Three new species of the genus Probles Förster (Hymenoptera, Ichneumonidae, Tersilochinae) from South Korea

Abstract Three closely related species of the genus Probles Förster, P. fulgida sp. n., P. korusa sp. n. and P. rukora sp. n., belong to the subgenus Euporizon Horstmann and differ from other Palearctic species of the genus by a combination of long and apically weakly sinuate ovipositor and short temple. These three species are assigned to a newly designated fulgida species-group, and a portion of the key for identification of this species-group is provided. Based on the shape of the ovipositor apex, the fulgida species-group resemble members of the subgenus Microdiaparsis Horstmann but are distinct in having a much shorter temple.


Introduction
Probles is a predominantly Holarctic genus (Nearctic species are mostly undescribed) with about 44 species in the Palearctic region (Yu et al. 2012) and some undescribed species in the Afrotropical and Oriental regions and Australia (Gauld 1984;Khalaim 2007bKhalaim , 2011. Townes (1971) mentioned a worldwide distribution of this genus but it probably does not occur in South America (Khalaim pers. data). The Palearctic fauna of Probles is rather irregularly studied: West European species were revised by Horstmann (1971Horstmann ( , 1981Horstmann and Kolarov 1988), and Palearctic species of five small subgenera, Microdiaparsis Horstmann, Probles s. str., Rhynchoprobles Horstmann and Rugodiaparsis Horstmann, were reviewed in two papers by Khalaim (2003Khalaim ( , 2007a, whereas the most species rich subgenus, Euporizon Horstmann, is virtually unstudied outside Europe. Some species of Probles have been recorded as parasitoids of the beetle families Ciidae, Curculionidae, Endomycidae, and Melandryidae in Europe (Horstmann 1971(Horstmann , 1981. Only two species of Euporizon, P. (E.) sibirica Khalaim, 2007 from Mongolia and Russian Siberia and P. (E.) vulnifica Khalaim & Sheng, 2009 from the Palearctic part of China, are known to occur in the East Palearctic region, and one Oriental species, P. (E.) vietnamica Khalaim, 2011, was recently described from Vietnam (Khalaim 2007a(Khalaim , 2011Khalaim and Sheng 2009). Six more undescribed species of Euporizon were reported from South Korea and Vietnam by Khalaim (2011).
Six tersilochine genera, including Probles, were found to occur in South Korea; and a key to these genera was provided in our previous paper on Korean Tersilochinae (Balueva et al. 2013). One abundant undescribed species of Euporizon comprises over half of the entire Korean material of Probles (Balueva et al. unpubl.). In this paper, we describe three closely related new species of Euporizon belonging to one species-group (designated here) and provide a portion of the key for identification of these species.

Materials and methods
This work is based on material of the Ichneumonidae collection of the Yeungnam University (Gyeongsan, South Korea, further YNU). More than 100 specimens of the genus Probles have been studied. From this material, three closely related species of the genus Probles are described. Most specimens, including all holotypes, are kept at Yeungnam University, with some specimens deposited at the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia (further ZISP) and the Natural History Museum, London, United Kingdom (further BMNH).
Photographs were taken at ZISP using a DFC290 digital camera attached to a Leica MZ16 stereomicroscope; partially focused photographs were combined using Helicon Focus software.
The genus belongs to the Tersilochus genus-group (Horstmann 1981) by having the first metasomal segment with a furrow between the glymma and the ventral part of the postpetiole, and the propodeum usually has a basal area (rarely with basal keel). Probles differs from other genera in this genus-group by the well-developed foveate groove of the mesopleuron, which is more or less upcurved anteriorly, elongate thyridial depression, weakly curved hind tibial spurs, and simple tarsal claws. Additional characters for distinguishing Probles from other Korean tersilochine genera are given in the key published in our previous paper (Balueva et al. 2013).
Euporizon is the least specialized and the most species rich subgenus of Probles, comprising about 36 species in the Palearctic region. This is the only subgenus of Probles found in South Korea.

