Gonioscelis bykanistes, Londt, 2004

Londt, Jason G. H., 2004, A review of the afrotropical genus Gonioscelis Schiner, 1866 (Diptera: Asilidae), with descriptions of new species, African Invertebrates 45, pp. 21-124 : 34-36

Gonioscelis bykanistes sp. n.

Figs 24–26 , 146

Etymology: Gr. bykanistes – trumpeter. Refers to the trumpet-shaped aedeagal tip.

Description: Based primarily on holotype ơ (NMSA).

Head: Antenna black, mostly dark red-brown setose. Facial swelling moderately developed, with poorly defined point at which dorsal region terminates below antennal sockets, mystax uniform orange, setae between gibbosity and antennal sockets smaller than main mystacal macrosetae. Frons and vertex weakly red-gold pruinose. Ocellar tubercle shiny black apruinose with black oc. Occiput silver pruinose except for largely apruinose area behind vertex, setae orange. Proboscis and palpus dark red-brown, orange setose.

Thorax: Black, thinly silver-gold pruinose (central parts of mesonotum somewhat shiny apruinose). Postpronotal lobes brown-orange, contrasting with adjacent mesonotum, with approx. 5 brown-yellow macrosetae and yellow setae. Mesonotal setae brown-yellow: ac not evident; approx. 5 pairs dc not extending anterior of transverse suture; 3 npl; 3–4 sa; 2–3 pa. Scutellum black, silver pruinose, with 6 brown-yellow mrg sct. Wing length 7.8 mm, membrane mostly pale brown, basally somewhat orange. Legs: Orange, except for dark red-brown anteroproximal parts of prothoracic femur and dark red-brown anterior stripe on metathoracic femur, setae mainly black, but dark red-brown and orange ones also present. Prothoracic coxa blackish, gold-silver pruinose, orange setose; femoral spur moderately pointed (angle approx. 40°).

Abdomen: Tergites black, thinly silver-gold pruinose (some areas shiny apruinose), orange setose. Sternites black, mostly shiny apruinose (only tiny spots of pruinescence on hind margins medially), setae orange.

Terminalia ( Figs 24–26 ): Short ep (proctiger projecting slightly beyond epandrial lobes), tapering gradually distally, with minor apical setae only; gcx with three distal projections, the most distal one possessing a small, darkly-sclerotised process and a few small setae basally; aedeagus with trumpet shaped distal end; hyp, in ventral view, with maximum breadth slightly greater than maximum length, tapering distally to well-defined bilobed apex (lobes lying almost parallel with one another).

Variation: A fairly uniform species. The mystax may be pale yellow-white (cream) in colour (more commonly found in females). Legs may vary considerably in colour from entirely pale orange to quite extensively dark red-brown. Male terminalia show little variation over the species range.

Type material: NAMIBIA: 4ơ 3^ paratypes, ‘ Namibia 22.iii.1984 / 10km SW Tsumeb. Rd 1/9 / 19 18'S 17 37'E / Stuckenberg & Londt / Mixed woodland and / roadside grass’; 2ơ 7^ paratypes, ‘ S.W. Africa (W36) / Otjikoko Süd Fm. [farm], / 33 mls. ENE. / Omaruru [21°26'S 15°56'E] / 10-13.ii.1972 ’, ‘ Southern / African Exp. / B.M. 1972-1’ ( BMNH) ; 1ơ paratype, ‘ S.W. Africa (W30) / Ameib Farm / 19 mls. NW. Karibib [21°56'S 15°50'E] / 31.i.-2.ii.1972 ’, ‘ Southern / African Exp. / B.M. 1972-1’ ( BMNH) ; 1ơ holotype, 2ơ 2^ paratypes, ‘ Namibia 29.iii.1984 / Gross Barmen Resort / 22 07'S 16 42'E / Londt & Stuckenberg / Roadside grass & dry / river bed at camp.’; 1ơ paratype, ‘ Otjiseva 45 / Windhoek. S.W.A. / SE 2216 Bd / 12 Mar. 1971 ’, ‘H11129’ ( NMNW) ; 9ơ 7^ paratypes, ‘ Namibia 29.iii.1984 / 26km N Windhoek. Road / 1/6. 22 20'S 17 04'E / Londt & Stuckenberg / Dry stream bed Acacia / riparian woodland.’; 2ơ 3^ paratypes, ‘S.W. Africa (W34) / Regenstein, 15 mls., / SSW. Windhoek, [22°35'S 17°05'E] / 8.ii.1972 ’, ‘ Southern / African Exp. / B.M. 1972-1’ ( BMNH) ; 5ơ 3^ paratypes, ‘ S.W. Africa (W34) / Regenstein, 15 mls., / SSW. Windhoek , / 7.ii.1972 ’, ‘ Southern / African Exp. / B.M. 1972-1’ ( BMNH) ; 2ơ 2^ paratypes, ‘ Arnhem 222 / SE 2218 Ca / Windhoek / 16 Feb. 1971 ’, ‘H1831’ ( NMNW) ; 1ơ paratype, ‘ South West Africa / Gobabeb [23°33'S 15°02'E] 8.II.1978 / Kuiseb River flowing / O. Lomholdt le.g.’ ( UZMD) ; 1ơ paratype, ‘ Swartbaas West 276 / Keetmanshoop / Se 2619 Dc / 19- 22 Apr. 1972 ’, ‘H11129’ ( NMNW) .

