Akatiomyia eremnos, Londt, 2013

Londt, Jason G. H., 2013, A remarkable new genus of robber flies, Akatiomyia gen. n., from the Western Cape Province of South Africa, and a new key to the genera of Afrotropical Stenopogoninae (Diptera: Asilidae), African Invertebrates 54 (1), pp. 57-57 : 58-61

Akatiomyia eremnos sp. n.

Figs 1 –10

Etymology: From Greek ερεμνός (black). Refers to the largely shiny black coloration of this species.

Description (based on all available material):

Head ( Fig. 3 ): Dark red-brown to black, mostly shiny apruinose, black, pale yellowish and white setose. Antenna ( Fig. 4 ): Dark red-brown to black; scape and pedicel weakly black setose; postpedicel asetose except for cluster of short, fine, tightly packed setae distally; style composed of at least two reasonably discernible segment-like elements (terminal sensory structure, if present, invisible through setae), a short proximal element and a longer distal element, both being entirely covered with short, fine, densely-packed setulae which appear longer distally (giving style a somewhat clavate appearance). Segmental ratios (scape taken as 1): 1:0.77:3.69:1.15. Scape slender (c. 3 times longer than broad), pedicel fairly robust (fractionally longer than broad), postpedicel elongate, slender (c. 8 times longer than broad), style, including setae, fairly robust (1.5 times longer than broad). Face: Dark red-brown to black, shiny apruinose except for narrow, silvery, laterally situated pruinose stripes adjacent to eye margin. Profile slightly convex ventrally. Face has a medial, vertical, shallow groove extending from between antennal sockets to epistomal margin. Mystax weak (c. 24 setae), mostly black (few pale yellow-white setae laterally on epistomal margin), covering little more than ventral half of face. Frons and vertex shiny apruinose, pale yellowish setose laterally. Ocellar tubercle prominent, weakly pale yellow setose. Occiput shiny blackish apruinose except for weakly silvery pruinose areas ventrally along eye margins, occipital setae short blackish dorsally, pale yellow-white ventrally. Eyes large (somewhat ‘goggle-eyed’), head much wider than high in anterior view; head width:face width ratio 3.7:1 (each eye clearly wider than face in anterior view). Palpus dark red-brown to black, apparently 2-segmented (proximal segment small, distal segment well developed, elongate), pale yellow-white setose. Proboscis dark red-brown to black, short (projects a little beyond level of face), straight, pale yellow-white setose.

Thorax: Dark red-brown to black, extensively shiny apruinose, macrosetae poorly developed brown-red, fine setae pale yellow-white. Prothorax small, narrow with single row of moderately developed brown-red antepronotal macrosetae. Mesonotum: Short and broad ( Fig. 5 ), shiny apruinose except for narrow silver pruinose posterolateral and posterior margins; macrosetae not evident except for 3 moderately developed brownred supra-alars; all fine mesonotal setae, which cover entire mesonotum, arise from shallow depressions, giving surface punctate appearance. Scutellum shiny apruinose, covered with fine, tiny whitish setae, apical macrosetae absent. Pleura dark red-brown to black, extensively silver pruinose except for substantial areas of anepisternum, katepisternum, meron and anepimeron which are shiny apruinose; setae white, largely confined to anepisternum and katatergite. Mediotergite largely silver pruinose except medially; anatergites asetose. Postmetacoxal area membranous. Legs: Dark red-brown to black except for distal tips of femora and proximal ends of tibiae which are narrowly orange-brown, macrosetae brown-red, fine setae whitish; coxae extensively silver pruinose, white setose; claws, pulvilli and empodia moderately well developed. Wings ( Fig. 2 ): Holotype 4.6× 2.1 mm, paratype ♂ 4.0× 1.9 mm, paratype ♀ 3.8× 1.7 mm (length measured from tip to humeral crossvein, width at widest level); extensively blackish stained except for paler central parts of most cells and an almost transparent narrow subtriangular window between 1 st radial and radial sector. Venation: Costa extends around wing margin terminating at point where first branch of anterior cubitus reaches margin; anterior cubital cell (cua 1), anal cell (a 1+2) and alula not bordered by C; posterior cubital (cup) cell closed before margin and stalked (all other veins reach margin independently). Haltere: Pale yellow-white.

