Pycnomerinx cogani Oldroyd, 1974

Londt, Jason G. H., 1990, Afrotropical Asilidae (Diptera) 20. The genus Pycnomerinx Hull, 1962 (Stenopogoninae), ANNALS OF THE NATAL MUSEUM 31, pp. 19-32 : 26-28

Pycnomerinx cogani Oldroyd, 1974

Figs 11-13 , 17

Pycnomerinx cogani Oldroyd, 1974:62 ; 1980:367.

Pycnomerinx moremensis Oldroyd, 1974:62 ; 1980:367. Syn. n.

Oldroyd (1974) described this species in a key. The full description reads as follows- 'Legs entirely black. Abdomen in both sexes sharply divided; first four segments black with broad, grey hind margins; segments 5-7 bright orange; terminalia black. Wings strongly spotted on forks and crossveins.' The available material was not fully itemised. All we are told is ' Type in London' and that the type-locality is 'Botswana, 16 km NE Ghanzi ... '. I have seen all the BM material and find that there are four specimens bearing this locality data, only one of which bears a 'type' label, as well as a number of other specimens collected during the same expedition. As there is no mention of paratypes in the formal description it must, unfortunately, be assumed that none of the other specimens have any type status.

Redescription: Based on holotype male unless otherwise stated. Similar to P. rhodesii except for the following features.

Head: Silver pruinose; all setae white. Antennae dark red-brown with yellow-white setae on scape and pedicel. Head width: face width ratio 4,1:1. Mystax shiny white.

Thorax: Gold-silver and silver-gold pruinose. Mesonotal setae shiny orange-yellow anteriorly and laterally, longish dark red-brown centrally and posteriorly. Macrosetae: 3 npl, ca 8 spal, ca 4 pal; acr absent and dc weak anteriorly; these setae moderately developed and forming part of a cluster of yellow and dark red-brown setae postsuturally. Scutellum with ca 12 yellow-white macrosetae and many paler setae marginally. Wing: 7,2 x 2,1 mm. Venation similar to rhodesii , brown; membrane slightly stained at some forks and crossveins. Legs: Dark red-brown. Length of tarsus ca 60-65 % that of tibia.

Abdomen: Dark red-brown to black anteriorly, T5 partly orange-brown, T6-8 largely orange-brown. Genitalia dark red-brown (topotypic ♂ illustrated-Figs 11-13 ).

Female: Similar to ♂.

Variation: There is a small degree of individual variation within populations. The dark pleural spot is not always as obvious as in the holotype. Specimens from the Moremi Reserve (including type of moremensis ) have legs largely orange-brown. Synonymy: Oldroyd described P. moremensis on a single female specimen. Apart from having orange-brown legs this specimen appears to be conspecific with cogani . Two other female specimens from the moremensis type-locality are available; one is similar to the holotype, the other has entirely dark red-brown legs. I do not accept the leg colour as sufficient grounds for the recognition of moremensis and therefore synonymise it with cogani at least until males with orange-brown legs are available.

Material examined: BOTSWANA: 3 ♀ (inc. holotype P. moremensis Oldroyd ), Moremi Reserve , 19°23'S, 23 °33'E (B11), 18-20.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 2 ♀, L. Ngami, 12 mls NE Sehithwa [= Sehitwa 20 023'S: 22 °45'E] (B9), 16-17.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 2 ♂ Kuke Pan , 20 059'S, 22°25'E (B7), 14-15.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 2 ♂ 1♀, 3 mls NE Maun [20 000'S: 23 °25'E] (B 17), 2l. iv.1972, Sth Afr Exp BM 1972-1 ( BM NM) ; 1 ♂ 1♀, Makarikari Pans , 20 008'S, 25 °32'E (B20), 22-23.iv. 1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♀, 2 mls N Gweta (B 19), 20 011'S, 25°15'E, 22.iv. 1972, Sth Afr Exp BM 1972-1 ( BM) ; 2 ♂ (inc. holotype P. cogani Oldroyd ) 2 ♀, 10 mls NE Ghanzi [22 °00'S:22 °OO'E] (B6), 14. iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; NAMIBIA: 1 ♀, Onze Rust 192, 24°09'S, 18 °02'E, 17-18.v.1973, Jacot-Guillarmod ( AM) . SOUTH AFRICA: Cape Province: 1 ♀, Roaring Sands Resort nr. Witsand , 2822CB, 17-18.iii.1982, J. Londt & L. Schoeman, Acacia woodland ( NM) . ZIMBABWE: 1 ♂, Matetsi [18 °14'S:25 °59'E], ii. 1934, R. H. R. Stevenson ( BM) .

Distribution: Apparently limited to southern Africa. Known from seven localities in Botswana, one in Namibia, one in Zimbabwe, and one in the northern Cape Province of South Africa ( Fig. 17 ).

Ecology: Only one specimen, collected in Acacia woodland, has any information concerning the type of habitat occupied by this species. In this respect it is similar to rhodesii . The species has, however, not been collected sympatrically with rhodesii . On the other hand cogani has been collected sympatrically with gweta from which it is readily distinguishable. Records indicate that adults, like rhodesii , fly during the latter part of summer (February to May) ( Table 2 ).

Figures

Figs 11-16. Pycnomerinx male genitalia aspects. 11-13. P. cogani Oldroyd (10 mls NE of Ghanzi). 11. Lateral. 12. Dorsal. 13. Ventral. 14- 16. P. gweta Oldroyd (2 mls NE Sehithwa). 14. Lateral. 15. Dorsal. 16. Ventral. Scale line = 1 mm.

Fig. 17. Distribution of Pycnomerinx species.