Other material: NAMIBIA:1ơ ‘Otjimbumbe [17°24'S 14°25'E] / Kunene Riv./ Mar.1923 ’ ~ ‘S. W. Africa / Mus. Exped.’ (SAMC); 1ơ 2^, ‘Kaross [Stream – 19°30'S 14°20'E] / S.W.A.’ ~ ‘Mus. Exped. / Feb. 1925 ’ (SAMC); 1ơ 2^, ‘Kamanyab [Waterhole – 19°38'S 14°50'E] / S.W.A.’ ~ ‘Mus. Exped. / Mar. 1925 ’ (SAMC); 1^, ‘Namibia 23.iii.1984 / 48km W Otavi. Road 69 / 19 35'S 16 55'E / Stuckenberg & Londt / Woodland with short / grass cover’; 2ơ 2^, ‘SWA / Outjo / IRC / 1916DA / 10.iii.79 / VB Whitehead’ (SAMC); 1ơ, ‘Tsumeb [19°14'S 17°43'E] / S.W. Protec.’ ~ ‘R.W. Tucker / Dec. 1919 ’ (SAMC); 1ơ 1^, ‘S.W. Protect. / Otjituo [19°40'S 18°36'E]’ ~ ‘RW Tucker / Jan. 1920 ’ (SAMC); 1^, ‘Namibia 26.iii.1984 / 54km S Khorixas.Road / 76. 20 43'S 14 49'E / Londt & Stuckenberg / Roadside grass and / flowers, sandy area.; 1^, ‘Namibia 24.iii.1984 / 18km W Outjo. Rd 65 / 20 10'S 15 59'E / Stuckenberg & Londt / Acacia scrub. Open / sandy area with grass’; 3^, ‘Namibia 24.iii.1984 / 28km E Khorixas.Rd 65 / 20 16'S 15 12'E / Londt &Stuckenberg / Mixed Mopani woodland’; 1^, ‘Namibia: Gross / Barmen 20°S 16°E / 03.iii.1989 / L.E. Schoeman’; 1ơ, ‘Rehoboth [23°19'S 17°05'E] / S.W.A.’ ~ ‘Bell-Marley / Nov– Jan 1938 ’ (SAMC); 1ơ, ‘Cayimaeis [?] / S.W.A.’ ~ ‘Mus. Exped. / Feb. 1925 ’ (SAMC). SOUTH AFRICA: 4ơ 2^, ‘S Africa: N Cape #15 / 14km S of Hotazel / 27 19'S 22 54'E 1050m / Date: 14.iii.1991 / Londt & Whittington / Ga-Mogara River Bed’; 2ơ 4^, ‘S Africa: N Cape #18 / 15km W Olifantshoek / 27 55'S 22 38'E 1575m / Date: 15.iii.1991 / Whittington & Londt / Ricky, bushy valley’; 3ơ 3^, ‘S Africa: N Cape #16 / 5km W Olifantshoek / 27 57'S 22 42'E 1350m / Date: 15.iii.1991 / Londt & Whittington / Acacia - Ziziphus veld’; 1ơ, ‘South Africa: N Cape / Witsand Nature Reserve / 28°34.694'S 022°27.752'E / 160m J Londt & T Dikow / 31.i.-1.ii.2004 Brulsand / dune area. Acacia savanna’.

Type locality: Namibia: Gross Barmen Resort .

Distribution, phenology and biology (Tables 1–2, Fig. 146 ): Found widely in the central Nama-Karoo, Savanna parts of Namibia, and the Northern Cape province of South Africa. Specimens have been collected between December and April, usually in open woodland or savanna situations where dominant trees may include Acacia (various species), Ziziphus mucronata (Buffalo-thorn) and Colophospermum mopane (Mopane) . Label data and personal experience show that the species is found resting on low vegetation in dry, sandy, or rocky situations.There are six Natal Museum prey records as follows: 2ơ 4^ (26 km N Windhoek 6) – Coleoptera ( Scarabaeidae 4, probably Curculionidae 2).

Similar species:A member of the large and widely distributed group of species possessing a poorly defined facial gibbosity. Although the species has a hypandrial shape quite similar to that of genitalis , these species are easily separated using other characteristics (e.g. the elongated epandrial lobes of genitalis ). The most significant distinguishing feature is the trumpet-shaped aedeagal apex. While a few species (e. g. lacertosus ) may have a slightly flared aedeagal tip, no other species approaches the condition found in bykanistes .

Figures

Figs 18–29. Gonioscelis male genitalia. 18–20. G. amnoni sp. n. (holotype). 18. Lateral. 19. Dorsal. 20. Ventral. 21–23. G. batyleon sp. n. (holotype). 21. Lateral. 22. Dorsal. 23. Ventral. 24–26. G. bykanistes sp. n. (Hotazel paratype). 24. Lateral. 25. Dorsal. 26. Ventral. 27–29. G. ceresae Oldroyd, 1974 (holotype). 27. Lateral. 28. Dorsal. 29. Ventral. Scale lines = 1 mm.

Figs 146–147. Distribution of Gonioscelis species found only in southern Africa. 146. closed circle = bykanistes, open circle = cuthbertsoni, closed square = hadrocantha, open square = mantis. 147. closed circle = engeli, open circle = scapularis, closed square = ventralis, open square = xanthochaites.