Heterospilus sicanus ( Marshall, 1888 ), 1971

Belokobylskij, Sergey A., Guarino, Salvatore, Savoldelli, Sara, Jucker, Costanza, Peri, Ezio, Broad, Gavin R. & Cerasa, Giuliano, 2024, The ectoparasitoid wasp Heterospilus sicanus (Marshall, 1888) (Hymenoptera, Braconidae, Doryctinae) as a natural enemy of Gastrallus pubens Fairmaire, 1875 (Coleoptera, Ptinidae) in Italy, ZooKeys 1201, pp. 233-253 : 233-253

Heterospilus sicanus ( Marshall, 1888)

Figs 1 , 2 , 3 , 4 , 5

Dendrosoter sicanus Marshall, 1888: 243.

Heterospilus sicanus : Tobias 1971: 194; 1976: 35; Shenefelt and Marsh 1976: 1312; Yu et al. 2016.

Atoreuteus ceballosi Docavo Alberti, 1960: 33, syn. nov.

Heterospilus ceballosi : Shenefelt and Marsh 1976: 1302; Yu et al. 2016.

Type material examined.

Holotype of Dendrosoter sicanus : female, Italy, “ Type ” (round with red border), “ sicanus Marsh. (Sicily) ” (handwriting), “ Marshall coll. 1904 – 120 ”, “ Almost certainly type of Dendrosoter sicanus Msh., G. Nixon , 25. I. 38 ” (handwriting by G. Nixon), “ This is definitely type of Dendrosoter sicanus Marshall. Paul M. Marsh, VI – 17 – 71 ” (handwriting by P. Marsh), “ B. M. Type Hym. 3 c. 1751 ”, “ NHMUK 010880780 ” ( NHMUK, London) . Holotype of Atoreuteus ceballosi : female, Spain, “ Tenerife, Bajamar, 8. V. 1901 ”, “ ♀ ”, “ Atoreuteus ceballosi Docavo n. sp. ”, “ Tipo ”, “ Heterospilus ♀ ceballosi Doc. , det. Papp J., 1983 ”, “ MNCN Cat. Typos N 11.246 ” ( MNCN, Madrid) .

Additional material examined.

Italy: Sicily, “ Ottavio Ziino ” Law History Library of the Law Department of the University of Palermo, 5. VI. 2023 (E. Peri, S. Savoldelli, C. Jucker and S. Guarino), 18 females, 15 males ( SAAF-UNIPA); Sicily, Vittoria, IX – X. 1899 (G. Mantero), 1 female ( ZISP). Russia: Crimea, Sebastopol, 5. V. 1917 (W. Pliginski), 8 females with the same label of the latter ( ZISP).

Redescription.

Female (holotype). Body length 2.6 mm; fore wing length 2.3 mm.

Head. Head not depressed, its width 1.6 × median length, 1.1 × width of mesoscutum. Head behind eyes weakly convex anteriorly, evenly and roundly narrowed posteriorly. Transverse diameter of eye 1.2 × longer than temple (dorsal view). Ocelli small, in almost equilateral triangle. POL 1.3 × Od, 0.35 × OOL. Diameter of antennal socket equal to distance between sockets, twice distance between socket and eye. Eye with sparse and short setae, without emargination opposite antennal sockets, 1.2 × as high as broad. Malar space 0.7 × height of eye, 1.2 × basal width of mandible. Face convex, its width 1.2 × height of eye and almost equal to height of face and clypeus combined. Malar suture absent. Clypeus with distinct lower flange. [Hypoclypeal depression covered by glue.] Occipital carina complete dorsally, ventrally joining hypostomal carina distant from base of mandible. Head below eyes (front view) roundly narrowed. Hypostomal flange distinct but narrow.

Antennae. Antenna slender, filiform, 20 - segmented, almost as long as body. Scape rather short and thick, 1.5 × longer than its maximum width. First flagellar segment slender, almost straight, subcylindrical, 5.5 × longer than apical width, almost as long as second segment. Penultimate segment 3.3 × longer than wide, 0.6 × as long as first segment, 0.9 × as long as apical segment; the latter pointed apically and without spine.

