Revision of the genus Xanthopimpla Saussure, 1892 (Hymenoptera, Ichneumonidae, Pimplinae) from Japan

Japanese species of the genus Xanthopimpla Saussure, 1892 are revised. A total of 15 species are recorded from Japan, including three new species, X. nipponensis sp. nov. X. sylvicola sp. nov. and X. yoshimurai sp. nov. and three species, X. honorata (Cameron, 1899), X. minuta Cameron, 1905 and X. trias Townes & Chiu, 1970, newly recorded from Japan. Host, habitat, overwintering and distribution patterns of Japanese Xanthopimpla species are discussed.


Introduction
is a large genus belonging to subfamily Pimplinae and containing 265 species from all zoogeographical regions ). Wasps of this genus have a bright-yellow-coloured body, usually with black spots, which makes this genus one of the most easily recognisable taxa amongst the Ichneumonidae. The distribution of this genus is strongly biased toward tropical or subtropical areas (Townes andChiu 1970, Gómez et al. 2014) and it is one of the major representatives of tropical ichneumonids in Asia (Townes and Chiu 1970). Wasps of this genus are known as solitary koinobiont endoparasitoids of lepidopterous larvae and pupae (Trehan and Butani 1950, Smith et al. 1993, Paull and Austin 2006 and are, therefore, potentially important natural enemies of crop and forest pests (Momoi 1966, Yasumatsu 1967, Townes and Chiu 1970. This genus is one of the well-studied groups of tropical ichneumonids and, thus, the distributional data of each species may be useful for biogeographical discussions. Momoi (1970) reviewed the species of this genus collected from Ryukyu Islands and recorded eight for Japan. However, a taxonomic study of Japanese species has not been conducted. In this research, the Japanese species of this genus is reviewed and their diversity from a biogeographical standpoint is discussed.

Materials and methods
In this study, the dried specimens deposited in the following collections were examined:

TARI
Taiwan Agricultural Research Institute Council of Agriculture, Executive Yuan, Taichung, Taiwan; TUA Tokyo University of Agriculture, Atsugi, Kanagawa, Japan.
A stereomicroscope (SMZ800: Nikon, Tokyo) was used for observation. Photographs (Figs 1,2) were taken by digital camera Tokyo) attached to the stereomicroscope. Digital images  were edited using Adobe Photoshop CC 2020.
Morphological terminology follows Broad et al. (2018). The following abbreviations are used in the description: holotype (HT), segment of antennal flagellum (FL), diameter of lateral ocellus (OD), ocello-ocular line (OOL), postocellar line (POL) and metasomal tergite (T). The following abbreviations are used for material data: female (F), male (M), Malaise trap (MT) and yellow pan trap (YPT). As the descriptions of the known species were already given by Townes and Chiu (1970) in detail, we, thus, omitted their description in this paper.

