Aleiodes aterrimus (Ratzeburg, 1852)

van Achterberg, Cornelis, Shaw, Mark R. & Quicke, Donald L. J., 2020, Revision of the western Palaearctic species of Aleiodes Wesmael (Hymenoptera, Braconidae, Rogadinae). Part 2: Revision of the A. apicalis group, ZooKeys 919, pp. 1-259 : 1

Aleiodes aterrimus (Ratzeburg, 1852) Figs 93-97 , 98-100 , 101 , 102-115

Bracon aterrimus Ratzeburg, 1852: 35; Shenefelt 1978: 1467.

Aleiodes aterrimus ; Belokobylskij et al. 2003: 398; Zaldívar-Riverón et al. 2004: 234.

Aleiodes grandis Giraud, 1857: 178; Papp 1991a: 77; Bergamasco et al. 1995: 5; Belokobylskij et al. 2003: 398; Papp 2005: 176 (as valid species) [examined].

Aleiodes (Neorhogas) grandis ; Papp 1985a: 159 (lectotype designation and as synonym of A. aterrimus ); Riedel et al. 2002: 106.

Aleiodes (Chelonorhogas) aterrimus ; Falco et al. 1997: 60.

Rogas grandis ; Shenefelt 1975: 1232.

Rogas (Rogas) grandis ; Tobias 1976: 87, 1986: 81 (transl.: 134).

Rhogas malaisei Shestakov, 1940: 7.

Rogas malaisei ; Shenefelt 1975: 1237.

Aleiodes malaisei ; Shaw et al. 1998: 63 (as synonym of A. grandis Giraud); Belokobylskij et al. 2003: 398 (as synonym of A. aterrimus (Ratzeburg)); Papp 2005: 176 (as synonym of A. grandis Giraud).

Rogas (Rogas) vicinus Papp, 1977a: 114, 115 [examined]. Syn. nov.

Aleiodes (Neorhogas) vicinis ; Papp 1991a: 78.

Type material.

Lectotype of A. grandis , ♂ (MNHN), "[Austria:] environs de Vienne". Holotype of R. vicinus (MTMA), ♀, "Yugoslavia, [Serbia:] Vojvonida, Fruška Gora Mts., Sremska Kamenica, 1-2.v.1972, Papp & Horvatovich", "Holotypus ♀ Rogas vicinus sp. n., Papp, 1977", "Hym. Typ. No. 2375, Mus. Budapest"; paratype of R. vicinus , ♀ (MTMA), "[Romania:] Transylvania, Szászkezd %, Silbernagel", "Paratypus ♀ Rogas vicinus sp. n., Papp, 1977", "Hym. Typ. No. 2376, Mus. Budapest"; 1 ♂ (MTMA), id., but No. 2375.

Additional material.

Austria, Belgium, British Isles (England V.C.s 8, 9, 10, 11, 12, 14, 15, 20, 22, 28, 29, 39), Czech Republic, Finland, Germany, Hungary, Netherlands (GE: Brummen (Leuvenheim); LI: Epen; ZH: Schoonrewoerd), Poland, Romania, Russia, Slovakia, Spain, Switzerland. Specimens in ZJUH, BZL, CNC, FMNH, HSC, MRC, MSC, MTMA, NMS, OUM, RMNH, SDEI, ZSSM.

Molecular data.

MRS024 (UK), MRS147 (UK).

Biology.

Univoltine, spending ca ten months of the year in the exposed mummy on an aerial twig. Collected from April-June, among broadleaved trees (but see paragraph below). Reared from arboreal Amphipyra spp.: A. pyramidea (Linnaeus) (29; M.G. Bloxham, C. Bystrowski, J. Connell, A.P. Fowles, G.M. Haggett, B.T. Parsons, D.L.J. Quicke, M.R. Shaw); A. berbera (Rungs) (5:1 [5 OUM]; G.C. Varley); Amphipyra sp. (8). Some of the forgoing specimens were reared and labelled in the period before it was known that there are two closely related and sympatric arboreal species of Amphipyra in Britain, and it is possible that British records from A. pyramidea (especially when collected on Quercus ; cf. Shaw, 1981) have been overstated at the expense of A. berbera ; however, both certainly serve as host. An account of frequency at one site is given by Shaw (1981).

