Four new spider species of the family Theridiosomatidae (Arachnida, Araneae) from caves in Laos

Abstract Four new species of the spider family Theridiosomatidae are described from caves in Laos: Alaria cavernicola sp. n. (♂♀), A. navicularis sp. n., (♂♀) A. bicornis sp. n. (♂♀), Chthonopes thakekensis sp. n. (♀). Diagnoses and illustrations for all new taxa are given. All holotypes are deposited in the Senckenberg Research Institute in Frankfurt am Main, Germany (SMF).


Introduction
Theridiosomatidae are small (usually ≤ 3 mm), widely distributed, and cryptozoic spiders, which can be found in damp, dark habitats (litter layer of forest or in caves) (Zhao and Li 2012). Coddington (1986) reviewed the genera of this family and proposed synapomorphies based on a cladistic analysis, including the combination of following characters: a pair of pits on the anterior margin of sternum near the labial base (absent in Chthonos Coddington, 1986), partly fused spermathecae (separated in Coddingtonia Miller, Griswold & Yin, 2009), especially large male palps (except for Menglunia Zhao & Li, 2012), and a long trichobothrium dorsally on tibia IV. Subsequently, an increasing number of new species have been described from all over the world. For example, some species from Latin America have been reported by Lopez (1994Lopez ( , 1996, Rodrigues and Ott (2005) and Rodrigues and Lise (2008). Chinese Theridiosomatidae have been reported from Gaoligongshan, Yunnan (Miller et al. 2009), tropical rainforest in Hainan and Xishuangbanna of Yunnan, and in caves in Guangxi, Chongqing and Guizhou (Zhao and Li 2012;Dou and Lin 2012;Chen 2010;Zhu and Wang 1992;Song and Zhu 1994). Other species have been described from insular states or areas (Barrion and Litsinger 1995;Saaristo 1996;Zhang et al. 2006;Shinkai 2009). According to the latest data, 18 genera containing 101 known species are recorded worldwide (Platnick 2014).
The earliest report on Theridiosomatidae from the Indochinese Peninsula was published by Simon (1901), who described two species, Andasta cyclosina and Theridiosoma nebulosum from Malaysia. About one hundred years later, two new genera (Chthonopes and Luangnam) were established by Wunderlich (2011) to accommodate three new species (C. cavernicolus, C. jaegeri and L. discobulbus) discovered from caves in Laos. Insufficient sampling could not hide the rich species diversity of this region, and still more species are waiting to be found. In this paper, we provide detailed descriptions, illustrations and distribution data for four new species from Laos.

Material and Methods
Specimens were examined and measured under a Leica M205 C stereomicroscope. Further details were studied under an Olympus BX43 compound microscope. All drawings were made using a drawing tube attached to an Olympus BX43 compound microscope, and then inked on ink jet plotter paper. Copulatory organs of males and females were examined and illustrated after they have been dissected and detached from the spiders' bodies. Vulvae were treated in lactic acid before illustration. All embolic divisions and vulvae were illustrated after being embedded in Hoyer's Solution. Photos were taken with a Canon EOS 60D wide zoom digital camera (8.5 megapixels) mounted on an Olympus BX43 stereomicroscope. The images were montaged using Helicon Focus 3.10 software. All type specimens are preserved in 85% ethanol solution. All material was collected by Peter Jäger by hand. Material is deposited in Senckenberg Research Institute, Frankfurt, Germany (SMF) and in the Institute of Zoology, Chinese Academy of Sciences, Beijing, China (IZCAS).
All measurements were made in millimeters; altitude is given in meters (m). Leg measurements are given as: total length (femur, patella, tibia, metatarsus, tar-sus). The terminology mostly follows Miller et al. (2009) and Zhao and Li (2012). Chaetotaxy of macrosetae is marked for dorsal (d), prolateral (p), retrolateral (r), and ventral (v) surfaces of legs. Metatarsal trichobothrium (Tm) is given as the ratio of the distance between the proximal margin of the metatarsus and the base of the trichobothrium divided by the total length of the metatarsus (Locket and Millidge 1953) and Tm value for each leg is given as Tm I, Tm II, Tm III, and Tm IV. The course of the duct system is illustrated as red line with a circle representing the copulatory opening and an arrow representing the fertilization duct pointing in direction of the Uterus externus.
Abbreviations used in the text: AME -anterior median eyes; DS -dorsal shield of prosoma; LE -lateral eyes; PME -posterior median eyes.   Etymology. The specific epithet is derived from the Latin word "cavernicola" = "living in caves", refers to that this species may mainly live in caves; adjective.
Distribution. See in Fig. 19. Etymology. This specific name is derived from the Latin word "navicularis" = "shaped like a boat", and refers to the shape of the median apophysis in the male palp; adjective.
Variation. The total length ranges from 3.42 to 3.70 in females (n = 4). Fig. 19. Etymology. This specific name is derived from the Latin word "bicornis" = "with two horns", referring to the median apophysis with a fingerlike and a hooked process in the male palp; used as an adjective.  (Figs 11B, 12D, 14A, 15D), and long embolus mostly enveloped by conductor in male, an utterly exposed scape protruding from beneath epigynal posterior margin and similar configurations of vulva in female, but the new species can be distinguished from the latter by the developed, strongly rugose tegulum (Figs 11C, 12C, 15C), the large median apophysis with 2 distal processes (Figs 12D, 14A, 15D) and the absence of a hooked process in paracymbium in male (Figs 12E, 15E), the oval median spermathecae (Figs 13C, E,  16B), the strongly sclerotized, long oval, lateral coils of copulatory duct (Figs 13E, 16B) and the narrow scape with two hoods in female (Figs 13C-E, 16A-C).

Diagnosis. This new species and
Description. Habitus see in Figs 11A, 13A. DS pear-shaped, brownish yellow, thoracic fovea black, with symmetric dark veins. Eyes with black bases. Cervical groove distinct. Sternum brown. Legs proximally yellow, distally dark yellow. Opisthosoma oval, dark, dorsum with a long, longitudinal white stripe and 3 pairs of white spots minishing in sequence.
Distribution. See in Fig. 19. Etymology. This specific name is taken from type locality; adjective. Diagnosis. The new species is similar to C. jaegeri Wunderlich, 2011(see Wunderlich 2011, figs 18d-f) in the shape of epigyne and the configurations of vulva, but can be distinguished from it by the presence of translucent accessory spermathecae (Figs 17D-E, 18C; absent in C. jaegeri) and the large, semi-circular main spermathecae (Figs 17E, 18C; circular in C. jaegeri).