Xenos yangi sp. nov.: A new twisted-wing parasite species (Strepsiptera, Xenidae) from Gaoligong Mountains, Southwest China Author Dong, Zhiwei State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650201, China Author Liu, Xingyue Department of Entomology, China Agricultural University, Beijing 100193, China Author Mao, Chuyang State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650201, China & Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan 650204, China Author He, Jinwu State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650201, China Author Li, Xueyan https://orcid.org/0000-0003-0457-7846 State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650201, China lixy@mail.kiz.ac.cn text ZooKeys 2022 2022-02-02 1085 11 27 http://dx.doi.org/10.3897/zookeys.1085.76484 journal article http://dx.doi.org/10.3897/zookeys.1085.76484 1313-2970-1085-11 F8153EFB1CAD457F89B24D1804CE9A29 BCB299CAB97C57AF829ABCA5F7172BD6 Xenos yangi Dong, Liu & Li sp. nov. Chinese name 杨氏胡蜂玥 Figs 1 , 2 , 3 , 4 , 5 Type locality. China, Yunnan, Longling County, Xiangda Township. Type materials. Holotype : male (KIZ0130767), "Gaoligong Mountains, Xiangda Township, Longling County, Yunnan Province, 24.4441083 N , 98.7239194 E , 1666 m, 20.XII.2019, local villagers leg.", kept in 75% ethanol, [red label]. (KIZ). Paratypes : four males (KIZ0130768-KIZ0130771), three neotenic females (KIZ0130772-KIZ0130774), same data as holotype (KIZ), kept in 75% ethanol, [yellow label]. Figure 1. Xenos yangi Dong, Liu & Li sp. nov., male adult (holotype) A dorsal view (PRN, Pronotum; AC, Acrotergit ; MN, Mesonotum; PC, Prescutum ; SL, Scutellum; POL, Postlumbium ; PN, Postnontum) B ventral view. Scale bar: 0.5 mm. Other material examined. One neotenic female, "Gaoligong Mountains, Xiangda Township, Longling County , Yunnan Province, 20. XII. 2019 , local villagers leg.", partially used for extracting genomic DNA (accession number MW222190 ; Zhang et al. 2021 ). One neotenic female and one male , "Gaoligong Mountains, Xiangda Township, Longling County, Yunnan Province, 20. XII. 2019 , local villagers leg.", both partially used for extracting genomic DNA in this study . Diagnosis. Male. Head transverse. Antenna (Fig. 2B ) four-segmented, 1st with distal lateral extension and wider than 2nd, 3rd and 4th flabellate with subequal length. Palpus twice as long as maxilla (Fig. 2C ). Mandible (Fig. 2D ) slender, widened at base, tapering at tip. Prescutum pentagonal. Scutellum longitudinally elongated, triangular. Proventrite posteromedially with a small U-shaped notch, forming a pair of small lobes (Fig. 2H ). Mesoventrite posteromedially bifurcated into a pair of long digitiform projections (Fig. 2I ). Tarsus four-segmented, without claws (Fig. 2E-G ). Penis colter-shaped (Fig. 2J ). Cephalotheca of male puparium (Fig. 4A ). Maxillae almost oval, bigger than mandible. Clypeus furrowed and close to mandible. Antenna half size of eye. Neotenic female (Fig. 4B-D ). Cephalothorax almost rectangular, 3/4 strongly contracted; birth opening, protuberance (Fig. 4C ); apex of mandibles straight (Fig. 4D ). Figure 2. Xenos yangi Dong, Liu & Li sp. nov., male adult A hind wing B right antenna C right maxilla and Xenos palpus D right mandible E foreleg (right) F midleg (right) G hind leg (right) H proventrite I mesoventrite J penis. Scale bars: 0.5 mm. A, B dorsal H, I ventral C-J, F lateral. Description. Male (Fig. 1 ). Length 5.6 mm (holotype), 5.5-8.1 mm (paratypes) (combined length of head, pronotum and abdomen). Coloration (Fig. 1A, B ): head, antenna, maxillary Xenos palpus , coxa, and abdomen black; femur, tibia and tarsus brown; hind wing semi-transparent. Head transverse, 1.44 mm in width. Compound eye raspberries-like, each composed of about 84 ommatidia, ommatidiaprominent and separated by chitinous bridges covered with micortrichia (Fig. 3A ). Antenna four-segmented (Fig. 2B ), scapus wider than pedicellus, scapus with distal lateral extension, pedicellus half as long as scapus, 3rd and 4th flabellate with subequal length, hirsute (Fig. 3B ). Mandible (Fig. 2J ) smooth, sword-like, gradually thicker from middle until 3/4, and then sharply tapering at tip. Maxillae and palpus (Figs 2C , 3B ) covered with short hairs, Xenos palpus twice half as long as maxillae, Xenos