Redescription of Pristidia cervicornuta (Araneae, Clubionidae), with a first description of the female

Abstract Pristidia cervicornuta Yu, Zhang & Chen, 2017 is redescribed based on new material from the type locality, Diaoluo Mountains of Hainan Island, China. The female is described and illustrated for the first time. In addition, this paper further illustrates the male, and provides a supplementary description.


Introduction
Pristidia Deeleman-Reinhold, 2001 is a relatively small genus, distributed exclusively in South East Asia, with only six species described so far, two of which are known from China (Yu et al. 2017; World Spider Catalog 2019). All Pristidia species were known from both sexes, except for P. cervicornuta Yu, Zhang & Chen, 2017. Pristidia cervicornuta was first described based on two male specimens from Mt. Diaoluo of Hainan Island, China (Yu et al. 2017). Recently new material has been collected from the type locality containing both sexes. The males were identified as P. cervicornuta based on comparison with the type specimens. On the basis of the morphological characters (Fig. 1) and DNA barcoding (Table 1), we credibly matched the females and males together as P. cervicornuta. Additionally, we found some characters 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
Specimens were examined with an Olympus SZX7 stereomicroscope; details were studied with an Olympus BX41 compound microscope. Female epigynes and male palps were examined and illustrated after being dissected. Epigynes were removed and cleared in warm lactic acid before illustration. Vulva was also imaged 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 Helicon Focus 6.80 software package.
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 terminology used in text and figure legends follows Yu et al. (2017) and Yu et al. (2012).
A DNA barcode was also obtained for matching. A partial fragment of the mitochondrial cytochrome oxidase subunit I (CO1) gene was amplified and sequenced for three specimens, using the primers LCO1490 (5'-GGTCAACAAATCATCATAAA-GATATTGG-3') and C1-N-2776 (5'-GGATAATCA-GAATANCGNCGAGG-3'). For additional information on extraction, amplification and sequencing procedures, see Malumbres-Olarte and Vink (2012). All sequences were analysed using BLAST and are deposited in GenBank. The accession numbers are provided in Table 1.
All specimens (including molecular vouchers) are deposited in the Museum of Guizhou Education University, Guiyang, Guizhou, China (MGEU, curator Hao Yu).  Diagnosis. Females of P. cervicornuta are similar to those of P. ramosa (the other only Pristidia species in China: Yu et al. 2012: 45, figs 9-11, 15-16) by the epigynal plate having 2 clefts situated at the posterior margin; they also resemble those of P. secunda (Deeleman-Reinhold 2001: 186, figs 191, 192) in the general shape of the vulva, but can be differentiated from P. ramosa by lacking atrium ( Fig. 2A, B, E) (vs. atrium present in P. ramosa), and can be easily distinguished by the indistinct insemination ducts (Fig. 2C, D, F) (vs. long insemination ducts in P. ramosa and P. secunda), and by the copulatory openings located in the middle of the epigynal plate ( Fig. 2A, B, E) (located on posterior margin in P. ramosa and P. secunda). Males of P. cervicornuta can be easily recognized by the distally forked, antler-shaped retrolateral tibial apophysis and by the thick, semitransparent, thumb-shaped tegular apophysis.
Abdomen lanceolate, white, with inconspicuous anterior tufts of sparse hairs, dorsum without pattern; venter white, with several pairs of inconspicuous muscular dots.
Epigyne (Fig. 2B-F). Epigynal plate slightly shorter than wide, margin not rebordered; posterior margin concaved in the middle, forming shallow depression; 2 clefts located at lateral borders of the depression; copulatory openings distinct and heavily sclerotised, located in the middle of the plate. Insemination ducts short and indistinct; spermathecae located anteriorly; spermathecal head small tubercle-like, located on lateral side of spermatheca; bursal surface hyaline, wrinkled and ribbed, inside pigmented and sclerotised; both spermathecae and bursae are subglobular; acicular fertilisation ducts located on the dorso-lateral sides of spermathecae.
Comments. There is almost no difference between the holotype male ( Fig. 4A-F) and the newly collected male specimen in the present study. However, two characters of the bulb were not presented in the original description. Additionally, some spines and hairs are lost in holotype male ( Fig. 4A-C). Consequently, a fuller description is provided here: the tegular hump (TH) is represented by an enlarged flange, hidden behind the embolus (E) and tegular apophysis (TA); a translucent flakelet (F) located at distal-retrolateral position of tegulum (T) (approximately 1 o'clock of tegulum), the flake is subtriangular with a membranous and blunt apex; the tibia has two long dorsal spines (TS) originating from trisection; the femur bears two short dorsal spines (FS) originating from its proximal part.
Natural history. Pristidia cervicornuta inhabits forest located in low elevation areas on Mt. Diaoluo. The male holotype was obtained from shrubs in a rubber-tea artificial community and the new materials were collected by beating twigs and branches of bush in an elm forest.