Mesosoma. Mesosoma not depressed dorso-ventrally, its length 1.6 × maximum height. Pronotal neck rather long, dorsally without convex lobe, with rather distinct submedial pronotal carina; side of pronotum with distinct, almost straight, and rather wide submedian oblique crenulate furrow. Mesoscutum highly and perpendicularly elevated above pronotum, maximum width of mesoscutum 1.3 × its median length. Median lobe of mesoscutum (dorsal view) protruding forwards, weakly convex anteriorly, with distinct and almost pointed anterolateral corners. Notauli wide, rather deep, densely and coarsely crenulate. Prescutellar depression deep, wide, with 4 carinae, finely sculptured between carinae, ~ 0.3 × as long as wide, 0.45 × as long as scutellum. Scutellum convex, with fine lateral carinae, its width 1.1 × median length. Subalar depression rather deep, wide, sparsely and coarsely rugose-striate. Precoxal sulcus deep, almost straight, rugulose, running along anterior 0.6 of lower part of mesopleuron. Metanotal tooth (lateral view) relatively long, wide, distinctly pointed apically. Metapleural lobe rather large, more or less wide, rounded posteriorly. Propodeum (lateral view) regularly convex-roundly slanted from base to apex, without lateral tubercles; propodeal spiracle small.

Wings. Fore wing 3.0 × longer than its maximum width, 0.9 × as long as body. Pterostigma 3.0 × longer than wide. Radial vein (r) arising before middle of pterostigma, distance from base of pterostigma to radial vein (r) 0.85 × distance from radial vein (r) to apex of pterostigma. Radial (marginal) cell not shortened. Metacarp (1 - R 1) 1.2 × longer than pterostigma. First radial abscissa (r) almost as long as maximum width. Second radial abscissa (3 - SR) as long as first abscissa (r), 0.25 × as long as the straight third abscissa (SR 1), 0.5 × as long as trace of first radiomedial vein (2 - SR). Trace of first radiomedial vein (2 - SR) 2.3 × longer than second radiomedial vein (r-m), 4.0 × longer than recurrent vein (m-cu). Recurrent vein (m-cu) distinctly postfurcal. First medial abscissa (1 - SR + M) curved. Discoidal (discal) cell 1.6 × longer than its width. Distance (1 - CU 1) from nervulus (cu-a) to basal vein (1 - M) ~ 0.5 of nervulus (cu-a) length; nervulus (cu-a) straight and almost perpendicular to longitudinal anal vein (1 - 1 A). Mediocubital vein (M + CU 1) almost straight. Parallel vein (CU 1 a) distinctly curved subbasally. Brachial (subdiscal) cell widely open distally, brachial vein (CU 1 b) absent. Hind wing 4.2 × longer than wide. First abscissa of costal vein (C + SC + R) 1.2 × longer than second abscissa (1 - SC + R); second abscissa (1 - SC + R) strongly sclerotised. Last costal abscissa (SC + R 1) 0.8 × as long as first (C + SC + R) and second (1 - SC + R) abscissae combined. Radial vein (SR) strongly desclerotised. Medial (basal) cell narrow, almost parallel-sided in its apical half, its length ~ 11.0 × maximum width, almost 0.3 × length of wing. First abscissa of mediocubital vein (M + CU) 0.8 × as long as second abscissa (1 - M). Recurrent vein (m-cu) unsclerotised, almost interstitial, straight, very weakly oblique toward base of wing.

Legs. Fore tibia with several rather slender spines arranged in longitudinal line. Hind coxa with basoventral tubercle, 1.3 × longer than its maximum width. Hind femur rather wide, without dorsal protuberance, 3.5 × longer than wide. Hind tarsus 0.9 × as long as hind tibia. Basitarsus not thickened, without ventral keel, 0.5 × as long as second – fifth segments combined. Second tarsal segment 0.7 × as long as basitarsus, 1.6 × longer than fifth segment (without pretarsus).

Metasoma. Metasoma 0.9 × as long as head and mesosoma combined, 1.8 × longer than its maximum width. First segment with short acrosternite. First tergite with not high but rather distinct and wide median area, with distinct dorsope, without spiracular tubercles; tergite distinctly and almost linearly widened from base to apex. Length of first tergite equal to its apical width, 1.4 × length of propodeum; maximum width of tergite ~ 2.0 × its minimum width. Median length of second tergite 0.45 × its basal width, 0.8 × length of third tergite. Combined length of second and third tergites 0.9 × basal width of second tergite, 0.7 × their maximum width. Second suture present, but fine, usually weakly curved laterally. Third tergite without transverse furrow. Ovipositor sheath rather slender, 0.8 × as long as metasoma, 1.1 × longer than mesosoma, 0.4 × as long as body, 0.5 × as long as fore wing.

