Prosoeca Schiner, 1867

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 : 48-51

Prosoeca Schiner, 1867

Prosoeca Schiner, 1867: 311 . Type species: Nemestrina westermanni Wiedemann, 1821 , by original designation.

Note: The provincial distributions below are based on the localities referred to in the original descriptions, supplemented with information gleaned from the type material in some instances. Distributions often had to be inferred. For example, “ Caffraria ” is assumed to be the eastern provinces, and “Cape of Good Hope” is likely to be the Western Cape. The country of origin of P. nigripes ( Macquart, 1840) is uncertain, but has been assumed to be South Africa, where the vast majority of Prosoeca species occur, so concurring with Bowden (1980). It should be strongly emphasised that all distributions referred to elsewhere in the literature should be treated with caution.

accincta Wiedemann, 1830: 631 (Nemestrina) . Western/Eastern Cape.

* atra Macquart, 1846: 228 ( Hirmoneura ). Western/Eastern Cape.

beckeri Lichtwardt, 1920: 98 . Western Cape.

caffraria Lichtwardt, 1910: 620 . Limpopo.

circumdata Lichtwardt, 1910: 620 . KwaZulu­Natal.

connexa Bezzi, 1924: 188 . KwaZulu­Natal.

flavipennis Lichtwardt, 1910: 618 . [Locality not stated, Eastern Cape material seen]

* fusca Loew, 1860: 324 ( Nemestrina ). Eastern provinces.

* ganglbaueri Lichtwardt, 1910: 616 . Eastern Cape.

handlirschi Lichtwardt, 1910: 621 . Western Cape.

ignita Bezzi, 1924: 183 . Limpopo.

lata Lichtwardt, 1910: 618 . KwaZulu­Natal.

lichtwardti Bezzi, 1924: 185 . Western Cape.

longipennis Loew, 1858: 367 (Nemestrina) . Western Cape.

* longirostris Macquart, 1846: 227 ( Hirmoneura ). Western Cape.

macularis Wiedemann, 1828: 581 (Nemestrina) . Western Cape.

minima Bezzi, 1924: 171 . Western Cape.

nigripes Macquart, 1840: 20 (Hirmoneura) . [“ Patrie inconnue ”]

nitidula Bezzi, 1924: 178 . Western Cape.

oldroydi Hull, 1958: 129 . KwaZulu­Natal.

olivacea Brunetti, 1929: 4 . KwaZulu­Natal.

ornata Lichtwardt, 1910: 622 . Western Cape.

peringueyi Lichtwardt, 1920: 98 . Northern Cape.

pygmea Hull, 1958: 130 . Western Cape.

quinque Lichtwardt, 1920: 101 . Eastern Cape?

rhodesiensis Bequaert, 1925a: 4 . [ Zimbabwe] Mpumalanga. Rec. n.

robusta Bezzi, 1924: 180 . Western Cape; Eastern Cape. major Bezzi, 1924: 181 . Syn. n.

rubicunda Bezzi, 1924: 177 . Western Cape.

sublineata Bequaert, 1926: 185 . Western Cape.

umbrosa Lichtwardt, 1910: 620 . KwaZulu­Natal.

* variabilis Loew, 1858: 368 ( Nemestrina ). Eastern provinces.

* variegata Loew, 1858: 368 ( Nemestrina ). Western Cape.

westermanni Wiedemann, 1821: 155 (Nemestrina) . Western Cape.

willowmorensis Lichtwardt, 1910: 617 . Western Cape.

zuluensis Lichtwardt, 1920: 100 . Limpopo.

Taxonomic changes: One new synonym is established, given that the author ( Bezzi 1924: 181) suggested that the two species concerned were merely a male and female of the same species, and my examination of the type material confirms this. Prosoeca major is synonymised with P. ro b u s t a. Prosoeca robusta , an unusually stout and large (ca 22 mm long) species with dark ground colouring, mostly pale vestiture and largely hyaline wings (darker tinged anteriorly), was described from a single male from Grahamstown (Eastern Cape). The proboscis length of the unique holotype is 26 mm. Prosoeca major was described from Groot Winterhoek, nr Tulbagh, Western Cape (female holotype) and a second female from Willowmore (Eastern Cape). The proboscis length of these two specimens is about 15 mm. They differ from the male only in minor colour characters, with the upper part of the thoracic pleuron and much of the mesonotum and scutellum bearing dark hairs intermingled with the pale ones (the hair almost entirely pale in the male). In addition the pale vestiture is dark yellow to orange in the females, but paler yellow in the male. However, I have seen a recently collected male from Besemfontein, nr Ladismith, whose vestiture is similarly dark to the P. m a j o r females, but with the proboscis longer (about 18 mm). These intergrading character states and the southern Cape distribution of the specimens in autumn (March/April), confirms the synonymy.

