Meteorus acerbiavorus Belokobylskij, Stigenberg and Vikberg, 2011

Stigenberg, Julia, Vikberg, Veli & Belokobylskij, Sergey A., 2011, Meteorus acerbiavorus sp. nov. (Hymenoptera, Braconidae), a gregarious parasitoid of Acerbia alpina (Quensel) (Lepidoptera, Arctiidae) in North Finland, Journal of Natural History 45 (21 - 22), pp. 1275-1294 : 1278-1286

Meteorus acerbiavorus Belokobylskij, Stigenberg and Vikberg , sp. nov.

( Figures 1 A–L, 2A–G, 3A–L, 5A, 5B)

Type material

Holotype. female, “ Finland 767:325. Enontekiö Lapland : Jehkats, June 2009, Harry Lonka leg.”, “From cocoon of Acerbia alpina Quensel (Arctiidae) ” ( ZISP).

Paratypes

Three females and three males ( ZISP) , four females and two males (RMNH), two females (NHRS-HYME 5221 and 5223) and two males (NHRS-HYME 5222 and 5240) (NHRS), three females and three males MZH), seven females and seven males (CHL), five males and two females (CGS) and six females and two males (CVV). Two females, two males, “ Finland 7679:3254. EnL (= Enontekiö Lapland): Jehkats, ex cocoon of Acerbia alpina taken 2006, Marko Mutanen leg.” ( ZISP) , one female (NHRS-HYME 5242) and three males (NHRS-HYME 5241, 5243 and 5244) (NHRS). Three females, four males, “ Finland 769:326. EnL: Lossujärvi, ex cocoon of Acerbia alpina taken 2.6.1992, Juha Kytömaa leg.” ( ZISP) ; one female and two males (RMNH), one female (NHRS-HYME 5246) and two males (NHRS-HYME 5245 and 5247) (NHRS), one female and three males (MZH), and one female and 20 males ( CVV) . Paratypes collected by H. Lonka are labelled with identical or nearly identical labels as holotype or uniform grid reference 767:325 is replaced by EUREF-FIN grid reference 7676:8254 .

Description

Female (holotype). Body length 4.6 mm; fore wing length 3.9 mm.

Head transverse, its width 1.7 times median length, 1.1 times width of mesoscutum. Head behind eye (dorsal view) distinctly and convex-roundly narrowed. Transverse diameter of eye (dorsal view) 1.3 times longer than temple. Frons flat, without medial tubercle, but with shallow and rather wide crenulate longitudinal median furrow. Ocelli medium-sized, arranged in triangle with base 1.5 times its sides; POL 2.0 times Od, 1.2 times OOL, Od 0.6 times OOL. Eye oval, with long and rather dense setae, weakly convergent below (front view of head), 1.5 times as high as broad. Malar space height 0.3 times height of eye, equal to basal width of mandible. Minimum width of face 0.8 times its maximum width at level of antennal sockets, 1.3 times its median height, 0.9 times high of eye. Subocular suture distinct. Tentorial pits rather large, distance between pits 2.2 times distance from pit to eye; diameter of pit about 0.5 times distance from pit to eye. Clypeal suture distinct and complete. Clypeus strongly convex, it lower margin almost straight and without tubercle, with fine flange; clypeal width 1.8 times its median height, 0.9 times minimum width of face. Mandible rather distinctly twisted. Occipital carina complete, fused ventrally with hypostomal carina. Palpar segments weakly thickened.

Antenna almost filiform, thickened, about 0.9 times as long as body, 27- segmented. Scape 1.6 times longer than maximum width. First flagellar segment 2.8 times longer than its apical width, equal to second segment. Penultimate segment 1.4 times longer than its width, 0.35 times as long as first flagellar segment, 0.8 times as long as apical segment. Apical segment pointed apically and with short spine.

Mesosoma length 1.5 times its height. Notauli shallow, wide, complete, coarsely rugose-reticulate with granulation. Prescutellar depression deep, almost straight, with five rather fine carinae, rugulose between carinae, 0.4 times as long as scutellum. Scutellum distinctly convex, without lateral carinae, posteriorly with deep and rather short transverse depression divided medially by high carina. Sternaulus shallow, wide, weakly curved, entirely coarsely rugose-reticulate with granulation. Propodeum (in lateral view) roundly convex in anterior half, strongly, weakly curvedly and vertically in posterior half.

