First description of the female of Clubiona milingae Barrion-Dupo, Barrion & Heong, 2013 (Araneae, Clubionidae)

Abstract Background Clubiona milingae Barrion-Dupo, Barrion & Heong, 2013 was described from a single male and no additional specimens have been recorded. The original description was brief and the illustrations were inadequate. New information Clubiona milingae is redescribed and illustrated based on new material from the type locality and the new distribution region (Jianfeng Mountains and Limu Mountains of Hainan Island, China). The female is reported for the first time.


Introduction
The Clubiona apiculata species group, first defined by Dankittipakul and Singtripop (2014) to accommodate four new species from Borneo, is one of the most distinct groups of the genus Clubiona sensu lato. The group presents a distinct set of characters and has been considered as putatively monophyletic (Dankittipakul andSingtripop 2014, Yu andLi 2019). The Clubiona apiculata group is a relatively small taxon, with only five species clearly documented, one of which is known from China (Yu and Li 2019). It is difficult to collect individuals of the apiculata group in the field because of their small size. At least two species have been described from only a few specimens of a single sex.
Clubiona milingae Barrion-Dupo, Barrion & Heong, 2013 was first described based on a single male from Mt. Jianfeng on Hainan Island, China and was not assigned to any of the existing species groups in the original publication (Barrion et al. 2013). Recently, new materials containing both sexes were collected from the type locality and near the type locality simultaneously. On the basis of the morphological characters, we matched the females and males together as C. milingae. Futhermore, we discovered that C. milingae possesses several characters associated with the apiculata-group and resembles Clubiona yaoi Yu & Li, 2019 (the only apiculata-group species recorded from China) due to their characteristic genital organs. Additionally, we found some characters were overlooked in the original description of the male. The aim of the current paper is to redescribe the male and report the female for the first time, providing detailed morphological descriptions and illustrations.

Materials and methods
Spiders were fixed and preserved in 80% ethanol. Specimens were examined with an Olympus SZX7 stereomicroscope; details were studied with an Olympus CX41 compound microscope. Female epigynes and male palps were examined and illustrated after dissection. Epigynes were removed and cleared in warm lactic acid before illustration. The image of the vulva was made after being embedded in Arabic gum. Photos were made with a Cannon EOS70D digital camera mounted on an Olympus CX41 compound microscope. The digital images were taken and assembled using the Helicon focus 6.80 software package.
All measurements were obtained using an Olympus SZX7 stereomicroscope and are given in millimetres. Eye diameters were measured at the widest point. The total body length does not include the chelicerae or spinnerets. Leg lengths are given as total length (femur, patella, tibia + metatarsus, tarsus). The terminology used in the text and figure legends follows Yu and Li (2019).
All specimens are deposited in the Museum of Guizhou Education University, Guiyang, Guizhou, China (MGEU, curator Hao Yu).

Diagnosis
Females of C. milingae can be easily distinguished from other members of the C. apiculata-group with the exception of C. yaoi (the only other C. apiculata-group species in China: Yu and Li 2019: 152, figures 2A-D), by the oblong bursae (bursae are spherical in all other apiculata-group species), but differing from C. yaoi by the copulatory openings situated at the medial portion of the epigynal plate posterior margin ( Fig. 2A, B, D) (vs. copulatory openings situated basolaterally in C. yaoi). Males also resemble those of C. yaoi in having a retrolateral tibial apophysis with a bifurcate tip (retrolateral tibial apophysis distally unforked in all other apiculata -group species), but can be recognised by the relatively long embolus and by the absence of a conductor (Fig. 3A-D) (vs. embolus represented by small spicule and conductor present in C. yaoi). In addition, the two species can by separated by their habitus: abdomen marked with numerous inconspicuous spots in C. milingae (Fig. 1A, D), but with a median heart-shaped mark which extends half the length of the opisthosoma in C. yaoi.

Biology
Most of the new material was collected by pitfall-traps set in a rubber-tea plantation.

Discussion
Clubiona milingae was first reported by Barrion et al. (2013) with a brief description and inadequate illustrations. Except for the holotype male, no additional specimens have been recorded until now. Barrion et al. (2013) did not assign the group placement of this species. Dankittipakul and Singtripop (2014) established the apiculata species group for four Borneo species. Maybe, due to the brief description, the inadequate illustrations, and the lack of female individuals, Clubiona milingae has not been assigned so far. In the present study, pairs of specimens were obtained from the type locality of C. milingae. The small body and widely separated PME, the presence of the apophysis on the dorsal cymbium and the strongly-developed retrolateral tibial apophysis in the male with the copulatory ducts connected to bursae at the central portion of the epigyne in the female, all indicate that this species should belong to the apiculata-group.
Although we have not examined the type specimen of C. milingae, our new topotypes bear a striking similarity to the original illustrations by Barrion et al. (2013). The slender and

Location of Hainan Island (green) and distribution records of Clubiona milingae (red circles).
First description of the female of Clubiona milingae Barrion-Dupo, Barrion ... long, filiform embolus, the expanded RTA with a bifurcate tip, the blunt DCA and the sperm duct nearly encircling the tegulum (Barrion et al. 2013: 8, f. 7A-E) leave no doubts that our identification is correct.