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Ovipositor slightly sinuate at apex, neither especially thin nor strongly upcurved (Fig. 24)  Remarks. This species-group is designated here for the first time as comprising three Korean species based on characters given in the key. This species-group resembles the subgenus Microdiaparsis as both have an apically sinuate ovipositor but is distinct in having a much shorter temple, which is about as long as the eye width in Microdiaparsis and only 0.4-0.5 times as long as the eye width in the fulgida species-group. Description. Head very strongly constricted and strongly rounded behind eyes in dorsal view (Figs 4,13,20); temple short, 0.4-0.5 times as long as eye width. Upper tooth of mandible somewhat longer than lower tooth. Clypeus slightly truncate apically, smooth, punctate in upper part. Malar space 0.7-0.8 times as long as basal width of mandible. Flagellum filiform, usually slightly clavate at apex (Figs 2, 12); subbasal flagellomeres 1.7-1.9 times as long as broad, subapical flagellomeres slightly elongate; flagellomeres 2 to 6(7) bearing apical finger-shaped structures on outer surface (Fig.  6). Vertex with sharp and dense punctures on smooth background, distance between punctures mostly shorter than one diameter of puncture (Fig. 20). Temple smooth and shining, with fine and moderately dense punctures. Hypostomal carina absent. Occipital carina complete.
Fore wing (Fig. 16) with second recurrent vein distinctly postfurcal; intercubitus about as long as abscissa of cubitus between intercubitus and second recurrent vein.
Metacarp not reaching apex of fore wing. First abscissa of radius about 1.5 times as long as width of pterostigma. Postnervulus intercepted below middle. Hind wing (Fig.  16) with nervellus vertical or slightly reclivous.
Legs slender. Hind femur about 4.0 times as long as broad and 0.8-0.85 times as long as tibia. Hind spurs slightly curved at apex. Tarsal claws not pectinate.
Composition. This species-group comprises three closely related species, P. fulgida sp. n., P. korusa sp. n. and P. rukora sp. n., occurring in South Korea. Comparison. Differs from the two other members of the fulgida species-group, P. korusa sp. n. and P. rukora sp. n., by the weaker and shorter foveate groove of the mesopleuron (Fig. 5), 22-segmented antennal flagellum (Fig. 2), flat clypeus (in lateral view), wings more extensively tinged with yellow, and more strongly sinuate apex of the ovipositor (Fig. 10).
forms and both species are represented in our material by many specimens. Thus, we consider P. korusa sp. n. and P. rukora sp. n. to be distinct species. Probles korusa sp. n. also resembles the European species P. curvicauda Horstmann, 1981, which also has a long ovipositor with strongly upcurved apex, but is distinct in having much shorter temple, a wider basal area of the propodeum and a somewhat shorter ovipositor sheath.
Description. Female: Body length 4.5 mm; fore wing length 3.15 mm. Head with temple 0.45 times as long as eye width in dorsal view (Fig. 13). Clypeus weakly convex in lateral view, densely punctate on upper 0.6, finely granulate near upper margin. Malar space about 0.8 times as long as basal width of mandible (Fig. 15). Antennal flagellum with 19-20 segments (19 segments in holotype) (Fig. 12). Face and frons very finely granulate, dull, with sharp and dense punctures. Temple with dense, fine and sharp punctures. Foveate groove long, extending across anterior 0.8 of mesopleuron (Fig. 15). Propodeum with basal area about 1.5 times as long as broad and almost half as long as apical area (Fig. 14); basal longitudinal carinae sometimes indistinct and propodeum with longitudinal wrinkles dorsally. Propodeal spiracle separated from pleural carina by 1.0-2.0 times diameter of spiracle. Apical longitudinal carinae usually weak, anteriorly usually indistinct. Hind femur 4.1 times as long as broad and 0.82 times as long as tibia. First tergite laterally before glymma mostly smooth, 4.0 times as long as broad posteriorly. Second tergite 1.65 times as long as anteriorly broad. Ovipositor weakly sinuate apically, with extreme apex thin and strongly uncurved (Fig. 18); sheath about 2.6 times as long as first tergite. Metasoma behind first tergite predominantly brown, yellowish ventrally, tergites 2-3(4) dorsally dark brown (Fig. 11).
Male. Unknown. Variation. The holotype has rather weak punctures on the temple. A female from the Russian Far East corresponds well with Korean material of this species but has the vertex conspicuously impressed posteriorly, weak notaulus, and a weaker foveate groove of the mesopleuron, and it may belong to a new species. This specimen is not included in the type series, and study of additional material is required to solve its status. Figures 16-18. Probles korusa sp. n., ♀, paratype (Fig. 16) and holotype (Figs 17, 18). 16 wings 17 posterior part of metasoma and first tergite, lateral view 18 apex of ovipositor, lateral view.