Aleiodes nigriceps Wesmael, 1838

van Achterberg, Cornelis & Shaw, Mark R., 2016, Revision of the western Palaearctic species of Aleiodes Wesmael (Hymenoptera, Braconidae, Rogadinae). Part 1: Introduction, key to species groups, outlying distinctive species, and revisionary notes on some further species, ZooKeys 639, pp. 1-164 : 85-90

Aleiodes nigriceps Wesmael, 1838 Figs 230-231, 232-242

Aleiodes nigriceps Wesmael, 1838: 109 ; Papp 1985a: 156 (lectotype designation).

Aleiodes circumscriptus var. nigriceps ; Shenefelt 1975: 1171.

Type material.

Lectotype, ♀ (KBIN) from Belgium examined.

Additional material.

*Austria, Belgium, British Isles (*England: V.C.s 3, 8, 12, 19, 20, 22, 23, 24, 25, 27, 28, 29, 30, 31, 33, 40, 58, 62, 65; *Wales: V.C.s 41, 45, 52; *Isle of Man: V.C. 71; *Scotland: V.C.s 75, 77, 83, 84, 89, 97, 99, 101, 105; *Ireland: V.C. H5), *Jersey, *Bulgaria, *Czech Republic, *Finland, France, Germany, Hungary, *Italy, *Lithuania, *Netherlands (FR: Terschelling (Formerum), GE: Putten, NB: Geertruidenberg; Oploo; Udenhout (de Brand), NH: Overveen; Muiderberg, LI: Tegelen; St. Pietersberg; Venlo; Maastricht, UT: Harmelen, ZE: Cadzand; Oostkapelle; ZH: Delft; Den Haag; Wassenaar; Leidschendam), *Norway, *Poland, *Portugal, Russia, *Slovakia, Spain, *Sweden and Switzerland. Specimens in NMS, BMNH, RMNH, BZL, SDEI, ZSSM, FMNH, MTMA, CNC, P.-N. Libert collection, JLC, WAE, H. Haraldseide collection, and MSC.

Molecular data.

MRS075 (England KU682221, CO1), MRS144 (Scotland KU682228, CO1), MRS613 (Wales KU682243, CO1), MRS783 (Austria KU682250, CO1).

Biology.

At least partly a plurivoltine parasitoid of larvae of low-feeding noctuine Noctuidae inhabiting grassy sites; most frequent in humid situations. Mummy (Fig. 231) dark brown or brown and slender, only slightly or not swollen, forming low down in concealment. Specimens (in NMS unless stated otherwise) reared from wild-collected Noctuidae identified as Diarsia rubi (Vieweg) (10 [2 are ZSSM]; G.M. Haggett, M.R. Shaw), Lycophotia porphyyrea (Dennis and Schiffermueller) (1 [ZSSM/ Netherlands]), Noctua fimbriata (Schreber) (1; J. Connell/Austria), Xestia c-nigrum (Linnaeus) (1; J. Connell/Austria), Xestia sexstrigata (Haworth) (3; G.M. Haggett), and indet. green noctuid (1). A further specimen was reared from a noctuid mummy collected in a Carex tussock (D.G. Notton). Specimens in NMS reared in culture experiments as follows: Xestia sexstrigata 6:20\20\\15+2, Xestia xanthographa (Denis & Schiffermueller) 4:47\47\\3+30 [several others were retarded but died], Noctua fimbriata 6:45\40\\24+0 [several others were retarded but died], Diarsia rubi 6:89\83\\74+9, Phlogophora meticulosa (Linnaeus) 7:43\19\\0+12 [several others were retarded but died]. No ovipositions resulted from the following culture experiments: Diarsia mendica (Fabricius) 1:5\0\\-, Xanthorhoe fluctuata (Linnaeus) 3:19\0\\-, Xanthorhoe montanata (Denis & Schiffermueller) 3:15\0\\-, Camptogramma bilineata (Linnaeus) 6:13\0\\-. While many of its hosts are univoltine with overwintering larvae, in which the parasitoid overwinters as an early instar larva, Aleiodes nigriceps has the capacity to be plurivoltine (e.g. in Diarsia rubi ), and its long summer flight period, including abundant males in late summer, indicates that it regularly is so. Experimental rearings suggest that even within the genera it uses as hosts it specialises narrowly, and these experiments also clearly distinguish between it and both Aleiodes pictus and Aleiodes leptofemur . The mummy forms low down, more or less in concealment, and is very seldom collected (unlike that of Aleiodes leptofemur ). The adult emerges soon after. In captivity adult females of this species are long-lived, but have always died off during the winter, and the flight period is ca May–September. Males are sluggish in their courtship, even towards conspecific females which, however, typically offer themselves for mating immediately.

