Leptomydas omeri, Stuckenberg, 1955

Stuckenberg, B. R., 1955, A New Mydaid Fly from South Africa (Diptera: Mydaidre), Annals of the Natal Museum XIII, pp. 243-246 : 243-246

Leptomydas omeri sp. n. Text-fig. 1.

Diagnosis.-A large, handsome species with narrow, coloured bands on the abdomen. It is distinguished from the other South Mrican species of the genus by the combination of brassy-yellow hairs on the thorax and silvery-white hairs at the base of the abdomen. The antennal club is bright, slightly reddishorange in colour.

Male.-Length exclusive of antennae 24 mm. Head black, extensively yellowish dusted in a broad strip along each of the inner orbits. A bushy, bright yellow pile present, more brassy on the frons and arranged in a tuft on each side. Face protruding prominently, reddish-brown on the sides, black in the middle and along the epistome. Vertex sunken. Frons with two adjoining depressions separated by an elevated bare ridge in the median line. This ridge merges anteriorly with a raised, bare, shining black area immediately above the antennae. Occiput black, yellowish dusted in a broad strip bordering each posterior orbit. Occipital pile white, becoming shining yellow on the vertex; longer below. Immediately behind the upper corner of each eye is a group of short, stiff, testaceous hairs. There appear to be seven postvertical bristles arranged in a line on each side, the inner two the longest, the others becoming progressively shorter outwards, the last three separated a little from the others. Antennae as long as four-fifths of the transverse diameter of the head. Basal segment short, stout, piceous, a little longer than broad. Second segment annular, shorter than broad, not even half the length of the first segment, fuscopiceous. Third segment very long, six times as long (including the terminal club) as the two basal segments together. There is a slight constriction between the stalk-like basal portion and the terminal club, the ratio between the two being 7: 5. Basal portion with a very narrow annular thickening at the extreme base; a slight tubular thickening occupies the apical third; black, with a faintly greyish sheen. Constriction between basal portion and terminal club pitch black, without a sheen. Terminal club shaped as illustrated, with a truncated tubercle on the apex; black basally, suddenly becoming bright, slightly reddish-orange. The anterior half of the under surface of the club, including the apex, is covered with a fine pruinescence that is brownish in some positions, silvery (especially around the margin of this area) in others. Proboscis shining black, two-thirds as long as the antennae.

Mesonotum rather dull black, a narrow dark reddish band along the entire lateral margins; finely granular above, less so on the sides and shoulders; a narrow granulose band present on each side of the median line, only clearly discernible anteriorly. Humeri testaceous. Mesonotum with a bright brassy pile, the hairs thin and depressed over a broad median strip, becoming longer, thicker and more erect towards the sides, in a dense tuft behind the humeral calli. Thoracic pleura shining black, except for the metapleuron, a narrow dorsal strip of the hypopleuron, and a large area of the pteropleuron, which are reddish-brown. Propleuron with two thin tufts of long, yellow hairs. Sternopleuron and hypopleuron bare; mesopleuron almost bare, except for a strip of shortish yellow hairs along the upper part of the extreme hind margin. Pteropleuron with some scattered, fine reddish hairs; metapleuron with two tufts of similar though more numerous hairs. Scutellum shining black, bare. Postnotum pitch black above becoming dark reddish on the lateral corners; with some long, erect, yellowish hairs above, and a tuft of long brassy hairs on each corner. Metasternum reddish-brown, bare on the sides, with some long pale hairs below, mostly on the posterior margin. Halteres fuscous.

Legs reddish-brown; first and second pairs of coxae dark fusco-piceous with golden hairs below and on the sides; posterior coxae reddish-brown, with golden hairs below, white hairs on the sides. Anterior femora darkened above. Hind femora moderately dilated, with two rows of strong spines below, ten spines in each row. Hind femora and tibiae with short, reclinate golden hairs above, with long pale hairs below and on the inner surface.

Wings hyaline, with a faint diffuse infuscation on the apical half, most noticeably around the end of the discaJ and first basal cells. Costal vein testaceous except at the extreme apex; humeral cross-vein and Be entirely testaceous; RI testaceous over three-quarters of its length; both branches of Rs testaceous on basal half; base of median vein and most of cubital vein testaceous; veins otherwise dark brown merging to black. First posterior cell broadly open, with a very short stalk; third posterior cell with the terminal cross-vein a little longer than the basal one.

Basal tergite of abdomen pitch black, more strongly shining than the metanotum, suddenly becoming broadly reddish-brown laterally; it is smooth with small scattered punctures, and with a long, erect, silvery-white pile, rather thin above but dense on the sides. The posterior margin is bordered by a bare, depressed strip on each side, the two not quite meeting in the median line. Second tergite with a strong transverse depression just behind the anterior margin, the depression bare and shining; remainder of tergite dull black, finely wrinkled over most of the upper surface; there are some silverywhite hairs bordering the anterior depression, and a dense tuft of similar but longer and erect hairs on each side, merging with the lateral tufts of the first tergite. Most of the upper part of the second tergite with fine, reclinate, goldenyellow hairs. Bullae shining black, bare. The posterior lateral corners below the bullae creamy-white; a rectangular, dark-yellow spot present above on the hind margin between the bullae. Tergites 3 -7 dull black, with many reclinate bright reddish-yellow hairs, and with conspicuous bands of lighter colour bordering the entire hind margins; on tergites 3-4 these bands are creamyyellow merging to brownish-yellow anteriorly, creamy on the corners; on tergites 5-6 yellowish-brown; on tergite 7 reddish-brown. These bands are broadened laterally in an anterior direction, only slightly on tergite 3, progressively more so on the succeeding tergites; on the seventh tergite the lateral portions of the band occupy nearly all of the sides of that sclerite. Sternites 2 -6 reddish-brown, the posterior corners slightly brownish-yellow; with a fuscous strip in the middle of the posterior margin-this strip is wide on the second sternite, progressively smaller on the succeeding sternites, virtually absent on the fifth and sixth. Seventh sternite a darker uniform, reddish-brown. Sternites 2 -3 with long, whitish hairs below; remaining sternites with shorter, stiffer, pale testaceous hairs. Genitalia as figured, dark reddish-brown, with short, stiff, brassy hairs.

Holotype: ♂, South Africa, Eastern Cape Province, Langekloof, near Haarlem , on mountain slopes; September, 1953; colI. P. Graham. Also two paratype males with same particulars. Holotype and one paratype deposited in the South African Museum , Cape Town; other paratype donated to British Museum ( Nat. Hist .), London .

In Bezzi's key (1924, pp. 202-204) this species runs to the alternate sections 3 and 8, but disagrees with both on the character of the vestiture mentioned in the diagnosis above. The slender abdomen and short hairs on the apical sternites indicate that omeri belongs to Bezzi's group III, the humeralis group.

I have much pleasure in naming this species in honour of Professor J. Omer­Cooper, formerly Professor of Zoology and Entomology at Rhodes University, Grahamstown.