Sculpture and pubescence. Vertex entirely distinctly and rather densely transversely striate, partly with very fine additional reticulation between striae; frons entirely densely and distinctly transversely striate [face covered in glue]; temple smooth. Mesoscutum densely and distinctly granulate, medioposteriorly with two posteriorly convergent carinae. Scutellum granulate. Mesopleuron entirely rugose-striate. Metapleuron entirely distinctly rugose-reticulate. Propodeum with rather wide, short and finely granulate-coriaceous basolateral areas, weakly delineated by carinae; areola finely delineated; basal carina 0.8 × as long as anterior fork of areola; posterior 0.7 of propodeum irregularly rugose-reticulate. Hind coxa densely granulate, transversely striate dorsally. Hind femur finely and densely granulate-coriaceous. First tergite with rather distinct and posteriorly convergent dorsal carinae, densely and distinctly longitudinally striate, with fine and dense additional reticulation between striae. Second tergite mostly distinctly longitudinally striate, laterally smooth over rather wide area, rugulose postero-medially. Remaining tergites smooth. Vertex almost entirely with rather dense, short and semi-erect setae arranged in rows. Mesoscutum with rather dense, relatively long and semi-erect pale setae at wide area along notauli and scattered across lobes, all lobes narrowly glabrous medially. Hind tibia dorsally with short, sparse, semi-erect setae; length of these setae ~ 0.3 × maximum width of hind tibia.

Colour. Body reddish brown, vertex, mesonotum, and posterior half of metasoma dark reddish brown. Antenna dark brown, four basal segments pale brown. Palpi yellow. Legs entirely pale brown. Ovipositor sheath mainly brown, black apically. Fore wing very faintly infuscate. Pterostigma almost entirely brown.

Variation. Head width 1.4 – 1.6 × median length. Transverse diameter of eye 1.1 – 1.3 × longer than temple (dorsal view). Malar space 0.6 – 0.7 × height of eye. Hypoclypeal depression round, its width 0.7 – 0.8 × distance from margin of depression to margin of eye, 0.4 – 0.5 × width of face. Face mainly smooth. Antennae 20 - segmented. First flagellar segment 4.5 – 5.5 × longer than its apical width. Penultimate segment 3.0 – 3.3 × longer than wide. Mesosoma length 1.6 – 1.7 × maximum height. Maximum width of mesoscutum 1.2 – 1.3 × its median length. Mesopleuron sometimes smooth in small submedial area. Basal carina of propodeum 0.8 – 1.0 × as long as areola anterior fork. Wings. Pterostigma 2.8 – 3.6 × longer than wide. Second radial abscissa (3 - SR) 1.0 – 1.3 × as long as first abscissa (r), 0.25 – 0.30 × as long as third abscissa (SR 1), 0.5 – 0.7 × as long as trace of first radiomedial vein (2 - SR). Discoidal (discal) cell 1.6 – 1.8 × longer than its width. Legs. Hind femur 3.5 – 3.8 × longer than wide. Hind tibia dorsal setae 0.3 – 0.4 × maximum width of hind tibia. First metasomal tergite 1.3 – 1.4 × longer than propodeum. Median length of second tergite 0.40 – 0.45 × its basal width, 0.7 – 0.8 × length of third tergite. Ovipositor sheaths 0.7 – 0.9 × as long as metasoma, 1.1 – 1.2 × longer than mesosoma. Body mainly dark reddish brown, sometimes ventrally distinctly paler. Legs entirely pale brown or yellow, anterior half of metasoma often yellow or pale reddish brown. Fore wing very faintly infuscate. Pterostigma brown or pale brown.

Male. Body length 2.6–2.8 mm; fore wing length 2.1 mm. Antennae slender, filiform, 21 - segmented, approximately as long as body. Hind wing with relatively small, complex, brown stigma-like enlargement, its length 0.7 – 0.8 × distance from base of wing to base of enlargement. Length of first metasomal tergite 1.1 × its apical width. Second tergite entirely striate. Median length of second tergite 0.75 × its anterior width, 1.2 × length of third tergite. Third tergite with shallow and crenulate transverse furrow in anterior one – third. Body mainly brown to dark brown, anterior third of metasoma paler. Otherwise similar to female.

Host.