Wings: fore wing 3.0 times longer than its maximum width. Radial (marginal) cell narrow and shortened, 3.5 times longer than maximum width. Metacarp (1–R1) 1.1 times longer than pterostigma, 5.0 times longer than distance between top of radial (marginal) cell and top of wing. Radial vein (r) arising behind middle of pterostigma, from its apical 0.4. Second radial abscissa (3–SR) almost equal to first abscissa (r), 0.1 times as long as the weakly curved third abscissa (SR1), 0.4 times as long as first radiomedial vein (2–SR), 0.5 times as long as second radiomedial vein (r-m). Second radiomedial (submarginal) cell short, its length 1.1 times maximum width. Recurrent vein (m-cu) weakly antefurcal. Discoidal (discal) cell shortly petiolate, 1.4 times longer than its maximum width. Distance from nervulus (cu-a) to basal vein (1–M) almost equal to nervulus (cu-a) length. Hind wing 3.8 times longer than wide. Second abscissa of mediocubital vein (1–M) 0.9 times as long as nervellus (cu-a) and basal vein (1r-m).

Legs: hind femur slender, 5.6 times longer than wide. Inner spur of hind tibia about 0.3 times as long as hind basitarsus. Second segment of hind tarsus 0.4 times as long as basitarsus, 1.3 times longer than third segment, 1.8 times longer than fifth segment (without pretarsus). Claws rather slender, weakly curved apically, without lobe or tooth.

Metasoma 1.1 times longer than head and mesosoma combined. First tergum with fine dorsope, with very small spiracular tubercles near its middle, ventral borders of tergum weakly separated at short distance in its basal half. Length of first tergum 2.0 times its apical width; apical width 2.8 times its minimum width. Second suture very shallow, but more or less distinct. Length of second and third terga combined 1.6 times larger than basal width of second tergum, 0.9 times their maximum width. Ovipositor subapically with distinct dorsal node. Ovipositor sheath 1.25 times longer than first tergum, almost as long as hind femur, 0.65 times as long as costal vein (C+SC+R) of fore wing.

Sculpture and pubescence: frons widely smooth, anteriorly with curved striation and with short striae along the median line. Anterior half of vertex almost smooth, its posterior half densely and distinctly punctate and with rather coarse rugosity laterally. Face distinctly and densely transversely striate with fine granulation; clypeus distinctly punctate-rugose. Temple almost smooth in anterior half and coarsely subvertically striate and with dense granulation and rugulosity in posterior half. Median lobe of mesoscutum densely and rather coarsely rugose-granulate, mostly rugosereticulate in the posterior third; lateral lobes rather distinctly and more or less sparsely punctate, with rugulosity anteriorly, usually smooth between punctulae. Scutellum entirely coarsely rugose-areolate. Mesopleuron entirely coarsely and densely rugosereticulate, widely with small and dense additional granulation. Propodeum entirely coarsely reticulate-areolate, with rather fine median longitudinal carina. Hind coxa entirely coarsely rugose-reticulate, dorsally with distinct, transverse and weakly undulate striation. Hind femur distinctly and densely punctate, almost smooth below. First metasomal tergum densely and smoothly striate, rugulose-striate in the basal quarter. Remaining metasomal terga smooth. Mesoscutum entirely covered by short and dense pale setae.

Colour: body black, metasoma behind first tergum dark reddish brown, reddish brown posteriorly and ventrally. Antennae entirely black. Palpi reddish brown basally, faintly paler apically. Legs dark reddish brown to reddish brown, hind coxa almost black. Ovipositor sheath dark brown. Wings faintly and evenly infuscate. Pterostigma brown, faintly paler basally; costal vein (C+SC+R) almost black.