Abdomen: Dark red-brown to black (including terminalia). Tergites entirely shiny apruinose, fine white setose (no macrosetae evident); setae arise from small depressions giving tergites punctate appearance. T1–6 well developed, T7–8 reduced, poorly sclerotized. Sterna entirely dull silver-gold pruinose, longish white setose. S1–6 well developed, S7–8 highly reduced, weakly sclerotized, hardly evident.

♂ terminalia ( Figs 6–8 ): Epandrium shorter than wide in dorsal view, lobes fused dorsally for about half length, tips broadly rounded. Proctiger simple, jutting out far beyond epandrial lobes. Gonocoxites well developed, jutting out slightly beyond level achieved by epandrium, dorsodistal lobe broadly rounded, with short, pointed, terminal process and unusual, long, slightly curved, setose process appearing to arise posterodorsally. Gonostylus elongate, straight, with enlarged proximal end and pointed distal tip. Hypandrium poorly developed, about 3 times as long as wide, with weakly sclerotized distal, dorsoventrally flattened lobe. Aedeagus S-shaped in lateral view, of fairly uniform width, with truncate tip.

♀ terminalia ( Figs 9 , 10): Ovipositor about as long as wide.T8 wider than long, almost parallel-sided in dorsal view. Acanthophorites moderately well developed, each with 5 pale, upcurved macrosetae. S8 (subgenital plate) weakly sclerotized distally, somewhat keel-like, jutting out slightly beyond proctiger in lateral view.

Holotype ( Fig. 1 ): 1♂ SOUTH AFRICA: ‘STH AFRICA: W Cape / 2.5 km SW Clanwilliam / Cedar Inn area 135m / 32°11'44"S 18°52'29"E / J & A Londt 8.ix.2012 / Renosterbos near dam’ ( NMSA-DIP. 66434; Type no. 2740).

Paratypes: 1♂ 1♀ SOUTH AFRICA: ‘STH AFRICA: Cape Prov / 4 km SW Clanwilliam / 32°11'30"S 18°52'20"E / 28.viii.1989 225m / J Londt B Stuckenberg / & P Croeser Sandy E / slope macchia nr dam’ (♂ NMSA-DIP 66435 , ♀ NMSA-DIP 66436 ; Type no. 2740) .

Note: Data are cited as they appear on labels, each line of information is separated by a slash (/).

Distribution, phenology and biology: Despite the apparently conflicting label data, all three specimens were captured at the same locality which is c. 4 km from Clanwilliam by road and 2.5 km as the crow flies. I collected all three specimens in an area of indigenous vegetation located behind a small development called the Cedar Inn which overlooks the Clanwilliam Dam. The two collecting episodes, one early in September, the other at the end of August, indicate that the species flies during spring. The locality is situated on the lower slopes of a hilly area known as the Uitkomsberge which reaches altitudes of only about 250 m. The area has rocky outcrops separated by sandy areas and boasts a wide variety of plant species. Figure 11 shows the exact spot where the holotype was collected as it perched at the end of a twig. Morphologically the species appears to be similar to species of Afroholopogon , Oligopogon and Rhabdogaster and so it is tempting to believe that its biology may also be similar to species allocated to these genera.

Figures

Figs 1, 2. Akatiomyia eremnos gen. et sp. n., male: (1) entire holotype, (2) left wing of paratype.

Figs 3–9. Akatiomyia eremnos gen. et sp. n.: (3) holotype head, anterior; (4) holotype antenna, lateral; (5) holotype thorax, dorsal; (6–8) paratype male terminalia, lateral (6), dorsal (7), ventral (8); (9,10) paratype female terminalia, lateral (9), dorsal (10). Scale bars = 1 mm.

Fig. 11. Site at which the holotype of Akatiomyia eremnos gen. et sp. n. was collected (note Clanwilliam Dam in background).