Sceliotrachelus Brues 1940

van Noort, Simon, Lahey, Zachary, Talamas, Elijah J., Austin, Andrew D., Masner, Lubomir, Polaszek, Andrew & Johnson, Norman F., 2021, Review of Afrotropical sceliotracheline parasitoid wasps (Hymenoptera, Platygastridae), Journal of Hymenoptera Research 87, pp. 115-222 : 115

publication ID	https://dx.doi.org/10.3897/jhr.87.73770
publication LSID	lsid:zoobank.org:pub:7137A82A-62E3-4958-A48C-B05BEA80FE60
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treatment provided by	Journal of Hymenoptera Research by Pensoft
scientific name	Sceliotrachelus Brues 1940
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Sceliotrachelus Brues 1940 View in CoL

Figs 29 View Figure 29 , 30 View Figure 30 , 31 View Figure 31 , 32 View Figure 32 , 33 View Figure 33 , 34 View Figure 34 , 35 View Figure 35 , 36 View Figure 36 , 37 View Figure 37 , 38 View Figure 38 , 39 View Figure 39 , 40 View Figure 40 , 41 View Figure 41 , 42 View Figure 42 , 43 View Figure 43 , 44 View Figure 44 , 45 View Figure 45 , 46 View Figure 46 , 47 View Figure 47 , 48 View Figure 48 , 49 View Figure 49

Sceliotrachelus Brues, 1908: 13 (original description; type: Sceliotrachelus braunsi Brues, 1908, by monotypy and original designation). Kieffer 1926: 561, 605 (description, keyed); Muesebeck and Walkley 1956: 397 (citation of type species); Masner 1964: 9 (description); Kozlov 1972: 134 (key to species); Masner and Huggert 1989: 113 (description, species list); Vlug 1995: 75 (catalogued, catalogue of world species); Veenakumari et al. 2019: 453 (key to genera of the Isolia -cluster, keyed); Lahey et al. 2019b: 44 (keyed).

Pulchrisolia Szabó, 1959: 395 (original description. Type: Pulchrisolia maculata Szabó, by monotypy and original designation); Masner 1964: 11 (treated as a synonym of Sceliotrachelus Brues); Masner and Huggert 1989: 29, 108 (genus resurrected).

Generic redescription to accommodate two new additional species.

Colour of head and mesosoma black; metasoma black to light brown or orange-brown; scape, pedicel, flagellar segments in female, legs orange-brown; club and flagellar segments in male black; wings either infuscate or dark with white areas.

Head wider than long, narrowing towards clypeus; frontal ledge absent; antenna 10-merous; clava subcompact, terminal segment tapering, 3-merous; arrangement of setae on ventral surface of each clavomere forming a chevron-shaped area with the posterior-most papillary sensillum at its point; male antennae filiform; toruli in close apposition, separated by less than one torular diameter, positioned on frontal protrusion close to mandibles, situated well below compound eyes; inter-antennal process present, acuminate distally; clypeus smooth, with convex margin; mandibles bidentate; frons micro-reticulate, finely punctate in dorsal half and along inner orbits, with minute setae medially; malar sulcus absent, malar space three-fifths of eye height; facial and malar striae absent; hyperoccipital carina present on dorsal margin of vertex, anterior profile with two raised areas corresponding with lateral ocelli; vertex anterior to hyperoccipital carina finely punctate, with minute setae, posterior of carina micro-reticulate; lateral ocelli positioned posterior of hyperoccipital carina, separated from inner margin of compound eye by more than 5 ocellar diameters; occiput micro-reticulate; occipital carina present, with or without occipital pit; occipital carina ventrally reaches, or approaches the anterior articulation of the mandible.

Mesosoma. Pronotal shoulder sharply angled transversely, with pronotal carina present posteriorly; pronotum transverse, weakly to strongly triangular with strong medial longitudinal sulcus (possibly representing convergence of two epomia); shoulders weak to strong, micro-reticulate to polished; pronotal cervical sulcus with depressions at ventral and dorsal apices, dorsal depression setose; admedian depressions present, widely spaced, longitudinally offset from deep posterior notaular grooves; mesoscutellar disc flanked by parallel longitudinal grooves, which fuse with the trans-axillar carina; axillar carinae present or absent; axillae moderately to strongly excavated; sculpture of mesoscutellum micro-reticulate to polished; mesopleuron polished, may be dorsally transversely ridged, or longitudinally compressed, much higher than long; transepisternal line absent; mesopleural carina strong, may form a flange posteriorly; foamy structures present posteriorly on metapleuron, concealing metapleural carina; metapleural pit present; submarginal vein of fore wing absent or spectral; marginal cilia of fore wing absent; wing microtrichia normal, or strong and needle-like; hind wing may have a strong thickened marginal vein.