Variation

Body length 4.3–4.6 mm; fore wing length 3.8–4.0 mm. Transverse diameter of eye (dorsal view) 1.2–1.4 times longer than temple. Ocellar triangle with base 1.3–1.5 times its sides; POL 2.0–2.2 times Od, 1.1–1.3 times OOL, Od 0.55–0.65 times OOL. Malar space height 0.25–0.3 times height of eye, 0.9–1.0 times basal width of mandible. Antenna with 25 (n = 4), 26 (n = 2) or 27 (n = 2) flagellomeres. First flagellar segment 2.7–3.0 times longer than its apical width, 1.0–1.1 times as long as second segment. Penultimate segment 1.4–1.7 times longer than its width, 0.55–0.8 times as long as apical segment. Length of mesosoma 1.5–1.6 times its height. Fore wing 2.9–3.2 times longer than its maximum width. Metacarp (1–R1) 1.1–1.25 times longer than pterostigma, 3.5–5.0 times longer than distance between top of radial (marginal) cell and top of wing. Recurrent vein (m-cu) weakly antefurcal or interstitial. Distance from nervulus (cu-a) to basal vein (1–M) 0.7–1.0 times nervulus length. Hind femur 5.5–6.8 times longer than wide. Second segment of hind tarsus 1.6–1.8 times longer than narrow fifth segment (without pretarsus). Length of first tergum 1.9–2.1 times its apical width; apical width 2.8–3.0 times its minimum width; dorsope more or less distinct. Length of second and third terga combined 1.5–1.6 times larger than basal width of second tergum, 0.9–1.0 times their maximum width. Ovipositor sheath 1.2–1.4 times longer than first tergum, 0.6–0.7 times as long as costal vein of fore wing.

Male. Body length 4.2–4.6 mm; fore wing length 3.6–3.8 mm. Head behind eye (dorsal view) almost parallel-side in anterior half distinctly and almost linearly narrowed in posterior half. Transverse diameter of eye (dorsal view) 1.1–1.2 times longer than temple. Eye very weakly convergent below (front view of head). Distance between tentorial pits 2.8–3.0 times distance from pit to eye. Width of clypeus 1.7– 1.9 times its median height, 0.8–0.85 times minimum width of face. Antenna setiform, with 24 (n = 15), 25 (n = 11) or 27 (n = 2) flagellomeres. Scape 1.3–1.5 times longer than maximum width. First flagellar segment 2.5–2.8 times longer than its apical width, 0.95 times as long as second segment. Apical segment apically without spine. Scutellum less strongly sculptured, rather finely rugulose medially, with curved transverse striae anteriorly. Propodeum with rather distinct median longitudinal carina. Second radial abscissa (3–SR) of fore wing 0.5–0.7 times as long as first abscissa (r), 0.06–0.10 times as long as third abscissa (SR1), 0.2–0.35 times as long as first radiomedial vein (2–SR). Recurrent vein (m-cu) almost interstitial or very weakly antefurcal. Hind femur thicker, 4.8–5.8 times longer than wide. Second segment of hind tarsus 1.4–1.6 times longer than narrow fifth segment (without pretarsus). Metasoma 0.8– 1.0 times as long as head and mesosoma combined. First tergum often with distinct spiracular tubercles and more or less distinct dorsope; length of tergum 1.8–1.9 times its apical width; apical width 2.9–3.0 times its minimum width. Length of second and third terga combined 1.4–1.5 times larger than basal width of second tergum, almost equal to their maximum width. Metasoma dorsally entirely black. Otherwise similar to female.

Biology. M. acerbiavorus sp. nov. is a gregarious larval parasitoid of Acerbia alpina Quensel (Arctiidae) reared from the cocoon of the moth. The parasitoid cocoons (Figure 48) are brown and their sizes are 5.0 × 1.9–2.0 mm.

Diagnosis

Meteorus acerbiavorus sp. nov. run in Huddleston’s (1980) revision of the western Palaearctic Meteorus to M. rubens (Nees) ( Figures 4 A–G, 5C, 5D), which is a widely distributed species in the Palaearctic region ( Huddleston 1980; Tobias 1986; Belokobylskij 2000; Chen and Wu 2000). Both species have a low number of antennal segments, the ventral borders of the first tergum joined or almost joined (separated only by approximately 25 µm), weakly curved toothless claws and medium-sized ocelli. The new species differs from M. rubens in having the eyes densely setose (sparsely in M. rubens ), the median lobe of mesoscutum entirely or mostly rugulose-granulate or granulate (usually widely smooth with punctation in M. rubens ), the scutellum entirely or at least marginally rugose-areolate (widely smooth in M. rubens ), the mesopleuron medially entirely or almost entirely coarsely and densely rugose-reticulate with granulation (widely smooth in M. rubens ), the hind coxa widely coarsely sculptured (widely smooth in M. rubens ), the ovipositor subapically with distinct dorsal node (small and indistinct in M. rubens ), the ventral borders of first metasomal tergum weakly separated by narrow space in its basal half (distinctly joined in short submedian part in M. rubens ), the body entirely or widely black (mostly pale brown or yellowish brown in M. rubens ), and the fore wing more or less darkened (hyaline in M. rubens ).

