Sisyrnodytes aterrimus Engel, 1929

Londt, Jason G. H., 2009, A review of Afrotropical Sisyrnodytes Loew, 1856 (Diptera: Asilidae: Stenopogoninae), African Invertebrates 50 (1), pp. 137-137 : 144-146

Sisyrnodytes aterrimus Engel, 1929

Figs 10–12 , 40

Sisyrnodytes aterrimus: Engel 1929: 170 ; Oldroyd 1957: 82–83 (figs 4, 5 ơ genitalia); 1974: 73; 1980: 368

(catalogue).

Redescription:

Male (based on holotype in excellent condition, slightly dusty).

Head: Dark red-brown to blackish, blackish setose.Antennae:Dark orange-brown except for tip of style which is pale yellowish. Scape and pedicel blackish setose. Major ventral setae of pedicel shortish, failing to project beyond level achieved by postpedicel. Basal element of style short (shorter than broad). Eye to face width ratio 2.5:1. Mystax shortish, black. Frons and vertex blackish setose. Laterally situated frontal setae not extending below antennal sockets. Occipital and postocular setae blackish. Palps and proboscis black setose.

Thorax: Dark red-brown to black. Pronotum black setose. Mesonotum entirely black setose except for few white setae corresponding in position to anterior acrostichals and asetose narrow paramedial strips, sutural and postsutural spots. Scutellum apruinose with poorly defined transverse groove (has crinkled appearance), disc asetose, apical setae blackish, difficult to count (c. 20). Pleural setae dark red-brown to black, katatergals long, shafts more or less smooth. Legs: Red-brown, black setose. Claws blackish; empodia short yellowish, pulvilli minute to absent. Wings 3.7× 1.5 mm, C black setose basally; membrane transparent. Haltere dark red-brown.

Abdomen: Dark red-brown, blackish setose, setae generally tiny except along lateral margins of terga.

Genitalia: Not dissected, but visible structures appear to conform to dissected and illustrated genitalia of the paratype ơ ( Figs 10–12 ). Epandrium greatly reduced and simple in structure, proctiger extending well beyond it. Gonocoxite with external lobe tapering to blunt tip and with ventral flange, internal lobe with forked distal end. Gonostylus slender, distinctly curved subapically, projecting beyond level attained by internal lobe of gonocoxite. Hypandrium flattish, almost oval in ventral view, proximal end only slightly broader than distal end. Aedeagus fairly robust with blunt tip.

Female: Similar to males except wings are weakly stained basally. Staining extends along most of the veins.

Variation: Wing length ơ 3.7–5.3 mm, ^3.4 –6.1 mm. The fairly large sample from Zomba was measured (except for 2 ơ 1^with wings missing) to give an indication of size range at a single locality: ơ 3.8–5.3 mm (– x= 4.4 mm, n=16), ^4.2 –6.1 mm (– x=5.0 mm, n=8). Females on average bigger than males. The holotype is more extensively blackish setose when compared with all other males. Most males have some white setae in the following places – dorsal part of mystax, frons and vertex, postocular region, prothorax, anterior and lateral (few) parts of mesonotum, posterior margins of T1–3 mediolaterally (not medially or laterally but in-between). Sexual dimorphism in setal coloration is strongly evident in as much as the entire head, in males (except for palpi and proboscis) is white setose, prothorax is mostly white and yellow setose (few dark red-brown setae), mesonotum extensively yellow and white setose (except for a few dark red-brown setae), legs extensively white setose except for macrosetae which are blackish, all abdominal terga have white setose posterior margins.

Type specimens examined: ZIMBABWE: ơ (holotype) ‘ Bulawayo [20°09'S: 28°35'E] / Rhodesia / 10.vi.1923 / R. Stevenson’ [poorly handwritten label], ‘ Sisyrnodytes / aterrimus / Engel / Holotype No: 12’ [red ink on white], ‘ Sisyrnodytes / aterrimus / n. sp. / Dr. E. O. Engel det.’, ‘ Sisyrnodytes / aterrimus / Type Engel’ [orange] (NMSA); 1 ơ (paratype) ‘ Bulawayo / 10.vi.1923 / R. Stevenson’ [printed], ‘ Sisyrnodytes / aterrimus / n. sp. / Dr. E. O. Engel det.’ (NMSA). Notes: The holotype is double mounted on a strip of card and a little green verdigris is present above and below the specimen. Engel (1929) called the two ơ specimens studied by him the ‘type and cotype’ respectively.As one of the specimens carries an old orange ‘type’ label I accept this specimen as the holotype; the other must therefore be considered a paratype. While the types were originally deposited in the Transvaal Museum, Pretoria, their Diptera collection was transferred in its entirety to the Natal Museum during the early 1970s.

