Prosoeca minimum (Bezzi) Barraclough, 2005

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 : 50

Prosoeca minimum (Bezzi) , comb. n.

Stenobasipteron minimum Bezzi, 1924: 171 .

Holotype ♀: SOUTH AFRICA: Western Cape: Cape Town / Table Mtn / K. H. Barnard [collector deleted]; R. Tucker / Feb. 1919 [on underside of previous label]; Stenobasipteron / minimum / type ♀ n. sp.; Holotype ♀ / Stenobasipteron / minimum Bezzi [pale red card]. In fair condition, although most tibiae appear to be missing (in SAMC).

Discussion: The unique female holotype was described from Cape Town’s Table Mountain (Western Cape) in 1919; the species may no longer be extant given the substantial impact of urbanisation there. In his original description, Bezzi (1924) commented that Stenobasipteron minimum was likely the smallest species of South African Nemestrinidae (Bezzi’s body length measurement of 7 mm appears to be accurate). It can now be stated that this is incorrect. Prosoeca pygmea Hull, 1958 is slightly smaller; curiously it was also described from the Western Cape (Mitchell’s Pass, 100 miles from Cape Town).

When I first saw the locality data of the holotype I became suspicious about its placement in Stenobasipteron , despite the reduced wing alula. Based on my examination of most known material of the genus, I found that it is largely restricted to eastern South Africa, with range extensions into Swaziland, Mozambique, Zimbabwe and Malawi. Table Mountain is about 1000 km southwest of the western limit of the genus in the Eastern Cape . This is unlike Prosoeca which is distributed through much of South Africa, including the Western Cape .

Examination of the holotype reveals that S. minimum does not belong to Stenobasipteron and I hereby transfer it to Prosoeca . It differs from Stenobasipteron in the following character states (character states of Stenobasipteron in parentheses): abdominal dorsum with brown medial vitta (striking body markings absent); head with ocellar protuberance remarkably well developed, bulbous and prominent in profile (ocellar protuberance small and barely evident above eye in profile); proboscis about two­thirds body length (1.0 to 2.0 times body length); abdominal dorsum with T 3 and T 4 bearing obvious erect vestiture (short and recumbent vestiture). Another character state atypical of Stenobasipteron is the development of profuse, elongate pile on the ocellar protuberance.