Octaseps

Jean- Paul Haenni & Dalton de Souza Amorim, 2016, Two new Afrotropical genera of Scatopsidae (Diptera), Mitteilungen Der Schweizerischen Entomologischen Gesellschaft 89, pp. 127-142 : 128-134

Octaseps alata sp. nov.

( Figs 1–10 )

Type locality.South Africa, Kwa-Zulu Natal: Karkloof Range, Geekie’s Farm, 29°16’ S30°21’ E.

Material examined. Holotype: ♂,labelled: Süd-Afrika, Kwa Zulu Natal, Howick District , Karkloof Range, Geekie’s Farm , 29°16’ S 30°21’ E, Malaise Trap, 11–29.X.2000, W. Barkemeyer leg. in coll. MHNN. Holotype dissected, slide mounted, in fairly good condition.

Diagnosis.Dorsal suture between thorax and abdomen forming asinuous Vshaped thickened rim laterally ( Fig. 4 ). Male terminalia ( Figs 9–10 ) with gonocoxites well-developed, parameres with teeth, aedeagus elongate, with an apically enlarged, flattened lobe.

Description.Male. 2.8 mm long (in alcohol). Head, body and legs black, hardly shining, densely pilose, especially on notum and on last abdominal segment. Labellum and palpi brownish, halters yellowish brown. Apical half of posterior tibia and all tarsi slightly lighter than remaining legs. Head ( Fig. 3 ) as high as long. Supraantennal eye-bridge well developed; antennae longer than head, flagellum with 8flagellomeres, wider than long, each bearing asingle whorl of setae, last flagellomere longer than two preceding ones; frons setose between antennae and eyebridge; palpus adpressed, elongate, obtusely pointed apically, as long as labella. Thorax with notum longer than wide; spiracular sclerite somewhat elongate, nearly twice as long as high, acute anterodorsally ( Fig. 5 ); an elongate row of about 20 supralar setae; scutellum rounded, with arow of lateral setae but devoid of pilosity on posterior third. Postnotal phragma elongate, as long as notum. Wing 2.4 mm long. Membrane very lightly brownish-tinged; anterior veins yellowish brown, posterior veins hyaline, R4+5 elongate, reaching Cat about 2/3 of wing length; base of A2/CuP somewhat inflated and strongly sclerotized, bearing ashort spinose microchetosity. Stem of halters with arow of setae and knob bearing asubbasal posterior patch of short setae near base ( Fig. 6 ). Abdomen constricted at level of first segment after base, dorsal suture between thorax and abdomen V-shaped, forming laterally a sinuous, thickened elevated rim ( Fig. 4 ); tergites 1–7 normally developed, tergite 2with apair of submedian lunules along anterior margin; sternites 2– 7present, normally sclerotized, 2–4 narrower; pregenital segment 7anteriorly with an entire, narrow, heavily sclerotized line of sclerotization; aweakly sclerotized area also present around spiracle 7, on pleural membranes joining tergite and sternite; tergite 7( Fig. 7 ) elongate, roof-shaped, with rounded posterior margin; sternite 7 Abbreviations: ae – aedeagus; gc – gonocoxite; ep – epandrium; pa – paramere.

( Fig. 8 ) shorter, posterior margin with median emargination surrounded by apair of submedian rounded lobes and sublateral shallow emarginations. Genital capsule ( Figs 9–10 ) rotated 180°; epandrium strongly sclerotized apically, with amedian shining projection; gonocoxites oblique, diverging apically, somewhat wingshaped,heavily sclerotized, strongly pilose apically; parameres complex, heavily sclerotized, teethed both basally and distally; aedeagus elongate, geniculate ( Fig. 9 ), widened medially and spatulate apically, with anearly translucent dorsal process ( Fig. 10 ). Sperm pump lying free in abdominal cavity, separated from genital capsule.

Female. Unknown.

Distribution.Only known from the type-locality in Kwa Zulu Natal, South Africa.

Etymology. The specific epithet of the name is a Latin adjective meaning «winged», as areference to the shape of the male genital capsule.

This genus lacks typical features of any of the tribes of Scatopsinae , hence placing the genus within the system is particularly challenging. There is no question that Octaseps belongs to the Scatopsinae . This is suggested by the sperm pump lying free in the abdomen, the fold in the wing between M2 and M4,and the presence of setation on the frons between the antennae and the eye-bridge, among other features synapomorphic for the subfamily ( Amorim 1982). The lack of setation on the wing membrane and veins also indicates that it does not belong in the Rhegmoclematini (although Diamphidicus also lacks this feature). The presence of pedicelar setae in Octaseps also shows that it does not fit into the Rhegmoclematini . Finally, the absence of the tegula of the halter is an apomorphic feature shared by all Scatopsinae except the Rhegmoclematini .

The elongate R4+5 joining costa beyond the middle of the wing is aplesiomorphic condition in the evolution of the family. In the Scatopsinae R4+5 reaching Cbefore the mid of the wing is seen only in Swammerdamella Enderlein, 1912 and other higher genera of Swammerdamellini – the relatively long R4+5 in Octaseps certainly excludes the genus from the clade that has Akorhexoza Cook, 1978 , Rhexoza Enderlein, 1936 , Quateiella Cook, 1975 etc. ( Amorim 2007). The shape of the anterior thoracic spiracular sclerite is also helpful in this discussion. In all genera of Swammerdamellini but in Pararhexosa Freeman, 1990 it is more or less elongated, the posterior end of the sclerite often being more slender than the anterior end. The anterior spiracle sclerite in Octaseps has adorso-anterior extension, a condition seen in the genera of Scatopsini , as well as in Pararhexosa .

The male terminalia bearing two pairs of well-developed processes, and a complex elongate aedeagus are features seen in all four genera of Scatopsini . Indeed, Octaseps has important similarities with Aztecatopse Haenni &Huerta, 2014 and the discussion in Haenni &Huerta (2014) applies here to aconsiderable extent. In fact, the similarities of Pararhexosa with Octaseps may actually suggest that the position of Pararhexosa in the Swammerdamellini is mistaken, and that the genus could more properly belong in the Scatopsini . The inclusion of Octaseps gen.nov. in the Scatopsini is clearly the best solution for the time being. The peculiar thickened suture between the thorax and the abdomen of Octaseps is unique among the Scatopsidae and is evidently an autapomorphy of the new genus.

Within the Scatopsini , the new genus may be more closely related to Apiloscatopse Cook, 1974 – agenus mainly Holarctic in distribution, also known from an Afrotropical species, A. labellata ( Cook, 1965) , from South Africa – or to Pharsoreichertella Cook, 1974 . A. labellata was originally described based on afemale and placed in the genus Scatopse ( Cook, 1965a) . Its precise position within the scatopsines, however, should be still considered as uncertain.

Figures

Figs 1 – 2. Octaseps alata sp. nov. ♂: — 1. Wing; — 2. Habitus (wings removed) (photographs Jessica Litman).

Figs 3 – 4. Octaseps alata sp. nov. — 3. Head and thorax, side view; — 4. Thorax and base of abdomen, subdorsal view showing the thickened rim between thorax and abdomen (marked) (photographs Jessica Litman).

Figs 5 – 10. Octaseps alata sp. nov. ♂: — 5. Spiracular sclerite; — 6. Halter; — 7. Tergite 7; — 8. Sternite 7; — 9. Genital capsule, ventral view; — 10. Genital capsule, dorsal view.