Checklist of the Clubiona japonica-group spiders, with the description of a new species from China (Araneae, Clubionidae)

Abstract In the present paper, a worldwide checklist of Clubiona japonica-group spiders is provided based on published literature and authors’ collections. A new japonica-group species, Clubiona grucollaris sp. n. (♀♂) from Guizhou Province and Hainan Island of China is diagnosed, described, and illustrated. A distribution map of this species is given.


Introduction
The genus Clubiona Latreille, 1804 contains 495 catalogued species and is widespread throughout most of the tropics and temperate regions of the world (World Spider Catalog 2017). Due to the high species diversity of Clubiona, several infrageneric classifications have been proposed by taxonomists, and therefore Clubiona species were assigned to a series of species-groups and/or subgenera (Simon 1932;Gertsch 1941;Lohmander 1944;Edwards 1958;Redner 1976, 1982;Mikhailov 1990Mikhailov , 1991Mikhailov , 1995Mikhailov , 2002Deeleman-Reinhold 2001;Wunderlich 2011).
Japoniona was established as a subgenus by Mikhailov (1990), including only one species-group: japonica-group. Later, the subgenus Japoniona was suppressed by Deeleman-Reinhold (2001) and reverted to japonica species-group. In the same book, Deeleman-Reinhold (2001) carried out intensive research on this group's limits, supplemented some characters to support the monophyly of the group, and provided a checklist of C. japonica-group species from Southeast Asia. During the past decade, at least nine species belonging to the japonica species-group were reported and described from southeast Asia, China, and India (Dankittipakul and Singtripop 2008;Jäger and Dankittipakul 2010;Dankittipakul et al. 2012;Keswani and Vankhede 2014;Wu and Zhang 2014). However, a few other known species are not assigned, although they exhibit typical japonica-group features. The first goal of this paper is to provide a checklist as complete as possible of the current japonica-group species.
Various field collections in Guizhou Province, China were carried out by the colleagues of Hubei University in 2014 and 2016. Four males and 20 females were collected in these field explorations, among which one pair were captured during mating; thus, they are conspecific. Additionally, one male collected from Hainan Island was examined, and no differences from the Guizhou specimens were observed. All specimens possess certain characters associated with the japonica-group, but can be easily distinguished from the other japonica-group species. This species is new to science and is described under the name of Clubiona grucollaris sp. n.

Materials and methods
The checklist is based on an examination of specimens deposited in the "Centre for Behavioural Ecology and Evolution" (CBEE) and reviews of the published literature, including several recent world catalogues of spiders (Lin and Li 2016;World Spider Catalog 2017).
Spiders were fixed and preserved in 80% ethanol. Specimens were examined with an Olympus SZX7 stereomicroscope; details were studied with an Olympus BX51 compound microscope. Male palps and female epigynes were examined and illustrated after being dissected. Spermathecae were cleared in boiling KOH solution to dissolve soft tissues. Photos were made with a Cannon EOS70D digital camera mounted on an Olympus BX51 compound microscope. The digital images were taken and assembled using Helifocus 3.10 software package. The drawings were made using an Olympus drawing tube. Most of the hairs and macrosetae are not depicted in the palp and epigyne images.
All measurements were obtained using an Olympus SZX7 stereomicroscope and given in millimetres. Eye diameters are taken at widest point. The total body length does not include chelicerae or spinnerets length. Leg lengths are given as total length (femur, patella + tibia, metatarsus, tarsus). The type specimens of the new species are deposited in College of Chemistry and Life Sciences, Guizhou Education University, Guiyang, Guizhou, China Abbreviations used are: A epigynal atrium; AER anterior eye row; ALE anterior lateral eyes; AM atrial margin; AME anterior median eyes; AME-AME distance between AMEs; AME-ALE distance between AME and ALE; The terminology used in text and figure legends follows Yu et al. (2012).