Bowden (1980) newly combined Nemestrina obscura Westwood, 1835: 448 , with Prosoeca and suggested that it may be a South African species. The type of this species is almost certainly lost, and despite intensive efforts it cannot be located. It is not in the Hope collections (Oxford), as suggested in the original description. The species was not recorded from the Afrotropics by Bezzi (1924) or Bernardi (1973). Paramonov (1953: 274) considered the provenance of the species as doubtful. Bernardi (1973: 254) treated it as an Australian species of Trichophthalma Westwood , although he later ( Bernardi 1989) omitted it from the Australian fauna, in agreement with Paramonov (1953). As there is no evidence that obscura was described from Africa, and particularly given that Westwood described it under the extralimital genus Trichophthalma with three other species of this genus, which were all subsequently recorded from Australia and Chile by Bernardi (1973), obscura is considered not to be an Afrotropical species of Nemestrinidae .

I have examined the holotype of Hirmoneura nigripes Macquart, 1840 (in Muséum national d'Histoire naturelle, Paris) and can confirm that it is a species of Prosoeca , and thus almost certainly from South Africa. No provenance is indicated in the original description. Previous treatment as an Australian species (e.g. Bernardi 1973: 250) is incorrect. The type specimen has not been tampered with (containing parts from different specimens) as suggested by Paramonov (1953: 272).

Discussion: With 35 named species, Prosoeca is by far the largest and most morphologically diverse genus of Nemestrinidae in South Africa, although unlike Stenobasipteron , most species tend to be relatively robust flies. Also unlike Stenobasipteron , Prosoeca species exhibit an extensive range of body and wing patterning, although the patterning is not evident in some species. Size ranges from slightly more than 5 mm in P. p y g m e a and P. minuta to 22–24 mm in species like P. robusta and P. ganglbaueri . Proboscis length ranges from about 4–5 mm to 45–50 mm. It is difficult to generalise about ecology and habitat preferences, but Prosoeca is likely to occur in most biomes, although none of the species appear to be strictly forest dwellers. The genus is distributed across most of South Africa and is likely to be represented in all provinces, although there are few records from Gauteng and the much larger North West province.

Barraclough (2005b) transferred two species of Stenobasipteron to Prosoeca , these being P. minima (listed above), and P. difficilis ( Bequaert, 1925a) , the latter only recorded from Zimbabwe. These two species were previously incorrectly combined with Prosoeca as minimum and difficilis (the gender of Prosoeca is feminine).

A substantial number of new Prosoeca species await description; in fact the fauna could be expected to muster well over 50 species, despite the likelihood of additional new synonymies. A brief study of P. ganglbaueri in the KwaZulu­Natal Drakensberg for example, suggests that two species are represented there, and that P. ganglbaueri , which is distributed from the Western Cape to the Northern Province, is probably a species complex. P. ganglbaueri has been a focus taxon in recent pollination biology studies (e.g. Anderson et al. 2006; Anderson & Johnson 2006) and a taxonomic review of the complex is certainly warranted. Other widespread species also warrant taxonomic attention for the same reason. Prosoeca rhodesiensis , previously only recorded from Zimbabwe and Malawi ( Bowden 1980), is recorded from South Africa for the first time (I have seen specimens from Mpumalanga), and hence is included in the above checklist. Unfortunately the accurate identification of most Prosoeca species must await a thorough taxonomic revision, with examination of all the type material.

Three pollination guilds centred on species of Prosoeca are already established in the literature. The first of these is the P. peringueyi guild (proboscis length 25–48 mm), which includes a second unidentified Prosoeca species ( Goldblatt & Manning 2000 2006). Prosoeca peringueyi is a west coast species from the Western and Northern Cape Provinces, which is also reported from southern Namibia ( Goldblatt & Manning 2006). Manning & Goldblatt (1996) reported that 28 winter­ and spring­flowering species of Iridaceae and Geraniaceae with extremely long and slender floral tubes are pollinated exclusively by these two species.

The P. ganglbaueri guild, in its restricted sense, includes two other species, namely P. longipennis and P. robusta ( Goldblatt & Manning 2000) . It operates throughout the highlands of eastern Southern Africa, southwards to the southern coast and adjacent mountains, and comprises late summer­ and autumn­flowering species, mostly in the Amaryllidaceae , Iridaceae and Orchidaceae ( Goldblatt & Manning 2006) . As stated above, P. ganglbaueri is probably a species complex and so this guild will have to be further qualified once the complex is revised. Goldblatt and Manning’s identification of P. robusta is problematic; their material of this species is reported from Mpumalanga with a proboscis length of 20–46 mm. In fact the species is restricted to the Western and Eastern Cape, with a proboscis length of 15–26 mm.

Two species ( P. rubicunda and P. n i t i d u l a) from the Western Cape have been referred to the Moegistorhynchus ­ Philoliche guild by Goldblatt & Manning (2000), but the taxonomy of these species is poorly understood and their identities should be treated with caution until a conclusive taxonomic revision of Prosoeca is completed (see also above under Moegistorhynchus ).

Relationships: Prosoeca is—based on external morphological characters—very closely related to Stenobasipteron . Reference should be made to Barraclough (2005b), where the distinctions between Stenobasipteron and Prosoeca are discussed in detail. It may eventually be proven that Stenobasipteron is a junior synonym of Prosoeca , but this should await a rigorous cladistic study of nemestrinine genera, inclusive of a study of internal characters of both sexes. For the time being, based on the characters presented in my generic key (above), it is possible to distinguish the generic concepts, although a few species with a partially reduced alula, for example, may be difficult to place.