Pristomerus roussei Meier, Viertler & Spasojevic 2025, sp. nov.
Creators: name: Meier, Noah
name: Viertler, Alexandra
name: Kapaale, Meekness
name: Katongo, Cyprian
name: Spasojevic, Tamara
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Ichneumonidae
Pristomerus
Pristomerus roussei

description: Pristomerus roussei Meier, Viertler & Spasojevic sp. nov.
Fig. 2
Material examined.
Holotype. • 1 ♀, ZM Northern Province, Mbala, Kalambo Falls (above waterfall), sweep net, 1170 m, -8.5961 / 31.2478, 21.viii–2.ix.2023, leg. N. Meier, T. Spasojevic, A. Viertler (NMBS). Paratypes. • 1 ♂, ZM Northern Province, Mbala, Kalambo Falls (above waterfall), sweep net, 1170 m, -8.5961 / 31.2478, 21.viii–2.ix.2023, leg. N. Meier, T. Spasojevic, A. Viertler (NMBS). • 1 ♂, ZM Mpulungu, Chitili stream, sweep net, -8.6390 / 31.2035, 21.viii–2.ix.2023, leg. N. Meier, T. Spasojevic, A. Viertler, voucher: 20-538 (NMBS). • 2 ♂, ZM Mpulungu, Kalambo delta, sweep net, 777 m, -8.5964, 31.1844, 21.viii–2.ix.2023, leg. N. Meier, T. Spasojevic, A. Viertler (LMNH). • 1 ♀, ZM Mpulungu, Mpulungu town, sweep net, 777 m, -8.7621, 31.1138, 21.viii–2.ix.2023, leg. N. Meier, T. Spasojevic, A. Viertler, voucher: 20-537 (NMBS). • 1 ♀, ZM Mpulungu, Kalambo Falls Lodge, sweep net, 786 m, -8.6241 / 31.2011, 21.viii–2.ix.2023, leg. N. Meier, T. Spasojevic, A. Viertler (LMNH). • 1 ♀, ZM Northern Western Province, 150 km W Solwezi, Ntambu, 12°18'S, 25°10'E; 11.11.2005; leg. M. Halada (LKG).
Diagnosis.
Moderate size; pale yellow with black spots on tergites 1–3 antero-dorsally; femora apically white-dotted; pterostigma anteriorly white; occiput without dark spots; face densely and very shallowly punctate; clypeus transverse with dispersed punctures dorsally and almost smooth ventrally; remainder of head coriaceous; malar space shorter than base of mandible; antenna with 30–33 flagellomeres, penultimate flagellomere quadrate; distance between posterior ocelli approx. as wide as one posterior ocellus; mesosoma densely punctate with pronotum and speculum nearly smooth; female femoral tooth distinct but clearly wider than high, followed by a row of minute denticles; ovipositor moderately long, apically weakly sinuous. Male with ocelli enlarged, inner margins of eyes slightly diverging ventrally, femur and femoral tooth stouter with femoral tooth long and acute, area superomedia much more slender than in female.
Differential diagnosis.
Pristomerus roussei sp. nov. is morphologically very close to Pristomerus masai Rousse & van Noort, 2015, which is suspected to represent a species-complex (Rousse and van Noort 2015). In the dichotomous key of Rousse and van Noort (2015), P. roussei ends at couplet # 36. It can be differentiated from P. masai by a wider distance between the posterior ocelli, a quadrate penultimate flagellomere (females and males) and the lack of dark marks on the occiput (females). Pristomerus roussei can be differentiated from P. wolof Rousse & van Noort, 2015 by the more strongly developed femoral tooth (females and males), the quadrate penultimate flagellomere rather than elongate (females and males), and by its more extensive dark metasomal colour (females).
Description.
