Stenobasipteron wiedemanni, Lichtwardt, 1910

Barraclough, David A., 2005, A review of the type material of the Southern African genus Stenobasipteron Lichtwardt, 1910 (Diptera: Nemestrinidae), with transfer of two species to Prosoeca Schiner, 1867, Zootaxa 1094 (1), pp. 41-51 : 48-49

Stenobasipteron wiedemanni

( Fig. 3 )

Stenobasipteron wiedemanni Lichtwardt, 1910: 614 .

Syntypes: ♂: SOUTH AFRICA: KwaZulu­Natal: Co­ / type [circular card, yellow perimeter]; Stenobasipteron / wiedemanni ♂ / det. Lichtwardt Lichtw.; Malvern, / Natal. / April, 1897 / G. A. K. Marshall / 1903­17.; Type [circular red card]; SYN­/ TYPE [circular card, red perimeter]; SYNTYPE of / Stenobasipteron / wiedemanni Lichtwardt / det. J. E. Chainey, 1999. In BMNH. In good condition. I have also seen a damaged female (proboscis detached) from NMW which is probably part of the syntype series. It is part of the important Winthem collection and was formerly identified as “ longipenis ” by Wiedemann. The current identification as Stenobasipteron wiedemanni is by Lichtwardt, and the locality data is “ cap. B. sp.” as indicated in the original description.

Discussion: This is the mostly commonly encountered and widespread species of Stenobasipteron . The body often has a characteristic orange hue. The species is readily distinguished from all congeners by the darkened femoral tips and the prominent anterior costal flexure in the male wing. Bequaert (1925a,b) considered that the presence of a bulla (upwardly blistered membrane) on the wing (in the first basal cell near the base of the first longitudinal vein) was an important character state distinguishing S. wiedemanni from all other species (arrowed in Fig. 3 ), but the use of this character is problematic. Although the bulla is prominently developed in S. wiedemanni , it is sometimes moderately developed in related, undescribed species of Stenobasipteron and therefore there is not a clearcut distinction. In addition, as recognised by Bequaert, the bulla is not as well developed in the female wing. Bequaert (1925: 17) suggested that the bulla is homologous with minute swellings (nygmata) in the wing membrane, occurring for example in some Neuroptera. However I believe the development of the bulla more likely has a structural role associated with the prominently developed anterior costal flexure of the male wing. This flexure is not evident in the female. The flexure is well illustrated in the original description ( Lichtwardt 1910: 615).

Based on the substantial amount of additional material that I have examined, S. wiedemanni is the only species of the genus recorded from the Eastern Cape and KwaZulu­Natal provinces of South Africa, where it is distributed mainly in forested areas. This is an important point as some recent publications by pollination biologists erroneously refer to the distribution of S. wiedemanni in Mpumalanga Province in the northeast of South Africa. Potgieter & Edwards (2005: Figs 3 & 4 ) for example suggest that S. wiedemanni occurs in Mpumalanga , although not in similar habitat (rocky grassland instead of closed­canopy moist forest). Manning et al. (1999) considered that S. wiedemanni occurred in more wooded savanna and at forest margins in Mpumalanga. This puzzling ecological divergence between the southeastern and northeastern provinces of South Africa is of course readily explained by the fact that two or more species of Stenobasipteron are certainly involved. I have seen one specimen from the Eastern Cape and KwaZulu­Natal which is not conspecific with S. wiedemanni (a female, probably of an undescribed species, from far northern KwaZulu­Natal).

Lichtwardt’s description was based on six specimens. As no holotype was designated they represent a syntype series. A single female from the Cape Province of South Africa was deposited in each of ZMHB in Berlin and NMW in Vienna (see above). Lichtwardt also recorded five syntypes from BMNH in London, all from South Africa: 1 female from the Cape, 1 male from Malvern, KwaZulu­Natal and three males from Karkloof, KwaZulu­Natal. Two male and one female syntypes are now present in BMNH, and I have examined one of the Karkloof males. I am certain that the syntype series is based on a single species. Any future lectotype designation will therefore not alter the species concept identified in this paper .

Figures

FIGURES 1–4. Wings of Stenobasipteron and Prosoeca. 1–3. Stenobasipteron. 1. S. arnoldi, female holotype. 2. S. gracile, male syntype. 3. S. wiedemanni, male syntype (bulla at base of first longitudinal vein arrowed). 4. Prosoeca umbrosa, male syntype.