Acnephalomyia platygaster (Loew, 1858) Londt, 2010

Londt, Jason G. H., 2010, A review of Afrotropical Acnephalum Macquart, 1838, including the reinstatement of Sporadothrix Hermann, 1907 and descriptions of two new genera (Diptera: Asilidae: Stenopogoninae), African Invertebrates 51 (2), pp. 431-431 : 455-457

Acnephalomyia platygaster (Loew, 1858) comb. n.

Figs 8 , 47–49 , 67

Acnephalum platygaster: Loew 1858: 338 [1860: 170]; Hermann 1907: 8; Kertesz 1909: 88 (catalogue); Curran 1934: 5–6; Oldroyd 1974: 26; 1981: 359 (catalogue).

Redescription (Based on ♂ holotype. Condition: Excellent; antennae broken off beyond pedicels; some minor mesonotal setulae have been rubbed off in the region of where the pin was inserted.):

Head: Dark red-brown to black, mainly white setose, extensively silver pruinose. Antenna: Scape and pedicel uniformly orange-brown. Segmental ratios 1.0:0.9:?:?:? – scape and pedicel subequal in length, white setose (ventral macrosetae broken off). Face dark red-brown to black, mostly apruinose except for lateral margins which are silver pruinose, mystax fine white, covering entire face (weakly centrally). Frons, vertex and postocular region dark red-brown to black, silver pruinose except for ocellar tubercle, mostly long white setose (some pale yellowish postocular macrosetae dorsally); angle subtended by eye margins at level of frons/vertex c. 1° (i.e. hardly divergent). Proboscis orange-brown to dark red-brown, white setose, straight. Palpus 2-segmented, white setose, second segment terminating in long distal projection.

Thorax: Dark red­brown to black. Pronotum mostly fine white setose, but with transverse rows of long brownish macrosetae. Mesonotum mixed white and brown setose, but with clumps of uniformly white setae, mostly anteriorly. Lateral macrosetae moderately well developed, pale yellowish (6 npl, 7–9 spal, 5 or 6 pal). Pleura largely asetose except for numerous, long white katatergals and dorsally situated anepisternals. Katepisternum dorsally white setose. Scutellum shiny black apruinose with moderately developed transverse subapical groove. About 14 moderately developed, yellowish apical macrosetae accompanied by slightly shorter, weaker white setae; disc weakly white setose laterally. Legs: Mostly orange-brown, parts of fem darker red-brown dorsally. Major setae erect yellowish, minor setae recumbent white. Ventral parts of tar and terminal end of tib short black setose. Claws black, long (shorter than tarsomere5); empodia slender yellow, about half length of claws; pulvilli minute (hardly discernible). Haltere yellow, base slightly darker.Wing:9.9× 4.2 mm.Veins brown-orange,membrane largely lacking microtrichiae. Membrane brown-orange stained proximally, becoming translucent distally. Vein C extends around wing margin, terminating at A 1, R 4 with short basal stump-vein, cell m 3 open.

Abdomen: Terga clearly broader than long, mostly dark red-brown to black, but narrowly orange-brown laterally. Orange-brown colour extends along posterior margins of more distal terga, progressively increasing in extent. Terga apruinose and entirely pitted by setal sockets. Entire abdomen fringed laterally with erect white setae. Posterolateral parts of terga white setose, these not extending onto medial parts. Large areas of terga appear asetose, but are covered with tiny blackish setae. Sterna orange­brown, finely gold pruinose, uniformly long white setose. Terminalia largely withdrawn between

T7 and S7 and somewhat obscured by setae. Genitalia of holotype not dissected, but exposed parts of hypandrium resembling those of a dissected ♂ from 60 km S Aus ( Figs 47–49 ): Epand reduced (half length of goncx), distally incised medially to form two distinct lobes in dorsal view. Proc moderately well developed, jutting out to almost level achieved by inner lobe of goncx. Exterior lobe of goncx broadly rounded proximally, tapering to an acutely pointed tip distally; interior lobe longish, fairly broad, jutting out to beyond level achieved by hypd. Hypd somewhat truncate basally, tapering rapidly toward midlength before extending to somewhat clavate distal lobe.

Variation and sexual dimorphism: There is considerable size variation in both sexes. For example males and females from 5 km SW Pofadder range in wing length as follows: ♂ 6.8–9.5 mm, ♀ 6.8–9.0 mm. The smallest ♂ measured had a wing length of only 4.3 mm while the largest measured 10.9 mm. A similar range was evident in females (4.9–9.5 mm). In general appearance males resemble females although males have more darkly stained wings and the extent of white setation along the posterior margins of the terga is greater in females. Antennal ratios of an intact ♂ specimen are as follows 1:0.8:3.1:0.2:1.5.

