Hesse (1969) redescribed this species as follows: Body in male usually with the head, thorax, scutellum, metanotum, tergite-1 and greater part, or entire, coxae black, and greater part or entire abdomen or at least its middle part, as well as the greater part of antennae and the legs, orange yellowish, but the last few abdominal segments (6 and 7 or 5-7 or sometimes even apical half 4-7) darkened to a variable extent or even black, or only so on sides, in some specimens; antennal segment-1 and sometimes base of 2, junction between 3 and club, and apical part of latter usually darkened to a variable extent; clypeus in some female yellowish on sides to a variable extent; base and rest of proboscis below yellowish reddish to a variable extent; hind margin of scutellum often obscurely reddish ; bullae shining reddish brownish to shining blackish brown or even black, pointed above and below, separated above by a variable space, as wide as, or narrower, or slightly wider than, vertical length of a bulla. Body in female entirely or mainly dark or black, rarely mainly dark reddish brownish, though occasionally with the middle segments of abdomen (tergites 3-5 or apical part of 2 and 3-6 or even 7) distally yellowish or yellowish brownish to a variable extent; tergite 8 apically and laterally, or sometimes entirely, often reddish brownish or yellowish brownish to a variable extent even if rest of abdomen is entirely black; antennae as in <; proboscis more extensively yellowish below; an infusion anteriorly on inner sides of humeral tubercles, sides of thorax anteriorly and two submedial, abbreviated, discal streaks and postalar calli sometimes reddish to a variable extent, and sides of metanotum occasionally obscurely infused with reddish; bullae reddish brownish to black, more widely separated than in male and usually smaller; legs mainly yellowish as in male. Integument of middle part of frons, clypeus, greater part of pleurae, postalar calli, and abdomen from tergite-2 in both sexes more or less shining, especially on head, pleurae, junction between tergites-1 and 2 and sides of abdomen, and usually with tergites 5 to apex, especially in female, more shining than rest of tergites above; integument of female with feeble bluish reflections in certain lights ; integument of thorax above in both sexes dulled by a broad central and two lateral streaks of fine, rugulose sculpture, separated submedially on each side by a streak of setiferous granules, and extreme sides of thorax smoother in female, but in male with numerous setiferous granules, and in both sexes with oblique rugae opposite wings; integument of scutellum and metanotum also rugulose, and that of tergite-1 transversely, finely and irregularly 'nadelrissig' and sparsely punctured; integument of rest of abdomen in male transversely, finely 'nadelrissig' and punctured, finer on tergites 2 and 3, coarser or more widely spaced on 4 and 5, becoming coarser, almost transversely wrinkled posteriorly, the abdomen in female sparsely punctured, more so on tergites-4 and 5, and posteriorly coarsely transversely striate. Vestiture relatively poorly developed, as in callosus, the female almost bare, with very much shorter hairs than in male; fairly dense and longish ones in male on head, in front of halteres, across hind margin of metasternum, on sides of hind coxae basally, on tergite-1 (especially sides), on basal part of venter, and shorter ones on sides of tergites-2 and 3, whitish; shortish ones on streaks and on sides of thorax in male also whitish, or becoming slightly more yellowish or even slightly more fulvous beyond middle ; fine hairs on abdomen in male on disc of tergite-2 and rest of tergites yellowish, becoming more fulvous and slightly longer posteriorly, and those on last 4 sternites also more fulvous; hairs in female short and sparse on head and even shorter on rest of body, those on head mainly dark, fulvous brownish, but longish ones on head below paler, greyish or greyish whitish; short, decumbent ones in streaks on thorax and even shorter and sparser ones on pleurae and tergite 1 in female fulvous brownish; very short and sparse ones on middle parts of abdomen dark, and longer reversed ones on last two segments blackish brown to black; hairs on legs longer and denser in male, paler in male, more yellowish whitish to sericeous yellowish, slightly deeper yellowish to fulvous brownish in female, those towards apices of coxae in female and on greater part of coxae in female fulvous; longish hairs on inner sides of hind tibiae in both sexes (longer in male) appearing darker; spines and spicules on legs fulvous reddish. Head with the antennae relatively long, much longer than thorax (excluding scutellum); segment-1 relatively short, slightly thickened, more so in male, about 2-3 times as long as 2; segment-3 long, its apical fourth, or more or less, slightly thickened; club elongate, about as long as, or often slightly longer than, segment-3, its basal part narrowed bottle-neck like; proboscis relatively slender, much longer than vertical length of eye, but shorter than thorax, its labella smallish; palps distinct, longer than antennal segment-2. Wings tinted yellowish brownish, usually more darkly so in female and infusions along veins in female, especially in hinder half, also more evident; veins yellowish, deeper so or more reddish in front half; appendix at base of second submarginal cell rather long; first posterior cell broadish, usually broader than hind border at about its middle; apex of discoidal cell more consistently shortly stalked; apical stalk of anal cell longish; hind margin of squamae yellowish brownish to brown; halteres yellowish brownish, often darker in female. Legs with the hind femora slightly thickened, slightly more so in male, armed below with a double row of reddish spines on tubercles from just before middle, and with 1 or 2, or a few, spines also on dorsolateral or dorsal aspect in apical parts; hind tibiae relatively stoutish, often slightly curved, armed with rather numerous spicules both below and laterally; basal segment of hind tarsi longer than claw-segment, more so in female. Oviscape in female with about 8-10 reddish, rather sharp-pointed, spines on a side. Hypopygium of male much like that of A. callosus, with the anal lobes rather narrowish and relatively short, the combined hind margin of the two together indented or bifid; sternite-8 also rather large, covering or almost covering 9; lobes of tergite-9 shortish, bluntly rounded, with rather longish, bristle-like hairs in punctures; sternite-9 slightly compressed, slightly keeled medially posteriorly, smoothish, but with some punctures dorso-laterally, its processes, as in case of callosus, blunt apically, hollowed below, with stiffish brush-like hairs below, each process directed inwards, touching apically, but their apices slightly divergent, pointing downwards and punctured above; aedeagal apparatus with the ventrally situated aedeagus itself bifid apically, ending into the two phallic tubes, each curving outwards, and the dorsal epimere tongue-shaped. Length of body: about 15.5-21.0 mm; Length of wing: about 11.0-15.5 mm.

Arenomydas partictus is a fairly large and striking sexually dichroic species that closely resembles A. callosus, but variable, species was originally described from a male specimen by Gerstaecker.

Type locality: South Africa, 'Africa australis' (= South Africa).

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

South Africa.

South Africa, Northern Cape, Namaqualand. Klipvlei near Garies (Museum staff, Nov. 1931).

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 grublike 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).

Succulent Karoo