Pycnomerinx gweta 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 : 28-30

Pycnomerinx gweta Oldroyd, 1974

Figs 14-17

Pycnomerinx gweta Oldroyd, 1974:65 ; 1980:367.

As in the case of cogani, Oldroyd (1974) described gweta in a key. The full description, drawn from three couplets, reads as follows-'Legs at least partly red or reddish'; 'Femora not entirely red'; 'Femora and tibiae both with black anterodorsal streak. Male abdomen entirely red; female abdomen completely covered with yellow grey tomentum, except for shining black terminalia. Wings clear.'

Again the material which was available at the time of description was not fully itemised and we must accept that only one specimen, the 'type', has any type status.

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

Head: Antennae with macrosetae dark red-brown, other setae white. Head width: face width ratio 4,8:1. Mystax white.

Thorax: Mesonotal setae mixed short yellow and longer dark red-brown. Macrosetae: 2-3 yellow npl, ca 8 yellow and dark red-brown spal, ca 5 yellow pal; acr absent and dc weak anteriorly; these setae weakly developed and forming part of a cluster of setae postsuturally. Scutellum with ca 14 yellow-white macrosetae and many paler setae marginally; disc lacking setae except for a few moderately developed ones adjacent to hind margin. Pleura uniformly gold-silver pruinose (black spot occupying most of anterior half of anepst and upper part of prpl absentalthough type has a 'greasy' mark corresponding to this area; other specimens lack this greasy mark and are uniformly pruinose). Wing: 6,5 x 2,1 mm. Venation dark brown. Legs: Femora dark red-brown dorsally, brown-yellow ventrally; tibiae brown-yellow except for dark red-brown parts ventrodistally; all setae pale yellow-white except for a single row of black ones ventrally on tarsomeres. Length of tarsus ca 60-65 % that of tibia.

Abdomen: Orange except for first two segments which are at least partly dark red-brown to black; segments uniformly fine silver-gold pruinose. Genitalia orange-brown (Lake Ngami cJ illustrated-Figs 14- 16).

Female: Similar to male but abdomen uniformly dark red-brown; uniformly strongly gold-silver pruinose except for shiny black terminal segments. Genitalia similar to rhodesii .

Variation: There is a small degree of individual variation within populations. The colour and number of setae may differ slightly, especially on antennae and mesonotum. Colour of abdominal terga is variable, smaller males may have orange parts reduced to the hind margins of terga (26 km N Windhoek cJ) or terga may be entirely dark red-brown (Gobiswater cJ). A female (Angola/Namibia border) has yellow-brown margins to otherwise dark red-brown terga. Smaller specimens may also have more extensively darkly coloured legs.

Material examined: BOTSWANA: 1 ♂, Moremi Reserve , 19 °23'S, 22°33' E (B11), 18-20.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♂, L. Ngami , 2 mls NE Sehithwa [= Sehitwa 20023'S:22°45'E] (B8), 15-16.iv. 1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♀, L. Ngami , 12 mls NE Sehithwa [= Sehitwa 20 °23'S: 22 °45'E] (B9), 16-17.iv.1972, Sth Afr Exp BM 1972-1 (BM) ; 1 ♀, Maun [20 000'S: 23 °25'E] (B 16), 21. iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♀, 25 mls W Gweta (B 18), 20017 'S, 24°54'E, 21-22.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♂ (holotype P. gweta Oldroyd ), 2 mls N Gweta (BI9), 20011'S, 25°15'E, 22.iv. 1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♂ 1 ♀, 18 mls NE Kalkfontein [22 °08'S:20053'E] (B3), 12-13.iv.1972, Sth Afr Exp BM 1972- 1 ( BM) ; 1 ♀, Farmers Brigade , 5 kms SE Serowe, 2226BD, v.1986, P. Forchhammer, Malaise trap 2 ( NM). NAMIBIA: 1 ♂ 1♀ Angola-S . W. Afr Border Beacon 39, Ovamboland , 18. iv.1970, H. D. Brown ( NM) ; 1 ♂, 38 km SE Ondangua, Ovamboland , 1715DD, 9.v.1971, H 2486 ( SMW) ; 1 ♂, Gobiswater Fm ., 12 mls N. Grootfontein [19 °32'S: 18 °05'E] (W50), 5.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♂, Waterberg Nat. Park Entrance , Road 2512 , 20 °32'S: 17 °20'E, 20.iii. 1984, Stuckenberg & Londt, Acacia thornveld ( NM) ; 1 ♂ 2 ♀, Okahandja , 2116DD, 24.iv. 1983, Londt & Stuckenberg, Riverine vegetation ( NM) ; 1 ♂, 26 km N Windhoek, Road 116, 22°20 'S: 17 °04'E, 29.iii.1984, Londt & Stuckenberg, Dry stream bed Acacia riparian woodland ( NM) .

Distribution: Apparently limited to southern Africa. Known from eight localities in Botswana and six in Namibia (Fig. 17).

Ecology: The limited label data and field experience suggest that, like the other species in the genus, it is associated with Acacia woodland. The species has been collected sympatrically with cogani and at the same locality (but slightly later in the year) as rhodesii (Serowe) . Records indicate that adults, like rhodesii , fly during late summer (March 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.