Ten new species of the spider genus Sinoderces Li & Li, 2017 from China, Laos and Thailand (Araneae, Psilodercidae)

Abstract Ten new species of the spider family Psilodercidae Machado, 1951 are described from tropical East Asia, including five species found in China: Sinoderces luohanensis Li & Li, sp. nov. (♂♀), S. xueae Li & Li, sp. nov. (♂♀), S. taichi Li & Li, sp. nov. (♂♀), S. wenshanensis Li & Li, sp. nov. (♂♀), S. aiensis Li & Li, sp. nov. (♂♀); three are from Laos: S. khanensis Li & Li, sp. nov. (♂♀), S. phathaoensis Li & Li, sp. nov. (♂♀), S. kieoensis Li & Li, sp. nov. (♂); and the rest are from Thailand: S. saraburiensis Li & Li, sp. nov. (♂), S. dewaroopensis Li & Li, sp. nov. (♂♀). Types of all new species are deposited in the Institute of Zoology, Chinese Academy of Sciences in Beijing, China.


Introduction
A great diversity of spiders of the family Psilodercidae Machado, 1951 has evolved throughout the zoogeographic regions of Indo-Burma, Sundaland, the Philippines and Wallacea. To date, 141 psilodercid species have been recorded from the various countries collectively known as "Tropical East Asia" (Li and Quan 2017;World Spider Catalog 2019). They are small, fragile, web-spinning spiders that inhabit dark, damp places, such as leaf litter, tree buttresses and caves. Previously classified as a subfamily within Ochyroceratidae Fage, 1912, Wunderlich (2004 opined that they deserved a family rank as they share several characters that distinguish them from other ochyrocertids (sensu Ochyroceratinae): they have book-lungs; their posterior tracheal opening is closer to the spinnerets than other ochyroceratids; they have only 0-3 cheliceral promarginal teeth (as opposed to 6-7 in other ochyroceratids); unlike other ochyroceratids, their labium is not incised; and the position of the bulb is usually at the end of the cymbium, and not near the middle as in other ochyroceratids. The group was subsequently elevated to its own family (Wunderlich 2008).
The genus Sinoderces  is currently included in the family Psilodercidae. Only two Sinoderces species have been documented so far, namely S. exilis (Wang & Li, 2013) and S. nawanensis Li & Li, 2017, both from China. In the present paper, we describe ten new species of Sinoderces from China, Laos and Thailand.

Material and methods
All specimens were collected in China, Thailand and Laos (Fig. 22), and preserved in 95% ethanol. Types of all new species are deposited in the Institute of Zoology, Chinese Academy of Sciences in Beijing, China. Specimens were examined and measured using a Leica M205 C stereomicroscope. Morphological details were studied with an Olympus BX41 compound microscope. Photos were taken with an Olympus C7070 wide zoom digital camera (7.1 megapixels) mounted on an Olympus SZX12 stereomicroscope. The images were montaged using Helicon Focus 6.7.1 image stacking software. The map was generated using ArcView GIS 10.2. All measurements are in millimeters (mm). Leg measurements are shown as total length (femur, patella, tibia, metatarsus, and tarsus). Leg segments were measured from the retrolateral side. Carapace length was measured from the anterior eye row to the carapace posterior margin. Terminology follows that of Deeleman-Reinhold (1995), Tong and Li (2007), and Li et al. (2014).

