neck-like, less so in g; proboscis in male usually a little shorter than vertical length of eye, in female as long as, or even a little longer than, this length; palps distinct, a little longer than antennal segment-2; postvertical spines not distinctly differentiated. Wings tinted smoky brownish, darker and more blackish in female and in female also more so anteriorly and along veins in hinder half, with the greater part of first posterior cell and apex appearing contrastingly clearer or whitish, especially in $; veins brownish to dark brownish; second submarginal cell tending to be much narrowed apically, sometimes even angularly closed or even shortly stalked on second vein; first posterior cell relatively broad; apex of discoidal cell shortly stalked; apical stalk of anal cell rather long; knobs of halteres yellowish brownish to dark brownish above. Legs stouter in male than in female; hind femora in male distinctly thickened, scarcely so or only very slightly so in female, armed below with a double row of reddish or fulvous reddish spines from just before middle and also with some distinct spines along upper lateral or dorsal part in apical part, more so in male; basal segment of hind tarsi longer than claw-segment, relatively longer in female. Oviscae in female armed with 7 or 8 slender, reddish spines on a side. Hypopygium of male with the lobes of tergite 9 obtusangular apically; sternite-8 rather large, often containing and projecting beyond 9; processes of sternite-9 calipers-like, directed inwards, their apices touching or even slightly crossing, bent downwards apically, slightly depressed or hollowed above in basal half, slightly more than apical half punctured above and on sides, the lower surface deeply hollowed out and outer edge of this fairly densely haired; aedeagal apparatus conical, narrowed apically, there with the ventral aedeagal process ending into two shortish, divergent, phallic tubules which are longer than the dorsal epimere. Length of body: about 11.5-13.5 mm (a female the longest); Length of wing: about 9.0-10.5 mm.

unknown.

Type locality: South Africa, 'Vom Hoffnungskap' (= Cape of Good Hope).

Arenomydas is southern African endemic genus with about 9 described species, with one record from southern Namibia (Kirk-Spriggs and Sinclair 2017).

South Africa.

South Africa, Western Cape, Strandfontein in Cape Peninsula (C. Thorn, Nov. 1960); Cape Flats (J. Theron, Nov. 1947); Hopefield (South African Museum, Sept. 1960).

The information below was extracted from Cannings and Scudder (2005): Dipterans are primarily aerial insects and the mesothorax, which bears the only pair of wings, dominates the thorax - the prothorax and metathorax are greatly reduced. The legs are normally rather simple and are used primarily for perching; in some groups, they are modified for prey capture or for signaling during courtship. The tarsi are nearly always 5-segmented. The functional wings are membranous and their pattern of veins is critical in fly classification and identification. During the evolution of flies, there has been a trend towards a reduction in veins, especially in the rear half of the wing – changes that evidently relate to improvements in two-winged flight. The hindwings, present in most other insects, are reduced in Diptera to small, club-like organs, called halteres, used for stabilising flight.

Herbivore - Nectarivore (nectar-eating)

The flies in this family are not known to hunt, catch or prey upon other insects as asilids do, but mainly feed on nectar (Hesse 1969).

Like the others, flies in the Mydidae family begin life as an egg, which hatches into a grub-like larva. Most of the fly life is spent in the larval stage, mainly eating and growing, as well as molting several times. Some flies may spend at least a year as a larva. The next stage is a pupa, during which the insect transforms into its final stage, emerging from the pupa as a winged adult, able to mate and reproduce. In many species, males stake out positions at favourable egg-laying sites and wait for females to arrive (Hesse 1969).

Specimens have been collected from September - November (very few records for August and December) (Kirk-Spriggs and Sinclair 2017).

Fynbos.