New cheiracanthiid spiders from Xishuangbanna rainforest, southwestern China (Araneae, Cheiracanthiidae)

Abstract Four new species of the genus Cheiracanthium C.L. Koch, 1839 from Xishuangbanna, Yunnan Province, China are described: C. daofeng Yu & Li, sp. nov. (♂♀), C. duanbi Yu & Li, sp. nov. (♂♀), C. gou Yu & Li, sp. nov. (♂), and C. wuquan Yu & Li, sp. nov. (♀). In addition, Sinocanthium Yu & Li, gen. nov., is described with the type species S. shuangqiu Yu & Li, sp. nov. A key to cheiracanthiid genera distributed in East and Southeast Asia is provided.


Introduction
Cheiracanthiidae Wagner, 1887 is a relatively large spider family with twelve genera and 354 valid species distributed worldwide, except for the Polar Regions (WSC 2020). The Cheiracanthiidae fauna of China is presently known by 42 described spe-cies, all of them belonging to Cheiracanthium C.L. Koch, 1839 sensu lato (Li 2020). The global diversity of this family remains insufficiently studied, and several new species have been described recently (Lotz 2015;Marusik and Fomichev 2016;Zhang et al. 2018;Li and Zhang 2019). The current paper reports new Cheiracanthiidae taxa from Xishuangbanna.
Xishuangbanna, which lies between 21°08'-22°36'N and 99°56'-101°50'E, is in southwestern China and shares a border with Myanmar in the southwest and Laos in the southeast. Xishuangbanna is a biodiversity hotspot, and a large number of new taxa across a wide variety of spider families have been discovered in this region recently (Li 2020). Seven Cheiracanthium species were reported from Xishuangbanna before the current study. They are C. exquestitum Zhang & Zhu, 1993, C. falcatum Chen, Huang, Chen & Wang, 2006, C. insigne O. Pickard-Cambridge, 1874, C. insulanum (Thorell, 1878, C. ningmingense Zhang & Yin, 1999, C. taiwanicum Chen, Huang, Chen & Wang, 2006, and C. unicum Bösenberg & Strand, 1906 During the examination of spiders collected from 2006 to the present in Xishuangbanna Tropical Botanical Garden in Menglun Town, four species recognized as new to science are described here and are temporarily placed in Cheiracanthium sensu lato. The fifth species is not readily assignable to any of the existing genera; thus, we established a new genus to accommodate it. Detailed morphological descriptions and diagnoses of the new taxa are given. The body and the copulatory organs are photographed and illustrated for each species. An identification key to cheiracanthiid genera occurring in East and Southeast Asia is provided.

