Mysmenidae, a spider family newly recorded from Tibet (Arachnida, Araneae)

Abstract The spider family Mysmenidae is reported from Tibet for the first time. Two new species, Chanea voluta sp. n. (male and female) and Mysmena lulanga sp. n. (male and female) are found in eastern Tibet in high altitude. Morphological descriptions, diagnoses and comparative photos are provided for the two new species.


Introduction
The eastern Tibet Plateau is one of the biodiversity hotspots in the world (Lei et al. 2015). The geographical location at the junction of different biogeographical realms, the wide range of habitats and climates along the extensive elevational range, the com-plex topography and the distinct geological history of this region have probably contributed to the evolution of an exceptionally species-rich and endemic-rich, specialized montane fauna. However, the lack of adequate research especially invertebrate results in multitudinous unknown new species to be discovered.
In a recent collection tour to eastern Tibet Plateau we yield a big number of spiders, including several new species. In this paper we described two new species of the family Mysmenidae. Mysmenidae includes 13 genera and 135 species worldwide (World Spider Catalog 2015). Of these mysmenid members elevation distribution drop from highest to lowest is nearly 3,300 meters. For example, Tamasesia marplesi was found at 3 meters off the coast of the jungle, in New Caledonia Island (Brignoli 1980). Maymena roca lives in the high mountain 3,300 meters above sea level, in Peru (Baert 1990). The new species described in this paper, i.e., Chanea voluta sp. n. collected from elevation between 2,140-3,060 meters and Mysmena lulanga sp. n. from elevation between 3,480-3,530 meters. The latter should be new highest record of elevation for spiders of the family Mysmenidae.
According to Li and Lin (2015) 4,282 species spider are recorded from China that belongs to 735 genera and 69 families. Of them, 37 mysmenid species of 8 genera (one Chinese mysmenid species, Calodipoena cornigera, is transferred to Mysmena, owing to Mysmena Simon, 1894 considered a senior synonym of Calodipoena Gertsch &Davis, 1936 by Lopardo andHormiga 2015) are reported from Beijing, Chongqing, Guangxi, Guizhou, Hainan, Liaoning, Sichuan, Taiwan and Yunnan. The two new species described in this paper is the first record of the family Mysmenidae from Tibet.

Material and methods
Specimens were examined and measured under a Leica M205 C stereomicroscope. Further details were studied under an Olympus BX43 compound microscope. Male palps and female genitalia were examined and photographed after they were dissected and detached from the spiders' bodies. Vulvae were removed and treated in lactic acid before taking photos. To reveal the course of the spermatic duct, male palps were also treated in lactic acid and mounted in Hoyer's Solution. All type specimens and preserved in 95% ethanol solution. Photos were taken with a Canon EOS 60D wide zoom digital camera (8.5 megapixels). The images were montaged using Helicon Focus 3.10.3 software (Khmelik et al. 2006).
All measurements are in millimeters, with leg measurements given in the following sequence: total length (femur, patella, tibia, metatarsus, and tarsus). The terminology mostly follows Lopardo et al. (2011) andMiller et al. (2009). The abbreviations used in text including: ARE -anterior eye row; ALE -anterior lateral eye; AME -anterior median eye; PRE -posterior eye row; PLE -posterior lateral eye; PME -posterior median eye. All specimens are deposited in the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing.  (Miller et al. 2009). The type species, Chanea suukyii, was known only from the type locality in the Gaoligongshan Mountains, Yunnan Province, China. This spider species mainly live in leaf litter of the subtropical evergreen broadleaf forest. According to Miller et al. (2009), the diagnostic features of this genus differs from other mysmenids by the long embolus coiled into at least 5 loops encircles the conductor and subtegulum (figs 49A, 51B ; Miller et al. (2009) mentioned that the presence of a pair of clypeal marcosetae in male is also treated as one of the generic characters. But these are lacking from C. voluta sp. n. (Figs 1A, 1C). Therefore, we think that the extremely long, coiled embolus and the long, coiled copulatory ducts and/or fertilization ducts may be the main diagnoses for this genus. The paired macrosetae on the clypeus in male may just be an identifying character to this type species.    Etymology. The specific name derived from the Latin word "volutus" = coiled, refers to the coiled embolus in male palp and the spiral fertilization duct in female vulva; adjective.
Legs: formula: I-II-IV-III. Leg I with a subdistal-ventral sclerotized femoral spot and a prolateral-submesial metatarsal clasping macroseta. Patellae I-IV with a dorsal seta distally. Tibiae I-IV with a dorsal seta proximally. Tibiae I and II with 3 trichobothria, but 4 on tibia III and IV. Metatarsi I-IV with only one trichobothrium.
Female (one of paratypes). Somatic characters see Fig. 1D Prosoma: Carapace near pear-shaped. Cephalic pars lower than in male. Eyes pattern, chelicerae, endites and sternum as in male.
Legs: Chaetotaxy and number of trichobothria same as in male, except for leg I without metatarsal clasping macroseta. Sclerotized femoral spot present at leg I and II. Leg formula: I-II-IV-III.
Distribution. Known only from the type locality (Fig. 10).

