Xestopelta Dasch 1964 a

Klopfstein, Seraina, 2014, Revision of the Western Palaearctic Diplazontinae (Hymenoptera, Ichneumonidae), Zootaxa 3801 (1), pp. 1-143 : 113-114

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Xestopelta Dasch 1964 a


Xestopelta Dasch 1964 a

Type species. Syrphoctonus vertebratus Cushman 1922

Diagnosis. Xestopelta species can readily be identified by the shape of the clypeus which has its margin thickened and protruding as a bilobed elevation ( Fig. 12 View FIGURE 12. A K), and by the yellow shoulder marks with the inner corners extending back as two parallel lines over most of the mesoscutum ( Fig. 13 View FIGURE 13. A D).

Face very finely coriaceous, thus shining in part, without vertical impressions, in females black with yellow inner eye margins, in males entirely yellow. Clypeus with apical margin thick, clypeus thus convex and protruding when viewed in profile. Antenna with apical flagellomeres wider than long in female but longer than wide in males, without tyloids and without long setae. Mesoscutum with notauli present or absent; smooth and shining, sometimes with some irregular and very weak punctures, yellow shoulder marks large, their inner corners usually extended as two parallel lines over most of mesoscutum ( Fig. 13 View FIGURE 13. A D); mesopleuron entirely smooth and shining, impunctate; epicnemial carina interrupted behind fore coxae. Propodeum with carinae partly ( X. sexcincta ) or fully reduced ( X. gracillima ), enclosing only lateral areas or no areas at all; propodeal spiracle inconspicuous; scutellum only carinate basally. Fore wing areolet absent; hind wing with 2–3 basal hamuli. Hind tibia orange ( X. gracillima ) or white with a dark apex ( X. sexcincta ). Female metasoma strongly compressed from apex of third segment, tergites 3 or 4 to 6 with hind margins usually concave, extending further back laterally than dorsally; tergites without transverse impressions. First tergite without median dorsal carinae. Second tergite with spiracle dorsal, above lateral fold, third tergite with spiracle below or behind the fold. Metasoma black with yellow markings on hind margins of some tergites. Ovipositor sheaths 0.3 times as long as hind tibia, parallel-sided and fully enclosing ovipositor, basally smooth, apically with sparse to dense but inconspicuous setae. Males with tergites 9 and 10 fused as a syntergum, sternite 9 about 1.5 times wider than long, emarginated apically, thus forming two lobes, their outer corners rounded.

Phylogeny. In the past, Xestopelta species have been associated mainly with the genus Promethes because of the smooth and shining mesosoma, or with Homotropus , which in general was often used as a taxonomic waste basket. Results from a molecular phylogeny ( Klopfstein et al. 2011), however, placed this genus with high support in the Diplazon genus group. Morphological examination, especially of the colouration of the female face and the morphology of the male apical sclerites, further support this placement. The position of Xestopelta within this genus group is unstable between different genes, and its resolution requires additional data.

Distribution. Holarctic and Afrotropical. Only five species belong to this genus, the Palaearcic Xestopelta gracillima and X. sexcincta treated here, the Nearctic X. vertebrata (Cushman) , and the Afrotropical X. alutacea (Bennoit) and X. lugens (Seyrig) .

Biology. Nothing is known about the host relations of this genus.

Notes. This genus was erected by Dasch (1964 a) to include X. vertebrata (Cushman) from the Nearctic and X. lugens (Seyrig) from Madagascar. The circumscription of the genus had to be expanded here to account for the morphology of the Western Palaearctic species. Especially, the epicnemial carina is interrupted in both Xestopelta gracillima and X. sexcincta , and the carination of the propodeum is only partly reduced in X. sexcincta .

Key to species

1. Propodeum with carinae mostly reduced, at most with pleural and traces of lateral longitudinal carinae. Hind tibia orange, apex slightly dark........................................................... Xestopelta gracillima (Schmiedeknecht)

- Propodeum with pleural and lateral carinae usually complete, apical transverse carina partly present or at least indicated by carinulae. Hind tibia white with dark subbasal and apical bands. (Female unknown).......... Xestopelta sexcincta (Brauns)