Materials and methods
Specimens were collected by fogging, pitfall trapping, and hand collecting from the canopy, tree trunks, and leaf litter in the tropical rainforest in Xishuangbanna Tropical Botanical Garden and preserved in 75 or 95% ethanol. All type specimens are deposited in the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing, China (curator: Jun Chen).
Specimens were examined using a LEICA M205C and an Olympus SZX7 stereomicroscope. Further details were studied under a CX41 compound microscope. Male and female copulatory organs were examined and illustrated after dissection. Left male palps are illustrated, unless otherwise indicated (photos of the right palp were horizontally mirrored in the figures to allow easier comparison with other species). Epigynes were removed and cleared in lactic acid or warm 10% potassium hydroxide (KOH) solution. Some vulvae were imaged after being embedded in Arabic gum. Images were captured with a Canon EOS 70D digital camera mounted on an Olympus CX41 compound microscope and assembled using Helicon Focus 6.80 image stacking software. All measurements were obtained using an Olympus SZX7 stereomicroscope and are given in millimetres. Eye diameters are taken from the widest distance. The total body length does not include chelicerae or spinnerets. Leg lengths are given as total length (femur, patella + tibia, metatarsus, tarsus). Most of the terminology in the text and figure legends follows Lotz (2015) and Zhang et al. (2018), and some follows Marusik and Fomichev (2016) and Morano and Bonal (2016). Abbreviations used in the text and figures are as follows: A atrium AAM atrial anterior margin AER anterior eye row AL abdomen length ALE anterior lateral eyes AME anterior median eyes AME-AME distance between AMEs AME-ALE distance between AME A DNA barcode was also obtained for species delimitation and matching of different sexes. A partial fragment of the mitochondrial cytochrome oxidase subunit I (CO1) gene was amplified and sequenced using the primers LCOI1490 (5'-GGT-CAACAAATCATAAAGATATTG-3') and HCOI2198 (5'-TAAACTTCAGGGT-GACCAAAAAAT-3'). For additional information on extraction, amplification, and sequencing procedures, see Morano and Bonal (2016). All sequences were analysed using BLAST and are deposited in GenBank. The accession numbers are provided in Table 1 Comments. The genus Cheiracanthium currently includes 215 extant species that are widespread in the Old World and represent 61% of the total number of Cheiracanthiidae species (WSC 2020). However, the genus remains inadequately studied because: (1) almost half of the species are known from a single sex or juveniles (37 from males, 59 from females, two from juveniles), and in some cases, the adults are apparently mismatched, or conspecific male and females have been described as separate species (Dankittipakul and Beccaloni 2012;WSC 2020); (2) original descriptions are rather brief and lack illustrations or the illustrations are inadequate (Zhang et al. 2018); (3) the diversity of this genus is still insufficiently known (Zhang et al. 2018).
Although several major taxonomic studies on a regional scale have been conducted, e.g., Edwards (1958) for the US, Wolf (1991) for Central Europe, Bonaldo and Brescovit (1992) for the Neotropical Region, Lotz (2007aLotz ( , b, 2011Lotz ( , 2014Lotz ( , 2015 for the Afrotropical Region, Deeleman-Reinhold (2001) for Southeast Asia, the genus Cheiracanthium has been widely considered paraphyletic (Wunderlich 2012;Marusik and Fomichev 2016). We agree with Bayer (2014) regarding the need of an extensive, largescale review of the genus. Consequently, the present study follows the WSC (2020) and temporarily places the four new species in Cheiracanthium sensu lato. Etymology. The specific name is derived from the Chinese pinyin 'dāo fēng', which means 'blade point', referring to the narrow, sharp conductor which is shaped like a blade; noun in apposition.
Palp (Figs 1A-C, 7A, 8A, 9A, 10A-C). Tibia with two apophyses: a retrolateral one that is relatively long and sclerotized, ca. 1/3 of palpal tibia length, with a moreor-less finger-like apex; a very minute, tooth-shaped dorsal apophysis; cymbial spur two times shorter than tibia, beak-shaped; cymbial fold strongly developed and conspicuous in ventral and retrolateral views for approximately 2/3 of cymbium length; tip of cymbium long, ca. 1/2 of cymbium length. Tegulum oval, 1.6 times longer than wide; median apophysis long and filamentous, more than 1/2 of tegulum length, with a curved tip resembling a sickle in ventral view; embolus filiform, originating on the retrolateral flank (approximately 1 o'clock on tegulum), surrounding base and ending at conductor apex, its tip curved behind conductor and extending to apex of cymbium; conductor large, shaped like a blade point, base wide, gradually tapering toward apex.
Epigyne (Figs 2A-D). Atrium ca. two times wider than long, atrial anterior margin eyebrow-shaped and heavily sclerotized, posterior and lateral margins inconspicuous; receptacles are faintly visible through epigynal plate in ventral view; two copulatory openings, large and conjoined, located at posterior portion of epigynal plate; transparent copulatory ducts coiled, forming four entwined loops (including three ascending coils and one descending coil); receptacle reniform, separated by diameter of receptacle.
Distribution. Known only from the type locality, Xishuangbanna, Yunnan, China.   Etymology. The specific name is derived from the Chinese pinyin 'duǎn bì', which means 'short dagger', and refers to the dagger-shaped retrolateral tibial apophysis; noun in apposition.
Diagnosis. The male of C. duanbi sp. nov. can be distinguished from all other Cheiracanthium species, except C. exquestitum (Zhang and Yin 1999: 287, figs 8, 9), by having a distally wide cymbial spur, a spine-like median apophysis, and a beak-shaped conductor but can be distinguished from C. exquestitum by having: (1) fig. 5) by the general shape of the atrium and vulva but can be distinguished by the copulatory ducts having three turns (vs. copulatory ducts with four turns in C. exquestitum, with two turns in C. rehobothense and C. gratum) and by the larger atrium (lateral margin of atrium close to the receptacle in C. duanbi sp. nov. vs. distant from the receptacle in C. fulvotestaceum).
Distribution. Known only from the type locality, Xishuangbanna, Yunnan, China. Etymology. The specific name is derived from the Chinese pinyin 'gōu', which means 'hook', and refers to the curved distal tip of the cymbial spur which is shaped like a hook; noun in apposition.

