Gibbasilus condylus, Londt, Jason G. H., 2016

Londt, Jason G. H., 2016, A review of the genus Gibbasilus Londt, 1986 in southern Africa (Diptera, Asilidae), African Invertebrates 57 (1), pp. 67-81 : 73-76

Taxon classification Animalia Diptera Asilidae

Gibbasilus condylus sp. n. Figs 9, 11-14, 15, 20B

Etymology.

L. m. condylus - prominence; refers to the lobed S8 in males.

Description.

Based on 2♂ and 6♀.

Head: Black, silver pruinose, black, pale yellow and white setose. Antenna: Black, fine silver pruinose, scape and pedicel black setose. Segmental ratios (scape as 1) = 1: 0.7: 1.4: 0.8 (style = 0.2, 0.5, 0.1). Style composed of three elements (small basal segment-like element, long middle rod-like element, terminal seta-like sensory element). Face black, fine silver pruinose, profile plane. Mystax long, well-developed, extending from epistomal margin to antennal sockets, macrosetae white along epistomal margin, otherwise black. Frons and vertex black, silver pruinose, fine, long, black setose. Ocellar tubercle with long, fine, black setae. Occipital region black, silver pruinose, black setose dorsally (may be a few orange), pale yellow laterally, fine white setose ventrally. Palpi 2-segmented, segment 1 white setose, 2 black setose. Proboscis shiny dark red-brown to black, fine white setose.

Thorax: Dark red-brown to black, fine, dull, silver pruinose, black, pale orange, pale yellow and white setose. Pronotum dark red-brown to black, white setose. Mesonotum black, entirely dull silver pruinose. Acrostichals numerous, mane-like, predominantly black except for few white setae anteriorly and a cluster of fine white setae posteriorly. Dorsocentrals well-developed, black, extending both anterior and posterior of transverse suture. Mesonotal macrosetae: Strong, orange and black, 2 npl (orange), 2 spal (black), 1 pal (black). Scutellum black, entirely silver pruinose; disc fine white setose, 2 long, black apical scutellar macrosetae. Pleura: Dark red-brown to black, entirely silver pruinose, pale yellow and white setose. Katatergal setae pale yellowish. Anatergites uniformly dull silver pruinose, asetose. Mediotergite weakly fine white setose medially. Legs: Coxae dark red-brown to black, fine, dull silver pruinose, fine white setose. Trochanters shiny black, apruinose, fine white setose. Femora slightly inflated, dark red-brown to black except for narrow orange distal tip, macrosetae mostly yellowish (except for 3-5 black proximoventral setae on fore femora). Tibiae mostly brown-orange becoming progressively darker distally, macrosetae mostly orange (a few black at distal tip). Tarsi dark red-brown with black and orange macrosetae. Claws dark red-brown to black, pulvilli and empodia well developed, brown-orange. Wings: ♂ 7.6 (7.4-7.8) × 2.6 mm, ♀ 7.6 (6.3-8.6) × 2.5 (2.1-2.9) mm. Veins brown, cells r1, m3, and cua closed and stalked, membrane unstained (wing tip may be slightly brown stained), entirely transparent and lacking microtrichia. Halter pale yellow to orange.

Abdomen: Entirely dark red-brown to black, extensively dull silver pruinose, except lateral margins of T2-5 and parts of S2-2 which are shiny apruinose. Terga fine short white setose except for narrow medial strip of fine black setae, T1-6 with 1-3 laterally situated pale yellow macrosetae (progressively diminishing in size and number towards terminalia). Sterna fine, longish setose. ♂ genitalia (Figs 11-14): Epandrium almost three times longer than deep in lateral view, with widest part proximal to mid-length; not very broadly rounded distally; lobes gradually diverging distally in dorsal view. Gonocoxite almost ⅓ as long as epandrium, smoothly rounded distally. Gonostylus elongate, almost half the length of epandrium, of approximately same width for entire length in ventral view, distally with a subtriangular upwardly directed process, best appreciated in lateral view. Hypandrium short, about four times as wide as long in ventral view, distal margin very slightly indented medially. Aedeagus long and thin, slightly dorsoventrally compressed, S-shaped distally, terminating in a 3-pronged tip. Posterior margin of S8 slightly indented medially with a terminal subrectangular, dorsoventrally compressed process projecting to approximately midlength of hypandrium. ♀ ovipositor (Fig. 9): Elongate, laterally compressed and knife-like. Length: depth ratio = 2.7: 1 (more robust when compared with other species).

Holotype.

SOUTH AFRICA: 1♂ "South Africa W Cape / Kagga Kamma Nat. Res. / 32°45'12"S, 019°34'23"E / J&A Londt 12.xi.2015 / 1080 m Sandy vynbos" (NMSA).

Paratypes.

4♀ "S Africa, Cape #65 / 22 km S Vanrhynsdorp / 31°46'S, 18°46'E 600 m / Date: 23.xi.1991 / Coll: J.G.H. Londt / Gifberg Edge old land" (NMSA); 1♀ "S Africa, Cape #65 / 14 km NNW Citrusdal / 32°31'S, 18°58'E 300 m / Date: 1.xi.1991 / Coll: J.G.H. Londt / Woody plants; sandy" (NMSA); 1♀ with identical label data as holotype (NMSA); 1♂ "Michells Pass [c. 33°23'S, 19°18'E, 485 m] / Ceres Div.", " Museum Staff / Oct. 1934" (SAM).

Remarks.

As mentioned earlier, this species bears a strong resemblance to alboala sp. n. (described above), but can easily be separated from that species as it has entirely transparent wing membranes, lacking the somewhat opaque, milky basal wing membranes diagnostic for alboala .

Distribution (Fig. 20B), phenology (Table 1) and biology.

Known from four fairly widely separated localities. Collected during the months of October and November. Specimens collected by me, at three localities, were found perching near the tops of the vertical stems of a tall unidentified species belonging to the Restionaceae or sunning themselves on stones. A typical habitat at the Kagga Kamma Nature Reserve is illustrated (Fig. 15). Although oviposition was not observed, it is probable that females use their knife-like ovipositors to insert eggs into suitable crevices found on these plants. The species is found sympatrically with crinitus .