Sisyrnodytes apicalis Oldroyd, 1957

Londt, Jason G. H., 2009, A review of Afrotropical Sisyrnodytes Loew, 1856 (Diptera: Asilidae: Stenopogoninae), African Invertebrates 50 (1), pp. 137-137 : 143-144

Sisyrnodytes apicalis Oldroyd, 1957

Figs 8, 9 , 42

Sisyrnodytes apicalis: Oldroyd 1957: 82 ; 1974: 73; 1980: 368 (catalogue).

Redescription:

Male (based on holotype in excellent condition; left prothoracic tarsus, left mesothoracic tarsomere 5, and terminal part of right prothoracic tarsomere 5 broken off).

Head: Dark red-brown to black, with black, white and pale brownish setae. Antennae: Dark brown except for tip of style which is yellowish. Scape and pedicel mostly black setose (a few pale brown setae dorsally on pedicel). Major ventral setae of pedicel project beyond level achieved by postpedicel. Basal element of style short (slightly longer than broad). Eye to face width ratio 2.5:1. Mystax shortish, black except for small group of white setae dorsally. Frons and vertex white setose except for c. 4 long black ocellar setae. Laterally situated frontal setae not extending below antennal sockets. Occipital setae mostly black, postoculars mixed white and yellowish. Palps and proboscis black setose (tip of proboscis has white setae).

Thorax: Dark red-brown to black. Pronotum white, brown and dark red-brown setose. Mesonotum entirely setose except for narrow paramedial strips, sutural and postsutural spots. Lateral macrosetae black, other setae mostly mixed white and pale brownish orange, but there are small clusters of uniformly white or black setae situated mainly anteriorly. Scutellum apruinose with poorly defined transverse groove (has a crinkled appearance); disc asetose, apical setae numerous black, yellowish and white (black setae constitute a posterior row, are best developed and number c. 40). Pleural setae mostly black except for some white and yellowish setae dorsally on anepisternum. Katepimeron black setose, katatergals black, long, shafts more or less smooth. Legs: Dark red-brown, mainly black setose (there are some small white and yellowish setae on pro- and mesothoracic legs). Claws longish, dark red-brown; empodia short yellowish (most appear broken); pulvilli minute to absent. Wings 5.9× 2.5 mm; C white setose basally; membrane pale brownish stained except for distal third of wing. Haltere dark red-brown.

Abdomen: Dark red-brown, black setose except for posterior parts of T1–3 which are mostly white setose.

Genitalia: Not dissected, but visible structures appear to conform to dissected and illustrated genitalia of a male from Strandforntein ( Figs 8, 9 ). Epandrium greatly reduced and simple in structure, proctiger (cerci) extending well beyond it. Gonocoxite with external lobe tapering to obliquely pointed tip, internal lobe dorsoventrally compressed. Gonostylus longer than internal lobe of gonocoxite, slender and with curved distal end. Hypandrium flattish, triangular in ventral view, with medial lobe extending as far as tip of internal lobe of gonocoxite and with a broadly rounded distal end. Aedeagus fairly robust with an obliquely pointed tip.

Female: Similar to male, but have more white setae (for example, antennal setae mixed white, dark red-brown and pale brown; mystax more extensively white in dorsal region; ocellar setae white; pleural setae more extensively white; legs more extensively white setose).

Variation: Wing length 4.6–6.6 mm. The male from Strandfontein (near type locality) agrees well with the holotype as does the Namibian male, although there are small differences in the latter (e.g. some mesonotal macrosetae (spal & pal) are pale yellowish). Holotype (examined): ơ SOUTH AFRICA: Western Cape: ‘Holo- / type’ [circular with red rim], ‘ Cape Town, / Milnerton. [33°52'S: 18°29'E] / Feb. 1926 ’, ‘S. Africa. / R.E. Turner. / Brit. Mus. / 1926–119.’, ‘ Sisyrnodytes / apicalis Oldroyd / det. H. Oldroyd 1957 / Holotype’ (BMNH). The specimen is double mounted on a strip of cellulose and a little green verdigris is present above and below the specimen.

Other specimens examined: NAMIBIA:1 ơ ‘ Namibia 22.iv.1983 / 146km E. Swakopmund [22°41'S: 14°32'E] / Open savannah / Stuckenberg & Londt’ ( NMSA) . SOUTH AFRICA: 1^‘ Strandfontein [34°05'S: 18°33'E] / C.P.’ ~ ‘Mus. Exp. / Feb. 1949 ’ ( SAMC) ; 1 ơ 5^‘ Strandfontein / March 1950 / Zinn, Hesse’ ( SAMC) .

Distribution, phenology and biology: Recorded from two localities on the sandy ‘Cape Flats’ near Cape Town, Milnerton (type locality) and Strandfontein, but also recorded some distance away from Swakopmund ( Namibia) ( Fig. 42 ). Collected in February, March and April (Table 1). While no ecological data is recorded on labels localities have sandy coastal dunes in common and so it is likely that the species inhabits this environment.

Similar species: This species is similar to aterrimus , major and vestitus .

Figures

Figs 6–12. Sisyrnodytes species, ơ terminalia: (6, 7) S. aethes sp. n., holotype, lateral and ventral (position of aedeagus faintly stippled); (8, 9) S. apicalis Oldroyd, 1957, Strandfontein, lateral and ventral; (10–12) S. aterrimus Engel, 1929, Bulawayo paratype: (10) lateral, (11) oblique view of gonocoxite, (12) ventral.Abbreviations: aed – aedeagus, el – exterior lobe of gonocoxite, epan – epandrium, goncx – gonocoxite, gonst – gonostylus, hypd – hypandrium, il – interior lobe of gonocoxite, proct – proctiger. Scale lines = 1 mm.

Fig. 42. Distribution of Sisyrnodytes apicalis Oldroyd, 1957 (•), subater Oldroyd, 1957 (·) and xeromyia sp. n. (9).