Cheiracanthium gou
Diagnosis. Males of this new species can be easily distinguished from all other Cheiracanthium species by the structure of the palp. The retrolateral tibial apophysis consists of a thin distal half and a wide basal half. The cymbial spur is partly membranous proximally and sclerotized distally with the distal tip blunt and thick, hook-shaped (Figs 5A-C, 7C, 8C, 9C). By contrast, in almost all known Cheiracanthium species, the retrolateral tibial apophysis and the cymbial spur cannot be easily divided into two parts, and the distal tip of the cymbial spur is usually sharply pointed, such as in C. daofeng sp. nov. and C. duanbi sp. nov. (Figs 1A-C, 3A-C, 7A, B, 8A, B, 9A, B).
Female. Unknown. Comments. According to the WSC (2020), a total of ten Cheiracanthium species from China are known only from females: C. approximatum O. P.-Cambridge, 1885, C. escaladae Barrion et al., 2013, C. fujianense Gong, 1983, C. hypocyrtum Zhang & Zhu, 1993, C. liuyangense Xie et al., 1996, C. olliforme Zhang & Zhu, 1993, C. potanini Schenkel, 1963, C. solidum Zhang et al., 1993, C. sphaericum Zhang et al., 1993, and C. longtailen Xu, 1993. Among them, C. escaladae is supposedly a Clubiona species based on epigyne morphology, C. approximatum and C. potanini are doubtful or invalid species because of the poor original illustrations and descriptions, C. liuyangense may be a synonym of C. taegense Paik, 1990, and C. longtailen is considered a junior synonym of C. pichoni Schenkel, 1963. The remaining five species can be tentatively considered valid species. In addition, C. spectabile (Thorell, 1887) from Myanmar is known by the male but is not illustrated. We cannot rule out the possibility that the above six species are conspecific to C. gou sp. nov.
Distribution. Known only from the type locality, Xishuangbanna, Yunnan, China. Etymology. The specific name is derived from the Chinese pinyin 'wǔ quān', which means 'five loops', and refers to the coiled copulatory ducts, forming five entwined coils; noun in apposition.
Diagnosis. The female of the new species is similar to those of C. japonicum Bösenberg &Strand, 1906 (Zhu andZhang 2011: 341, fig. 246A, B), C. simaoense Yin, 1999 (Zhang andYin 1999: 286, figs 6, 7), C. turiae Strand, 1917(Deeleman-Reinhold 2001, and C. virescens (Sundevall, 1833) (Zhu and Zhang 2011: 346, fig. 250A, B) by the general shape of the atrium and receptacles and the coiling of the copulatory duct around the distal part of the receptacle. The new species can be easily distinguished by the different number of copulatory duct coils (copulatory ducts with five turns in C. wuquan sp. nov. vs. three turns in C. simaoense and C. virescens and four turns in C. japonicum and C. turiae) (Figs 6C-G).
Epigyne (Figs 6C-G). Atrium large, slightly wider than long, located at posterior portion of epigynal plate, with arched anterior hood and indistinct posterior margin; two copulatory openings, large and contiguous, located at basolateral atrial borders; receptacles and copulatory ducts conspicuous through epigynal plate in ventral view; transparent copulatory ducts coiled, with five ascending turns, connecting receptacle anteriorly; receptacles elongated and separated by 1.5 diameters, pear shaped, ducts coil around distal part.
Male. Unknown. Comments. Due to the large and long, ovoid receptacles and the slender copulatory duct encircling the anterior part of the receptacles, we justifiably place C. wuquan sp. nov. in Cheiracanthium sensu stricto. Until now, five Cheiracanthium species from China are known from males only: C. antungense Chen & Huang, 2012, C. echinulatum Zhang, Zhang & Yu, 2018, C. gobi Schmidt & Barensteiner, 2000, C. ningmingense Zhang & Yin, 1999, and C. chayuense Li & Zhang, 2019(WSC 2020. Based on the palpal structure, with the exception of C. ningmingense, the other four species do not belong to Cheiracanthium sensu stricto (Wunderlich 2012). C. ningmingense is presently known from Ningming county in Guangxi (type locality), Shimen county in Hunan, and Xishuangbanna in Yunnan. However, C. ningmingense maybe a junior synonym of one known species.
Distribution. Known only from the type locality, Xishuangbanna, Yunnan, China.  (Figs 11A, B, 4G, H, 6A, B) but is consistently separable by the shape of the epigyne. Sinocanthium gen. nov., as in most Cheiracanthium species, has a yellow body, a wide cephalic part, long legs, subequal eyes, and parallel eye rows of equal width occupying the greater width of the head. It can be distinguished from Cheiracanthium sensu lato by the absence of copulatory ducts (Fig. 11E, G) (vs. copulatory ducts with variable lengths but distinct in all Cheiracanthium species, including C. daofeng sp. nov., C. duanbi sp. nov., and C. wuquan sp. nov. (Figs 2C,D,4C,D,6E,G), and by the atrium located anteriorly with a rebordered posterior margin (Figs 11C, D, F) (vs. atrium located anteriorly or centrally, atrial hood located anteriorly in Cheiracanthium).
Description. Same as for the species.

Composition. Type species only.
Comments. Based on the original figures and text descriptions of the epigynes, Cheiracanthium sensu lato can be further divided into at least four or five different taxa (Wunderlich 2012). The morphology of the epigyne exhibits very high diversity. However, all Cheiracanthium species related to the generotype have copulatory ducts, even though the shapes, lengths, and courses of the copulatory ducts are variable. Despite the variable shapes, the atria of the different taxa are located posteriorly or centrally and are usually rebordered anteriorly and laterally. Obviously, Sinocanthium shuangqiu sp. nov. cannot be placed in Cheiracanthium sensu lato because of the peculiar structure of the epigyne, so we described a new genus to accommodate it. Although we examined only one female of S. shuangqiu sp. nov., our specimen is strikingly different from all Cheiracanthium species: The atrium is located anteriorly, the atrial posterior margin is rebordered, and copulatory ducts are absent, supporting our decision.      Etymology. The specific name is derived from the Chinese pinyin 'shuāng qiú ', which means 'double ball', and refers to the two bulb-shaped receptacles; noun in apposition.
Diagnosis. The new species is easily distinguished from other cheiracanthiids by the epigyne, which has a fan-shaped fovea that is rebordered posteriorly and by the absence of copulatory ducts.
Male. Unknown. Distribution. Known only from the type locality, Xishuangbanna, Yunnan, China.