Family Psilodercidae Machado, 1951
Genus Sinoderces  Type species. Sinoderces nawanensis  Diagnosis. The genus is distinguished (together with Thaiderces ) from all the other genera in Psilodercidae by the absence of an apical protrusion on the male cymbium. It is distinguished from the genus Thaiderces by the presence of a single tooth on the cheliceral retromargin and the long embolus of the palpal bulb (Liu et al. 2017 of highly elongated and looped spermathecae. The spermathecae conjure an image of the headband worn by the Chinese mythological Monkey King with two blunt ends that meet and curl upward ( Fig. 2A).
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected at a cave's entrance at an elevation of 270 m.  (Fig. 3). Females can be distinguished by the hairless upper part of abdomen (vs. a row of hairs on the same position in S. nawanensis) (Fig. 4B). The two pairs of spermathecae have a similar shape, but the terminus of the long pair of spermathecae bends upward in S. luohanensis sp. nov. (vs. bending downward in S. nawanensis) (Fig. 4A).
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected at a cave entrance at an elevation of 196 m.  (Fig. 5B, C), in contrast to the straight embolus, less than half the bulb length in S. kieoensis sp. nov. (Fig. 18B-D). The bulb of S. phathaoensis sp. nov. tapers and narrows more sharply (Fig. 5) than that of S. kieoensis sp. nov. (Fig. 18). The male clypeus has two crotched apophyses.
Male palp : The whole structure is relatively simple. Bulb yellow, conical. Embolus arising distally from the bulb, no conductor. Tibia projected distally. Tibia dark yellow, femur and trochanter light yellow.
Epigyne (Fig. 6A, B): The epigyne is wide and extends to the edge of the abdomen (Fig. 6B). Two pairs of curved spermathecae, the anterior pair of spermathecae resemble a germinating seedling, and the other pair is like a twisted hook (Fig. 6A).
Male palp (Fig. 7A-D): Bulb pale yellow, conical. Embolus arising distally from the bulb, slightly curved; no conductor; tibia with a stout apical protrusion, tipped with many bristles (Fig. 7A). Femur and trochanter light yellow with few hairs.
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected at a cave entrance at an elevation of 397 m. Etymology. This name is in honor of Wenjing Xue, a good friend of the first author of the paper who has been helpful to his study and life. The case is feminine and genitive.

Sinoderces xueae
Diagnosis. Sinoderces xueae sp. nov. resembles S. taichi sp. nov. in having a similarly shaped conductor and embolus. However, the males can be distinguished by the following: five spines on the distal part of the palpal cymbium, vs. six in S. taichi sp. nov; the slightly sigmoid embolus and short conductor (Fig. 9) vs. a coiled embolus and long conductor in S. taichi sp. nov. The margin of the epigyne of S. xueae sp. nov. is thin (Fig. 10B) whereas in S. taichi sp. nov. thick (Fig. 12B).
Description. Male (holotype). Total length 1.94; carapace 0.66 long, 0.72 wide; abdomen 1.28 long, 0.59 wide. Carapace round, brown, with dark brown lateral margins and one wide median brown band, clypeus yellow and chelicerae dark brown (Fig. 10E). Cheliceral promargin with one tooth, followed by a lamina, retromargin with a small tooth (Fig. 21E). Labium brown. Sternum brown (Fig.  10E). Legs yellow, joints darker. Male palp (Fig. 9A-D): The overall color is yellow, bulb dark yellow, ovate; embolus arising retrolaterally and distally from the bulb, slightly sigmoid. Conductor arising prolaterally and proximally from the bulb. Embolus and conductor slightly separated (distance less than a diameter of the bulb). Tibia with five spines distally (Fig. 9B). Femur and trochanter yellow with few hairs.
Epigyne (Fig. 10A, B): Some bristles present above the epigyne (Fig. 10B). Internal genitalia with two pairs of spermathecae, curved, the anterior pair is longer than the posterior pair (Fig. 10A). The whole entire spermathecal structure is symmetrical.
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected in pristine forests. Etymology. In ventral view (Fig. 11A), the embolus and conductor resemble the yin-yang symbol representing the philosophy behind the Chinese martial art of Taichi; noun in apposition.