Molecular analysis
There was some variation in the black maculation on the body amongst specimens identified as X. clavata Krieger, 1914. To clarify the variability amongst species, molecular phylogenetic analysis was conducted for X. clavata and some closely-related species, based on the partial sequences of the mitochondrial gene, cytochrome c oxidase subunit I (COI) and the nuclear gene, 28S rDNA (28S). All specimens used for DNA analysis were collected adults and preserved in 99.5% ethanol. Total genomic DNA was extracted from the right middle legs using a DNeasy Blood and Tissue Kit (Qiagen, The Netherlands) according to the manufacturer's protocol for animal tissues. Voucher specimens and their extracted genomic DNA were deposited in the Osaka Museum of Natural History. The DNA samples were stored in a freezer (at -40 °C) and the voucher specimens were dried and mounted. The partial sequences of one mitochondrial gene, cytochrome c oxidase subunit I (COI) and one nuclear gene, 28S rDNA (28S), were amplified using the primers designed by Folmer et al. (1994) for COI and Campbell et al. (1993) for the 28S D2 region. These primer sets amplified approximately 640 and 580 bp products, respectively. An overview of the DNA samples is given in Table 1.
Polymerase chain reactions (PCRs) were conducted in 30 μl final volumes using ExTaq Hot Start (Takara Bio Inc., Japan). The PCR programme for COI comprised initial denaturation for 5 min at 94-95 °C followed by 35-40 cycles of denaturation at 94 °C for 15 s, annealing at 46 °C for 15 s, extension at 72 °C for 15 s and a final Table 1. Information on the individual ID, accession numbers, collecting date, site and depository of each DNA-sequenced specimen of Japanese Xanthopimpla (X. clavata, X. yoshimurai sp. nov., X. trias, X. naenia and X. niponensis sp. nov.) shown in Fig. 7 (OMNH) extension at 72 °C for 10 min. The reaction conditions for the 28S rRNA fragment were the same, except the annealing temperature was modified to 50 °C and 57 °C and the extension time was modified to 30 s and 60 s, respectively. The PCR products were purified using Illustra Exo-ProStar (GE Healthcare, USA). The purified PCR products were mixed with primers and sent to the CDM Center (Takara Bio Inc.) and run on an ABI 3730xl DNA Analyzer (Applied Biosystems). All sequences generated in this study were submitted to INSD under accession numbers LC632431-LC632459 and LC633946-LC633973, as summarised in Table 1.
The forward and reverse sequences were checked, assembled and edited using Seaview (Gouy et al. 2010). Alignment of the protein-coding COI gene was straightforward and performed manually. The 28S rRNA was aligned according to the secondary structure models (Gillespie et al. 2005). All sequence alignments were concatenated using MacClade 4.08a (Maddison and Maddison 2005). The molecular dataset was analysed using Maximum Likelihood (ML) and Bayesian approaches. For Maximum Likelihood (ML) analyses, MEGA X (Kumar et al. 2002) with the Tamura 3-parameter model and a neighbour-joining (NJ) starting tree was used. For Bayesian analysis, the COI characters were separated into three partitions (first, second and third codon positions). The best-fit model was estimated independently for each partition using hLRTs as implemented in the model test (Nylander 2004), resulting in the 28S (GTR+I) and COI first and second positions (GTR+G) and the COI third position (HKY+G). Bayesian analysis was conducted using MrBayes (Ronquist and Huelsenbeck 2003) with two runs of four chains each for 2,000,000 generations, and trees were sampled every 1,000 generations. The first 50% of the trees were discarded as burn-in and a 50% majority consensus tree from the remaining trees was used to calculate posterior probabilities.

Results
In total, 15 species of Xanthopimpla were identified in Japan (Table 2), whereas no X. brullei Krieger, 1899 (including a voucher specimen used in Schulz (1906)) were found. Twelve species were re-described and three of them, X. honorata (Cameron, 1899), X. minuta Cameron, 1905 andX. trias Townes &Chiu, 1970, are newly recorded from Japan. The other three are new to sci-ence. Although the molecular analysis did not resolve the phylogenetic relationships amongst the analysed species (X. clavata and closely-related species) because of the low bootstrap values and posterior probabilities, several clades were clearly recognised (Fig. 7A, B). Xanthopimpla trias, X. naenia Morley, 1913 and X. nipponensis sp. nov. were recovered as distinct clades. The individuals that were treated as X. clavata were found to comprise two distinct clades with high bootstrap values in ML and posterior probabilities in Bayesian Inference (except those in the 28S analysis that were low for X. clavata). Due to slight, but stable differences in body maculation (see description), we considered these as distinct species and described one of them as X. yoshimurai sp. nov. 3 Areolet absent (vein 3rs-m completely absent) (Fig. 3O) (Fabricius, 1775) -Punctuation on T III to T V sparser i.e. T IV having the punctures on its sublateral black spots separated by 1.3-6.0 × their diameter and T III having few or no punctures between its black spots (Fig. 6D)  Black spots on T IV each with about 20 punctures (Fig. 6D). Hind tibia with 0 to 4 pre-apical bristles, most or all of them scattered close to apex of tibia (Fig. 5D)   Ovipositor sheath 0.8 × length of hind tibia. T I, III and V with a pair of black spots (Fig. 1C)  Comparative diagnosis. This species belongs to the regina species group sensu Townes and Chiu (1970). This species is very similar to X. konowi and can be distinguished by two character states in combination: black spots on T IV each with about 10 punctures; pre-apical bristles on hind tibia 1 to 4, slender, scattered from apex towards the middle of tibia. Distribution. Japan (Okinawa Is.?). Outside Japan, this species has been recorded from Indonesia, Malaysia and Philippines ).
Bionomics. Unknown in Japan.

