Sisyrnodytes vestitus Oldroyd, 1974

Londt, Jason G. H., 2009, A review of Afrotropical Sisyrnodytes Loew, 1856 (Diptera: Asilidae: Stenopogoninae), African Invertebrates 50 (1), pp. 137-137 : 168-169

Sisyrnodytes vestitus Oldroyd, 1974

Figs 35, 36 , 44

Sisyrnodytes vestitus: Oldroyd 1974: 73 ; 1980: 369 (catalogue).

Redescription:

Male (based on holotype in excellent condition).

Head: Dark red-brown with dark red-brown, white and pale orange setae. Antennae: Dark red-brown except for tip of style which is yellowish. Scape and pedicel dark red-brown setose. Major ventral setae of pedicel project beyond level achieved by postpedicel. Basal element of style short (only slightly longer than broad). Eye to face width ratio 2.0:1. Mystax shortish, dark red-brown except for a few small white setae dorsally. Frons and vertex white and pale orange setose. Laterally situated frontal setae not extending below antennal sockets. Occipital setae dark red-brown, postoculars mixed white and pale orange. Palps and proboscis black setose.

Thorax: Dark red-brown. Mesonotum entirely setose except for narrow paramedial strips, sutural and postsutural spots. Lateral macrosetae dark red-brown (npl) and pale orange (spal & pal), other setae mostly mixed dark red-brown, white and pale orange, but there are small clusters of uniformly white setae situated anteriorly and at level of transverse suture. Scutellum apruinose with poorly defined transverse groove (has crinkled appearance); disc asetose, c. 12 dark red-brown major apical setae accompanied by weaker yellowish setae. Pleural setae dark red-brown and orange. Anepisternum orange setose anterodorsally, dark red-brown posterodorsally, katepimeron orange setose, katatergals dark red-brown, long, shafts more or less smooth. Legs: Dark red-brown, mainly dark red-brown setose (there are some small white and orange setae dorsally on pro- and mesothoracic legs). Claws longish, dark red-brown; empodia yellowish, pulvilli minute to absent. Wings 5.3× 2.5 mm. C white setose basally; membrane pale brownish stained basally. Haltere dark red-brown.

Abdomen: Dark red-brown; dark red-brown setose except for posterior parts of T1–2 which are white setose (a few white setae also on T3).

Genitalia:Not dissected, but visible structures conform to dissected and illustrated genitalia of a male from Gemsbok Pan ( Figs 35, 36 ). Epandrium greatly reduced and simple, proctiger extending well beyond it. Gonocoxite with external lobe tapering to fairly acute tip, internal lobe slender, fairly long. Gonostylus fairly long, slender.Hypandrium flattish, sub-triangular in ventral view, with fairly broad (in ventral view) medial lobe projecting beyond all other structures.Aedeagus fairly robust, tapering to broadly-rounded apex.

Female: Similar to male, but possess far more white and yellowish setae (e.g. mystax is yellow and white setose—one has a few dark red-brown setae along epistomal margin; antennae yellow setose; thorax, including legs, predominantly yellowish setose; abdomen with all visible terga equipped with white setae posteriorly); wing membranes are weakly orange stained adjacent to veins.

Variation: Wing length ơ 5.2–6.4 mm (– x= 5.7 mm, n=4), ^6.4 –7.1 mm (– x= 6.8 mm, n=2); males generally smaller than females. The South African male is somewhat red-brown setose where other males are pale orange and this may represent geographical variation.

Type specimens examined (both NMSA): NAMIBIA: ơ (holotype) ‘ 22m. [probably miles = c. 35 km] up Auob / riv. [see comment below] April 1933 / G. van Son’, ‘ Sisyrnodytes / vestitus sp. n. / det. H. Oldroyd 1971 / Holotype’ [white]; 1 ơ (paratype) ‘V.–L. Kal. Exp. / Gemsbok Pan. [26°07'S: 18°57'E] / 23/4 – 5/5/ 30.’, ‘ Sisyrnodytes / vestitus sp. n. / det. H. Oldroyd 1971 / Paratype’ [white]. Note: The paratype is a male and not a female as recorded by Oldroyd (1974).

Type locality: While a gazetteer gives the coordinates of the Auob River as 26°27'S: 20°38'E (which is in Botswana) this is a long river traversing much of Namibia. Although the collecting site has been given as 22 miles (c. 35 km) up the river, it is not known from where this measurement was taken .

Other specimens examined: NAMIBIA: 1 ơ 2^‘ Namibia 22.iv.1983 / 111km W of Windhoek / 2116 CC Stuckenberg / & Londt sparse bush / and thornveld’ ( NMSA) . SOUTH AFRICA: 1 ơ ‘ Kuruman [27°28'S: 23°26'E] / 8 April 1933 / G. van Son’ ( NMSA) .

Distribution, phenology and biology: Known only from central Namibia and the Northern Cape Province of South Africa ( Fig. 44 ).Adults, active during April and May (Table 1), fly during late summer when these localities usually receive some rainfall. Little is known of the biology, but I collected species in ‘sparse bush and thornveld’.

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

Figures

Figs 31–38. Sisyrnodytes species, ơ terminalia in lateral and ventral aspects: (31, 32) S. oligotrichus sp. n., holotype; (33, 34) S. subater Oldroyd, 1957, Serowe; (35, 36) S. vestitus Oldroyd, 1974, Gemsbok Pan paratype; (37, 38) S. xeromyia sp. n., holotype. Scale lines = 1 mm.

Fig. 44. Distribution of Sisyrnodytes aethes sp. n. (•), irwini Oldroyd, 1974 (·) and vestitus Oldroyd, 1974 (9).