Serratacosa, a new genus of Lycosidae (Araneae) from the southern slopes of the Eastern Himalayas

A new wolf spider genus, Serratacosa gen. nov., is erected based on the type and new species, S. medogensis gen. et sp. nov. and two newly combined species, S. himalayensis (Gravely, 1924) (from Hogna Simon, 1885) and S. multidontata (Qu, Peng & Yin, 2010) (from Pardosa C.L. Koch, 1847). All of them are from the southern slopes of the Eastern Himalayas. Descriptions of the new genera and species, and a redescription of S. multidontata are provided together with digital images, illustrations and a distribution map.


Introduction
The southern slopes of the Eastern Himalayas are one of the most important biodiversity hotspots worldwide (Myers et al. 2000), having high species richness and a high number of endemic species, such as the spider genera Himalmartensus Wang & Zhu, 2008(Amaurobiidae Thorell, 1870 and Himalcoelotes Wang, 2002(Agelenidae C.L. Koch, 1837, which are only known from this region. The wolf spider family Lycosidae Sundevall, 1833 is the sixth most diverse spider group, comprised of 125 genera and 2430 valid species worldwide (World Spider Catalog 2021). Some well-revised genera have distinctive distributional regions, such as Acantholycosa Dahl, 1908 (revised by Marusik et al 2004) found in Europe, Asia and North America; Hippasa Simon, 1885 (revised by Wang et al. 2015) found in Asia and Africa, Ovia Sankaran, Malamel & Sebastian, 2017(revised by Sankaran, Malamel & Sebastian 2017and Lu et al. 2018 found in China, Laos, Singapore and India. But many genera are still non-monophyletic and need to be further revised, such as Arctosa C. L. Koch, 1847 and Pardosa C. L. Koch, 1847 (Piacentini & Ramirez 2019).
Here a new genus, Serratacosa gen. nov., is erected to accommodate these two species, S. himalayensis (Gravely, 1924) comb. nov. and S. multidontata (Qu, Peng & Yin, 2010) comb. nov., along with the type species of the new genus, S. medogensis gen. et sp. nov. from the same area of China (Medog of Tibet).

Material and methods
All specimens are preserved in 75% ethanol and were examined, illustrated, photographed and measured using a Leica M205A stereo microscope equipped with a drawing tube, a Leica DFC450 camera and LAS software ver. 4.6. Male pedipalps and epigynes were examined and illustrated after dissection. Female genitalia were cleared in 90% lactic acid. Eye sizes were measured as the maximum dorsal diameter. Leg measurements are shown as total length (femur, patella and tibia, metatarsus, tarsus). All measurements are given in millimeters.

Diagnosis
This new genus shares similar characters with some Lycosinae genera, such as Costacosa Framenau & Leung, 2013 (male pedipalps with serrated median apophysis), Hogna Simon, 1885 and Trochosa C. L. Koch, 1847 (epigynes with inverted T-shaped septum). However, the new genus can be distinguished from all above mentioned genera by: median apophysis ventral surface with a semicircular protruding lobe, strongly sclerotized, dorsal surface with an oval sclerite (with keel-shaped ventral spur in Costacosa, whereas in Hogna and Trochosa oblique, with stout spur near base); terminal apophysis twisted, strongly grooved (sickle-shaped in Costacosa, Hogna and Trochosa); embolus long, sinuous

Etymology
The generic name is derived from the Latin word 'serratus' ('锯齿状的' in Chinese), which means serrated, and the lycosid generic suffix '-cosa'; referring to the serrated anterior edge of the median apophysis; gender feminine.

Description
Cephalothorax. Carapace gray brown, with light brown longitudinal marking on mid-line, eye region black. Fovea longitudinal. Radial furrows distinct. Chelicerae brown, with three promarginal and three retromarginal teeth. Labium and endites yellow brown, longer than wide. Sternum yellow brown and scutellate, with sparse brown setae.
opisthosoma. Oval, yellowish-brown, with lanceolate cardiac mark on anterior half and with black irregular markings on posterior half. Venter of abdomen yellow-brown.

Remarks
The types of Hogna himalayensis were unavailable for our research, but it is clear from the descriptions and figures of Tikader & Malhotra (1980: 382, figs 255-257) and Buchar (1997: 14, figs 15-17), that the median apophysis is serrated and the epigynal septum inverted T-shaped.

Discussion
Based on the following characteristics, Serratacosa gen. nov. can be identified as a member of the subfamily Lycosinae: median apophysis transverse, with ventrally directed spur and dorsal surface with a sinuous channel; epigyne with an inverted 'T-shaped' median septum (Dondale 1986;Piacentini & Grismado 2009).
Wolf spiders mainly live in open habitats (Jocqué & Alderweireldt 2005). Serratacosa gen. nov. is distributed from the southern slopes of the Eastern Himalayas to the very dense forests on the southern slopes. Both S. medogensis gen. et sp. nov. and S. multidontata (Qu, Peng & Yin, 2010) comb. nov. were found in dense forests. All three species addressed in this study have been recorded from the southern slopes of the Eastern Himalayas, which might indicate that the species differentiation of the members of the genus Serratacosa gen. nov. is closely related to the uplift of the Qinghai-Tibet Plateau. It can be proposed that there are still many undescribed species on the southern slopes of the Eastern Himalayas awaiting discovery and description.