Ipodoryctes signipennis ( Walker, 1860 )

Gupta, Ankita, Belokobylskij, Sergey A., Achterberg, Cornelis Van, Pattar, Rohit, Broad, Gavin R., Gracy, R. G. & Sushil, S. N., 2024, Parasitoid complex of doryctine wasps (Hymenoptera: Braconidae) reared from Pongamia pinnata (L.) (Fabaciae) coleopteran complex (Coleoptera) with description of two new species from India, Zootaxa 5506 (3), pp. 402-427 : 403-409

Ipodoryctes signipennis ( Walker, 1860)

( Figs 1–4 )

Spathius signipennis Walker, 1860: 309 .

Rhaconotus signipennis : Shenefelt & Marsh 1976: 1341.

Ipodoryctes (Ipodoryctes) signipennis : Belokobylskij & Zaldivar-Riveron 2021: 44.

Dendrosotinus flavistigmus Belokobylskij, 1983: 184 ; 2001: 134 (as synonym).

Material examined. SRI LANKA: “Type” (round label with green border), “63 52”, “ signipennis ” (handwriting by Walker?), “ B.M. Type Hym. 3c 1394”, “ NHMUK010635962 ”, 1 female (holotype) ( NHMUK) .

INDIA: 1 female, “N 22 – 583, ex larva of Acigona steniella [= Bissetia steniellus (Hampson, 1899) , Lepidoptera : Crambidae ], C.I.E/A. 15440”, “India, Jalandhar, Selkiana, 20. VIII. [19]83”, “ NHMUK012857653 ” ( NHMUK) ; 1 female, “ Dehra Dun [= Dehradun, Uttarakhand State], U.P., J.C.M. Gardner , 22.IV.1930 ”, “ex dry stems.”, “Cage No.195”, “1110”, “1939-227”, “ Rhaconotus signipennis Walk., G. Nixon det. 1939”, “ NHMUK012857654 ” ( NHMUK) . 2 females, [India: Karnataka; Bengaluru ], 23.VIII.2023, ex cerambycid beetles infested Pongamia pinnata (L.) wood logs, coll. R . Pattar , Code- NIM/ NBAIR / Hym / Brac / Rhac /230823 ( NIM) .

Re-description. Female (holotype). Body length 2.7 mm; fore wing length 2.4 mm.

Head width 1.6 × its median length (dorsal view). Head behind eyes (dorsal view) strongly and roundly narrowed; transverse diameter of eye 3.3 × length of temple (dorsal view). Ocelli medium-sized, arranged in triangle with base 1.1 × its sides; POL almost equal to Od, 0.5 × OOL. Eye glabrous, weakly emarginated opposite antennal sockets, 1.15 × as high as broad. Malar space 0.3 × as height as eye, about as long as basal width of mandible. Face with rather wide median vertical and weakly convex area. Face width 0.85 × height of eye and 1.3 × height of face and clypeus combined. Malar suture absent. Clypeus with distinct ventral flange; upper margin of clypeus distinctly above lower level of eyes. Hypoclypeal depression subcircular, its width 0.9 × distance from edge of depression to eye, 0.4 × width of face. Occipital carina not fused ventrally with hypostomal carina being narrowly obliterated above base of mandible. Vertex weakly convex. Head below eyes distinctly and almost linearly narrowed (front view). Maxillary palpi 1.2 × longer than height of head.

Antennae slender, weakly setiform, with 24 antennomeres, 1.2 × as long as body. Length of scape 1.6 × its maximum width. First flagellomere 4.0 × longer than its apical width, 1.1 × longer than second flagellomere. Penultimate flagellomere 4.0 × longer than wide, 0.7 × as long as first flagellomere, 0.9 × as long as apical flagellomere; the latter acuminate apically and without spine.

Mesosoma. Length about twice its height. Pronotum anteriorly straight or weakly convex (dorsal view), dorsally almost straight (lateral view). Pronotal carina distinct, distances from carina to both (anterior and posterior) sides of pronotum subequal. Mesoscutum elevated above pronotum in rather high, gradual curve. Notauli complete, relatively deep and crenulate. Median lobe of mesoscutum without median furrow. Prescutellar depression rather deep, weakly and roundly directed postero-laterally, with three carinae, almost smooth. Precoxal sulcus rather deep, straight, weakly oblique, coriaceous, running along anterior 0.7 of lower part of mesopleuron. Subalar depression rather shallow, narrow, crenulate with granulation. Metanotum with short and pointed posteriorly tooth (lateral view). Metapleural lobe distinct, relatively narrow and rounded distally.

