Moegistorhynchus Macquart, 1840

Barraclough, David A., 2006, An overview of the South African tangle­veined flies (Diptera: Nemestrinidae), with an annotated key to the genera and a checklist of species, Zootaxa 1277, pp. 39-63 : 47-48

Moegistorhynchus Macquart, 1840

Moegistorhynchus Macquart, 1840: 12 . Type species: Nemestrina longirostris Wiedemann, 1819 , by designation of Bequaert (1935: 491).

braunsi Bequaert, 1935: 495 . Western Cape.

brevirostris Wiedemann, 1821: 156 (Nemestrina) . Western Cape. longirostris Wiedemann, 1819: 13 (Nemestrina) . Western Cape; Northern Cape.

perplexus Bequaert, 1935: 498 . Western Cape.

Discussion: These are large (15 to 20 mm), striking flies with conspicuously patterned wings and often with a remarkably elongate proboscis ( Fig. 2 ). Moegistorhynchus longirostris is by far the most commonly encountered species, with a range extension from the Western Cape into the Northern Cape. It has the distinction of having the longest proboscis of all known Diptera species worldwide, reaching 90 to 100 mm long in some specimens. In addition to the three other valid species, I have identified two new species of Moegistorhynchus from montane areas in the southern part of the Western Cape (Barraclough, in prep.).

A pollination guild of long­tubed flowers centred on M. longirostris was established in the literature by Manning & Goldblatt (1997), who reported it pollinating—partly or exclusively—20 late spring and early summer flowering species of Iridaceae , Geraniaceae and Orchidaceae . Goldblatt & Manning (2000) also refer M. longirostris and one of my new Moegistorhynchus species to the Moegistorhynchus ­ Philoliche guild, together with two species of Philoliche Wiedemann (Tabanidae) and two of Prosoeca (see below). The guild operates along the western and southwestern coasts and adjacent mountains in the winter rainfall zone ( Goldblatt & Manning 2006). As there are still notable taxonomic difficulties with the nemestrinids in this complex, this guild is not further reviewed here.

Relationships: Moegistorhynchus is the most easily recognised genus within the Nemestrininae, all of which have a well developed proboscis. The characteristic and extensive reticulation in the apical half of the wing occurs in no other South African genus, although the relationships of Moegistorhynchus are uncertain. Bernardi (1973) considered Moegistorhynchus to be closely related to the largely Palaearctic genus Nemestrinus Latreille , given that some species of Nemestrinus also have reticulate wing venation, but in fact he offered no convincing phylogenetic evidence. In his figures of wing venation (p. 242), both reticulate­veined species of Nemestrinus have the fifth posterior cell without any crossveins, unlike all known species of Moegistorhynchus .

Figures

FIGURES 2 – 4. Adult flies in the field. 2. Moegistorhynchus longirostris visiting Laperouisia anceps (Cape west coast) [C. Paterson­Jones]. 3. Stenobasipteron wiedemanni visiting Isoglossa sp. (KwaZulu­Natal) [G. Upfold]. 4. Atriadops species at rest (Mpumalanga) [M. Picker].