Gonioscelis melas, 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 : 72-73

Gonioscelis melas sp. n.

Figs 9–10 , 86–88 , 150

Etymology: Gr. melas – black. The name referring to the uniformly black colour of the species.

Description: Based primarily on holotype ơ (NMSA).

Head: Antenna black, setae black. Facial swelling pronounced, mystax uniform black, a few weakly developed setae between gibbosity and antennal sockets. Frons and vertex thinly gold pruinose. Ocellar tubercle silver pruinose with black oc. Occiput silver pruinose except behind vertex, setae black. Proboscis and palpus black, black setose.

Thorax: Black, thinly gold pruinose. Postpronotal lobes dark red-brown, contrasting to some extent with adjacent mesonotum, black setose. Mesonotal setae black: ac weak, not clearly differentiated; approx. 12 pairs dc, clearly extending anterior of transverse suture; 3 npl; 4–5 sa; 3 pa. Scutellum black, gold-silver pruinose, with 4 black mrg sct. Wing length 6 mm, membrane mostly dark red-brown ( Fig. 9 ). Legs: Dark red-brown to black, femora appearing darker than rest, all setae of femora black, other segments with black and white setae (white mainly on tibiae). Prothoracic coxa black, silver pruinose, black setose; femoral spur ( Fig. 10 ) difficult to measure but very sharply pointed (angle approx. 10°).

Abdomen: Tergites black, apruinose except for silver posterior margins, setae black. Sternites black, apruinose except for small patch of silver pruinescence medially on hind margins, setae black.

Terminalia ( Figs 86–88 ): Proctiger projecting very slightly beyond epandrial lobes, lobes hardly tapering and equipped with fine setae; gcx with four distal projections and a few long fine setae; hyp, in ventral view, slightly broader than long, tapering rapidly distally to acutely pointed end with fine setae.

Variation:A remarkably uniform and easily recognisable species.There is some variation in size, the smallest specimen having a wing length of 5.3 mm (the holotype is one of the larger specimens).

Type material: SOUTH AFRICA: 1^ paratype, ‘ Sth Africa Cape Prov / Aninaus Pass 2917BA / 15km W. of Steinkopf / 4.ix.1983 J Londt & / B Stuckenberg Rocky / hillside & dry river’; 1ơ holotype, 1ơ 1^ paratypes, ‘ Sth Africa Cape Prov / 25km N. Kamieskroon / 2917DD 5.ix.1983 / Stuckenberg & Londt / Rocky hillside veget.’; 1^ paratype, ‘ Cape Province / Namaqualand / Springbok, Hester / Malan Nature Res. [= Goegap Nature Reserve 29°40'S 18°00'E] / 15-21.x.1987 / F.W. and S.K. Gess’ ( AMGS) ; 1^ paratype, ‘ Sth Africa Cape Prov / 17km S. Kamieskroon / 3017BD 5.ix.1983 / Londt & Stuckenberg / Slope with succulent / plants and bushes’; 1ơ paratype, ‘ Sth Africa Cape Prov / 10km E Garies / 3017DB 3.ix.1981 / J. Londt, L. Schoemen / and B. Stuckenberg / Succulent Karoo’; 1^ paratype, ‘ Sth Africa Cape Prov / 8km E of Kamieskroon / 3018AA 5.ix.1983 / Londt & Stuckenberg / Montane old land with / rocks & bushes nearby’; 1^ paratype, ‘S Africa : Cape #66 / 23 km S Vanrhysdorp / 31°47'S 18°46'E 600m / Date: 2-4.xi.1991 / Coll: J.G.H. Londt / Gifberg Flat summit’; 2^ paratypes, ‘ Sth Africa Cape Prov / Gifberg. 23km SE Van / Rhynsdorp. 3118DC / Date : 15 Sept. 1982 / Coll: L.E. Schoeman’; 1ơ 1^ paratypes, ‘N. Cape / Nieuwoudtville / Flower Res. / 3119 Ac / 16 Oct. 1996 / VB Whitehead’ ( SAMC) ; 1^ paratype, ‘ S Afr C.P. / Bidouw Valley / 3219AB / VB Whitehead / 4.ix.1983 ’ ( SAMC) ; 1^ paratype, ‘ Pakhuis Pass [32°09'S 19°02'E] / C.P.’ ~ ‘ S.A. M. / 9: 1961’ ( SAMC) ; 2ơ paratypes, ‘ Sth Africa Cape Prov / Vredehoek. Sutherland / 3220BC / Date : 18 Oct. 1981 / Coll: L.E. Schoeman; 1^ paratype, ‘ S Africa: N Cape #28 / Besemgoedkop 31 km N / of Sutherland 1670m / 32°11'21"S: 20°36'03"E / 8.xi.1998 J&B Londt / Rocky ridge Macchia’; 1^ paratype, ‘S Africa : Cape #74 / 31 km N of Sutherland / 32°11'S 20°36'E 1600m / Date: 6.xi.1991 / Coll: J.G.H. Londt / Besemgoedkop and area’ .

