Eusterinx (Ischyracis) africana Humala, 2024

Humala, Andrei E., 2024, First record of the genus Eusterinx Förster (Hymenoptera: Ichneumonidae: Orthocentrinae) from the Afrotropical Region, with description of a new species from South Africa, Zootaxa 5537 (2), pp. 281-287 : 283-286

Eusterinx (Ischyracis) africana Humala , sp. nov.

( Figs 1–6 )

Material examined. Holotype: female, South Africa, Kwazulu-Natal, Royal Natal Nature Reserve, Gudu Forest , 1680–1730 m, 28°40.90ʹ S, 28°55.78ʹ E, Malaise trap, 29.V–21.IX.2006, leg. M. Mostovski ( SAMC, catalogue number: SAM-HYM-P103720).

Diagnosis. Eusterinx africana sp. nov. is characterized by the combination of the following characters: occipital carina significantly reduced, fore wing with areolet lacking (vein 3 rs-m absent), nervulus interstitial; area superomedia elongate, 2.5 × as long as maximum wide, apophyses of propodeum strongly developed; legs slender; T1 very slender, 4.1 × as long as wide posteriorly; sheath of ovipositor 0.5 × as long as hind tibia.

Description. Female (holotype). Body length 3.6 mm, fore wing length 2.7 mm ( Fig. 1 ).

Head 1.2× as wide as high; eyes glabrous, large and strongly convex; inner orbits strongly convergent downwards; face nearly polished with sparse setae; maximum face width at level of antennal sockets 1.4 × as high, 0.44 × as wide as head ( Fig. 3 ). Antenna with 18+ flagellomeres (tip of antenna missing), all flagellomeres longer than wide; first flagellomere 5.5 × as long as wide; second flagellomere 0.95 × as long as first flagellomere. Malar space about 1.5 × as long as basal width of mandible, subocular sulcus indistinct; anterior tentorial pits small; clypeus convex, small, narrow, 0.65 × as high as wide. Mandibles slender, strongly twisted inwards and tapered apically, lower tooth strongly reduced and invisible in front view. Maxillary palps very long, almost reaching middle coxa. Occiput polished; occipital carina mostly reduced, only short part developed dorsally; temple 0.3 × as long as eye length. Ocelli of moderate size; ratio of ocellar-ocular line: maximum diameter of lateral ocellus: postocellar line as 28: 27: 22 ( Fig. 2 ). Head distinctly narrowed behind eyes, temple short, 0.2 × as long as the width of compound eye.

Mesosoma 1.55 × as long as maximum high; pronotum polished with distinct epomia; mesoscutum finely punctured, covered with dense setae; notauli well developed, meeting in the centre of mesoscutum ( Fig. 4 ) and continuing as a fine median longitudinal carina not reaching scutellum. Notauli anteriorly with small tubercles to the outside of their base; epicnemial carina complete ventrally, almost reaching upper part а mesopleuron; mesopleuron polished and mostly glabrous with short sternaulus; metapleuron coriaceous. Propodeum nearly smooth with all carinae developed and with a pair of strong apophyses flattened dorsoventrally ( Figs 4, 5 ); anterior transverse carina forming a strong crest; area superomedia elongate and slightly narrowing posteriorly, 2.4 × as long as maximum wide ( Fig. 5 ).

Legs very slender, hind coxa granulate, hind femur 5.3 × as long as wide, tibial spurs short and slender, hind basitarsus 0.4 × as long as hind tibia; ratio of hind tarsomeres as 54: 32: 24: 15: 22; claws simple.

Wings. Fore wing without areolet (vein 3rs-m absent), radius (vein 2r&Rs) originates from the middle of stigma, nervulus (vein 1cu-a) interstitial, postnervulus intercepted in lower 0.4; in hind wing nervellus reclivous, not intercepted, discoidella lacking.

Metasoma. T1 slender, 4.1 × as long as maximum width posteriorly, with longitudinal striae; dorsal carina lacking; small spiracle at the level of 0.55 tergite, sternite fused with tergite, reaching the level of 0.8 of tergite; T2 coriaceous, 1.35 × as long as maximum width posteriorly with weak irregular longitudinal striae and small thyridium ( Fig. 6 ); other tergites weakly granulate, with sparse setiferous punctures; T7 deeply incised posteriorly and desclerotized medially. Ovipositor nearly straight, tapered at apical quarter; ovipositor sheath 0.5 × as long as hind tibia.

Colour. Dark-brown; clypeus, tegula and lower pronotum reddish-brown; palps whitish, mandible, basal antennomeres, and wing bases yellowish; propleuron, lower pronotum and epicnemium reddish-brown; metasoma, except T1 and T2 brown, posterior margins of T2–T5 yellowish; T1 blackish, sclerotized areas on S2–S5 lightbrown. Fore and mid legs and hind trochanters yellowish, hind coxa in basal 0.8 dark-brown, hind femur reddish-brown, infuscate in basal half, apical third of hind tibia and tarsus infuscate; ovipositor sheaths yellowish, darkened in apical third. Wings hyaline, veins including pterostigma brown.

Male. Unknown.

Comparison. Compared to other Ischyracis species that lack a closed areolet, the new species is characterized by its small size and considerably reduced occipital carina. E. tenuiventris differs from it by the distinctly postfurcal nervulus and reticulate sculpture of metapleuron; E. petiolata and E. bispinosa are distinguished by a longer ovipositor 0.85–1.0 × as long as hind tibia (vs. 0.5 × in E. africana sp. nov.), the allied E. ganica and E. fulvipes are distinguished by area superomedia 1.2 –1.8× as long as maximum wide (vs. 2.5 × in E. africana sp. nov.), predominantly yellow hind coxae, and slenderer T2 1.6 × as long as posterior width (vs. 1.35 × in E. africana sp. nov.).

Distribution. Currently known only from South Africa (Kwazulu-Natal).

Etymology. The species is named after the type locality.

Figures

FIGURES 1–6. Eusterinx africana sp. nov., female holotype. FIGURE 1. Habitus, lateral view. Scale bar 1.0 mm. FIGURE 2. Head and mesoscutum, dorsal view. Scale bar 0.2 mm. FIGURE 3. Head, anterior view. Scale bar 0.2 mm.