Before becoming mummified the host moves to a narrow twig, to which the mummy will be very strongly glued. In the early stage of the mummification process (Fig. 99 ), in which the anterior end of the host is particularly contracted, the parasitoid larva strongly protrudes anteriorly to spread the necessary glue (Fig. 101 ). The resultant almost semi-circularly domed and hard mummy (Fig. 100 ), in which the parasitoid occupies approximately abdominal segments 4-7 of the host, forms in ca May-June and persists through the remainder of the summer and the following winter until the adult emerges in ca April-May. (The univoltine hosts overwinter in the egg stage.) The swollen part of the mummy, which is moderately densely lined with silk, is externally usually matt chalky buff in colour, but dark brown diamond-shaped patches centred dorsally on intersegmental areas tend to remain (Fig. 97 ), and sometimes (perhaps especially when the mummy is unable to dry as it forms) these are coalesced to leave a single shiny dark brown patch covering most of the dorsal surface. Some of the mummies examined might be of somewhat stunted final instar hosts, but others are more clearly penultimate instar. The outcomes of an experiment involving six females and cultured A. pyramidea larvae were unfortunately marred by unavoidably high temperatures and then disease overcoming the cultures so that no mummies resulted, but the following observations were made: (i) 2nd to 5th instar hosts were potentially attractive; (ii) 2nd instar hosts were, however, often ignored or else tended to be abandoned after being paralysed with a single jab (i.e., without oviposition subsequently taking place); (iii) 3rd instar hosts were often ignored, but when attacked seemed the most smoothly parasitised, sometimes with a single paralysing jab being followed, after a short pause, by a single insertion of the ovipositor for presumed oviposition, although the pattern observed for 4th and 5th instars also occurred with 3rd instars; (iv) 4th and (2 only) 5th instar hosts were embraced the most enthusiastically, but it required several (3-5) injections to subdue them, and then there were usually several (3-4) separate sequential and lengthy (often as long as 80 seconds) insertions of the ovipositor (which may or may not all have been actual ovipositions), the parasitoid turning between insertions and always grasping the host with all six legs during the insertion; (v) antennation of the host was minimal, and there was no post-oviposition association; (vi) all temporarily paralysed hosts hung from the substrate by one or usually more prolegs until they recovered, presumably preventing their falling from their pabulum; (vii) there is no long-term physiological venom effect. The behaviour of adults observed toward the different instars is intriguing, and the experiment would be well worth repeating under better circumstances.

Although the above is a consistent pattern for this species, it does not account for a small number of specimens (14 ♀, 4♂ in BZL, MRC, MTMA, NMS, SDEI, ZSSM) examined from various localities in central Europe (Czech Republic, Germany, Hungary) and S. Russia. These specimens share small but rather consistent morphological differences from the usual form, in particular tendencies towards: more intense sculpture on the metasomal tergites (T3 being more or less strongly punctate or even rugose-punctate); the hind wing marginal cell parallel-sided in basal three fifths; shorter 3-SR in fore wing; basal cell of fore wing with more, and more evenly distributed, setae; fewer antennal segments; wing membrane slightly brownish. These differences are not absolutely consistent and would be easy to let pass without comment were it not for the fact that they are correlated with an apparently different phenology, as (of the ten specimens with dates recorded) five ♀ were collected in July and one in August, with only three ♀ in May and one in June (none in April). This is in marked contrast with the earlier flight time of the usual form, and the usual hosts (arboreal Amphipyra spp.) are not available after early June. A further ♀ specimen (MTMA) examined and returned in 1997 by MRS but apparently no longer in the main MTMA collection was labelled "Hungaria, Fót, Somlyó-hegy, 30.vii.1958, Ehik"; "Ex Panchrysia deaurata Esp [J. Papp’s handscript]"; "ex Pytometra deautate [sic]". Unfortunately, no mummy had been preserved, but this plusiine noctuid feeds on Thalictrum (a low plant, not a tree) and it is unlikely for an arboreal Amphipyra , even if fallen from a tree above, to have been mistaken for it. The date, whether referring to collection of the host larva or emergence of the adult parasitoid, is also out of step with arboreal Amphipyra species. We considered but rejected the possibility that these specimens belong to a separate species, and instead conclude that under certain circumstances A. aterrimus can have a partial 2nd brood (in the southern part of its range) which uses different hosts, and that the morphological variation is merely seasonal. The material (which does not conform to A. sapporensis (Watanabe), see below) is being returned to holding institutions determined as A. aterrimus but with "var: T3 sculpture etc." appended to facilitate recall if necessary. It should be added that this form has (on account of its heavy metasomal sculpture and extensively parallel-sided marginal cell in the hind wing) sometimes been misidentified as A. rugulosus , but the two species are always easily separated by the sculpture of the mesoscutum and scutellum, as well as by leg colour.

