Ischnothyreus mengyang Tong & Li, 2021

Tong, Yanfeng, Sun, Xiaochen, Li, Shuqiang & Bian, Dongju, 2021, Taxonomic study of the genus Ischnothyreus (Araneae, Oonopidae) from Xishuangbanna Rainforest, southwestern China, ZooKeys 1034, pp. 165-197 : 165

Ischnothyreus mengyang Tong & Li sp. nov. Figures 7 , 8 , 9 , 20G-I , 22E, F , 23E, F

Type material.

Holotype ♂: China, Yunnan, Jinghong City, Mengyang Town, Xishuangbanna Natural Reserve, monsoon forest; 21°24.161'N, 101°36.412'E; 791 m; 16.VI.2013; Q. Zhao and Z. Chen leg. (SYNU-387). Paratypes 5♂12♀: same data as for holotype (SYNU-388-404).

Diagnosis.

The new species is similar to I. taunggyi Tong & Li, 2020 in the male palp and the large, sclerotized process of male cheliceral fang, but can be distinguished by the broad retrolateral lobe of male palp (Fig. 8F ) (vs small, ear-shaped retrolateral lobe in I. taunggyi ; Tong et al. 2020: fig. 9F) and by the long abdominal dorsal scutum of the female (5/6 of the abdomen length (Fig. 9A ) vs less than 1/2 of the abdomen length in I. taunggyi ; Tong et al. 2020: fig. 10A).

Description.

Male (holotype). Body: habitus as in Fig. 7A-C ; body length 1.86. Carapace: 0.95 long, 0.78 wide; pale brown, with egg-shaped patches behind eyes, surface of elevated portion of pars cephalica smooth, sides finely reticulate, lateral margin straight, smooth (Fig. 7D, E ). Clypeus: height about 0.74 times ALE diameter (Fig. 7G ). Eyes: see Fig. 7D, G . Sternum: pale orange (Fig. 7F ). Mouthparts: chelicerae, endites and labium brown; chelicerae straight, base of fangs with large, sclerotized process, fang groove with a few small denticles (Figs 7H-J , 22E, F ); anteromedian tip of endites with one strong, tooth-like projection (Fig. 7F ). Abdomen: 0.92 long, 0.55 wide; dorsal scutum well sclerotized, pale orange, covering approximately 4/5 of the abdomen length and 3/4 of the abdomen width, not fused to epigastric scutum; epigastric and postgastric scutum well sclerotized, pale orange, fused, postgastric scutum covering about 3/4 of the abdomen length (Fig. 7A-C ). Legs: pale orange, femur I with 2 prolateral spines, tibia I with 4 pairs, metatarsus I with 2 pairs of long ventral spines. Leg II spination similar to leg I except femur with only 1 prolateral spine. Legs III and IV spineless. Palp: trochanter with ventral projection, cymbium brown; bulb with 2 ventral protuberances, one large and another very small, distal end of bulb elongated, with one narrow leaf-shaped prolateral projection and a distal hook-shaped membrane, retrolateral lobe broad (Figs 8 , 20G-I ).

Female (paratype, SYNU-393). Same as male except as noted. Body: habitus as in Fig. 9A-C ; body length 1.96. Carapace: 0.94 long, 0.82 wide. Mouthparts: chelicerae and endites unmodified. Abdomen: 1.05 long, 0.73 wide; dorsal scutum covering 5/6 of the abdomen length, about 2/3 of the abdomen width. Epigastric area: postgastric scutum with central anchor-shaped structure (Fig. 9H ). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, complex winding tube, ending in a very small nipple-shaped atrium (Fig. 23E, F ).

Etymology.

The specific name is a noun in apposition taken from the type locality.

Distribution.

Known only from the type locality.

Figures

Figure 7. Ischnothyreus mengyang sp. nov., male holotype A-C habitus, dorsal, lateral and ventral views D-G prosoma, dorsal, lateral, ventral and anterior views H-J left chelicerae, anterior, posterior and lateral views. Abbreviation: stp = strong, tooth-like projection. Scale bars: 0.4 mm (A-G); 0.1 mm (H-J).

Figure 8. Ischnothyreus mengyang sp. nov., male holotype, left palp, SEM A-C prolateral, retrolateral and dorsal views D, E palpal bulb, prolateral and retrolateral views F-H distal part of palpal bulb, dorsal, prolateral and retrolateral views. Abbreviations: hsm = hook-shaped membrane; lpp = leaf-shaped prolateral projection; nsm = needle-shaped membrane; rl = retrolateral lobe; vpr = ventral protrusion.

Figure 9. Ischnothyreus mengyang sp. nov., female paratype A-C habitus, dorsal, lateral and ventral views D-G prosoma, dorsal, lateral, ventral and anterior views H epigastric region, ventral view. Abbreviation: ass = anchor-shaped structure. Scale bars: 0.4 mm (A-H).

Figure 20. Ischnothyreus spp., left male palp A-C I. cristiformis sp. nov. D-F I. mangun sp. nov. G-I I. mengyang sp. nov. J-L I. qidaoban sp. nov. M-O I. qiuxing A, D, G, J, M prolateral view B, E, H, K, N dorsal view C, F, I, L, O retrolateral view. Scale bars: 0.1 mm (A-F, M-O); 0.2 mm (G-L).

Figure 22. Ischnothyreus spp., left male chelicerae A, B I. cristiformis sp. nov. C, D I. mangun sp. nov. E, F I. mengyang sp. nov. G, H I. qidaoban sp. nov. A, C, E, G anterior view B, D, F, H posterior view. Abbreviations: ccp = cockscomb-shaped process; hsp = helmet-shaped process; lsp = large, sclerotized process.

Figure 23. Endogyne of Ischnothyreus spp., A, B I. cristiformis sp. nov. C, D I. mangun sp. nov. E, F I. mengyang sp. nov. G, H I. qidaoban sp. nov. I, J I. qiuxing A, C, E, G, I ventral view B, D, F, H, J dorsal view. Abbreviations: a = apodemes; bsa = bell-shaped atrium; cd = central oval depression; csa = circular atrium; nsa = nipple-shaped atrium; oa = opening of the atrium; rsa = rectangular-shaped atrium; wt = winding tube. Scale bars: 0.2 mm.