palpus narrower. Pronotum (Fig. 1A ) quadrangular with a protuberant apex. Acrotergit (Fig. 1A ) with two ends turned up, central depression. Mesonotum (Fig. 1A ) saddle-shaped, central M-shaped depression, pseudo-haltere on both sides. Prescutum (Fig. 1A ) pentagonal with round tops. Scutellum (Fig. 1A ) acutely triangular. Postlumbium (Fig. 1A ) broad, generally rounded, but emarginate anteriorly. Postnotum (Fig. 1A ) triangular. Figure 3. Xenos yangi Dong, Liu & Li sp. nov., male adult (SEM micrographs) A compound eye (lateral) B maxilla and Xenos palpus (lateral) C fourth antennomer (dorsal). Hind wing sector with nine veins (Fig. 2A ). C and Sc fused, half length of costal margin. R1 and R2 veins almost glued together, R2 vein extending from middle to wing apex; R3 vein from middle to outer margin of wing; R4 vein terminated at distal 1/4 of the wing and approximating R5 vein. MA, CuA1, CuA2 and CuP veins present and uninterrupted. Proventrite laterally with anepisternum angulately curved at middle, and posteromedially with a small U-shaped notch, forming a pair of short lobes (Fig. 2H ); Mesoventrite with basisternum transversely rectangular, anterolaterally roundly prominent, posterolaterally hook-like, sternellum broadly rhombic, posteriorly bifurcated into a pair of long digitiform projections (Fig. 2I ). Foreleg (Fig. 2E ) coxa expands, trochanterofemur with a protuberance near coxa, tibia longer than femur, widened near tarsus, tarsus four-segmented, 1st tarsomere with oval pit outside, 4th tarsomer without claws. Midleg (Fig. 2F ) coxa as long as trochanterofemur, other parts similar to those of foreleg. Hind leg (Fig. 2G ) trochanter half length of femur, femur strong. Abdomen 10-segmented as long as thorax, black; segment I tergites and sternites shrink; segment II-VIII sternites distinctly broader than tergites, segment IX narrower than segment VIII, with caudally elongated subgenital plate; segment X tube-like, curved. Anus flat. Penis colter-shaped (Fig. 2J ). Cephalotheca of male puparium (Fig. 4A ). Cephalotheca elliptical. Maxilla almost oval, bigger than mandible. Clypeus furrowed and close to mandible. Antenna half size of eye. Neotenic female (Fig. 4B-D ). Length 11.0-16.0 mm, maximum breadth of abdomen about 4.5-5.0 mm (Fig. 4B ); cephalothorax 2.2 mm in length and 1.76 mm in width (Fig. 4C, D ). Coloration: cephalothorax brownish yellow, abdomen yellow. Cephalothorax almost rectangular, 3/4 strongly contracted; birth opening, protuberance (Fig. 4C ); apex of mandible straight (Fig. 4D ); abdomen slender, four birth organs. Figure 4. Xenos yangi Dong, Liu & Li sp. nov. A male cephalotheca frontal view (CP, Clypeus; AN, Antenna; EYE, Eye; MD, Mandible; MX, Maxillae ) B female ventral view (BC, brood canal; BOR, birth organs) C, D female cephalothorax ventral view (BO, birth opening; SBHP, segmental border between head and prothorax; OS, mouth opening; MD, mandible). Scale bar: 0.5 mm. Comparative notes. Considering the geographic distance and host association of those species of Africa and Americas, we mainly compared the male adult, the cephalotheca of the male papurium, and the neotenic female of this new species with ten described known species distributed in Asia (nine species) and Europe (one species) (Table 1 ). These species were originally described based on the male adult, the cephalotheca of the male papurium, and/or the neotenic female (Table 1 ). The new species can be distinguished from X. moutoni (China: Yunnan, Anhui, Taiwan), X. dianshuiwengi (China: Fujian), X. formosanus (China: Taiwan), X. provesparum (Indonesia) and X. oxyodontes (Japan) based on the external characters of male adult. The male adult of X. moutoni maxilla as long as Xenos palpus and the postlumbium is straight anteriorly and posteriorly ( Kifune and Maeta 1985 ). The male adult of X. oxyodontes (Japan) has the postlumbium rounded anteriorly and posteriorly ( Nakase and Kato 2013 ). The proventrite is not concaved in X. dianshuiwengi (China: Fujian), X. formosanus (China: Taiwan) and X. provesparum (Indonesia) ( Kifune and Maeta 1985 ; Kifune 1986 ; Yang 1999 ). Table 1. Distribution and described stages of 11 Xenos species from Asia and Europe. Literature in which the species was originally described is highlighted in bold.

