Gibbasilus arenaceus Londt, 1986

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 : 71-72

Taxon classification Animalia Diptera Asilidae

Gibbasilus arenaceus Londt, 1986 Figs 7, 20A

Gibbasilus arenaceus Londt, 1986: 2. figs 1 (habitus), 2 (antenna), 3 (wing), 4-7 (♂ terminalia), 8 (♀ ovipositor), 9-12 (pupa).

Description.

The species was fully described by Londt (1986) who provided illustrations of the general habitus, antenna, wing, ♂ terminalia, ♀ ovipositor and pupa as indicated above. The species bears a strong resemblance to the newly described crinitus sp. n. (see below). A new illustration of the ♀ ovipositor is here provided for comparative purposes (Fig. 7). The length: depth ratio of the ovipositor = 4.0: 1.

Material examined.

SOUTH AFRICA: 1♀ paratype "South Africa, Cape Prov. / Botterkloof Pass [c. 31°40'S, 19°16'E 660 m], top of / Sept. 13, 1972, 3119Cd / 2230 ft., ME&BJ Irwin / White sand dune assoc." (NMSA)*; 4♂ 1♀ paratypes "Brandkop [c. 31°42'S, 19°07'E 875 m] Area / Calvinia District / South-West Cape / 14 October 1964 / B&P Stuckenberg" (NMSA, 1♂ BMNH)*; 6♂ 8♀ "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 / 24 km S Vanrhynsdorp / 31°48'S, 18°46'E 600 m / Date: 3.xi.1991 / Coll: J.G.H. Londt / Gifberg. Flat summit" (NMSA); 1♂ holotype "South Africa, Cape Prov / 2.5 mi. S. Elandsbaai [c. 32°19'S, 18°21'E 10 m], 30 ft / Sept. 16, 1972, 3218Ad / ME&BJ Irwin, / Coastal sand dunes" (NMSA)*; 1♂ 1♀ paratypes "Pakhuis Pass [c. 32°09'S, 19°02'E 875 m] 950 m / Clanwilliam Dist. / 17-19 Oct 1964 / B+P Stuckenberg" (NMSA)*.

Remarks.

This species bears a strong resemblance to crinitus sp. n., described below, but can be separated from that species on features of the male terminalia (inn particular the poorly developed pale setae found along the posterior margin of S8).

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

Known from six localities approximately centred on the towns of Vanrhynsdorp and Clanwilliam. Collected during the months of September, October and November. Specimens collected by me 22 km south of Vanrhynsdorp, on the road to the Gifberg, were found perching near the tops of the vertical stems of a tall unidentified plant species belonging to the family Restionaceae growing on the edge of an old ploughed field (31°46'16"S, 18°45'56"E 545 m). 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.