Remarks.
Although Schulz (1906) recorded this species from Japan, based on a single specimen collected from Nago, Okinawa Island, no additional material was available to us. Townes and Chiu (1970) pointed out that this species occurs in the Greater Sunda Islands. Momoi (1970) also noted that "This species is unknown to me. No new material from Ryukyus is available". Thus, the distribution record of this species from Japan may be based on misidentification.
Bionomics. In Japan, adults were collected in all months, except for November. In Honshu, winter is passed in the stage of adult (Fig. 8A). The wintering adults were resting under the leaf of broad-leaved, evergreen trees, such as Castanopsis cuspidata, Ilex pedunculosa and Camellia japonica. Sometimes, multiple individuals were observed under the leaves of a single tree or even on a single leaf. All wintering specimens observed were female exclusively. This species is one of the common species of Japanese Xanthopimpla and adults are frequently found flying in or along the forest edge including somewhat open habitat. Although the host of this species is unknown, a female was observed to lay eggs into experimentally supplied cocoons of Galleria mellonella (Linnaeus, 1758) and its offspring emerged successfully. One male was reared from an unidentified small lepidopterous pupa.
Remarks. This is the first record of this species from Nakanoshima Is., Kakeroma Is., Tokunoshima Is., Taketomi Is. and Yonaguni Is. Both Momoi (1970) (published on 20 July 1970) and Townes and Chiu (1970) (published in 1970, but without data for month and day) synonymised X. minomensis under X. clavata and, in this study, we accept the former treatment, based on the ICZN 21.3.

Metopius sesamiae
Xanthopimpla sesamiae: Townes et al. 1961: 67. Comparative diagnosis. This species belongs to the citrina species group sensu Townes and Chiu (1970). This species can be distinguished from other species of this species group by the following combination of character states: stigma light brown; area superomedia receiving lateral section of anterior transverse carina behind the centre ( Distribution. Japan (Amamioshima Is., Okinawa Is. and Iriomote Is.). Outside Japan, this subspecies has been recorded from China, India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Philippines, Singapore, Taiwan, Thailand and Vietnam ).
Bionomics. In Japan, adults were collected in April, May, June, October and November. In Iriomote Is., the first author collected this species in the forest path with sunlight. We record a host, Pithecops corvus ryukyuensis Shirozu, 1964 (Lepidoptera, Lycaenidae), here.
Comparative diagnosis. This species belongs to the regina species group sensu Townes and Chiu (1970). This species can be distinguished from other species of the group by the following combination of character states: face with a low, sublateral, vertical ridge on each side (Fig. 3B); front edge of notaulus with a sharp-edged transverse crest; median black mark on mesoscutum well separated from black mark in front of scutellum (Fig. 1D); scutellum subconically elevated (Fig. 3J); pre-apical bristles on hind tibia 0 to 4, moderately slender, most or all of them close to apex of tibia (Fig. 5D); T II to IV each with a pair of black spots (Fig. 1D); T III with relatively sparse, coarse punctures (Fig. 6D); black spots on T IV each with about 20 punctures; ovipositor straight, slightly decurved at tip; ovipositor sheath 1. Distribution. Japan (Okinawa Is., Ishigaki Is. & Iriomote Is.). Outside Japan, this species has been recorded from China, India, Indonesia, Malaysia, Myanmar, Taiwan, Thailand, Togo and Vietnam ).
Bionomics. In Japan, adults were collected in March, May, June, July and October. In Iriomote Is., the first author collected this species in the forest edge. Dendrolimus spectabilis (Butler, 1877) (Lepidoptera, Lasiocampidae), is recorded as a host of this species in Japan (Kashima 1961).
Remarks. At least part of the records of "X. iaponica" and "X. japonica" (misspelling of iaponica) may be due to misidentification of this species and some of the rest may be of X. pedator. We could not examine the voucher specimens of Iwata (1960), Kashima (1961) and Momoi (1970). Re-identification of these specimens is an issue for future study. Comparative diagnosis. This species belongs to the trunca species group sensu Townes and Chiu (1970). This species can be distinguished from other species of this group by the following combination of character states: notaulus extending to the level of posterior edge of tegula (Fig. 3I); scutellum convex; hind wing with vein 1A indistinct; mesoscutum marked with black (Fig. 1E); propodeum with lateromedian longitudinal carina present behind anterior transverse carina (Fig. 4E); propodeum, T II and VI entirely yellow (Figs 1E,4E) Distribution. Japan (Yakushima Is., Amamioshima Is. and Okinawa Is.). Outside Japan, this species has been recorded from China, India, Malaysia, Nepal, Philippines, Sri Lanka, Taiwan, Thailand and Vietnam ).

