Stuckenbergomyia Smith, 1971

Sinclair, Bradley J., 2019, Revision of the southern African genus Stuckenbergomyia Smith, 1971 (Diptera, Empidoidea) and proposal of a new subfamily, African Invertebrates 60 (1), pp. 133-145 : 133

Stuckenbergomyia Smith, 1971

Stuckenbergia Smith, 1969: 125 [preoccupied by Stuckenbergia Tchernychev, 1898: 24 (fossil Porifera)]. Type species: Stuckenbergia tumbinensis Smith (original designation).

Stuckenbergomyia Smith, 1971: 699. Replacement name for Stuckenbergia Tchernychev. Other references: Sinclair and Cumming 2006: 77 (classification).

Diagnosis.

The genus (as in Figs 1, 10, 20) is characterised by an elongate postpedicel, stout antennal stylus, three complete wing veins from cell dm (discal medial) and a short spur vein, that extends from or near cell cua.

Redescription.

Head: Holoptic with enlarged facets on upper two-thirds or dichoptic (facets not enlarged); eyes bare (ommatrichia absent). Face nearly completely membranous, U-shaped to base of antennal sockets. Ocellar triangle elevated in holoptic species; pair of ocellar setae very short, indistinguishable from other setae on triangle. Antenna inserted at middle of eye height; scape and pedicel subequal in length; scape bare, pedicel with circlet of subapical setulae; postpedicel elongate, tapered, 2 –3× length of scape and pedicel combined; two-articled stylus, with short, apical peg-like receptor. Proboscis (as in Fig. 19) projected forwards, about as long as head. Palpus straight, strap-like; bearing numerous setulae, held obliquely to proboscis, with narrow palpifer (Fig. 10); lacinia absent. Labrum slender, straight without pair of apical epipharyngeal blades. Hypopharynx straight, slender, subequal in length to labrum. Labellum well developed, with pseudotracheae.

Thorax: Moderately to strongly arched. Acrostichals biserial or 4-serial; dorsocentral setae uniserial and better developed posteriorly; numerous postpronotal and notopleural setae; 1 postalar seta; 2 or more pairs of marginal scutellar setae. Prosternum separate; laterotergite bare.

Legs: Lacking modified setae and processes; base of fore tibia with posteroventral gland (Fig. 12). Acropod with broad pulvillus.

Wing (Length 2.5-3.2 mm) (as in Fig. 11): Broad with often well-developed anal lobe; alula developed or undeveloped. Basal costal seta present; pterostigma narrow, at apex of cell sc (subcostal). Costa strongly reduced beyond R4+5 or M1; Sc incomplete, reduced at pterostigma; R4+5 unbranched terminating at wing apex; cell dm present; M1+2 branched, complete; M4 complete; short spur vein from apex of cells bm (basal medial), cua or between basal cells; CuA+CuP complete, fading towards wing margin.

Abdomen: Sclerites well developed, bearing scattered slender setae; tergite 8 slender medially, strap-like, symmetrical. Segment 8 rotated nearly 45° to right.

Male terminalia: Symmetrical, rotated 45° to right; held apically, upright or arched anteriorly over abdomen. Cercus thinly sclerotised, weakly pigmented, clothed in slender setae; hypoproct broad with fine setae on posterior margin. Epandrial lamellae narrowly joined; surstylus undifferentiated, subapical or broadly articulated. Hypandrium trough-shaped, without apical lobes; postgonite sickle-shaped, slender, closely associated with phallus; ventral apodeme broad, plate-like. Ejaculatory apodeme elongate, narrow. Phallus mostly membranous, with expanded apex.

Female.

Similar to male, dichoptic, eye facets not enlarged. Apex of abdomen somewhat truncate with segment 8 partially retracted into segment 7. Female terminalia (based on S. namibiensis ) (Figs 2, 6): Cercus flattened, quadrate and broad. Epiproct divided into pair of narrow, widely separated sclerites. Hypoproct broad, quadrate. Spermathecal receptacle small, spherical, darkly sclerotised; duct consisting of sclerotised rings, extending 2-3 abdominal segments (Figs 2, 7).

Distribution.

Described species of Stuckenbergomyia are recorded from Mozambique, Namibia and South Africa. An undescribed female (in Natural History Museum, London), representing an additional species, is recorded from Zimbabwe (Fig. 22) (Umtali [now Mutare], Vumba, 19°05'S, 32°45'E), but the specimen is said to be in poor condition ( Smith 1969) and was not examined in the present study.

Remarks.

Stuckenbergomyia can be identified by using the key to genera in Sinclair and Cumming (2017).

Specimens have only been collected by Malaise traps, yellow pans and light traps and there are no direct observations on habits. Adult mouthpart morphology (i.e. angle of proboscis; absence of epipharyngeal blades) and the observation of pollen grains in the dissected male and female abdomens of S. namibiensis , provides evidence that Stuckenbergomyia visits flowers and feeds on pollen.