Daspletis vulpes Loew, 1858

Londt, Jason G. H., 2010, A review of Daspletis Loew, 1858 with the addition of a remarkable South African species (Diptera: Asilidae: Stenopogoninae), African Invertebrates 51 (1), pp. 183-183 : 195-196

Daspletis vulpes Loew, 1858

Fig. 14

Daspletis vulpes: Loew 1858: 337 ; Londt 1983: 296 , figs 25–27.

Londt (1983) recorded material (all NMSA): BOTSWANA: 2ơ 3 miles [ca 5 km] W Ramboekas Pan [?], part of K.G.N.P. [ Kalahari Gemsbok National Park , 25°41'S: 20°20'E], i. v.1970, Lamoral. SOUTH AFRICA: 2^15 km SE Van Zylsrus, 2622 CC, Acacias /grass/shrubs, 22.iii.1982, Londt & Schoeman; 1^55 km W Van Zylsrus, 2721BA, Acacias /dry grass, 22.iii.1982, Londt & Schoeman; 6ơ 8^ca 5 km W Hotazel, 2722 BB, Acacias /grass/shrubs, 23.iii.1982, Londt & Schoeman; 1^Roaring Sands Resort nr Witsand, 2822 CB, Acacia woodland/sandy area, 17–18.iii.1982, Londt & Schoeman .

New material (all NMSA): BOTSWANA: 1ơ Serowe [22°25'S: 26°44'E], v.1988, [Forshhammer], Bush Day. SOUTH AFRICA: 2ơ 1^20 km N Hotazel, 27°07'S: 22°59'E, 1050 m, Kuruman R. banks, 14.iii.1991, Whittington & Londt; 1ơ 14 km S Hotazel, 27°19'S: 22°54'E, 1050 m, Ga-Mogara R. bed, 14.iii.1991, Londt & Whittington; 3ơ 2^Witsand Nat. Res., 28°32'09"S: 22°30'18"E, 1200 m, white sand Stipagrostis amabilis dune, 6.iii.2001, Londt; 1ơ Witsand Nat. Res., 28°33'29"S: 22°29'36"E, 1230 m, red sand rocky Acacia scrubland, 8.iii.2001, Londt; 1^Witsand Nat. Res., 28°33'37"S: 22°29'05"E, 1200 m, white sand low vegetation, few trees, 5–8.iii.2001, Londt.

Other records: Loew’s (1858) holotype was collected by Wahlberg from ‘N’Gami’.Although it is not known exactly where the specimen was collected it was probably in the Ngamiland District of present day Botswana that incorporates the Okavango Delta (ca 20°S: 23°E) and so, to further add to the known distributional information this point is plotted in Fig. 14 . Ricardo (1925) records ‘A male from Livingstone [17°45'S: 25°59'E], N.W. Rhodesia [ Zambia] (Dr A. Douglas), in poor preservation, and a female from the same locality in Brit. Mus. Coll. [BMNH]’.This record is repeated by Oldroyd (1974).Although I have not studied these specimens, I accept the identifications as correct.

Distribution, phenology and biology: D. vulpes appears to be fairly widely distributed in the central region of Southern Africa ( Fig. 14 ), records occurring mainly from the northern parts of the Northern Cape Province of South Africa. One male is known from Botswana (Serowe) and a male was recorded by Ricardo (1925) from Livingstone ( Zambia), that I have not studied. This species flies at the same time as D. stenoura and can be found sympatrically. It is active in the adult phase from November through to March (no records for February) (Table 1). Natal Museum prey records include (sex of predator in brackets): Orthoptera (2): Acrididae (^),? Lentulidae (ơ); Hymenoptera (1): Sphecidae (^).

DISCUSSION Taxonomy

Microstylum and Daspletis form a distinctive pair within the Stenopogoninae and are not easily confused with other Afrotropical genera in the subfamily (see key in Londt 1999). Dikow (2009 a) established the sister-group relationship between these two genera within the Enigmomorphini based on a world-wide sample of Asilidae species and seven morphological characters (maxillary palpus one-segmented; sensory pit in distal palpomere absent; prementum laterally compressed proximally; labella reduced, fused entirely to prementum; lacinia same height throughout; anatergal setae composed of regular setae only; and superoposterior anepimeron with regular setae only). Unfortunately Dikow’s (2009 b) ‘total evidence’ study excluded the Daspletis species as no ethanol preserved specimens were available, so we do not know exactly where it would have been placed in that particular analysis.

Unfortunately Microstylum , with about 80 catalogued Afrotropical species (Oldroyd 1980) has not been adequately revised and so the validity of the characters used to differentiate these genera from one another have not been fully tested (see key in Londt 1999). The four main features used to separate Daspletis from Microstylum were as follows. All Daspletis species possess (1) a facial swelling (gibbosity) that occupies about three-quarters of the face and is entirely setose (i.e. occupied by the mystax); (2) well developed presutural dorsocentral macrosetae; (3) a vein M 1 that is not strongly arched anteriorly; and (4) a postmetacoxal membrane that is covered with long setae. While I have looked at many Microstylum specimens and can testify that most have less developed facial swellings, poorly developed presutural dorsocentral macrosetae, strongly arched M 1 veins, and largely asetose postmetacoxal membranes, I have to report having seen specimens that do not fully conform with all these characters.

As already mentioned above, when comparing vespertilio with other Daspletis species, there are two species groups within Daspletis , each with four species, and these are separated in the key to species that follows. The vulpes species group appears to be quite distinctive while the hermanni species group appears to represent a cluster of species that has more in common with species of Microstylum . What is needed is a detailed cladistic analysis that incorporates a much wider range of species from both genera and other Enigmomorphini in order to better establish the relationships that exist between these taxa.

Figures

Fig. 14. The distribution of Daspletis Loew, 1858 species in southern Africa: hirtus (circles), setithoracicus (squares), vespertilio (triangles), vulpes (diamonds).