Wings. Length of fore wing 2.8 × its maximum width. Radial (marginal) cell not shortened. Metacarp (1- R 1) 1.2 × longer than pterostigma. Radial vein (r) arising weakly before middle of pterostigma. First radial abscissa (r) forming distinct obtuse angle with second abscissa (3- SR). Second radial abscissa (3- SR) almost twice longer than first abscissa (r), 0.55 × as long as the straight third abscissa ( SR 1), 1.3 × longer than first radiomedial vein (2- SR). Second radiomedial (submarginal) cell very weakly widened distally, 2.5 × longer than wide, 1.4 × longer than narrow brachial (subdiscal) cell. First medial abscissa (1- SR +M) weakly sinuate. Recurrent vein (m-cu) postfurcal. Mediocubital vein (M+ CU 1) weakly curved to anal vein (1-1A) in distal half. Distance (1- CU 1) from nervulus (cu-a) and basal vein (1-M) equal to nervulus (cu-a) length. Brachial (subdiscal) cell distally strongly and almost linearly closed very weakly behind recurrent vein (m-cu); posterior abscissa of anal vein (3-1A) (behind brachial vein (CU1b)) shortly present. Hind wing 4.7 × as long as wide. First costal abscissa (C+SC+ R) 0.7 × as long as second abscissa (1- SC + R). First abscissa of mediocubital vein (M+CU) 0.7 × as long as second abscissa (1-M). Recurrent vein (m-cu) present, unsclerotised, weakly curved towards base of wing, antefurcal.

Legs. Hind coxa with distinct baso-ventral tubercle, about 1.5 × longer than wide (with tubercle). Hind femur with low and wide dorsal protuberance, length of femur 2.8 × its maximum width. Hind tarsus about as long as hind tibia. Hind basitarsus 0.6 × as long as combined length of second to fifth segments. Second tarsal segment 0.5 × as long as basitarsus, twice longer than fourth segment, 1.3 × longer than fifth segment (without pretarsus).

Metasoma almost as long as head and mesosoma combined, with six dorsally visible tergites. First tergite without subbasal lateral processes. Maximum width of first tergite about twice its anterior width; its length about equal to posterior width. Second tergite with distinct and smooth anterior area separated by coarse sculpture, without transverse sub-posterior furrow; with distinct, narrow and weakly curved smooth posterior area, this area 0.4 × as long as remaining anterior part of tergite. Median length of second tergite 0.45 × its anterior width, 1.1 × length of third tergite. Second suture deep, rather wide, distinctly regularly curved. Sixth tergite moderately enlarged, weakly evenly curved on posterior margin, without median emargination and latero-posterior lobes. Sixth tergite 0.8 × as long as fifth tergite, 1.15 × longer than fourth tergite. Ovipositor sheath 0.45 × as long as metasoma, 1.7 × longer than first tergite, 0.65 × as long as mesosoma, 0.3 × as long as fore wing.

Sculpture and pubescence. Vertex and frons entirely densely granulate, without rugosity; face densely granulate, almost smooth on narrow vertical median stripe and below; temple coriaceous, almost smooth below. Mesoscutum entirely densely granulate, without additional rugosity along notauli, densely rugose in medio-posterior area. Scutellum densely granulate. Mesopleuron medially widely coriaceous, granulate dorsally, almost smooth below precoxal sulcus. Propodeum with basolateral areas delineated by distinct carinae and finely densely coriaceous, with median carina in basal 0.4; remaining part of propodeum rugose, with incompletely delineated wide areola. Hind coxa entirely densely granulate and without rugosity dorsally. Hind femur densely granulate dorsally, coriaceous laterally, almost smooth ventrally. First metasomal tergite with widely separated and subparallel dorsal carinae. First tergite entirely, second tergite mainly (except smooth anterior and posterior areas), and third to fifth tergites in anterior 0.7–0.8 (but almost entirely laterally) coarsely and rather sparsely striate and partly with fine rugulosity; third to fifth tergites smooth posteriorly. Sixth tergite densely and distinctly semi-circularly striate and rugosegranulate medio-basally. Second to fifth tergites laterally coarsely striate and with very fine rugulosity between striae. Vertex with rather short and relatively sparse semi-erect pale setae directed forward. Mesoscutum entirely with very dense short and semi-erect pale setae. Metapleural lobe with dense white pubescence. Hind tibia dorsally with dense semi-erect pale setae; length of these setae about 0.5 × maximum width of hind tibia.