Holotype: NAMIBIA: ♂ ‘ Svakop / Africae. ’, ‘ J. Wahlb’, ‘10.’, ‘258.’, ‘ Acnephalum / platygaster’ [white, typed] ( NHRS – not ZMHB as indicated by Oldroyd (1974)). Notes: The specimen is not a female as stated by Loew and the pin does not carry a type label. I have attached a pink type label and my identification label accordingly. Wahlberg’s precise place of collection is not known. I presume he visited Swakopmund (22°40'S: 14°31'E) situated near the mouth of the Swakop River and so suggest that this could be considered the type locality.

Specimens examined: NAMIBIA: 1♀ Gobabeb [23°33'S: 15°02'E], ii.1984, Marsh, feeding on pollen of ♀ Welwitschia (SANC) ; 1♀ Outskirts of Aus overlooking town, 2616CA, 30.viii.1983, Stuckenberg & Londt, rocky area/shrubs ( NMSA) ; 6♂ 5♀ 60 km S. Aus , 2716AB, 1.ix.1983, Londt & Stuckenberg,broken veld at base of small hill ( NMSA) ; 2♂ 30 km N Rosh Pinah , 2716DA, 1.ix.1983, Londt & B Stuckenberg, green bushes & flowers ( NMSA) ; 2♂ 7♀ 30 km NW Karasburg, 2718DA, Karasberg Mts , 28.viii.1983, Londt & Stuckenberg ( NMSA) ; 4♂ 2♀ 50 km NW Karasburg, 2718DA, Karasberg Mts , 28.viii.1983, Londt & Stuckenberg ( NMSA) ; 1♂ Klinghardt Mts , 27°19'S: 15°46'E, 11.ix.2005, Gess ( AMGS) ; 1♀ Heioab , 27°24.41'S: 16°00.21'E, 17 ix.2003, Gess ( AMGS) ; 1♀ Aurus [27°38'S: 16°13'E] Mts , 25 x.1979, Whitehead ( SAMC) ; 1♂ Aurus Mts , 26 x.1977, Whitehead ( SAMC) ; 1♂ 2♀ Namaskluft , 27°52.00'S: 16°52.03'E, 26.ix.2003, Gess ( AMGS) ; 1♂ 1♀ 25 km W Ariamsvlei , 2819BA, 27.viii.1983, Londt & Stuckenberg, very arid broken veld ( NMSA) ; 6♂ 3♀ 15 km E Karasburg , 2818BB, 27.viii.1983, Londt & Stuckenberg, arid roadside vegetation ( NMSA) ; 3♀ Gt. Karas Mts. [nr Karasburg, 28°01'S: 18°45'E], xi.1936, Mus. Staff ( SAMC) ; 1♀ Obib [28°05'S: 16°45'E], 29 x.1977 ( SAMC) ; 1♀ Obib , 28 x.1977, Whitehead ( SAMC) ; 1♀ E Oranjemund, foot of Skilpad , 28°28'S: 16°40'E, 23.ix.1997, Gess ( AMGS) ; SOUTH AFRICA: 1♀ 10 km E Kakamas , 2820DA, 6.ix.1982, Schoeman ( NMSA) ; 1♂ Richtersveld N. Park, Pootjiespram , 28°05'S: 16°57'E, 16.ix.1995, Gess ( AMGS) ; 3♀ 26 mi [c. 42 km] North Postmasburg [28°19'S: 23°04'E], x.1939, Mus. Staff ( SAMC) ; 1♂ 1♀ Bushmanld. [Bushmanland], Henkries [28°55'S: 18°07'E], x.1911, Lightfoot ( SAMC) ; 1♀ Brakf [Brakfontein, 28°56'S: 17°05'E], Richtersveld , 18 xi.1933, van Son ( NMSA) ; 2♂ 1♀ 80 mi [c. 130 km] W Pofadder , 2918BC, 5.ix.1972, Irwin, 2980 ft [c. 910 m], roadside flowers ( NMSA) ; 2♂ 1♀ 20 km NE Springbok , 2918CA, 7.ix.1983, Londt & Stuckenberg, rocky hillside & dry watercourse veget ( NMSA) ; 4♂ 3♀ 5 km SW Pofadder , 2919AB, 7.ix.1983, Londt & Stuckenberg, dry riverbed trees ( NMSA) ; 1♂ 2♀ Bushmanld., Jackals Water [29°03'S: 17°54'E], x.1911, Lightfoot ( SAMC) ; 1♂ 10 km E Pofadder , 29°06'05"S: 19°30'26"E, 29.viii.2002, Londt, 930 m, sandy area & rocky hillside slope ( NMSA) ; 1♂ 3♀ Putsonderwater [29°14'S: 21°53'E], x.1939, Mus. Staff ( SAMC) ; 3♂ 3♀ Near Prieska , 29°40'S: 22°45'E, ix.1994, Stuckenberg, 1000 m, roadside grass ( NMSA) ; 1♀ 2 mi [c. 3 km] SW Brandkop, 3119AC, 12.ix.1972, Irwin, 1300 ft [c. 395 m], stream bed ( NMSA) ; 1♀ Visrivier 50 km E Calvinia on Williston Rd, 990 m, 31°26'15"S: 20°16'48"E, 10 xi.1998, Londt, river edge vegetation ( NMSA) ; 1♀ Lamberts Bay Rd N Elands Bay [32°18'S: 18°21'E], 26.ix.1978, Whitehead ( SAMC) ; 6♂ 32♀ Willowmore [33°17'S: 23°29'E], undated (1♂ 3♀), 1 xii.1908 (1♀), 5 xi.1909 (3♀), 10 xi.1909 (1♀), xi 1910 (1♀), 15 x.1911 (1♂), 25 x.1911 (1♀), 1 xi.1912 (1♀), xi.1914 (1♀), ix.1915 (1♂), 10 x.1916 (3♀), 20 xi.1916 (1♀), x.1917 (3♀), x.1919 (1♀), 4 x.1919 (1♂ 1♀), 10 x.1919 (2♀), 10 x.1920 (1♂), 15 x.1920 (1♀), 18 x.1920 (1♂ 5♀), 27 x.1920 (1♀), 10 xi.1920 (1♀), 1 xi.1921 (1♀), Brauns ( NMSA) .