Genus Mysmena Simon, 1894
Mysmena Simon 1894: 558. Type species by original description Theridion leucoplagiataum Simon, 1879: 258 (= M. leucoplagiata (Simon, 1879)). (2015) Comments. The genus Mysmena was erected by Simon in 1894 initially as a genus of Theridiiae with the type species Theridion leycoplagiatum Simon, 1879; later transferred to Symphytognathidae by Forster (1959), and then to Mysmenidae from Symphytognathidae by Forster and Platnick (1977). In recent years, research on species description reports of this genus mainly comes from China (Miller et al. 2009;Lin and Li 2008, 2013a, 2013b, Japan (Ono 2010), Queensland (Lopardo and Michalik 2013) and Canada (Lopardo et al. 2008). Lopardo and Hormiga (2015) suggested that Calodipoena, Itapua, Calomyspoena, Tamasesia, and Kekenboschiella are synonymized with Mysmena basing on the results of phylogeny and evolutionary of the family Mysmenidae. Several optimized synapomrophies shared by most of this genus were proposed, include the spermatic duct switchback distally benting at a right angle, the presence of a long ventral scape, the weakly sclerotized fertilization ducts and the vulva with a distinguishable wall (Lopardo and Hormiga 2015).  (Lin & Li, 2014) by the lack of cymbial spur and the female abdomen without posterior projection, or by a simple embolus and the epigynum with a long scape. Further distinguished from other Mysmena species in Sulawesi (Baert 1988), New Guinea (Baert 1982(Baert , 1984Forster 1959), Samoa (Marples 1955), North America (Lopardo and Dupérré 2008) and Latin America (e.g. Baert and Maelfait 1983;Gertsch 1960;Gertsch and Davis 1936;Levi 1956) by the shorter embolus and the lack of membranous copulatory duct (Figs 6A-B, 9B).
Legs: formula: I-II-IV-III. Leg I with a prolateral-mesial metatarsal clasping macroseta. Sclerotized femoral spot present at leg I and II. Patellae I-IV with a dorsal seta distally. Tibiae I-IV with a dorsal seta proximally. Tibiae I and II with 3 trichobothria, but 4 on tibia III and IV. Metatarsi I-IV with only one trichobothrium.
Female (one of paratypes). Somatic characters see Fig. 5D Prosoma: Carapace near pear-shaped. Cephalic pars lower than in male. Eyes pattern, chelicerae, endites and sternum as in male.
Legs: Chaetotaxy and number of trichobothria same as in male, except for leg I without metatarsal clasping macroseta. Sclerotized femoral spot present at leg I and II. Leg formula: I-II-IV-III.
Distribution. Known only from the type locality (Fig. 10).

Discussion
Finding the species Chanea voluta sp. n. allowed us to clearly place the genus Chanea within the Mysmenidae, by the presence of the most important characters of the genus that the type species C. suukyii and C. voluta sp. n. both share: an extra-long (at least five loops) coiled embolus, and the very long (at least ten loops) spiral copulatory duct or/and fertilization duct. In addition, another significant common feature between them is the relatively small spermatheca located far from the epigastric groove. These common features indicate that these species belong to the same genus. As for the clypeal setae in male, although quite typical for Chanea suukyii, we think this may be only a species specific character. Like the front cheliceral setae found in the males of some Mysmena species, some species have them (e.g. M. arcilonga, M. rostella, M. vangoethemi, M. taiwanica), but others do not. This same situation also appears in the genus Gaoligonga. The scape may be present or absent; the same is true in other mysmenid species. However, these characters are still in doubt.
In conclusion, the monophyly and circumscription of the genus Chanea and its relationships within Mysmenidae needs more study (Lopardo and Hormiga 2015).