Bionomics.
In Japan, adults were collected from June to November. Host is unknown.
Remarks. This is the first record of this species from Japan. Although this species is divided into five subspecies, X. minuta minuta Cameron, 1905, X. minuta aurangabadensis Patil & Nikam, 1995, X. minuta lita Townes & Chiu, 1970, X. minuta lotipes Townes & Chiu, 1970and X. minuta quadrula Chao, 1997, Pham et al. (2011 commented that "all of these subspecies could readily be synonymised…". The characteristics of the Japanese specimens match well with the description of X. minuta minuta sensu Townes and Chiu (1970), but we refrained from considering subspecies here.

Xanthopimpla modesta (Smith, 1860)
Comparative diagnosis. This species belongs to the stemmator species group sensu Townes and Chiu (1970). This species can be distinguished from other species of the group by the following combination of character states: dorsal part of occiput with black area (Fig. 3C); mesoscutum without black mark in front of scutellum ( Fig. 1F) or, if present, black mark on median lobe with deep notch anteriorly; hind tibia with 12-18 pre-apical bristles (Fig. 5F); propodeum and T I without black marks (Fig. 4F); ovipositor sheath 1.1-1.2 × length of hind tibia.
Remarks. This species is divided into two subspecies, X. modesta modesta (Smith, 1860) and X. modesta microcephala Krieger, 1914. All Japanese materials are identified as the former.
Remarks. In Japan, distribution of this species is restricted to Yaeyama Islands of Ryukyus. A black spot of mesoscutum is sometimes absent in Japanese specimens. Comparative diagnosis. This species belongs to the incompleta species group sensu Townes and Chiu (1970). This species can be distinguished from other species of this species group by the following combination of character states: face with moderate-sized punctures; propodeum with area superomedia partly (indistinctly) or completely separate from second lateral area (Fig. 4G); mesoscutum medially with three continuous black spots and these spots sometimes united into a single large black area (Fig. 1G, H); femur entirely yellow or sometimes with black areas (Fig. 5G, H) Distribution. Japan (Honshu, Shikoku, Kyushu, Yakushima Is., Amamioshima Is., Tokunoshima Is., Okinawa Is., Ishigaki Is. and Iriomote Is.). Outside Japan, this species has been recorded from China, India, Malaysia, Philippines, Taiwan and Vietnam ).

Bionomics.
In Japan, adults were collected from April to November. In Tokunoshima Is., the first author collected this species along the edge of forest. Matsumoto and Sugimoto (1998) recorded a host, Nipponopsyche fuscescens Yazaki, 1926 (Lepidoptera, Psychidae), in Japan. In this study, we record the second host of this species, Manatha sp. (Lepidoptera, Psychidae).
Remarks. This is the first record of this species from Ishigaki Is. and Iriomote Is. Townes and Chiu (1970) described the differences in body colouration between materials from Japan and other areas. We recognised these differences as intraspecific variations and concluded that Japanese population should be treated as X. naenia. Comparative diagnosis. This species belongs to the terebatorix species group sensu Townes and Chiu (1970). This species resembles X. brevicauda brevicauda Cushman, 1925 in the body colouration and the short ovipositor, but it can be distinguished by the punctures on the face, separated by more than their diameter, except for punctures on the median part, separated by 0.2 × their diameter (separated by about 0.7 × their diameter in X. brevicauda brevicauda), the propodeum with equal width of anterior and posterior margins of area superomedia (anterior margin narrower than posterior margin in X. brevicauda brevicauda), the hind trochanter without black marking (with large black marking in X. brevicauda brevicauda) and the base of hind fifth tarsomere not yellowish (yellowish in X. brevicauda brevicauda).
Colouration (Figs 2A, B, 3D, 4H, 5I). Body (excluding wings) yellow. Apex of mandible and ocellar area black. Dorsal surface of scape and pedicel blackish-brown. Flagellum dark yellowish-brown to dark brown. Mesoscutum with three black spots anteriorly and a black spot in front of scutellum. Propodeum without black spots. Wings hyaline. Veins and pterostigma blackishbrown to brown, except for yellowish-brown wing base and base of pterostigma. Base of hind tibia and hind tarsal tarsomere tinged with black. Hind fifth tarsomere darkened. T I, T III to T V and T VII with a pair of black spots. T II sometimes (not including HT) with a pair of very small black spots. Ovipositor dark reddish-brown. Ovipositor sheath black.
Male (n = 1). Similar to female. Length of malar space 0.2 × length of basal mandibular width. Pre-apical bristles of mid-tibia 3. Apical bristle of mid-tibia 4. T II with a pair of conspicuous black spots.
Distribution. Japan (Honshu, Shikoku and Kyushu). Bionomics. In Japan, adults were collected in February, May to October and December. In Honshu, winter is passed in the stage of adult (Fig. 8C). The wintering habit of this species is similar to that of X. clavata and these species are sometimes found wintering sympatrically, adults resting under the leaf of broad-leaved, evergreen trees, such as Castanopsis cuspidata, Ilex pedunculosa and Camellia japonica. All wintering specimens observed were female exclusively. Host is unknown.