Notes: Curran (1934) records ‘ Female, foot of Van Rhyn’s Pass, Cape Province, November 21 (Mrs. Cockerell)’. I have seen this specimen (1♀ ‘ Foot of Van / Rhyns Pass C.P. / Nov. 21 W. P.C. ’, ‘ Acnephalum

/ platygaster ’ (AMNH)) and can report that it was misidentified and should be referred to andrenoides . Females are difficult to identify because of similarity to andrenoides and so some mistakes may have been made when there were no associated males.

Distribution, phenology (Table 3) and biology: Most of the records are from southern Namibia and the Northern Cape Province of South Africa ( Fig. 67 ). Adults have been collected in August through to and including December.Although a specimen has been recorded as ‘feeding on pollen of ♀ Welwitscha’ (see list above) such behaviour is clearly highly unlikely. Asilids may, however, perch on flowers visited by potential insect prey and so could confuse some collectors.

Similar species:A large species with male genitalia similar to dorsalis , eremia , leukoros , and probolos .Apart from the distinctive shape of the hypandrium,many males have wings that are darkly stained proximally. Females not associated with males may be confused with those of andrenoides and so a few records may, for that reason, be misplaced.

Figures

Figs 6–11. Wing venation (none removed from specimens): (6) Acnephalum olivierii Macquart, 1838, holotype; (7) Acnephalomyia andrenoides (Wiedemann, 1828), lectotype ♂ Dasypogon andrenoides Wiedemann, 1828 (the shadow in the region of the anal cell is a leg situated below the wing); (8) Acnephalomyia platygaster (Loew, 1858), ♂ from 60 km S Aus; (9) Sporadothrix gracilis Hermann, 1907, ♂ from 39 km WNW of Upington; (10) Ammodaimon platythrix sp. n., holotype ♂; (11) Astiptomyia bikos sp. n., paratype ♀.

Figs 44–51.Acnephalomyia male terminalia:(44–46) A. leukoros sp. n.paratype, lateral,dorsal and ventral; (47–49) A.platygaster (Loew, 1858) topotypic ♂ lateral, dorsal and ventral; (50, 51) A. probolos sp. n. paratype, lateral and ventral. Scale lines = 1 mm.

Fig.67. Distribution of Acnephalomyia species:A. leukoros sp. n.– triangles; A.platygaster (Loew,1858)– circles.