Type locality: South Africa: 25 km N Kamieskroon.

Other material: SOUTH AFRICA: 1?, ‘Namaqual. / O’okiep [29°36'S 17°52'E]’ ~ ‘R. Lightfoot / Oct. 90 [1890]’, ‘ Gonioscelis / nigripennis ơ / Ric. / det. E.O. Engel’ (ZSMC) [ Engel (1925) recorded this specimen under nigripennis , a species he had not studied. The genitalia are damaged and the gender is indeterminable].

Distribution, phenology and biology (Tables 1–2, Fig. 150 ): Recorded from the northern parts of the South African west coast (Northern Cape province), the northern parts of the Western Cape province and in the vicinity of Sutherland (also in the Northern Cape). Most localities lie in an area of winter rainfall, with possible exception of more arid places in the south-east of the distribution that lie on the margins of the winter rainfall area. Material has been collected in September, October and November. Individuals rest on the ground, often in high altitude rocky areas with succulent vegetation.

Similar species:A highly distinctive species seemingly similar to ceresae , haemorhous , hispidus , pickeri and scapularis in that males possess a single distomedial hypandrial projection. However, the species is otherwise somewhat different in being smaller, almost entirely shiny black, and possessing long, laterally compressed prothoracic femoral spurs. Superfically the species appears similar to punctipennis and its allies ( chloris , exouros , kedros , iota , xanthochaites ), but can be readily separated from these species. At least one specimen has been incorrectly identified as nigripennis , probably because of its black colour, but that species is otherwise different.

Figures

Figs 6–9. Gonioscelis species, wing, showing some variation encountered. 6. G. ventralis Schiner, 1867 (Vaalbos National Park) microtrichial colours results in central parts of cells appearing darker than areas adjacent to veins. 7. G. cuthbertsoni sp. n. (Angwa Bridge) showing very weak spotting at forks and crossveins.8. G. punctipennis Engel, 1925 (10 km W Garies) showing strong spotting at forks and crossveins. 9. G. melas sp. n. (31 km N Sutherland) showing generally dark wings caused mainly by black microtrichia.

Figs 10–17. Gonioscelis species, left prothoracic femur, showing variation in spur development and method of measuring spur angle (16–17). 10. G. melas sp. n. (25 km N Kamieskroon). 11. G. chloris sp.n. (4 km SW Clanwilliam). 12. G. longulus Ricardo, 1925 (Paul Roux). 13. G. cuthbertsoni sp. n 7 km SE Angwa Bridge). 14. G. macquartii Jaennicke, 1867 (Nguruma). 15. G. nigripennis Ricardo, 1925 (Erikson’s Drift). 16. G. xanthochaites sp. n. (Aus). 17. G. hadrocantha sp. n. (Roçadas). Scale lines = 1 mm.

Figs 77–88. Gonioscelis male genitalia. 77–79. G. macquartii (Jaennicke, 1867) (Nguruma). 77. Lateral. 78. Dorsal. 79. Ventral. 80–82. G. maculiventris Bigot, 1879 (holotype). 80. Lateral. 81. Dorsal. 82. Ventral. 83–85. G. mantis (Loew, 1852) (De La Rey). 83. Lateral. 84. Dorsal. 85. Ventral. 86–88. G. melas sp. n. (25 km N Kamieskroon holotype). 86. Lateral. 87. Dorsal. 88. Ventral. Scale lines = 1 mm.

Figs 150–151. Distribution of Gonioscelis species found only along the west coast of South Africa. 150. closed square = ceresae, cross = iota, open circle = melas. 151. closed circle = chloris, open circle = exouros, closed square = kedros, open square = punctipennis.