Species	Distribution	Male	Cephalotheca of male puparium	Neotenic female	Primary larvae
Xenos yangi Dong, Liu & Li sp. nov.	China: Yunnan	This study	This study	This study	NA
Xenos moutoni (Buysson, 1903)	China: Yunnan, Anhui, Taiwan	Kifune & Maeta, 1985	Buysson, 1904	Buysson, 1903	NA
Xenos circularis Kifune & Maeta 1985	China: Taiwan	NA	NA	Kifune & Maeta, 1985	NA
Xenos yamaneorum Kifune & Maeta, 1985	China: Taiwan	NA	Kifune & Maeta, 1985	Kifune & Maeta, 1985	NA
Xenos formosanus Kifune & Maeta, 1985	China: Taiwan	Kifune & Maeta, 1985	Kifune & Maeta, 1985	Kifune & Maeta, 1985	NA
Xenos dianshuiwengi Yang, 1999	China: Fujian	Yang, 1999	NA	NA	NA
Xenos oxyodontes Yuta & Makoto 2013	Japan	Yuta & Makoto, 2013	Yuta & Makoto, 2013	Yuta & Makoto, 2013	NA
Xenos vespularum Kifune & Maeta, 1975	Japan	Kifune & Maeta, 1975	Kifune & Maeta, 1975	Kifune & Maeta, 1975	NA
Xenos hebraei Kinzelbach, 1978	India	NA	Kinzelbach, 1978	Kinzelbach, 1978	NA
Xenos provesparum Kifune,1986	Indonesia	Kifune, 1986	Kifune, 1986	Kifune, 1986	NA
Xenos vesparum Rossius, 1793	Europe; Northern Africa	Rossius, 1793	Rossius, 1793	Rossius, 1793	Pohl & Beutel, 2005

NA: Not availabl The new species can be distinguished from X. circularis (China: Taiwan), X. yamaneorum (China: Taiwan), X. vespularum (Japan), X. hebraei (India) and X. vesparum (Europe; Northern Africa) by the female cephalothorax. It is almost circular or ovoid in X. yamaneorum , X. circularis , X. vespularum and X. vesparum ( Kifune and Maeta 1975 ; Kifune and Maeta 1985 ). The female cephalothorax is slightly wider than long in X. hebraei . Besides that, this new species can be also separated from X. yamaneorum and X. vespularum by the oval maxillae of the male cephalotheca (the two compared species lack the oval maxillae of the male cephalotheca). Distribution. China (Yunnan). Biology. The hosts of this new species are Vespa velutina (Fig. 5A ) and Vespa bicolor (Fig. 5B ). It parasitizes in the host abdomen. Its body partly protrudes from the portion between the two abdominal segments of the hosts. One wasp can usually carry 1-4 parasite individuals (Fig. 5C ). After emergence, male adults fly away from their hosts (Fig. 5D ). Neotenic females remain in the host's abdomen with their anterior cephalothorax protruding. When neotenic females are removed from their host abdomen, they can be seen to be covered with larval exuviae. Figure 5. Xenos yangi Dong, Liu & Li sp. nov. and its host wasp. A Vespa velutina B Vespa bicolor C wasp host parasitized by the new species (red arrows: male puparium (left), female(right)) D living male. (dorsal view). Etymology. The specific epithet is dedicated to the late famous Chinese entomologist Chi-Kun Yang, who made significant contributions to the studies on Strepsiptera in China. Figure 6. Phylogeny tree of Xenos species inferred from mitochondrial cytochrome c oxidase subunit 1 ( COI ) using Maximum parsimony method. In total, 48 COI sequences of different Xenos species were used to investigate their phylogenetic relationships. two sequences (str6-b-female and Xenos -male) were sequenced in this study, and that of Xenos cf. moutoni (MW222190.2) was sequenced in Zhang et al. (2021) . Other 45 sequences were published by the following studies ( Benda et al. 2021 ; McMahon et al. 2011 ; Nakase and Kato 2013 ; Juzova et al. 2015 ; Carapelli et al. 2006 ). Stylops ater Reichert, 1914, Melittostylops hesperapium Kinzelbach, 1971, Halictoxenos tumulorum Perkins, 1918 and Crawfordia warnckei Kinzelbach, 1970 (outgroup) were used as outgroups. The phylogenetic trees were constructed using Maximum Parsimony (MP), and Maximum Likelihood (ML). Branch support values are described as Maximum Parsimony (MP)/Maximum Likelihood (ML) in MP tree.