On the genera Qiongocera and Relictocera (Araneae, Psilodercidae) from Southeast Asia

Abstract Four new species are described in two psilodercid genera, Qiongocera Li & Li, 2017 and Relictocera Li & Li, 2017: Qiongoceraluoxuan Li & Li, sp. nov. (♂♀) from China, Relictocerawugen Li & Li, sp. nov. (♂♀) and R.sigen Li & Li, sp. nov. (♂) from Vietnam, and R.qianzi Li & Li, sp. nov. (♂♀) from Thailand. These genera were previously thought to be monotypic. In addition, one species of the genus Merizocera Fage, 1912 is transferred to Relictocera: Relictoceramus (Deeleman-Reinhold, 1995), comb. nov. (♂♀). The types of the new species are deposited in the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing.


Introduction
The spider family Psilodercidae Machado, 1951 was previously considered to be a subfamily of Ochyroceratidae Fage, 1912by Machado (1951, and this was supported by Deeleman-Reinhold (1995). Psilodercids were elevated to family rank by Wunderlich (2004Wunderlich ( , 2008. Recently, phylogenetic analyses suggest that Psilodercidae are the sister group to the lineage encompassing Sicariidae Keyserling, 1880 and Scytodidae Blackwall, 1864 (Shao and Li 2018).
While studying material from China, Thailand, and Vietnam, we found four new species belonging to two genera: Qiongocera and Relictocera, previously thought to be monotypic (Liu et al. 2017). The goal of this paper is to provide descriptions of the new species as well as new updated diagnoses for the two genera.

Materials and methods
Types are deposited in the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing. All specimens collected were preserved and observed in a 95% ethanol solution. The specimens were measured and examined under a Leica M205C stereomicroscope, and further morphological details were observed using an Olympus BX41 compound microscope. The male palp was dissected from the left side of the spider for further examination. The carapace measurements include the clypeus (except for Relictocera sp. which has a distinct clypeus). The length and width ratios were measured according to the length of the cymbium (including the cymbial protrusion) to its width. The internal genitalia of the female and the male palp were dissected and immersed in lactic acid for digestion. An Olympus C7070 wide zoom digital camera (7.1 megapixels) mounted on an Olympus SZX12 stereomicroscope was used to take photos at different focal plans. The photos were assembled with the image stacking software Helicon Focus 6.7.1 to generate high quality photos before further editing with Adobe Photoshop CC 2014. Leg measurements are given as total length (femur, patella, tibia, metatarsus, and tarsus). Leg segments were measured from their retrolateral side. All measurements are given in millimetres (mm). Terminology follows Li et al. (2014), Tong and Li (2007), and Deeleman-Reinhold (1995). Emended diagnosis. Qiongocera resembles Flexicrurum but can be differentiated by the following combination of characters: 1) cymbium with a tilted protrusion (vs. cymbium with a strong lateral protrusion and with a small postero-lateral protrusion   bearing a strong seta; 2) laminar apophysis half the width and length of bulb (vs. bulbal apophysis length equals and width, 15 times shorter than that of bulb in Flexicrurum); 3) simple process on the distal end of bulb (vs. a complex processes with more than one extension in Flexicrurum); and 4) a short embolus (vs. a long embolus in Flexicrurum).

Key to species of Qiongocera (males only)
1 Bulb with laminar apophysis on distal part and with 2 unequal parts of a plierlike processes (Fig. 1A); body dark brown (Fig. 1D)  Etymology. The species name is a noun in apposition derived from the Chinese pinyin "luόxuán" (helical) and refers to the helical shape of the bulb in the distal half.

Relictocera sigen
Female. Unknown. Distribution. Known only from the type locality (Fig. 13). Etymology. The species name is a noun in apposition derived from the Chinese pinyin "qiánzĭ" (pincer) and refers to the unique structure of the bulb appendages which are similar to the gripping jaws of a pincer (Fig. 11C, D).

Relictocera qianzi
Diagnosis. Males of R. qianzi sp. nov. can be distinguished from all other congeners by the bulb bearing two unequal parts, a strongly swollen palpal patella, and a partly swollen tibia (Fig. 11C-D). Males can be easily distinguished from R. mus by the blunt tips of the bulbal appendages (vs. sharply pointed tips); a hairy snout-liked clypeus with a straight base (vs. a spade-shaped clypeus with a distinct rounded base in R. mus); carapace with trident pattern medially (vs. absence of pattern); the female can be distinguished from other species by the pair of ovoid spermathecae flanked laterally with a pair of translucent ducts (vs. a pair of horizontal ducts bearing round spermathecae).
Distribution. Known only from the type locality (Fig. 13).