Other material examined (all BMNH unless stated otherwise): MALAWI: 1 ơ ‘ Nyasaland / Valley of N. Rukuru [River, 09°53'S: 33°56'E] / Karonga Dist. / 2,000 to 4,000 ft. / 15–18 July , 1910 / S.A. Neave’; 1^‘ Nyasaland / N.W. shore of / Lake Nyasa / nr. Karonga [09°56'S: 33°56'E]. / vii.1910 / S.A. Neave’; 1^‘ N.W. shore of L. Nyasa. / fm. Florence Bay [Chitimba, 10°36'S: 34°12'E] to Karonga. / 30 June 6 July 1910, 1,650 ft. / S.A. Neave’; 9 ơ 1^‘ Nyasaland / Lingadzi [Forest Reserve, 13°58'S: 33°48'E] / Nr. Domira Bay . / 1700 ft 30.6.15 / Dr. W.A. Lamborn’; 1^‘ Nyasaland / Protectorate / abt. 6 miles S.E. of / Lake Pamalombe [L. Malombe, 14°38'S: 35°12'E]. in flowers of the “sausage / tree”. in company with / bees

( Trigona spp. ). / 10.viii.1911. / R. Newstead. / 1912.188'; 18 ơ 9^‘ H. S. Stannus / Zomba [15°23'S: 35°20'E] / Nyasaland’; 1^‘ Nyasaland / Namurawa [?] / 1915 / c. Mason’. ZAMBIA: 1 ơ 6^‘ N.W. Rhodesia / Chilanga [09°14'S: 32°27'E] / 4.iv, 12 13 14 19 22.vii, 16.viii.13 [ơ] [each specimen with different date] / R.C. Wood / On rocky path’; 1^‘ N.E. Rhodesia: en route from / Luangwa to Petauke [14°15'S: 31°20'E]. / Sept. 14–17.1910. / S.A. Neave’; 1^‘ N.E. Rhodesia / Luangwa to / Petauke / 14–17 Sep. 1910 / S.A. Neave’; 1^‘ N.E. Rhodesia / Karonga [? Kalonga, 14°36'S: 31°15'E] / July 13, 1910 / S.A. Neave’; 1 ơ 3^‘ N.E. Rhodesia / Upper Luangwa R. [15°36'S: 30°25'E] / 27 July 13 August 1910 / S.A. Neave’; 1 ơ 1^N.E. Rhodesia: / Upr. Luangwa Riv. / Junctions of Luwumbu / & Mwailesi Rivers. / 27.vii.–13.viii.1910 / S.A. Neave’. ZIMBABWE: 2 ơ ‘ Sanyati [River, 17°30'S: 29°23'E] Valley / S. Rhodesia. / Sept. – Dec., 1925. / R H R Stevenson’ ( NMSA); 1 ơ ‘ Victoria Falls [17°56'S: 25°50'E] / S. Rhodesia / 29.7.1922 / Rhodesia / Museum’ .

Distribution, phenology and biology: Recorded from Malawi, Zambia and Zimbabwe ( Fig. 40 ). This distribution overlaps with that of major , but as of yet the species have not been recorded together at the same locality. Adults are active from June through September (Table 1), as cited by Oldroyd (1957), although one record exists for April (this may be an error in labelling—perhaps ‘iv’ should read ‘vi’). The species therefore flies during winter. Biological data are minimal – one label states that the specimen was collected in flowers of the sausage tree ( Kigelia africana ) and was found in the company of bees of the genus Trigona . The significance of this observation is unknown. Some specimens were collected on rocky pathways. One female from Zomba is pinned with a heteropteran of the family Lygaeidae .

Similar species: This species is similar to apicalis , 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. 40. Distribution of Sisyrnodytes aterrimus Engel, 1929 (•), major Adams, 1905 (·) and nilicola (Rondani, 1850) (9).