On the northernmost Orchestina species in China, with a first description of the female of O. zhiwui (Araneae, Oonopidae)

Abstract Orchestina zhiwui Liu, Xu & Henrard, 2019, a species previously known only from males collected in Jiangxi Province, was found in Liaoning, ca 2200 km northeast of the type locality, including specimens of both sexes. The previously unknown female of this species is described, and the male is redescribed. A key to species of the genus Orchestina from China is provided.


Introduction
Orchestina Simon, 1882 is among the most speciose genera of the goblin spider family (Oonopidae), with 162 extant and 33 fossil species (WSC 2021). It has an almost global distribution and occurs in the Northern Hemisphere in the region south of 45°N (Marusik et al. 2018). In China, the genus is known from 13 species Li 2011, 2014;Liu et al. , 2019, and the northernmost localities were previously known from Zhejiang Province (Fig. 4;Li and Lin 2016).
While studying spiders collected on Fenghuang Mountain in the Liaoning Province, China, we found Orchestina specimens; this locality is distant from their known range. A detailed study of the males revealed that the specimens belong to Orchestina zhiwui Liu, Xu & Henrard, 2019, a species known only from males collected in Jiangxi. The goals of our paper are to provide a key and distribution map to all species of Orchestina occurring in China, redescribe the male and provide the first description of the female O. zhiwui with detailed illustrations for both sexes.

Material and methods
The specimens were examined using a Leica M205C stereomicroscope. Details of body parts and measurements were studied under an Olympus BX51 compound microscope. Photos were made with a Canon EOS 750D zoom digital camera (18 megapixels) mounted on an Olympus BX51 compound microscope. Vulvae were cleared in lactic acid. For scanning electron microscopy (SEM), specimens were air-dried, sputter coated using IXRF SYSTEMS, and imaged with a Hitachi TM3030 SEM. Photos were stacked using Helicon Focus 7.6.1 and processed using Adobe Photoshop 21.1.2. All measurements in the text are expressed in millimeters. Terminology and taxonomic descriptions follow Henrard and Jocqué (2012) and Tong and Li (2011). All material studied is deposited in Shenyang Normal University (SYNU) in Shenyang, China.
Habitats. All specimens were collected in leaf litter in a mountain forest. Distribution. China (Liaoning and Jiangxi) (Fig. 4).

Morphology
While studying the morphology of O. zhiwui, we found a character that is undocumented in other Orchestina species: slit organs anteromedially on the chelicerae of the male (Fig. 2I). The chelicerae of many Orchestina species were quite well illustrated by Henrard and Jocqué (2012) and Izquierdo and Ramírez (2017), but this character does not appear in any descriptions or images. Possibly this character is related to the very long chelicera of the male.

Distribution
Although the record from Liaoning is the northernmost record of this species in China and extends its known distribution limits over 1200 km to the northeast (see Fig. 4), it is not the northernmost species of the genus in Asia. That record belongs to O. storozhenkoi (Saaristo & Marusik, 2004) described from the Maritime Province of Russia. It was described in a monotypic genus, Ferchestina Saaristo & Marusik, 2004, which was later synonymized by Platnick et al. (2012). This species is found on tree trunks (Saaristo and Marusik 2004)