Diagnosis.

Antennal segments of female (38 –)39– 43, of male (38 –)39– 44; pale area of facial (= inner) orbita of female usually narrow or absent (Fig. 239); OOL 1.6 × diameter of posterior ocellus; face usually wholly black or dark brown, rarely wholly yellow brown; mesopleuron without distinct rugulae; mesosternum yellowish or reddish, if darkened then dark area usually not sharply defined; width of hypoclypeal depression 0.4-0.5 × minimum width of face (Fig. 239); mesoscutum antero-laterally and pronotum medio-anteriorly often black or dark brown; face without distinct rugae or only a few rugae medio-dorsally; ventrally mesopleuron usually widely orange brown; malar space partly or completely and temple near eye orange brown; length of first tergite of ♀ 1.1-1.2 × its apical width; second tergite comparatively wide (Fig. 234); fore and hind femora comparatively slender (Figs 235-236); pterostigma partly darkened anteriorly; mummy slightly or not swollen and dark brown or brown; middle third of hind femur partly or entirely dark brown. Very similar to Aleiodes pictus ( Herrich-Schaeffer, 1838) , but Aleiodes pictus has the antennal segments of ♀ (35 –)36– 40, of ♂ (36 –)37– 41, the mesopleuron with some rugulae (at most very weakly evident in Aleiodes nigriceps ), the mesosternum almost always strongly darkened or black and dark area usually sharply defined, malar space somewhat longer than in Aleiodes nigriceps , and the mesoscutum antero-laterally and pronotum medio-anteriorly more often yellowish (but variable in both species). The yellowish colouration is frequently more brownish in Aleiodes pictus (tending to orange in Aleiodes nigriceps ), the legs are on the whole less slender, and the paler area at the extreme apex of the hind femur tends to be more extensive. In practice, the majority of specimens of Aleiodes nigriceps have both the mesosternum and third tergite completely yellowish orange, and such specimens are easy to recognise as this combination is rarely approached in Aleiodes pictus . In extreme examples of Aleiodes nigriceps the mesoscutum and (less often) even the scutellum may be wholly black, and when the tergites and scape are also predominantly dark they may resemble Aleiodes nigricornis , but in that species the hind femur is only very rarely extensively darkened, and the number of antennal segments is greater (though with a small overlap).

Description.

Redescribed ♀ (NMS), "Culture: [Wales], Anglesey, Llangristiolus, from ♀ 3:2 [ex] Diarsia rubi in Xestia sexstrigata , ovip. 28.v.[20]08, mum. 4.iv.[20]09, em. 22.v.2009, died viii.2009, ♀ 2/09, M.R. Shaw". Length of fore wing 4.4 mm, of body 5.5 mm.

Head. Antennal segments 43, length of antenna 1.3 × fore wing, its subapical segments about 1.6 × as long as wide; frons granulate-coriaceous, with satin sheen; OOL 1.6 × diameter of posterior ocellus (POL 1.4 times); vertex granulate-coriaceous, with satin sheen; clypeus distinctly convex and largely smooth; ventral margin of clypeus thick and depressed (Fig. 239); width of hypoclypeal depression 0.4 × minimum width of face (Fig. 239) and face mainly coriaceous with some rugulae medio-dorsally; length of eye 2.3 × temple in dorsal view and temple roundly narrowed behind eye (Fig. 241); occiput behind stemmaticum coriaceous and occipital carina absent medio-dorsally, its interruption slightly less than width of stemmaticum (Fig. 241); clypeus partly above lower level of eyes (Fig. 239); length of malar space 0.4 × height of eye in lateral view; eyes moderately protruding (Figs 239-241).

