A new Xilithus species from Hubei, China (Araneae, Phrurolithidae)

Abstract Background The genus Xilithus Liu & Li, 2023 contains 22 species, three of which are known from Hubei Province, China: X.acerosus (Yao, Irfan & Peng, 2019), X.auritus (Fu, Zhang & Zhang, 2016) and X.xingdoushanensis (Yao, Irfan & Peng, 2019). New information One new Xilithus species from Hubei, China is described: X.qizimeishanensis Liu & Hu sp. nov. Morphological description, digital photos and distribution map are provided.


Introduction
The spider family Phrurolithidae Banks, 1892 contains 25 extant genera and 404 species (World Spider Catalog 2024).Xilithus Liu & Li, 2023 is the seventh largest genus in the family and contains 22 species; four of them are known only from males and two from females (Liu et al. 2022, Kamura 2022, Lin et al. 2023, Mu and Zhang 2023, World Spider Catalog 2024).Species of Xilithus are usually small to medium spiders (2.5-5.0 mm), which have unique copulatory organ characters: males have a thin and long embolus, and a prolateral tegular apophysis; females have a pair of large atriums on epigynal plate (Liu et al. 2022, Mu andZhang 2023).Eighteen Xilithus species have been found in China so far, three of which are known from Central China (Fu et al. 2016, Yao et al. 2019).Based on the specimen collected in Qizimeishan National Nature Reserve, Hubei, China, one new Xilithus species is described in the current paper.

Materials and methods
The specimen examined in this study was preserved in ethanol absolute and deposited in the Centre for Behavioural Ecology and Evolution, College of Life Sciences, Hubei University in Wuhan.The specimen was examined using an OLYMPUS SZX7 stereo microscope.Photographs were taken with a LEICA M205 C stereo microscope, and final multifocal images were produced with Helicon Focus (Version 7.7.0).The epigyne was removed and treated in a warmed 0.1 mg/ml Protease K solution before study.The leg measurements are shown as total length (femur, patella, tibia, metatarsus, tarsus).All measurements in the text are given in millimetres.The map was created with ArcGis (Version 10.8.1).
Copulatory openings (CO) trumpet-like, located at posterior margin of median septum (MS).Copulatory ducts (CD) short and C-shaped, the length of copulatory ducts (CD) almost twice the diameter of the spermathecae (S).Bursae (B) three times longer than wide, and exceed the anterior edge of the atria (A).Glandular appendages (GA) short, pointed anteriorly.Connecting tubes (CT) very short, between the base of glandular appendages (GA) and spermathecae (S).Spermathecae (S) double globular.Fertilization ducts (FD) short, located interiorly on spermathecae (S), pointed anteriorly (Fig. 2A, B).Male: unknown.

Etymology
The specific name is derived from the type locality.

Distribution
Known only from the type locality (Fig. 3).

Notes
Liu et al. (2022)divided Xilithus species into five species groups: acerosus-, acutus-, leibo-, lingyun-, and ovatus-groups.The two large oval atria (A) separated by noseshaped median septum (MS) and the organs of endogyne gathered together on ental of median septum (MS) of X. qizimeishanensis Liu & Hu sp.nov.show that the new species clearly belongs to lingyun-group.