Sinoderces taichi
Diagnosis. Sinoderces taichi sp. nov. resembles S. xueae sp. nov. in having a similarly shaped conductor and embolus. However, the males can be distinguished by the following: six spines on the distal part of the palpal cymbium, as against vs. five in S. xueae sp. nov.; a coiled embolus and long conductor. The edge margin of the epigyne is very thick (Fig. 12B).
Male palp (Fig. 11B): Short and thick. Bulb dark yellow, ovate. Embolus arising prolaterally and proximally from the bulb, coiled (Fig. 11). Conductor arising retrolaterally and distally from the bulb. Embolus and conductor slightly separated (distance less than diameter of bulb). Distal part of the tibia with a row of six spines. Femur and trochanter dark yellow with few hairs.
Epigyne (Fig. 12A, B): Some bristles present above the epigyne (Fig. 12B). The anterior pair is a symmetric c shape. The anterior pair are tubular structures. The posterior pairs are membranous (Fig. 12A).
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected in pristine forest within a protected zone. Etymology. The specific name refers to the name of the hill at the type locality; adjective.
Male palp (Fig. 13): Bulb light, ovate, Conductor almost parallel to the palpal axis. Embolus arising terminally from the bulb, straight and needle-like. Conductor arising close to embolus, membranous. Embolus and conductor completely separated. Tibia, femur and trochanter light yellow with hairs.
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected from leaf litter at an elevation of 1556 m. Etymology. The specific name refers to the name of the cave; adjective. Diagnosis. Sinoderces aiensis sp. nov. can be distinguished from all other known species by the light-colored bulb, a curved conductor with a slightly curved tip (Fig. 15) and an embolus shaped like the Nike swoosh logo (Fig. 15B, C). There is a finger-like  projection at the junction of the tarsus and the tibia. Females may be recognized by the antler-like spermathecae (Fig. 16A).
Male palp (Fig. 15): The palp is almost light yellow. Bulb light, ovate; conductor with a slightly curved tip and the embolus like the Nike swoosh logo. Tibia with a stout apical protrusion, the protrusion with many bristles (Fig. 15B). Oval femur with hairs.
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected from a cave at an elevation of 125 m. Male palp (Fig. 17): Bulb pale yellow, ovate. Embolus shaped like a swan; the top of tarsus darker than the rest. Embolus is grossly extended and twisted apically. No conductor. Tibia with a slight bump densely covered by bristles. Femur with sparse hairs.

Sinoderces saraburiensis
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected in a cave at an elevation of 73 m.   Diagnosis. Sinoderces kieoensis sp. nov. resembles S. phathaoensis sp. nov. in having a similar shaped bulb in males. Males can be distinguished from by the straight embolus, with less than half the bulb length in S. kieoensis sp. nov. (Fig. 18B-D), in contrast with to the curved, embolus almost half as long as the bulb (Fig. 5 B, C). The bulb of S. kieoensis sp. nov. (Fig. 18) is thicker and more blunt than that of S. pathaoensis sp. nov. (Fig. 5).

Sinoderces kieoensis
Description. Male (holotype). Total length 2.28; carapace 0.72 long, 0.78 wide; abdomen 1.56 long, 0.63 wide. Carapace round, yellow, with brown lateral margins. The brown line is close to the center with a circular brown spot. Clypeus brown, medially with one pair of bifurcate apophyses. Chelicerae dark yellow. Cheliceral promargin with one tooth, connected to a lamina, retromargin with one small tooth (Fig. 21J). Endites brown. Labium brown. Sternum dark yellow. Leg measurements: I missing, II missing, III missing, IV missing. Abdomen elongated; dorsum dark brown, with yellow stripe; ventrum dark yellow; the color of the abdomen gradually darkens from anterior to posterior.
Male palp (Fig. 18): Bulb yellow, conical. The center of the bulb with slight constriction. Embolus arising distally from bulb, straight. No conductor. Tibia dark yellow. Femur and trochanter light yellow.
Distribution. Known only from the type locality (Fig. 22). Natural history. Collected in a cave at an elevation of 286 m.