Pycnomerinx rhodesii (Ricardo, 1925)

Londt, Jason G. H., 1990, Afrotropical Asilidae (Diptera) 20. The genus Pycnomerinx Hull, 1962 (Stenopogoninae), ANNALS OF THE NATAL MUSEUM 31, pp. 19-32 : 22-26

Pycnomerinx rhodesii (Ricardo, 1925)

Figs 1-10 , 17

Habropogon rhodesii Ricardo, 1925:274 .

Pycnomerinx annulatus Hull, 1962:145 .

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

Taxonomy: Ricardo (1925) did not designate a holotype but merely stated ' Types (male and female), and another from Bulawayo (R. Stevenson, 1923)'. I have seen all three specimens, the BM pair bearing both circular red 'Type' labels as well as circular blue 'Syntype' labels. The single NMZ male bears two handwritten labels 'Paratype' and ' Habropogon rhodesii n. sp. Ricardo'. I consider all three specimens syntypes and designate the BM male as lectotype and the two females paralectotypes accordingly.

Redescription: Based on lectotype male unless otherwise stated.

Head: ( Figs 1-4 ): Dark red-brown to black; gold-silver pruinose; all setae pale yellow-white. Antennae missing (other topotypic specimens have dark red-brown antennae with white setae on both scape and pedicel-Fig. 3). Ratio of maximum head width (in anterior aspect) to width of face (measured at level corresponding to maximum width of head) 4,1:1. Face silver pruinose except for lower margins adjacent to eyes and area beneath mystax which are shiny dark red-brown. Lower 60 % of face gently gibbose ( Fig. 1 ). Shiny yellow-white mystax composed of moderately well-developed setae (no obvious macrosetae) and confined to facial gibbosity. Frons and vertex uniformly pruinose except for small, dull, central spot just above antennal bases. Vertex ( Fig. 2 ) more or less in the same plane as dorsal surfaces of eyes and not markedly depressed as in most Asilidae . Ocellarium weakly pruinose. Occipital region entirely pruinose but more intensely so bordering eyes. Palp ( Fig. 4 ) single-segmented, dark red-brown with whitish setae laterally. Proboscis dark red-brown.

Thorax: Dark red-brown to black; gold-silver pruinose. Mesonotum uniformly pruinose; all setae shiny orange-yellow. Macrosetae: 2 notopleurals (npl), ca 8 supra-alars (spal), ca 9 postalars (pal). Acrostichals (acr) and dorsocentrals (dc) absent anteriorly, weakly developed and forming part of a cluster of yellowish setae postsuturally. Scutellum with ca 12 yellowish macrosetae and many paler setae marginally; disc lacking setae except for a few small ones adjacent to hind margin. Prosternum ( Fig. 6 ) with upper margin poorly demarcated. Pleura gold-silver pruinose except for a large black spot occupying most of anterior half of anepisternum (anepst) and upper part of propleuron (prpl). Katatergal macrosetae (ktg) white; metanepisternum and anatergites lacking setae. Postmetacoxal area entirely membranous. Wing: Length (measured from tip to humeral crossvein) 7,3 mm, breadth (measured through first fork of radial sector) 2,5 mm. Venation ( Fig. 5 ) brown-yellow; membrane unstained and uniformly covered with microtrichia. Legs: Dark red-brown; tibiae slightly paler dorsoproximally; all setae pale yellow-white except for a few black ones ventrally on tarsomeres. Length of tarsus ca 55-60 % that of tibia.

Abdomen: Dark red-brown to black anteriorly, becoming increasingly orange-brown distally; hind margins of most segments silver to gold-silver pruinose; setae, pale yellow, moderately well developed, except for a group of macrosetae laterally on first tergum (Tl). Genitalia orange-brown (Matopo Hills d illustrated - Figs 7-9 ); rotated through 90°. Epandrium fused with hypandrium laterally ( Fig. 7 ) but very faint 'suture' may be visible. Gonocoxite ( Fig. 9 ) of fairly elaborate form and possessing a flattened, finely setose median lobe (the flattened parts of opposing lobes being more or less in the same plane). Aedeagus short and apparently with a single very short terminal penisfillum. Cerci appear largely fused ( Fig. 8 ).

Female (paralectotypes): Similar to male but abdomen hardly showing any orange-brown coloration; legs somewhat browner. Genitalia (Fig. lO-Farmers Brigade S? illustrated). Subgenital plate produced distally as a scoop-shaped digging organ. Acanthophorites in two groups of about 6 in number. Cerci with group of fine setae distally.

Variation: There is a small degree of individual variation within populations. The colour and number of setae may differ slightly and pruinescence may be more golden in some individuals. The dark pleural spot is not always as obvious as in the type series. Namibian specimens tend to be smaller and may have the antennal flagellum brown.