Until recently, the only reported host of this species was Cryphalus piceae (Ratzeburg, 1837) ( Coleoptera , Curculionidae , Scolytinae) ( Tobias 1971; Kenis et al. 2004; Wegensteiner et al. 2015). However, the first author checked material assigned to this species deposited in the collection of the Zoological Institute RAS (St Petersburg, Russia) determined by Dr V. I. Tobias as H. sicanus (Marshall) ( Tobias 1971) . This sample comprised seven females and ten males with the label: “ Teberda, Sev. Kavkaz [North Caucasus, Karachay-Cherkess Republic], on Cryphalus picaae, T. Guryanova [leg], 24 VI [19] 64 ”, “ Dendrosotinus sicanus Marsh., Tobias det. 1965 ”. Our redetermination of these specimens showed that they actually belong to another genus and species, Dendrosotinus (Gildoria) similis Boucek, 1955 . Thus, the host of H. sicanus was unknown before this study and Gastrallus pubens Fairmaire, 1875 ( Coleoptera , Anobiidae ) is the first and only known host of H. sicanus .

Distribution.

According to Taxapad, the world catalogue of Ichneumonoidea ( Yu et al. 2016), besides Italy (Sicily), H. sicanus has also been recorded in Spain ( Falco Gari et al. 1993), Croatia ( Papp 1977), Serbia ( Brajkovic 1989), and Hungary ( Papp 1984); however, at least some of these records require confirmation. In Russia, this species has only been found in Crimea (new record; see ‘ Additional material examined’), whereas its records from the North Caucasus of Russia ( Tobias 1971, 1976) were erroneous (for details see ‘ Remarks’ under the ‘ Hosts’ section).

Comparative diagnosis.

Heterospilus sicanus (Marshall) is very similar to H. corsicus ( Marshall, 1888) , but differs from the latter by having the head behind the eyes convex anteriorly and roundly narrowed posteriorly (evenly roundly narrowed posteriorly in H. corsicus ), eyes setose, transverse diameter in dorsal view 1.1 – 1.3 × length of temple (glabrous, transverse diameter 1.5 – 1.6 × length of temple in H. corsicus ), antenna slender (thickened in H. corsicus ), mesosoma 1.6 – 1.7 × longer than its height (1.8 × in H. corsicus ), medial lobe of mesoscutum without pointed anterolateral corners (with pointed corners in H. corsicus ), radial vein (r) of fore wing arising slightly before middle of pterostigma (almost from or behind middle in H. corsicus ), setae on dorsal side of hind tibia short, ~ 0.3 × as long as maximum width of tibia (long, 0.5 – 0.7 × in H. corsicus ), and pterostigma almost entirely brown (yellow in H. corsicus ).

Western Palaearctic Heterospilus species with an almost entirely sculptured vertex can be differentiated using the key below.

Figures

Figure 1. Heterospilus sicanus (Marshall, 1888) (female, holotype) A habitus, dorsal view B habitus, lateral view C head, mesosoma and base of metasoma, lateral view D head, mesosoma and base of metasoma, dorsal view E propodeum, metasoma and ovipositor, dorsal view F head and mesoscutum, dorsal view G wings H labels.

Figure 2. Heterospilus sicanus (Marshall, 1888) (female) A habitus, lateral view B – D head, frontal, antero-lateral and lateral view E maxillary palp F, G head, dorsal and postero-dorsal view H antenna I mesosoma, dorsal view J pronotum, antero-dorsal view K mesosoma, lateral view L propodeum, dorsal view.

Figure 3. Heterospilus sicanus (Marshall, 1888) (female) A mesosoma, ventro-lateral view B fore wing C hind wing D fore leg (white arrows indicate short stout spines on its front tibia surface and black arrow those on the apical part) E middle leg F hind leg (black arrow indicates a distinct antero-ventral basal tubercle on the coxa) G metasoma, dorsal view H first tergite, dorso-lateral view I ovipositor and one of its sheaths J ovipositor apex.

Figure 4. Heterospilus sicanus (Marshall, 1888) (male) A habitus, lateral view B head, front view C head, lateral view D head dorso-lateral view E head dorsal view F labial palpus G maxillary palpus H antenna I mesosoma, dorsal view J pronotum, antero-dorsal view K mesosoma, lateral view.

Figure 5. Heterospilus sicanus (Marshall, 1888) (male) A pronotum and propleuron, dorso-lateral view B fore wing C hind wing D metasoma, dorsal view E metasoma dorso-lateral view F metasoma, lateral view.