Plectiscus oblongus Varga, 2024

Varga, Oleksandr, 2024, Two new species of the genus Plectiscus Gravenhorst, 1829 (Hymenoptera, Ichneumonidae: Orthocentrinae) from Kenya, Zootaxa 5453 (2), pp. 291-297 : 292

Plectiscus oblongus Varga , sp. n. ( Fig. 1 )

LSID urn:lsid:zoobank.org:act:9F9C9C6C-D646-4063-AC55-AD8C3450ED76

Material examined. Holotype: ♀, KENYA: Coast Prov., Taita Hills, Ngangao Forest , 3.36100º S, 38.34186º E, 1848 m, Malaise trap, indigenous forest, 29.11– 13.12.2011, leg. R. Copeland (deposited in: ICIPE) . Paratype: ♀, Coast Prov., Taita Hills, Vuria Forest , 3.41428º S, 38.29178º E, 2162 m, Malaise trap, just inside indigenous forest, 14– 28.10.2011 leg. R. Copeland (deposited in: ICIPE); this specimen has only first three flagellomeres of one antenna present .

Diagnosis. Plectiscus oblongus sp. n. is characterized by the combination of the following characters: body yellow ventrally ( Fig. 1A ); antenna with 27 flagellomeres, first flagellomere 4.2× as long as wide; temples weakly narrowed behind eyes, gently rounded (dorsal view) ( Fig. 1D ); propodeum with only lateral longitudinal carina present posteriorly ( Fig. 1D ); fore wing with vein 2 rs-m about as long as the distance between 2 rs-m and 2 m-cu; vein 3rs-m absent; hind wing with nervellus not intercepted, strongly reclivous ( Fig. 1F ); first tergite 2.2× as long as posterior width, longitudinally striate; second tergite 2.0× as long as posterior width, longitudinally striate to the apex ( Fig. 1H ).

Plectiscus oblongus sp. n. differs from the other Afrotropical species in having longer antenna with 27 flagellomeres; more slender and more strongly sculptured metasomal tergite 2; and more abundant yellow body colouration.

Description. Female. Holotype ( Fig. 1 ). Body length approximately 6.7 mm. Fore wing 4.0 mm.

Head ( Figs 1B–E ) smooth and sparsely pubescent. Antenna with 27 flagellomeres, first flagellomere 4.2× as long as wide. Face about 0.6× as long as wide, indistinctly sculptured, densely pubescent; eyes weakly divergent to clypeus. Malar space 1.7× basal width of mandible; subocular sulcus distinct. Clypeus 0.8× as long as wide, convex centrally. Mandible bidentate, strongly bent outward; lower tooth small and hardly visible. Temples weakly narrowed behind eyes, gently rounded (dorsal view). Frons and vertex smooth; length of the ocellar-ocular distance about 1.5× maximum diameter of lateral ocellus; occipital carina absent.

Mesosoma ( Figs 1C–D, F–G ) generally smooth. Propleuron sparsely pubescent. Pronotum smooth. Mesoscutum densely pubescent; notauli absent. Scutellum densely pubescent, with carinae present only on anterior 0.1. Mesopleuron smooth; epicnemial carina absent. Metapleuron smooth; pleural and submetapleural carinae present. Propodeum smooth, with only lateral longitudinal carina present posteriorly.

Legs relatively stout; hind femur 3.4× as long as wide, third tarsomere of hind tarsus about 1.2× as long as fifth tarsomere; tarsal claws simple.

Wings ( Fig. 1F ). Fore wing with vein 2 rs-m about as long as the distance between 2 rs-m and 2 m-cu; vein 3rs-m absent; vein 1cu-a weakly postfurcal to M & Rs; hind wing with nervellus not intercepted, strongly reclivous.

Metasoma ( Fig. 1H ) longitudinally striate anteriorly and sparsely pubescent. First tergite 2.2× as long as posterior width, longitudinally striate; carinae hardly visible among striation; lateral oblique grooves distinct. Second tergite 2.0× as long as posterior width, distinctly longitudinally striae to apex, with deep and long basolateral grooves. Remaining part of metasoma smooth. Ovipositor sheath about 0.5× as long as hind tibia, apical part widened and pubescent.

Colour. Body generally brown dorsally and yellow ventrally. Head brown except antenna underside, face narrowly below antennal sockets, clypeus apically, mandible (except apices) yellow. Propleuron entirely, pronotum and mesopleuron ventrally yellow. Fore and mid coxae and all trochanters ivory, remaining parts of legs yellow with dorsal brown stripes.

Male. Unknown.

Variability. The paratype female has the metasoma more laterally compressed starting from third tergite, entirely yellow pronotum and partly ivory ventrally hind coxae.

Etymology. The new species is named after the elongate metasoma, especially the second tergite.

Distribution. Kenya.

Figures

FIGURE 1. Plectiscus oblongus Varga, sp. n., holotype female. A—Lateral view of habitus; B—Frontal view of face; C— Lateral view of head and mesosoma; D—Dorsal view of head and mesosoma; E—Dorsal view of mandible. Lower (internal) teeth arrowed with red; F—Wings; G—Frontal view of epicnemium; H—Dorsal view of metasomal tergites 1–2.