Diagnosis.

Maximum width of hypoclypeal depression 0.3-0.4 × minimum width of face (Fig. 109 ); ventral margin of clypeus obtuse apically and not protruding outwards (Fig. 111 ); OOL of ♀ distinctly longer than diameter of posterior ocellus; mesoscutal lobes densely and finely punctate-coriaceous, rather matt; scutellum densely and finely coriaceous; mesosternal sulcus shallow, obsolescent or absent; vein 1-CU1 of fore wing 0.2 × vein 2-CU1 (Fig. 102 ); vein 2-SC+R of hind wing subquadrate or vertical (Fig. 102 ); hind tarsal claws with conspicuous and robust blackish pecten (Fig. 113 ); head black; hind tibia largely to completely black; metasoma of both sexes black; 4th-6th tergites of ♂ flat and densely short setose, except a narrow glabrous strip centrally.

Dr K. Samartsev (in litt.) kindly brought to the first author’s attention that the East Palaearctic A. sapporensis (Watanabe, 1937) occurs in southern European Russia (Middle and Lower Volga territories). Aleiodes aterrimus and A. sapporensis differ only slightly, mainly by the colour of the extreme base of the hind tibia (completely dark brown in A. sapporensis and usually narrowly pale yellowish in A. aterrimus ) and by the shape of temple in dorsal view (roundly narrowed in A. sapporensis and rather linearly narrowed in A. aterrimus ). There is also a slight difference in the proportions of the face ( A. sapporensis has facial width 1.50-1.60 × medial height including clypeus and A. aterrimus 1.65-1.75 ×). A. sapporensis seems to have the lateral carinae of propodeum more protruding and has 58-66 antennal segments.

Description.

Redescribed ♀ (RMNH) from England (Pamber Forest). Length of fore wing 7.3 mm, of body 8.6 mm.

Head. Antennal segments of ♀ 59, length of antenna 1.1 × fore wing, its subapical segments rather robust; frons largely superficially granulate; OOL 1.8 × diameter of posterior ocellus, and superficially rugulose-granulate and shiny; vertex superficially rugulose-granulate, rather shiny; clypeus with some punctures; ventral margin of clypeus thick and not protruding forwards (Fig. 111 ); width of hypoclypeal depression 0.3 × minimum width of face (Fig. 109 ); length of eye 1.3 × temple in dorsal view (Fig. 110 ); vertex behind stemmaticum superficially granulate-rugulose; clypeus near lower level of eyes; length of malar space 0.4 × length of eye in lateral view.

Mesosoma. Mesoscutal lobes densely and finely punctate-coriaceous, rather matt; precoxal area of mesopleuron largely smooth medially, densely punctate anteriorly and posteriorly; metapleuron densely punctate; metanotum with nearly complete median carina; scutellum punctate-coriaceous; propodeum rather convex and coarsely reticulate-rugose, medio-longitudinal carina nearly complete, and with slightly protruding carinae laterally.

Wings. Fore wing: r 0.4 × 3-SR (Fig. 102 ); 1-CU1 slightly oblique, 0.2 × 2-CU1; r-m 0.6 × 3-SR; 2nd submarginal cell medium-sized (Fig. 102 ); cu-a inclivous, straight; 1-M nearly straight posteriorly; 1-SR wide; surroundings of M+CU1, 1-M and 1-CU1 largely glabrous. Hind wing: marginal cell linearly widened, its apical width 2.0 × width at level of hamuli (Fig. 103 ); 2-SC+R short and vertical; m-cu absent; M+CU:1-M = 12:11; 1r-m 0.7 × 1-M.

