Tetractenion rosei Reynolds Berry & van Noort, 2020

Berry, Terry Reynolds & Noort, Simon van, 2020, Revision of the endemic Afrotropical genus Tetractenion (Hymenoptera, Ichneumonidae) with an identification key to genera of Banchinae for the region, ZooKeys 1007, pp. 49-84 : 49

Tetractenion rosei Reynolds Berry & van Noort sp. nov. Fig. 6

Type material.

Holotype ♂: Cameroon, Yaoundé, 1953, C.I.E. Coll. 15098. Pres. by Com. Inst. Ent., B. M. 1962-1. Exetastes sp. ♀ det. J. F. Perkins (NHMUK).

Differential diagnosis.

Tetractenion rosei is immediately distinguishable from other Tetractenion species by the reddish color of the head and pronotum in combination with a yellow body, completely yellow legs with venation on the wings also yellow. The head is not narrowed straight behind the eyes but rather rounded, distinguishing the species from T. acaule and T. pascali . The malar space nearly as long as the basal mandible width separates T. rosei from T. acaule , T. pseudolutea , and T. ibayaensis . Tetractenion acaule is the only other species besides T. rosei possessing a thickened and well-defined carina on the pronotal collar.

Pectinate hind tarsal claws separate the species from T. acaule and T. luteum . Sparse microtrichia on the wings distinguishes the species from T. luteum and T. pascali , and the pterostigma is yellow distinguishing the species from T. acaule and T. ibayaensis . Metasomal tergites II and III are longer than wide separating T. rosei from T. ibayaensis ; and T. acaule , T. luteum , and T. ibayaensis , respectively.

Description.

Color: head and pronotum reddish, black area restricted to region of ocelli. Body, legs, antennae yellow. Wings with sparse microtrichia, venation yellow, pterostigma yellow.

Head rounded behind eyes; occiput deeply and angularly excavated, occipital carina strong, extending to lower gena at mandibular base; malar space nearly as long as basal mandibular width; eyes very large; face and clypeus moderately and evenly punctate on a shiny background; face with three lobes, tentorial pits deep; clypeus small, laterally convex with declivity, apically invaginated, clypeal edge convex; mandibular teeth triangular, lower tooth longer than upper tooth; antenna long, slender and apically tapered.

Mesosoma stout with a shiny background; mesopleuron moderately punctate, epicnemial carina ending at anterior edge of mesopleuron; pits on the mesopleuron and propodeum shallow; mesonotum moderately punctate; pronotum sparsely and finely punctate on a shiny background with a well-defined carina on collar; mesoscutum deeply punctate, mesoscutal lobes hardly present, notauli posteriorly meeting before reaching the scutellum; propodeum weakly convex, deeply punctate posteriorly confluently grading into transverse wrinkles, posterior transverse carina indistinct, lateral longitudinal carinae present, spiracle small and round.

Metasoma indistinctly punctate on a shiny background; tergite I more than twice as long as wide, tapered anteriorly, slight dorso-ventral depression in medial region, glymma present, spiracle in front of middle and protruding; tergites II and III longer than wide; gastrocoeli on tergite II indistinct; tergites IV-VIII higher than wide.

Hind wing with Cu1 shorter than cu-a such that Cu2 arises above the middle of these combined veins. Legs very long, hind femur reaching beyond metasomal apex, length of tibia III plus tarsus III as long as body, spurs of tibia III longer than half metatarsal length; tarsal claws pectinate.

CT 1.6; ML 0.9; IO 1.4; OO 2.2; Fl1 3.5; B 9.3 mm; F 8.6 mm.

Etymology.

Named because of the reddish color of the head and pronotal collar. Noun in apposition.

Distribution.

Cameroon.

Comments.

This is a rare species known only from one female specimen. Sampling in other areas of the Afrotropical region has so far not produced any further specimens. The wings are inter-locked in such a way that a useful diagnostic character of the wings cannot be seen, i.e., whether the ramellus is present or not.

Figures

Figure 6. Tetractenion rosei sp. nov. Holotype A habitus, lateral view B habitus, dorsal view C head, anterior view D wings (inset: data labels).