Metasoma. Ovate, sessile with indistinct lateral carina; T1 transverse in dorsal view; T2 large, as long as wide, comprising more than half to 4/5ths of metasomal length; foamy structures present anterolaterally on T1 and on S1; posterior margin of T1 with fringe of long setae; anterior margin of T2 with transverse furrow covered by elongate setae of posterior margin of T1, containing minute setae that often accumulate a white exudate; scattered long setae present on S2; tibial spur formula 1-2-2; protibial spur with comb of setae.

Diagnosis.

Sceliotrachelus is recognizable by the median longitudinal sulcus on the pronotum and the presence of long setae on sternite 2. These two characters separate the genus from all other sceliotrachelines. Additional diagnostic characters are: the malar sulcus with tract of long, straight setae; hyperoccipital carina present with the lateral ocelli positioned posterior to its margin; widely spaced admedian depressions on the mesoscutum; notauli present; transaxillar and axillular carinae fused; axillar area as wide as or wider than mesoscutellum; transepisternal line absent; metapleuron with lateral projection in ventral half; ventral surface of coxae, trochanters, and portion of femur and S2 with long setae; scrobe present on dorsal surface of hind femur; foamy structures present on propodeum, metapleuron, T1, and S1; anterior margin of T2 with a transverse, setose furrow; submarginal vein of fore wing absent.

Sceliotrachelus shares morphological affinities with Afrisolia , Isolia and Pulchrisolia , together forming the Isolia -cluster, which is defined by the combed fore tibial spur. Additional putative synapomorphic characters centre on the foamy structures present on the propodeum in these four genera ( Lahey et al. 2019b; Veenakumari et al. 2019). Pulchrisolia is hypothesized as being distinct from Sceliotrachelus by the presence of a short, tubular submarginal vein on the fore wing (but this is also present in S. karooensis sp. nov.); a transverse frontal ledge just above the toruli (except for P. ankremos ), no setae on sternite 2, and absence of the lateral projection on the lower metapleuron ( Masner and Huggert 1989; Lahey et al. 2019b).

Species richness.

Sceliotrachelus braunsi Brues, 1908 (South Africa) (Figs 29 View Figure 29 - 36 View Figure 36 , 49 View Figure 49 ).

Sceliotrachelus karooensis van Noort, sp. nov. (South Africa) (Figs 37 View Figure 37 - 42 View Figure 42 , 49 View Figure 49 ).

Sceliotrachelus midgleyi van Noort, sp. nov. (South Africa) (Figs 42 View Figure 42 - 48 View Figure 48 ).

Distribution.

The genus Sceliotrachelus is, as far as known, confined to the Eastern and Western Cape Provinces of South Africa (Fig. 50 View Figure 50 ).

Biology.

Unknown, but likely to be parasitoids of arthropods living in the leaf litter habitat (see discussion).

Key to species of Sceliotrachelus

1	Pronotum and occiput glabrous (A); occipital pit present (A); acetabular carina (ac) and mesopleural epicoxal sulci (mes) not converging, fore and mesocoxae separated by more than one fore coxal width (B); fore wing of normal shape, twice as long as wide (C)	Sceliotrachelus karooensis van Noort, sp. nov.
-	Pronotum and occiput setose (a); occipital pit absent (a); acetabular carina (ac) and mesopleural epicoxal sulci (mes) converging, fore and mesocoxae separated by less than one fore coxal width (b); fore wing narrow and elongate, at least 3 × longer than wide, anterior and posterior margins subparallel (c)	2
2	Genal and pronotal rugae present (A); mesoscutellum compressed, narrow, 2.5 × wider than long (B); mesoscutellar disc medially with broad, shallow, longitudinal excavation, axillar carinae weakly raised (B); costal margin of hind wing with thick band of black sclerotization that runs nearly the entire length of the wing (B); fore wing extending beyond posterior margin of T2	Sceliotrachelus braunsi Brues
-	Genal and pronotal rugae absent (a); mesoscutellum broader, twice as wide as long (a); mesoscutellar disc square, medially and longitudinally evenly raised into a hump, laterally defined by strongly raised longitudinal axillar carinae (b); costal margin of hind wing not sclerotized; fore wing not reaching posterior margin of T2 (c)	Sceliotrachelus midgleyi van Noort, sp. nov.