Legs. Tarsal claws with conspicuous and robust blackish pecten (Fig. 113 ); hind coxa largely densely punctate; hind trochantellus rather robust; length of hind femur and basitarsus 4.7 and 6.5 × their width, respectively; length of inner hind spur 0.4 × hind basitarsus.

Metasoma. First tergite evenly convex, as long as wide apically; 1st and 2nd tergites with medio-longitudinal carina and coarsely longitudinally rugose, but posterior quarter of 2nd tergite irregularly rugose and no median carina; medio-basal area of 2nd tergite triangular and rather distinct (Fig. 106 ); 2nd suture deep and narrow; basal half of 3rd tergite finely punctate-rugose, remainder of metasoma superficially micro-sculptured; 4th and apical half of 3rd tergite without sharp lateral crease; ovipositor sheath wide, with long setae and apically truncate (Fig. 95 ).

Colour. Black; antenna (except scapus and pedicellus), palpi, tegulae, fore and middle telotarsi, veins and pterostigma dark brown; coxae, trochanters and trochantelli, apical third of hind femur (ventrally extended to its apical two-thirds), hind tibia (except pale yellowish basal ring) and hind tarsus black, remainder of legs yellowish brown; wing membrane subhyaline.

Variation. Hind femur usually only apically dark brown, but sometimes entirely dark brown; coxae black or sometimes largely yellowish brown. Two females (both NMS, from different localities) have vein r-m of fore wing absent. Males are very similar, apical tergites type 3, with fringe very weak to negligible; hind femur often only apically blackish, but sometimes up to apical 0.6 darkened. Antennal segments: ♀ 57(3), 58(1), 59(5), 60(7), 61(3), 62(6), 63(5), 64(1); ♂ 51(1), 52(1), 53(3), 54(1), 55(5), 56(7), 57(6), 58(5), 59(3), 60(1), 62(2); females have on average ca four more antennal segments than males. The antennal segments for the specimens of the abnormal series (see above) are scored separately here: ♀ 54(2), 55(1), 56(2), 57(3), 58(3), 60(1); ♂ 54(1).

Distribution.

Austria, *Belgium, British Isles (England), Czech Republic, *Finland, Germany, Hungary, *Netherlands, Poland, *Romania, Russia, Serbia, Slovakia, Spain, *Switzerland.

New synonymy.

The synonymy of Rogas vicinus Papp, 1977, with Aleiodes aterrimus (Ratzeburg, 1852) is based on the examination of the types listed above. The differences between R. vicinus and R. grandis (= A. aterrimus ) listed in the original description (head less constricted posteriorly, apical antennal segments more robust, 1st metasomal tergite less robust and 2nd tergite somewhat longer) fall within the normal variation of A. aterrimus .

Figures

Figure 101. Larva of Aleiodes aterrimus (Ratzeburg) mummifying Amphipyra pyramidea (Linnaeus), with its anterior (indicated by the arrow) projecting from the ventral opening in the host to spread adhesive over a wide area.

Figures 93 - 97. Aleiodes aterrimus (Ratzeburg), ♀, England, Pamber Forest 93 habitus lateral 94 detail of fore wing with arrow indicating lost vein r-m 95 ovipositor sheath lateral 96, 97 mummies of Amphipyra sp. showing variation in markings.

Figures 98 - 100. Aleiodes aterrimus (Ratzeburg), ♀, England, Pamber Forest 98 parasitised caterpillar of Amphipyra sp. 99 early stage of mummy 100 later stage of mummy.

Figures 102 - 115. Aleiodes aterrimus (Ratzeburg), ♀, England, Pamber Forest, but 102 from Austria, Wien 102 fore wing 103 hind wing 104 mesosoma lateral 105 mesosoma dorsal 106 metasoma dorsal 107 fore femur lateral 108 hind femur lateral 109 head anterior 110 head dorsal 111 head lateral 112 hind tibia and tarsus lateral 113 outer hind tarsal claw 114 base of antenna 115 apex of antenna.