Perasis transvaalensis Ricardo 1925
Creators: name: Londt, Jason G. H.
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Asilidae
Perasis
Perasis transvaalensis

description: Perasis transvaalensis Ricardo
Figs 1–3, 9–15
Perasis transvaalensis Ricardo, 1925: 245–245 (as transvalensis) (South Africa, Delarey); Oldroyd, 1980: 354 (catalogue).
Perasis capensis Engel, 1929: 162 (unavailable name: first published as synonym).
Perasis maura: Engel 1929: 162 not Macquart (misidentification).
Perasis meridionalis Hermann, 1920: 177 (unavailable name: no description provided).
Saucropogon transvaalensis: Hull, 1962: 104.
General description: See Ricardo (1925). Entire topotypic Ψ (Figs 1–2), right wing of topotypic ♂ (Fig. 3). Description ♂
Genital capsule of dissected male rotated counter-clockwise through about 90° (Note: this character is variable. Of 15 ♂ examined 8, were rotated counter-clockwise, 7 clockwise, and the degree of rotation varied between approx. 45–90°). Epandrium in dorsal view (Fig. 10) obviously longer than wide (length: breadth ration = 1: 1.38), in lateral view (Fig. 9) broad, slightly curved, proximally slightly constricted ventrally, distally with broadly rounded end. Proctiger in dorsal view (Fig. 10) narrowly rounded distally and projecting to same level attained by epandrial lobes. Hypandrium in ventral view (Fig. 11) tapering sharply to narrow, somewhat truncated distal end. Gonocoxite in lateral view (Fig. 9) with somewhat rounded appearance, dorsal lobe slender (usually visible in dry condition); gonostylus in lateral view (Fig. 4) rounded apically and bearing an obviously backwardly-directed dorsal spine. Aedeagal base in ventral view (Fig. 12) with long distally directed lateral projections.
Description of female genitalia (Figs 13–14: Topotypic Ψ):
Terminalia dorsoventrally compressed. Hypogynium (Fig. 13) with well-developed setose lateral lobes and a pair of smaller, somewhat truncate distomedial lobes bearing fine setulae. Proctiger with supraanale (cerci) fused basally, bilobed distally (Fig. 14); subanale (Fig. 13) composed of two sclerotised lobes, apparently fused proxiomedially.
TYPE SPECIMENS. Ricardo (1925) described transvaalensis on ‘ Types (male and female) from Delarey, W. Transvaal (Dr. Braun), and another from same locality in South African Mus. Coll.’. This suggests that Ricardo saw only three specimens, one being in the SAMC collection (see comment below and listing of material studied). Although Hermann did not publish the description of capensis there is a specimen in the NMSA which bears an orange type-label similar to those commonly used by Hermann. The specimen is a typical example of transvaalensis.
MATERIAL STUDIED. I have seen one type specimen from the BMNH and a pair from the SAMC which I consider to be the types. While there are a number of other specimens with similar label data in other collections, there is no evidence that Ricardo studied any of these additional specimens. As she did not designate a holotype, I regard the three specimens mentioned above as syntypes and so here designate the SAMC male as lectotype and the other specimens as paralectotypes. A complete list of material allocated to this species is as follows: SOUTH AFRICA: 1Ψ (intended holotype of capensis), ‘Waterberg / Distr. [24°00’S 28°00’E] 1898–99 / v. Jutrzencka’, ‘ Perasis / capensis / Herm. / Type’ [cream, handwritten] (NMSA); 2♂ 1Ψ, Waterberg / Distr., 1898–99 / v. Jutrzencka (NMSA); 5♂ 5Ψ, Nylsvley Nature Reserve, 24°37.749’S: 028°40.964’E, 11.xi.2003, Londt, 1056m, Acacia savannah, Hide area adjacent to vley (NMSA); 4♂ 1Ψ, Wtb. [Waterberg] Dist., Platriver, [Platrivier - 25°10’S 28°05’E], 1–11 1903, Jutrencha (NMSA); 1♂ lectotype 1Ψ paralectotype (transvaalensis), ‘Delarey [=Delareyville - 2625CB] / W. Transvaal / Dr. Brauns / i.1917 ’, ‘♂ Paratype / Perasis / transvaalensis / n. sp. Ricardo’. (SAMC); 1♂ paralectotype (transvaalensis), ‘Delarey / W Transvaal / Dr. Brauns / 15 i 1917 ’ (BMNH); 8♂ 4Ψ, Delarey, i.1917, Brauns (NMSA 7♂ 3Ψ, NMNH 1♂ 1Ψ); 1Ψ, Delarey, 15.i.1917, Brauns (NMNH); 1Ψ, Delarey, i.1919, Brauns (ZSMC); 1Ψ, SA Lombard Nature Reserve, 27°37’S 25°29’E, 12.iii.1991, Londt & Whittington, 1250m, Sand, Acacia thornveld (NMSA); 1Ψ, 36 km E Bultfontein, 28°23’S 26°29’E, 11.iii.1991, Whittington & Londt, nr Vet River Branch (NMSA); 1Ψ, Weenen, [28°51’S 30°05’E], xi–xii.1923, Thomasset (BMNH); 1♂, Weenen, xii.1923, Thomasset (BMNH); 1♂, Weenen, i. 1924, 2840 ft., Thomasset, Thorn country (NMNH); 1Ψ, Rolfontein Nature Reserve, Springbok flats, 30°02’12”S 24°45’30”E, 25.iii.2006, Londt, Short Aristida grassland (NMSA); 1♂ 1Ψ, Scottburgh, [30°17’S 30°45’E], 7.i.1976, Quickelberge (DMSA).
Distribution, phenology and biology. The known distribution is illustrated in Fig. 15. The data suggest that transvaalensis is a grassland and savanna species occurring in a region receiving summer rainfall. Specimens have been collected from November through to March (i.e. mid-summer and during the rainy season).
While there is little biological information documented, I have collected the species at three localities, where all specimens were found resting on open sandy substrates in savanna dominated by Acacia trees. The series collected at Nylsvley Nature Reserve were found on the sandy banks of the Nyl River, above the level that might be flooded during particularly wet weather. They flew fairly sluggishly, often within a few centimeters of the ground, landing on open sandy areas between grass tussocks where they were easy to net. The species appeared to be quite common at this site, but was absent from other sites sampled within the reserve. Feeding and reproductive behaviour was not observed.
An intriguing common denominator for all known localities appears to be the occurrence of permanent flowing water nearby. The following rivers (names in brackets) are to be found in the vicinity of each of the known collection sites: Nylsvley Nature Reserve (Nyl River), Platrivier (Plat River), Delareyville (Harts River), S. A. Lombard Nature Reserve (Vaal River), 36 km E Bultfontein (Vet River), Weenen (Bushmans River), Scottburgh (Mpambanyani River), Rolfontein Nature Reserve (Orange River). It is possible, therefore, that the species requires conditions associated with the sandy banks of permanent flowing water and may, therefore, only be found within a short distance of rivers.
description: Published as part of Londt, Jason G. H., 2007, A review of Afrotropical Perasis Hermann, 1905 (Diptera: Asilidae: Laphriinae), pp. 9-18 in Zootaxa 1521 on pages 14-17, DOI: 10.5281/zenodo.177463