Genaemirum phagocossorum Rousse, Broad & van Noort

Rousse, Pascal, Broad, Gavin R. & van Noort, Simon, 2016, Review of the genus Genaemirum Heinrich (Hymenoptera, Ichneumonidae, Ichneumoninae) with interactive identification keys to species, ZooKeys 636, pp. 77-105 : 86-88

Genaemirum phagocossorum Rousse, Broad & van Noort sp. n. Figs 1, 2

Type material.

HOLOTYPE ♀: SOUTH AFRICA, Mpumalanga, Sappi Ndubazi plantation, near Machadadorp, N. 2006, B. Slippers, emerged from Eucalyptus nitens logs infested with cossid larvae of Coryphodema tristis , SAM–HYM–P 025037a (SAMC). PARATYPE. 1♂ same label data, SAM–HYM–P 025037b (SAMC).

Diagnosis.

Female. Body length 16 mm. Black to dark reddish-brown overall with isolated yellow markings on head and mesosoma (pronotal shoulders, middle of mesoscutum, scutellum, dorsal section of mesopleuron below tegulae); vertex black with two small isolated lateral yellow spots, scrobe black dorsally and medially, dark reddish-brown laterally, separated from inner eye margins by yellow horizontal bands; lower face reddish-brown; legs black to dark reddish-brown; wings hyaline; antenna with 30 flagellomeres; lower gena not produced laterally; clypeus transverse, with ventral margin trisinuate; lower face reticulate, separated from upper face by a transverse ledge below toruli; upper frons and vertex smooth, with localised weak striations in an otherwise polished scrobe; scrobe dorsally demarcated by cordate raised sublamelliform carina; mesosoma sparsely punctate; metasoma sparsely punctate, polished, except for tergites 1-3, which are medially striate. Male. Body length 16 mm. Colouration similar to female except for face, which is dirty yellow with two black bands extending from toruli to clypeal-genal junction; vertex black with lateral yellow spots; gena with vertical yellow band adjacent to posterior eye margin; propodeum dorsally black; lower gena normal and frons without transverse carina; scrobe with horizontally curved striations; ocellar triangle reticulate, black; metasomal tergites more densely punctate than in female.

Differential diagnosis.

The uniquely shaped cordate, sublamelliform raised carina dorsally demarcating the scrobe readily separates females of this new species from all the other described species, each of which has a diagnostically shaped horizontal carina, with various uniquely shaped projections in this region. The male is distinguishable from the only other known male ( Genaemirum varianum ) by the extent of the scrobe: extending to the inner eye margins in Genaemirum varianum , terminating laterally well before the inner eye margin in Genaemirum phagocossorum ; scrobe sculpture, which is less extensive in Genaemirum phagocossorum ; and overall body colour (body uniformly dark reddish-brown in Genaemirum phagocossorum ; metasoma and hind femora and tibiae ochreous yellow, contrasting with dark reddish-brown head and mesosoma in Genaemirum varianum ).

Etymology.

From the latin “cossus” for "worm or grub found in wood", which is the likely host ( Cossidae ), and “phago” = latin for "a glutton". Noun in the genitive case.

Description.

FEMALE. Color. Head dark reddish fading to black dorsally and on lower gena, with yellow markings: facial and frontal orbits and a postero-lateral isolated dot on vertex; mesosoma very dark reddish fading to black dorsally, with yellow markings: dorsal margin of pronotum, subtegular ridge, centre of mesoscutum, scutellum and middle of metanotum; metasoma uniformly dark reddish; flagellum uniformly black; legs dark reddish, mid and hind tibiae and tarsi black; wings hyaline, venation testaceous to black.

Head. Mandible rather stout, mid-longitudinally densely punctate, teeth smoother with upper tooth about twice as long as lower tooth; malar space 0.5 × as long as mandible basal width; lower gena not expanded; occipital and hypostomal carinae joining at 0.6 × basal mandible width before mandible, distinctly expanded at their junction into a blunt triangle; clypeus strongly transverse, about twice as wide as high, in profile flat, ventral margin with median and lateral lobes, unevenly punctate with punctation denser dorsally; face strongly transverse, about three times as wide as high, laterally punctate on coriaceous background, punctation denser medially on transversely rugose background; lower frons quite smooth, flat and steeply elevated above toruli, separated from upper frons by a bisinuate transverse carina; upper frons coarsely rugose; vertex coriaceous with sparse punctures, punctation distinctly denser on inter-ocellar area; temple and gena densely punctate; temple moderately swollen behind eye; ocellar triangle wider than long, ocelli rather small, POL 1.0, OOL 1.3; antenna stout, widened slightly before middle, with 30 flagellomeres, basally elongate, flagellomeres 7-9 subquadrate, following flagellomeres transverse.

Mesosoma. Pronotum finely and densely punctate fading ventrally to coarsely longitudinally puncto-striate, pronotum collar enlarged and epomia strong; mesopleuron finely and densely punctate, somewhat rugose-punctate postero-ventrally, speculum barely smoother ventrally, posterior suture deeply crenulate, epicnemial carina nearly reaching pronotal margin below subtegular ridge, subtegular ridge strongly expanded; metapleuron densely and finely punctate, crenulate along pleural carina; mesoscutum evenly rounded, finely and densely punctate, notaulus distinct to anterior third, scuto-scutellar groove quite smooth; scutellum finely and more sparsely punctate, without lateral carina, quite flat in profile; propodeum typical of the genus, gently and evenly rounded in profile with median areas fused, carination distinct but very weak, densely punctate with punctation obsolescent mid-basally and distinctly coarser mid-posteriorly. Legs. Fore and mid tibiae with short and rather dense bristles along anterior faces, bristle sockets large and cupular.

Metasoma. Petiole with lateral and submedian dorsal carinae strong, abruptly enlarged into second tergite from level of spiracle; second tergite sparsely punctate laterally, medially longitudinally strigose; following tergites unevenly and sparsely punctate except tergite 2 medially and tergite 3 mid-basally longitudinally strigose; gastrocoelus deep, thyridia separated by 1.6 × their own width; ovipositor sheath slightly protruding beyond metasomal apex.

MALE. Yellow markings more expanded, encompassing also mandible, clypeus, median face, genal orbits and pronotal collar; flagellum not widened with 33 flagellomeres, flagellomeres 7-14 with tyloids on outer surface and 6-32 with differentiated bristle mid-ventrally; lower frons transversely striate, transverse carina strongly attenuated; parameres simple; otherwise similar to female.

Biology.

Reared from logs of Eucalyptus nitens (H. Deane & Maiden) Maiden ( Myrtales : Myrtaceae ), which were heavily infested with Coryphodema tristis (Drury) ( Lepidoptera : Cossidae ), but specific host association was not established. Coryphodema tristis is regarded as an agricultural pest in southern Africa because its host-plant range includes food crops, chiefly quince and apple trees ( Rosales : Rosaceae , Cydonia oblonga Miller and Malus pumila Miller var. domestica Schneider). It is also considered to be a major forestry pest of Eucalyptus nitens , which is extensively cultivated in South Africa for the pulp and mining industry ( Gebeyehu et al. 2005, Boreham 2006, Adam et al. 2013, Degefu et al. 2013). This likely host record suggests the potential for using Genaemirum phagocossorum sp. n. as a biocontrol agent of this pest species. However, the low number of reared specimens suggests that it is not a common parasitoid of this lepidopteran pest. See further discussion on biology under the genus treatment.

Distribution.

South Africa.