This new species distinctly differs from the North American M. dimidiatus (Cresson) ( Muesebeck 1923) in having the second abscissa of mediocubital vein (1– M) of hind wing not longer than nervellus (cu-a) and basal vein (1r-m) (longer in M. dimidiatus ), the eyes weakly convergent below (distinctly convergent in M. dimidiatus ), the second radial abscissa (3–SR) of fore wing usually equal to the first abscissa (r) (longer in M. dimidiatus ), and the first metasomal tergum mostly strongly striate (finely rugulose-striate in M. dimidiatus ). This new species is a gregarious parasitoid of arctiid Acerbia alpina Quensel in comparison with Desmia funeralis (Hübner) (Pyralidae) as a host of solitary M. dimidiatus .

Remarks

Studied material of M. acerbiavorus sp. nov. reared by three collectors in different time in two localities (Jehkats and Lossujärvi) of Enontekiö Lapland showed distinct differences in the colouration and sculpture of the body. The material by H. Lonka (Jehkats, 2009) ( Figure 3A, 3D, 3G, 3J ) is almost completely dark and with widely distributed coarse sculpture on mesosoma (including entirely coarsely rugose-striate scutellum). The specimens collected in the same locality by M. Mutanen (2006) ( Figure 3B, 3E, 3H, 3K ) are also mainly black but with paler red areas on the head behind the eyes and on the metasoma behind the petiole. Scutellum of these specimens medially with smoothed and fine sculpture, mesopleuron usually with more large smooth areas and the basal part of petiole mainly smooth. The most aberrant specimens belong to the material collected by J. Kytömaa (1992) in Lossujärvi ( Figure 3C, 3F, 3I, 3L ). These specimens have the palest colouration of the body with a red ring around eyes, reddish basal half of petiole and yellowish brown to reddish brown second metasomal tergite, and widely light reddish brown legs. The sculpture of this material is basically less strong having more widely smooth or almost smooth lateral lobes of mesoscutum, posterior areas of mesopleuron and median part of scutellum, and basal 0.3 of petiole. This material also has one female and one male with deformed first tergum, which is short and strongly widened in its distal half.

Figures

Figure 1. Morphological characters of the female of Meteorus acerbiavorus sp. nov. (A) head, front view; (B) head, dorsal view; (C) head, lateral view; (D) basal and apical segments of antenna; (E) mesosoma, lateral view; (F) hind femur; (G) apical segments and claw of hind tarsus; (H) metasoma, lateral view; (I) first tergum of metasoma, dorsal view; (J) first tergum of metasoma, ventral view; (K) fore wing; (L) hind wing. Scale bar: a – for (K), (L) (1 mm); b – for (E) (1 mm); c – for (G) (0.5 mm); d – for (H–J) (1 mm); e – for (A–D), F (1 mm).

Figure 3. Morphological characters of Meteorus acerbiavorus sp. nov. specimens collected by H. Lonka ((A), (D), (G), (J)), M. Mutanen ((B), (E), (H), (K)) and J. Kytömaa ((C), (F), (I), (L)) (photos): (A–C) – mesoscutum; (D–F) – mesoscutum and scutellum; (G–I) – mesopleuron; (J–L) – first metasomal tergum.

Figure 4. Morphological characters of the female of Meteorus rubens (Nees) (photos): (A) habitus, lateral view; (B) head, dorsal view; (C) head, lateral view; (D) head, front view; (E) mesoscutum and scutellum, dorsal view; (F) mesosoma, lateral view; (G) first metasomal tergum, dorso-lateral view.