Colour. Head yellow. Mesosoma light reddish brown, infuscate posteriorly. Metasoma reddish brown, only reddish laterally, sixth tergite reddish yellow.Antenna brownish yellow, infuscate toward apex, almost black apically. Palpi pale yellow. Legs yellow, their fifth tarsal segments infuscate. Ovipositor sheath black. Fore wing very faintly and evenly infuscate. Pterostigma entirely pale yellow.

Male. Unknown.

Main variation on the basis of new reared Indian material. Body length 4.1 mm, fore wing 3.7 mm. Head width 1.4 × its median length (dorsal view). Transverse diameter of eye 2.5 × length of temple. Ocelli arranged in triangle with base 1.2 × its sides; POL 1.3 × Od, 0.8 × OOL. Malar space height 0.4 × height of eye, 1.3 × basal width of mandible. Hypoclypeal depression 0.6 × as wide as face. Antennae with 29 antennomeres. Scape 1.8 × longer than its maximum width. First flagellomere 4.8 × longer than its apical width. Penultimate flagellomere 3.4 × longer than wide, 0.5 × as long as first flagellomere. Mesosoma 1.8 × longer than high. Length of fore wing 3.2 × its width. Second radial abscissa (3- SR) 1.8 × longer than first radial abscissa (r). First abscissa of mediocubital vein (M+CU) of hind wing 0.6 × as long as second abscissa (1-M). Legs. Hind femur almost 3.0 × longer than wide. Hind basitarsus 0.65 × as long as second-fifth segments combined. Second tarsal segment 1.2 × longer than fifth segment (without pretarsus). Median length of second metasomal tergite 0.4 × its basal width. Ovipositor sheath 0.6 × as long as metasoma, 2.0 × longer than first tergite, 0.8 × as long as mesosoma, 0.4 × as long as fore wing. Sculpture and pubescence. Hind coxa rugose dorsally, reticulate laterally. Hind tibia setae length 0.7 × maximum width of hind tibia. Colour. Head and proximal two-thirds of antenna yellowish brown. Mesosoma reddish brown.

Hosts. The possible host of this species could be any of the coleopteran species which emerged from the same infested logs of Pongamia pinnata (L.), viz. Niphona nr. obscura Breuning, 1938, indeterminate taxon from the tribe Acanthocinini , or Moechohecyra sp. Ipodoryctes signipennis was previously reared in India from Acigona steinella ( Lepidoptera ) ( Fig. 4E ). Hence, to clear the doubt on coleopteran hosts, post-emergence of beetles and wasps the infested logs were kept in rearing cages and observed for another two months in the laboratory; however, no lepidopteran emergence was noticed.

Previous reported hosts of Ipodoryctes signipennis (Walker) are the larvae of Chilo auricilius Dudgeon, 1905 and Scirpophaga incertulas (Walker, 1863) ( Crambidae ) ( Rao et al. 1968; Yu et al. 2016) ( Figs 3 , 4 ), which bore into and feed on the stems of various grasses ( Poaceae ), including sugarcane, rice and maize. These larvae remain hidden inside grass stems. There are some examples in Doryctinae of species attacking hosts of different insect orders ( Belokobylskij 1996), for example, in the genera Rhoptrocentrus Marshall, 1897 , Rhaconotinus Hedqvist, 1965 , Rhaconotus Ruthe, 1854 , etc., therefore it might not be too surprising if I. signipennis is a parasitoid of both concealed Lepidoptera and Coleoptera , although the difference in host substrate is intriguing.

Figures

FIGURE 1. Ipodoryctes signipennis (Walker) (holotype, NHMUK). (A) Habitus, lateral view. (B) Head, mesosoma and metasoma, dorsal view. (C) Head, front view. (D) labels.

FIGURE 2. Ipodoryctes signipennis (Walker) (Karnataka, NIM). (A) Head, front view. (B) Head, dorsal view. (C) Mesonotum, dorsal view. (D) Mesosoma, lateral view. (E) Wings. (F) Propodeum. (G) Metasoma, dorsal view.

FIGURE 3. Ipodoryctes signipennis (Walker) (Karnataka, NIM). (A) Habitus, lateral view. (B) Metasoma and ovipositor, dorsal view.

FIGURE 4. Ipodoryctes signipennis (Walker) (A, C: NHMUK012857653; B, D: NHMUK012857654). (A) Habitus, lateral view. (B) Habitus, dorsal view. (C) Body, dorsal view. (D) Body, lateral view. (E) Labels.