Xanthopimpla manilensis
Remarks. This is the first record of this species from Kyushu, Kuchinoerabujima Is, Takarajima Is., Tokunoshima Is. and Miyako Is. We examined the voucher specimens of "X. japonica" used in Uchida (1956) and Kusigemati (1976) and confirmed that all of them are identified as this species.
Colouration (Figs 2F,3F,4L,5M). Body (excluding wings) yellow. Apex of mandible and ocellar area black, the latter black area weakly expanded outside of ocellar area. Occiput with a median darkened area. Antenna reddish-yellow, except for a yellow area of scape. Mesoscutum with a transverse black band anteriorly and a black spot in front of scutellum, the antero-median area of the band partly tinged with reddish-brown. Propodeum with a pair of semicircular black spots on combined areas externa and lateralis. Wings hyaline. Veins and pterostigma blackish-brown to brown, except for yellowish-brown wing base and base of pterostigma. Hind trochanter with a pair of small black spots. Apex and base of hind tibia tinged with black. Base of first tarsomere and apical part of fifth tarsomere of hind leg sometimes darkened. Widened part of longest bristle on hind tarsal claws darkened. T I, III, V and VII with a pair of black spots. T II sometimes (including HT) with a pair of small black spots. Ovipositor dark reddish-brown. Ovipositor sheath black.
Bionomics. In Japan, adults were collected from May to July, October and December. The authors collected this species along a path inside the broad-leaved forest in Kyushu and Amamioshima Is. Host is unknown.
Etymology. The species name is from Latin "silva" + "colo", which is based on the habitat of this species.
Colouration (Figs 2H,I,3G,4N,5O). Body (excluding wings) yellow. Apex of mandible and ocellar area black. Dorsal surface of scape and pedicel blackish-brown. Flagellum dark yellowish-brown to dark brown. Mesoscutum with a transverse black band anteriorly and a black spot in front of scutellum, the band usually (including HT) divided into three black spots. Propodeum with a pair of semicircular black spots on area externa. Wings hyaline. Veins and pterostigma blackish-brown to brown, except for yellowish-brown wing base and base of pterostigma. Hind trochanter with a small dark spot. Base of hind tibia narrowly tinged with black. Hind fifth tarsomere sometimes weakly darkened. T I nearly always (except for a single paratype) with a pair of black spots, its lateral sides not enlarged anteriorly. The black spots of T I united each other (into a single band) in a single paratype. T II rarely (fore paratypes) with a pair of small, weak black spots. T III to T V and T VII with a pair of black spots. Ovipositor dark reddish-brown. Ovipositor sheath black.
Bionomics. In Japan, adults were collected in January, February, June to September and December. Winter is passed in the stage of adult (Fig. 8B). The wintering adults were resting under the leaf of broad-leaved, ever-green trees, such as Castanopsis cuspidata, Ilex pedunculosa and Camellia japonica as X. clavata, X. nipponensis and X. trias. This species is often found with X. clavata. Sometimes multiple individuals composed of these two species were observed under the leaves of a single tree or even on a single leaf. All wintering specimens observed were female exclusively.
Etymology. The specific name is after Hiroyuki Yoshimura (Sanda City), who collected part of the paratypes and first noticed the differences in body maculation from X. clavata.
Remarks. Although this species is morphologically very similar to X. clavata and these two species can be distinguished from each other by mainly body colouration, the difference in colouration is quite stable. Furthermore, the DNA sequences of COI and 28S rRNA are considerably different from each other and both species formed distinct clades with high supporting values in phylogenetic analysis, respectively (Fig. 7). For these reasons, we concluded this is a distinct species.