Material examined: BOTSWANA: 2 ♂, Sepopa [18 °13 'S:22 °1 3 'E], W. Okavango , 29.iii. 1973, Nat. Mus. Bulawayo ( NMZ) ; 2 ♂, Serowe [22 °25'S: 26 °44'E], iv.1983, Forchhammer ( NM) ; 4 ♂ 1 ♀, Farmers Brigade ,S kms SE Serowe, 2226BD, 19.iv.1983 8.W. 28. iv. l. v.1984 ii.1986, P. Forchhammer, Hillside N slope, Malaise trap 1 ( NM) ; 1 ♀, Farmers Brigade, S kms SE Serowe, 2226BD, iii.1986, P. Forchhammer, Malaise trap 2 ( NM) ; 2 ♂ 2 ♀, Farmers Brigade, 5 kms SE Serowe, 2226BD, iv. v.1986, P. Forchhammer, Malaise trap 3 ( NM) ; 1 ♂, Forestry Nursery , ca. 6 kms SE Serowe, 2226BD, 22.iv.1985, Forchhammer, 1300m, Malaise trap 3 ( NM) . MOZAMBIQUE: 1 ♀, Macaneta [25 °52'S: 32 °14'E], 30.iv.1980, H. R. Feijen ( NM) ; 2 ♀, Goba [probably 26°12'S: 32 °08'E], 13.iv. 12. v.1980, H. R. Feijen ( NM) . NAMIBIA: 1 ♀, Hoas 273, Outjo , 1914DC, 1O- 11.v.1973, H 12865 ( SMW) ; 1 ♂, 10 km SW Tsumeb, Rd 119, 19 °18'S: 17 °37'E, 2 l. iii. 1984, Stuckenberg & Londt, Mixed woodland and roadside grass ( NM) ; 1 ♂ 1 ♀, Kombat [19 °43'S: 17 °42' E] (W48), 1 -6.iv.1972, Sth Afr Exp BM 1972-1 ( BM) ; 1 ♂ 2 ♀, 15 km NE Grootfontein, J. Scribante Skitbaan, Rd8/2, 19 °28'S: 18 °15' E, Stuckenberg & Londt, 2l. iii.1984, Grassy road verges ( NM) ; 1 ♂, 21 km SE Steinhausen, Rd 57, 21 °53'S: 18OZ7'E, 18.iii.1984, Stuckenberg & Londt, Dry Acacia woodland ( NM) ; 1 ♂, 7 km SW Gross Barmen, 2216BA, 24. iv.1983, Stuckenberg & Londt, Thornveld ( NM) ; 1 cJ', 25 km W of Windhoek, 2216DB, 22. iv.1983, Londt & Stuckenberg, Thornveld ( NM) ; 3 cJ' 1 ♀, 13 km S Windhoek, 2217CA, 18.iv.1983, Stuckenberg & Londt, Rocky slopes , Mixed Thornveld ( 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) ; 3 ♂ 2 ♀, Aris , 30 km S Windhoek, 2217CA, 18. iv.1983, Stuckenberg & Londt, Thornveld ( NM BM) ; 1 ♀, 24 km N Witvlei, Road 57 , 22°16'S: 18 °26'E, 18.iii.1984, Londt & Stuckenberg, Acacia thornveld and grassy verge of road ( NM) ; 1 ♀, Gobabis [22 °30'S: 18 °58'E], ii/ iii. 1971 ( NM) ; 1 ♂ 2 ♀, Noachabeb 97, Keetmanshoop , 2718AD/BC, 22-28.iv.1972, H 8026 ( SMW) . SOUTH AFRICA: Cape Province: 1 ♂, 17 km SE of Kuruman, 2723CB, 23.iii.1982, J. Londt & L. Schoeman, Rocky hilltop / grass ( NM) . Natal: 1 ♂ 1 ♀, Mhlopeni Nat Reserve , 8 km SE of Muden, 2930AB, 8.iv.1983, Londt Barraclough & Seymour, Thornveld ( NM) ; Transvaal: 1 ♂, Satara [24°19'S: 31 °47'E], K. N. P. Survey, 26.iv. -l. v.1969, Potgieter & Strydom ( NM) ; 1 ♂ 1 ♀, Kruger National Park, vicinity of Skukuza , 2431DC, 9-12.iv.1985, J. Londt, Bushveld ( NM) ; 1♀ Brits Dist. Silkaatsnek (2527DB), 21.iii.1972, J. A. van Reenen ( NM) ; 2♀ [25 °45'S: 28 °10'E], 18. iii. 9. iv.1967, D. H. Jacobs, KAM298JR ( NM) ; 1 ♀, Naboomspruit, 2529AA, iv.1980, B. Meyer, Dept Entomology, Univ Pretoria ( NM) . ZIMBABWE: 1 ♂ 1 ♀, (lectotype and paralectotype), Bulawayo [2001O'S:28°43'E], 11 12.iv.1923, R. Stevenson ( BM) ; 1 ♂ (paralectotype), Bulawayo [2001O'S: 28°43'E], 12. iv.1923, R. Stevenson ( NMZ) ; 3 ♂, Matopo Hills [20036'S:28 °28'E], iv. 1932, Miss A Mackie ( BM NM) .

Distribution: Apparently limited to southern Africa. Distributed widely from northern Namibia in the west through Botswana and eastern Zimbabwe into the eastern parts of South Africa (Transvaal and Natal) and southern Mozambique ( Fig. 17 ). It is of interest that the British Museum expedition of 1971-72 failed to collect specimens of rhodesii in northern Botswana where good collections of both cogani and gweta were made.

Ecology: The little that is known is gleaned from available label data and personal field experience. The species is found in grass in Acacia woodland (= bushveld or thornveld) areas. Records indicate that adults fly during the latter part of summer (February to May) ( Table 2 ).

Figures

Figs 1-6. Pycnomerinx rhodesii Ricardo. 1-2. Head aspects. 1. Lateral. 2. Dorsal. 3. Outer view of right antenna. 4. Right palp. 5. Winll. 6. Prosternum, anterior aspect. (1 -4 & 6- Skukuza cf; 5-25 km W of Windhoek 0"). Scale Jines = I mm.

Figs 7-10. Pycnomerinx rhodesii Ricardo, genitalia. 7-9. Skukuza d. 9. Ventral. 10. Farmers Brigade S?, lateral. Scale line = 1 mm.

Fig. 17. Distribution of Pycnomerinx species.