Hesse (1969) described this species as follows: Body, including legs, usually entirely black, though in one male specimen it is mainly dark brownish; antennae and clypeus in female sometimes also brownish; knees more reddish brownish, and tarsi paler brownish; bullae reddish brownish, relatively small and narrowish in both sexes, more or less carinate along the vertical length, very widely separated in both sexes. Integument of middle part of frons, clypeus, extreme base of tergite-1, transverse depression between tergites-1 and 2, anterior part of pleurae, to a certain extent posterior episternal and metasternal parts, coxae and, in female, last two abdominal segments, more shining than rest of surface; integument of almost entire body, scutellum, metanotum, pleurae, abdomen, coxae, femora and tibiae with very fine areolar microsculpture, rendering most of these parts, apart from the more evident and coarser sculpture on some of them, duller than in most other species; integument of thorax above more extensively dulled by dense rugulose sculpture, more or less in streaks of fine and coarser sculpture, and with the sides, unlike those of the other species, also densely covered with rugulose sculpture; the more shiny last two abdominal segments in female transversely wrinkled as in most other forms, and last one more coarsely so. Vestiture even in male, rather poorly developed, being sparser on head than in other species, and that on disc of thorax also relatively shorter, and hairs on legs sparser; the longer, more conspicuous hairs on head and propleurae dark brownish to almost black in both sexes; short, decumbent ones in streaks on thorax above slightly more fulvous brownish; rest of sparse hairs on metapleurae and short, scarcely discernible, ones on metasternal part and sides of tergite-1 in both sexes also dark brownish or black; short and sparse ones in male on middle parts of abdomen and the slightly longer and denser ones posteriorly, especially last segment, dark brownish; reversed hairs on last two abdominal segments in female blackish brown or black; hairs on lobes of tergite-9 and processes of sternite-9 more fulvous; hairs on legs in both sexes dark; spines and spicules on legs reddish to fulvous reddish. Head with the interocular space on head below scarcely narrower than, or as wide as, or even slightly wider than, interocular space on vertex; clypeus markedly prominent, protuberant, transversely inflated or timidly lip-like, more inflated than in all the preceding species, usually medially incised or notched apically; buccal cavity rather broad; proboscis much reduced, short, stoutish, stumpy, scarcely or not projecting beyond buccal cavity, its labella small and short; palps distinct, longer than antennal segment 2; antennae rather stoutish, usually shorter than thorax; segment-1 slightly thickened, shortish, about 2.3-2.4 times length of 2; segment 3 slightly longer than club, its apical fourth or less distinctly thickened knob-like; club elongate, subtriangular, conical, broadened apically, trapezoidal, there sharply, almost concavely truncate below the slightly forked terminal prominence. Wings tinted brownish to dark blackish brown, usually more so along course of veins, the middle of first posterior cell and hind border usually clearer and apex the clearest, almost hyaline; veins brownish to dark brown; apex of first posterior cell rather very shortly stalked or even angularly subtending on costal margin, apparently less distinctly stalked than in preceding species; apex of third posterior cell (rather than apex of discoidal cell as in other species) shortly stalked or even meeting apex of discoidal cell at a point; squamal margin dark; halteres very dark to almost black. Legs, especially hind ones, rather long; hind femora slightly thickened, less so in female, armed below with the usual double row of spines from near base or just before middle, without any dorso- or latero-apical ones; tibiae rather stoutish, especially hind ones, the latter with distinctly fewer spicules than in most of the other species, the lateral ones wanting or minute ; basal segment of hind tarsi distinctly much longer than claw-segment; claws slender, relatively more so and longer in male also more rapidly curved down apically in male than in female. Oviscape in female with 7 or 8 reddish spines on a side. Hypopygium of male with the anal lobes broader, larger than in other species, not so very sharply pointed apically; processes of sternite-9 comparatively longer, more slender, distinctly more sinuous or S-curved than in other species, their apices more curved down; central, dorsal (anterior) epimere of aedeagal apparatus very much shorter than ventral (posterior) aedeagal process which ends in two phallic tubes, relatively shorter than in other forms, in form of a short stump in front of base of aedeagus. Length of body: about 12-16 mm; Length of wing: about 8-11 mm.

Type locality: South Africa, Western Cape, Dikbome.

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

South Africa.

Koup Karoo, Dikbome, Merweville (Museum Expedition, Oct. 1952) (male holotype, male paratype and female paratype); Mynaardskraal, Letjiesbos near Beaufort West (Museum Staff, Oct. 1941) (female allotype) (Hesse 1969).

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