Mesosoma. Mesoscutal lobes finely coriaceous, with satin sheen, but medio-posteriorly longitudinally rugose; notauli narrow, moderately impressed and finely crenulate, but posteriorly lost in rugose area; prepectal carina narrow lamelliform and reaching anterior border; precoxal area of mesopleuron coriaceous and without rugae medially; mesopleuron above precoxal area (except small smooth and shiny speculum) coriaceous, but antero-dorsally rugose; medially metapleuron coriaceous, matt; mesosternal sulcus narrow and moderately deep, but posteriorly shallow and with a carina; mesosternum rather angulate posteriorly; scutellum nearly flat, coriaceous and largely non-carinate laterally; propodeum rather flat and coriaceous but posteriorly with some rugae, median carina complete, without tubercles.

Wings. Fore wing: r 0.2 × 3-SR (Fig. 232); 1-CU1 horizontal, 0.5 × as long as 2-CU1; r-m 0.7 × 2-SR, and 0.4 × 3-SR; second submarginal cell medium-sized (Fig. 232); cu-a oblique, but not parallel with CU1b, straight; 1-M nearly straight posteriorly. Hind wing: apical half of marginal cell somewhat widened apically (Fig. 232); 2-SC+R short and longitudinal; short stub of m-cu present, pigmented.

Legs. Tarsal claws setose; hind coxa superficially coriaceous, with satin sheen; hind trochantellus 2.3 × longer than wide; length of fore and hind femora 6.3 and 5.6 × their width, respectively (Figs 235-236); inner apex of hind tibia without comb; length of inner hind spur 0.3 × hind basitarsus.

Metasoma. First tergite 1.2 × as long as wide posteriorly, convex, but posteriorly flattened; first and second tergites and base of third tergite densely longitudinally rugose; second tergite robust (Fig. 234), with distinct median carina, matt; medio-basal area of second tergite obsolescent; second suture shallow and crenulate; third tergite (except basally) largely coriaceous, remainder of metasoma largely smooth and rather shiny; fourth and apical third of third tergite without sharp lateral crease; ovipositor sheath largely densely setose.

Colour. Black or brownish black; antenna brown, but scapus and pedicellus dorsally and laterally and apical third of antenna dark brown; palpi and tegulae pale yellowish (Fig. 230); outer orbita posteriorly and dorsally brownish yellow (Figs 240-241) and remainder of head black; mesopleuron (except dorsally), mesosternum and metapleuron medially orange brown; hind femur (except basally) dark brown (Fig. 235); scutellum, first tergite medio-apically, second and third tergites, part of fourth tergite and remainder of legs brownish yellow; veins (except dark brown veins 1-SR, 1-M, r and CU1) brown; pterostigma yellowish, but anteriorly and posteriorly darkened (Fig. 232); wing membrane subhyaline.

Variation. Length of fore wing 4.3-4.4 mm; antennal segments of ♀ 38(1), 39(9), 40(44), 41(44), 42(27), 43(13), 44(2), 45(1); of ♂ 37(1), 38(4), 39(31), 40(82), 41(113), 42(33), 43(12), 44(7), 45(3); vein r of fore wing 0.2-0.5 × vein 3-SR; length of first tergite of ♀ 1.1-1.2 × its apical width; pterostigma medially yellow or dark brown; medio-posteriorly mesoscutum black or brownish yellow; second and third tergites yellowish, infuscate or dark brown laterally, mesosternum orange brown or infuscate.

Notes.

The two sexes have about the same number of antennal segments. The lectotype of Aleiodes nigriceps has the antenna mutilated; according to the original description it had 40 or 41 segments. Aleiodes nigriceps is often considered to be a synonym of Aleiodes circumscriptus , e.g. Papp (1985) but the selection of a neotype for Aleiodes circumscriptus in the present work resolves that issue (and the two species differ in, among other things, the number of antennal segments).