Rhabdogaster nyx, Londt, 2006

Londt, Jason G. H., 2006, A review of the Afrotropical genus Rhabdogaster Loew, 1858 with descriptions of new species (Diptera: Asilidae: Stenopogoninae), African Invertebrates 47, pp. 243-313 : 270-271

Rhabdogaster nyx sp. n.

Figs 71–73

Etymology: From Greek nyx (night). Refers to the dark coloration of this species.

Description: Based on holotype ơ unless otherwise stated.

Head: Black, silver pruinose, black setose. Antenna (^paratype) black, setae black. Face entirely pruinose (weak in dorsal part of mystax). Mystax entirely black, occupying approx. lower two-thirds of face.Frons and vertex entirely apruinose (or at least appearing so). Occiput entirely pruinose, upper occipital setae black, lower occipitals white. Proboscis dark red-brown, setae white; palpi dark red-brown, plp 1 white setose (a few black), plp 2 black setose.

Thorax: Dark red-brown to black, gold-silver pruinose, black and white setose. Mesonotum extensively apruinose, pruinescence confined to lateral and posterior margins and 2 narrow medial strips from anterior margin to transverse suture (following usual course of dorsocentral setae), all setae black. Pleura extensively pruinose except for large spots on an- and katepisternum, setae pale yellow-white. Scutellum almost entirely apruinose except for narrow anterior margin, with approx. 4 black strong sctl s accompanied by approx. 6 more minor setae. Postmetacoxal bridge entirely silver-gold pruinose. Legs: cx dark red-brown, silver-gold pruinose, white setose (some black setae on cx 2); troc dark red-brown; fem dark red-brown proximally (leg 3 more extensive than others), orange distally, yellow-white setose (leg 3 has row of black macrosetae anteroventrally); tib entirely orange, black and yellow-white setose; tar dark red-brown, mainly black setose. Wing 6.3 x 2.4 mm, veins orange to brown, membrane somewhat opaque, slightly orange stained, almost entirely microtrichose. Discal and costal cells entirely microtrichose (weak at proximal end of costal cell).

Abdomen: Black, silver pruinose, black and white setose. Tergites extensively apruinose except for small anterolateral parts, setae short black except laterally where there are a few longer white setae. Sternites entirely pruinose, setae long, mixed black and white. Terminalia ( Figs 71–73 ): epand in lateral view fairly robust, projecting beyond limits attained by both external lobes of goncx and hypd, tapering to narrowly-rounded tips; in dorsal view lobes narrowly joined proximomedially; hypd in lateral view thickset, curved, longer than external lobe of goncx and shorter than epand, with upturned setose distal end of characteristic shape; in ventral view broadly-rounded proximally, tapering rapidly to moderately long, slightly clavate medial process with rounded apex. In lateral view external lobe of goncx suboval, internal lobe well-developed with somewhat truncate distal end; gonst in ventral view almost straight.

Variation: Little variation exists between the three specimens.

Holotype: ơ SOUTH AFRICA: Western Cape: ‘ Gt. Wint-hoek [= Groot Winterhoek mountain – 3308S:1906E] / Tulbagh / 3.800 ft. ’ ~ ‘ April 1916 / R.M. L.’ (1ơ).

Paratypes: SOUTH AFRICA: Western Cape: 1^1? same data as holotype (1? SAMC, 1^BMNH); 1^‘ Gt. Wint-hoek / Tulbagh / 4.500 ft. ’ ~ ‘ Nov. 1916 / Lightfoot’ ( SAMC) .

Note: The condition of these specimens is generally poor. The holotype has the antennae broken off beyond pedicels and cracked abdominal sternites, the female paratype lacks its forelegs, the abdomen is cracked and the wings tattered, the third specimen lacks its abdomen beyond segment 2, the antennae are broken off beyond pedicels and the left wing is missing.

Distribution, phenology and biology (Tables 1, 2): Recorded only from South Africa. Known only from the type locality, a regionally high mountain (summit 2078 m). Tulbagh, a small town some 20 km south of the Groot Winterhoek mountain, lies at about 300 m a.s.l. and so the collecting sites at 3800 and 4500 ft (approx. 1160 and 1370 m) are on the upper slopes of the mountain.That this species has not been collected elsewhere, and not in recent times, probably means that it is confined to the infrequently visited higher altitudes of Western Cape mountains, and may even be found only on this particular peak. Collected in April and November in a winter rainfall area.

Similar species: R. melas sp. n.

Figures

Figs 68–79. Rhabdogaster species, male terminalia: (68–70) R. nuda Loew, 1858, Stellenbosch: (68) lateral, (69) dorsal, (70) ventral; (71–73) R. nyx sp. n., Gt. Winterhoek holotype: (71) lateral, (72) dorsal, (73) ventral; (74–76) R.oldroydi (Lindner, 1973), Fish River: (74) lateral, (75) dorsal, (76) ventral; (77–79) R. oresbios sp. n., Cathedral Peak paratype: (77) lateral, (78) dorsal, (79) ventral. Scale bars = 1 mm.