Discussion
Host and habitat of Japanese Xanthopimpla The host records of Japanese Xanthopimpla remain poorly documented. According to Yasumatsu (1967), Townes and Chiu (1970) and Matsumoto and Sugimoto (1998), the following three patterns of host preference are recognised:

1) Parasitoids of stem borers
Xanthopimpla flavolineata, X. modesta modesta, X. punctata and X. stemmator belong to this category. All these species have a long ovipositor for the genus to attack the lepidopterous borers in plant stems. They are, thus, important or potentially important natural enemies of crop pests. In Japan, X. flavolineata, X. punctata and X. stemmator are collected in somewhat open areas (e.g. meadows, open forest and crop fields).
2) Parasitoids of large moths with exposed habitats Species of the regina group belong to this category, which parasitises the larvae and pupae of larger moths, such as Saturniidae and Lasiocampidae, in cocoons in somewhat exposed habitats. These species are rather large and have a robust body and long ovipositor. In Japan, X. konowi and X. pedator are collected in forest areas (e.g. Mt. Omoto-dake and Shiramizu of Ishigakijima Island) where their hosts are abundant.

3) Parasitoids of bagworm moths
Xanthopimpla naenia seems to be a specialist parasitoid of bagworms (Psychidae). Nipponopsyche fuscescens and Manatha sp. were recorded as the hosts of this species in Japan. Bagworms carry unique portable cases that function as defensive shelters. Possibly because of the difficulty in being utilized as a host, they are attacked by specialised parasitoids (e.g. Sericopimpla Kriechbaumer, 1895 and Paraphylax Förster, 1869). However, how a few species of Xanthopimpla became parasitic on psychids is unclear.
The hosts of other species of Japanese Xanthopimpla are almost unknown. Given that most species are found in forest habitats, they possibly use hosts that are abundant in the forest, such as microlepidopterans, in leaf rolls and cocoons. Xanthopimpla clavata was observed to lay eggs in cocoons of Galleria mellonella (Linnaeus, 1758), which were experimentally exposed to the wasp in a cage. The offspring emerged successfully. Another male was reared from an unidentified small lepidopterous pupa collected in the field. These observations suggest that this species may utilie a wide range of lepidopterans as hosts.
Overwintering females of Xanthopimpla in the Palaearctic area of Japan The genus Xanthopimpla generally thrives in the tropics and subtropics. Data from collected specimens in the Ryukyus indicate that the adults are active almost all year round and that many species are possibly multivoltine originally. However, their activity is restricted by the low temperature of winter. To the best of our knowledge, in Honshu, Shikoku and northern Kyushu, which have a winter season, most of the species, including X. clavata, X. nipponensis, X. yoshimurai and X. trias, pass the winter in the adult stage. The wintering adults rest under the leaves of broad-leaved evergreen trees (Fig. 8), such as Quercus glauca, Castanopsis cuspidata, Ilex pedunculosa and Camellia japonica. Sometimes, multiple individuals belonging to two or three species cluster under the leaves of a single tree or even on a single leaf.
All wintering individuals were female. This is similar to other ichneumonids overwintering as adults under evergreen leaves, such as Zatypota maculata (Matsumoto & Takasuka, 2010) (Matsumoto and Takasuka 2010). Males are found in the active season and so, overwintered females and their daughters lay fertilised and unfertilised eggs, of which, the latter grow up as males; however, males never seem to live long enough to overwinter. Some ichneumonids have been found wintering under the bark of a dead tree. In this case, wasps are rather safe because they are settled in a narrow space and will not fall to the ground. In contrast, Xanthopimpla clinging to leaves are directly exposed to changes in temperature and wind. It thus is possible that they have not adapted to the severely cold winter in northern Japan. This may explain why none of the species of the genus Xanthopimpla are distributed in northern Japan.

Distribution patterns of Japanese Xanthopimpla
Most Japanese Xanthopimpla species are also distributed in Southeast Asian countries, whereas a few species are unknown beyond Japan and provisionally considered as Japanese endemics. The biogeographical border of the Palaearctic and Oriental Regions is called the Tokara Gap (Watase line), which lies between Yakushima Island and the Tokara Islands (the north-eastern islands of Amamioshima Island). Thus, the faunas of Yakushima Island and Amamioshima Island are usually very different from each other. However, the range of distribution of any Japanese Xanthopimpla is not limited by this line, except for that of X. honorata honorata. A total of seven species, X. clavata, X. minuta, X. naenia, X. pedator, X. punctata, X. sylvicola and X. trias, are distributed both in the Palearctic and Oriental parts of Japan beyond the Gap ( Table 2). The reason for this pattern is still unclear, but these data possibly indicate the natural dispersal of the group (e.g. flying by themselves or carried away by a typhoon).
Xanthopimpla nipponensis and X. yoshimurai are endemic to Japan at present, but detailed distribution data for many more species are needed for a comprehensive faunal study of this group in Asia.