Family Clubionidae Wanger, 1887 Genus Clubiona Latreille, 1804
The japonica-group Diagnosis. In general, members of the japonica-group can be recognized by the following combination of characters (see also Dankittipakul and Singtripop 2008): dark colour pattern of carapace and dorsum of opisthosoma (Figs 1-3); the male retrolateral tibial apophysis small and not branched (Figs 5, 10), the sperm duct is sinuate and distinct (Figs 6-7), the embolus filiform or reduced (Figs 4-9, 11), the conductor sclerotized with variable shapes (e.g. a small tubercle in C. picturata Deeleman-Reinhold, 2001, long and filiform in C. biembolata Deeleman-Reinhold, 2001 and C. filicata O. Pickard-Cambridge, 1874, large and beak-shaped in C. japonica L. Koch, 1878 and C. grucollaris sp. n., Figs 4-12); the female epigyne has a relatively large atrium situated anteriorly, and the copulatory openings are located in rebordered groove of atrial margin (Fig 13). The japonica-group resembles the corticalis-group in having the similar simple palp bulb in male, the atrium and copulatory openings located anteriorly in female, however, the latter can be distinguished from the former by: (1) the lack of a colour pattern on the opisthosoma; (2) the presence of a inflated tegulum with indistinct sperm duct; (3) the conductor membranous or absent; (4) the presence of a ventral tibial apophysis in many species; (5) the atrium is significantly smaller or absent; (6) copulatory openings are often located at anterior part of the epigynial plate, instead of close to the middle part in the japonica-group. All the provided corticalisgroup characters are according to Deeleman-Reinhold (2001) and recent clubionid papers such as Wu and Zhang (2014) and Liu et al. (2016). Taxonomic notes. Dankittipakul and Singtripop (2008) divided the Southeast Asia japonica-group into two lineages. It appears that this standard of division may also apply to the japonica-group from China. The species of the 1 st lineage have a large sclerotized and beak-shaped conductor that aligned transversely on apical part of the bulb (Figs 4-6, 15-17), such as C. circulata Zhang & Yin, 1998, C. calycina Wu & Zhang, 2014 and C. grucollaris sp. n., etc. Members of the 2 nd lineage share the following characters: the reduced embolus; a long and filiform conductor; and the embolus and conductor fused with each other, forming an apical appendage together and situated on the apical portion of the tegulum (Figs 7-12). The 2 nd lineage includes C. filicata and C. filoramula Zhang & Yin, 1998. In spite of the variable conductor in the male palp, the female genitalia of the two different lineages are very similar. The epigynial plate has a large atrium situated anteriorly, and the atrium is bounded by an atrial margin. The posterior atrial margins are often not rebordered. Copulatory openings relatively small, located in rebordered groove of basolateral atrial margin (Figs 13,18). Vulva consisting of anterior spermathecae and posterior bursae. The bursae are membranous, larger than the spermathecae (Figs 14, 19).
Palp (15)(16)(17). RTA dark, small but strong, triangular; cymbium longer than wide, bulb nearly spherical and proapically membranous; sperm duct distinct and sinuate, U-shaped or reversed S-shaped; embolus slender and filiform, originated at 8-9 o' clock position in prolateral view, its tip slightly overpasses the genital bulb; conductor with a heavily sclerotized and beak-shaped apex, its base part membranous and crane's neck-shaped; tegular apophysis small and petal-shaped in retrolateral view.
Epigyne (18)(19). Atrium large and nearly inverted trapezoidal, with a shallow depression, located at anterior portion of epigynal plate, anterior atrial margin "M" shaped; spermathecae and burse are prominently through epigynal plate in ventral view; two copulatory openings located at basolateral atrial borders; spermathecae consisting of papilliform base, tubular stalk and ovoid head, ascend spirally; bursae globular and translucent; fertilization ducts short, acicular.     Natural history. Clubiona grucollaris sp. n. mainly inhabit the upper levels of the forest and most specimens were collected by canopy fogging, while a few spiders were obtained by beating twigs and branches of vegetation. The type locality, Fanjing Moun-tain Nature Reserve, extending from 27°49'50" to 28°01'30"N and 108°49'30"to 108°18'30"E, is the core zone and the highest peak of the Wuling Mountains, and is known for its high floral biodiversity (Wang et al. 2015). The evergreen broadleaved forests, where the holotype was obtained, are located in low elevation areas (alt. 300-600 m) of the Reserve.