Two new species of the genus Trilacuna (Araneae: Oonopidae) from Jinyun Mountain of Chongqing, China

Two new species of the genus Trilacuna Tong & Li, 2007, T. jinyun Tong, Zhang & Li, sp. nov. (♂♀) and T. jiuchi Tong, Zhang & Li sp. nov. (♂♀), are described from Chongqing, China. Photos of the habitus and copulatory organs are provided.


Introduction
The family Oonopidae is a diverse group of spiders with 1872 extant described species in 114 genera. Oonopids are small (1-3 mm), two-clawed, ecribellate spiders that can be abundant in leaf litter, under bark of trees, in forest canopies and in subterranean habitats (Saaristo 2001;Tong 2013). Trilacuna Tong & Li, 2007 is a larger genus of the family. Currently, a total of 35 species have been reported. All the species are known from Asia and occur in Iran and from the Korean Peninsula south to Sumatra (Li 2020;WSC 2020).

Material and methods
The specimens were examined using a Leica M205C stereo microscope. Details were studied under an Olympus BX51 compound microscope. Photos were made with a Canon EOS 750D zoom digital camera (18 megapixels) mounted on an Olympus BX51 compound microscope. Vulvae were cleared in lactic acid. For scanning electron microscopy (SEM), specimens were air-dried, sputter coated using IXRF SYSTEMS and imaged with a Hitachi TM3030 SEM. Photos were stacked using Helicon Focus 7.6.1 and processed using Adobe Photoshop ver. 21.1.2. All measurements were taken using an Olympus BX51 compound microscope and are in millimeters. Measurements of palps are given as follows: total length (femur + patella + tibia + tarsus).
The following abbreviations are used in the text and fi gures: ab = anterior branch ALE = anterior lateral eyes ap = apodeme as = anterior sclerite bp = basal protrusion cp = circular projection db = dorsal branch ehb = elevated hair base fl p = fl ag like protrusion fl s = fork like sclerite lb = lateral branch ldi = labium deep incision mb = median branch pe = posterior extension PME = posterior median eyes PLE = posterior lateral eyes psp = posterior spiracle rls = nine-teeth-rake like sclerite rss = rectangular shaped structure sar = sclerotized, recurved arches sdb = strongly curved distal branch sls = slender line-like structure tba = transverse bars tsc = transverse sclerite vb = ventral branch wss = worm-shaped structure All material studied is deposited at the Shenyang Normal University, Shenyang, China (SYNU) and Southwest University, Chongqing, China (SWUC).

Differential diagnosis
This new species is similar to Trilacuna simianshan Tong & Li, 2018, but males can be distinguished by the large fl ag like protrusion and the broad dorsal branch of embolus system (Fig. 2E, F, H), and females by the rectangular shaped structure of endogyne (Fig. 4F). Males of T. simianshan have a rectangular projection and narrow dorsal branch of embolus system, and females have a cone-shaped structure of endogyne (Tong et al. 2018: fi gs 3a-f, 5i).

Etymology
The specifi c name is a noun in apposition and refers to the type locality. EYES (Fig. 1A, G). Well developed, arranged in a compact group; ALE, PME and PLE subequal; ALE-PLE separated by less than ALE radius, PME touching each other; posterior row recurved from above, procurved from front.    (Figs 3B, 4E): middle part of posterior margin of epigastric scutum (pe) much extended posteriorly, with sclerotized recurved arches (sar) between posterior spiracles (psp). Endogyne (Fig. 4F): with a rectangular shaped structure (rss), at the posterior end of the rectangular shaped structure is a slender line-like structure (sls) extending anteriorly; with two lateral apodemes (ap).

Differential diagnosis
Males of this new species are similar to the males of Trilacuna angularis Tong &Li, 2007 andT. rastrum Tong &Li, 2007, but can be distinguished by the nine-teeth-rake like sclerite and the fork like sclerite of the embolus system ( Fig. 6E-H). Males of T. angularis and T. rastrum both have a four-teeth-rake like sclerite but lack the fork like sclerite (Tong & Li 2007: fi gs 5-10, 15-18). Females of this new species are similar to the females of Trilacuna rastrum Tong & Li, 2007, but can be separated by the wormshaped structure of the endogyne, which is not present in T. rastrum (Tong & Li 2007: fi g. 6).

Etymology
The specifi c name is derived from the Chinese pinyin, 'jiuchi', which means 'nine teeth', referring to the nine-teeth-rake like sclerite of the male embolus system.    CARAPACE (Fig. 5D, F-G). 0.86 long, 0.73 wide; sides granulate; lateral margin rebordered. EYES (Fig. 5D, G). Well developed, arranged in a compact group; ALE largest, PLE smallest; ALE-PLE separated by less than ALE radius, PME touching each other; posterior row recurved from above, procurved from front. CLYPEUS (Fig. 5G). Nearly straight in frontal view, ALE separated from edge of carapace by about 1.3 times their diameter. MOUTHPARTS (Fig. 5E, G). Chelicerae straight; labium rectangular, anterior margin deeply incised; endites slender, distally strongly curved branched. STERNUM (Fig. 5E). With radial furrows between coxae I-II, II-III, III-IV; surface reticulated. base (bp) and a fork like sclerite (fl s) in prolateral view, a broad median branch (mb) and a nine-teethrake like sclerite (rls) in dorsal view, and a lateral long curved branch (lb) in retrolateral view.

Discussion
Trilacuna was originally diagnosed by the enlarged male palpal femora, the very complicated embolus system, the branched endites and the notched labium (Tong & Li 2007). These characters were later recognized as shared by a more inclusive group: the "Dysderoides complex", that includes Bannana Tong & Li, 2015, Dysderoides Fage, 1946, Himalayana Grismado, 2014, and Trilacuna (Grismado et al. 2014Tong & Li 2015). Males of Trilacuna differ from those of the other genera of the "Dysderoides complex" by usually lacking the furrow connecting the posterior tracheal spiracles, and females differ by having a long postepigastric scutum covering almost the whole ventral abdomen ).
However, as already discussed by Grismado et al. (2014) and Malek-Hosseini et al. (2015), some species, i.e., T. aenobarba (Brignoli, 1978), T. bangla Grismado & Ramírez, 2014 Also worth mentioning are T. jinyun sp. nov. and T. simianshan. Both species have two very long branches on the embolus system (Figs 2C-D, 4A-B; Tong et al. 2018: fi g. 2c-d), which make them quite different from all other species of Trilacuna. However, the enlarged male palpal femora and somatic features like the deeply incised labium and the branched endites make the placement in the genus Trilacuna reasonable.