Female: 4 specimens (measurements of the holotype in brackets). Colour. Pale yellow. Scape, pedicel, frons, stemmaticum and occiput pale brown; mandibular teeth and flagellum black; mesoscutum apart from notauli and posterior parts orange; wings hyaline, venation brown, pterostigma black, proximal corner translucent; legs orange, femur apically with a white spot, hind tibia basally and apically slightly infuscate, hind tarsus except basal 0.2 of first tarsal segment black; tergites 1–3 on the anterior half black; ovipositor sheath black; ovipositor dark brown, basally and apically testaceous.
Head. Face 2.5 × (2.5 ×) wider than high, densely and very shallowly punctate; inner margins of eyes subparallel, distance between posterior ocelli ~ 1.0 × (1.0 ×) as wide as diameter of one posterior ocellus, distance between posterior ocelli and margin of compound eye 1.1 × (1.1 ×) wider than diameter of one posterior ocellus; clypeus 2.0 × (2.0 ×) wider than high and moderately convex, with dispersed punctures dorsally, almost smooth ventrally; malar space ~ 0.7–0.75 × (0.75 ×) base of mandible; frons, vertex and temple coriaceous; occipital carina joining hypostomal carina distinctly above mandible base; antenna with 31–33 (33) flagellomeres, penultimate flagellomere ~ 1.0 × (1.0 ×) as long as wide.
Mesosoma. Moderately elongate; pronotum nearly smooth posteriorly, with longitudinal striations in its impression and punctures ventrally; mesopleuron and metapleuron with space between punctures less than maximum diameter of punctures, between punctures smooth and shining, mesopleuron with a shallow oblique and transversely strigose furrow below speculum, speculum smooth; mesoscutum densely punctate, between punctures smooth and shiny, notaulus distinct on anterior third of mesoscutum; scutellum densely punctate; propodeum densely punctate, propodeal carination complete, superomedial area ~ 2.3–2.5 × (2.3 ×) as long as its maximum width.
Wings. Fore wing ~ 4.5–4.9 mm (4.9 mm) with M between 2 rs-m and 2 m-cu ~ 1.25–1.5 × (1.25 ×) as long as 2 rs-m, 2 m-cu with a small bulla covering anterior 0.2–0.4 of 2 m-cu; hind wing with nervellus intercepted at lower 0.7 (0.7), second abscissa of CU not pigmented.
Legs. Tooth on hind femur distinct, clearly wider than high, followed by a row of minute denticles. Hind tibia with dispersed spines between normal setation. Tarsal claws pectinate with two distinct denticles.
Metasoma. Posterior half of tergite 1, tergite 2, and anterior of tergite 3 longitudinally aciculate, following tergites coriaceous; thyridium elongate, elliptic; ovipositor sheath ~ 1.5 × as long as hind tibia, apically weakly to moderately sinuous; ovipositor notch rather weak, its distance from ovipositor tip ~ 1.5 × basal width of first tarsal segment of hind leg.
Male: 4 specimens. Similar to female; stemmaticum with ocelli slightly raised and ocelli enlarged, distance between posterior ocelli approx. as wide as diameter of one posterior ocellus, distance between posterior ocelli and margin of compound eye less than half diameter of one posterior ocellus; inner margins of eyes distinctly diverging ventrally; antenna with 29–31 flagellomeres; mesoscutum laterally almost smooth, impunctate; femur swollen, femoral tooth stronger, long and acute, apically with a distinct row of denticles; dark marks on metasoma sometimes absent or reduced.
Etymology.
Dedicated to Pascal Rousse, who contributed greatly to our current understanding of Afrotropical Pristomerus species.
description: Published as part of Meier, Noah, Viertler, Alexandra, Kapaale, Meekness, Katongo, Cyprian & Spasojevic, Tamara, 2025, Spotlighting Darwin wasps (Hymenoptera, Ichneumonidae) in Zambia: a new species and the urgent need for further exploration, pp. 341-367 in ZooKeys 1234 on pages 341-367, DOI: 10.3897/zookeys.1234.144751