Ischnothyreus cristiformis 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 cristiformis Tong & Li sp. nov. Figures 1 , 2 , 3 , 20A-C , 22A, B , 23A, B

Type material.

Holotype ♂: China, Yunnan, Mengla County, Xiaolongha, Xishuangbanna Biodiversity Conservation Corridor, montane monsoon forest; 21°24.161'N, 101°36.412'E; 791 m; 16.VI.2013; Q. Zhao and Z. Chen leg. (SYNU-379). Paratypes. 1♀: same data as for holotype (SYNU-380); 3♂1♀: Xiaolongha, Xishuangbanna Biodiversity Conservation Corridor, Qidaoban, valley forest; 21°24.808'N, 101°37.874'E; 711 m; 18.VI.2013; Q. Zhao and Z. Chen leg. (SYNU-381-384).

Diagnosis.

The new species is similar to I. mangun sp. nov. and I. xiaolongha sp. nov. by the lamella-like membrane of the male palp and short dorsal abdominal scutum, but can be distinguished by the large cockscomb-shaped sclerotized process (Fig. 1H-J ) of the male cheliceral fang (vs the unmodified cheliceral fang (Fig. 4H, I ) in I. mangun sp. nov. and the tongue-shaped sclerotized process (Fig. 17H-J ) in I. xiaolongha sp. nov.), the broad rectangular-shaped retrolateral lobe of the bulb (Fig. 2F ) (vs the leaf-shaped lobe (Figs 5F , 18F ) in I. mangun sp. nov. and I. xiaolongha sp. nov.). The female differs from I. mangun sp. nov. and I. xiaolongha sp. nov. by the large bowl-shaped atrium (Fig. 3H ) (vs small rectangular-shaped atrium (Fig. 6F ) in I. mangun sp. nov. and small bell-shaped atrium (Fig. 19H ) in I. xiaolongha sp. nov.).

Description.

Male (holotype). Body: habitus as in Fig. 1A-C ; body length 1.64. Carapace: 0.88 long, 0.65 wide; yellow, with egg-shaped patches behind eyes, surface of elevated portion of pars cephalica smooth, sides finely reticulate, lateral margin straight, smooth (Fig. 1D, E ). Clypeus: height about 2/3 of ALE diameter (Fig. 1G ). Eyes: see Fig. 1D, G . Sternum: pale orange (Fig. 1F ). Mouthparts: chelicerae, endites and labium orange; chelicerae straight, base of fangs with large cockscomb-shaped sclerotized process, fang groove with a few small denticles (Figs 1H-J , 22A, B ); anteromedian tip of endites with one strong, tooth-like projection (Fig. 1F ). Abdomen: 0.76 long, 0.44 wide; dorsal scutum well sclerotized, pale orange, covering 1/3 of the abdomen width and approximately 2/3 of the abdomen length, fused to epigastric scutum; epigastric and postgastric scute well sclerotized, pale orange, fused, postgastric scutum covering about 2/3 of the abdomen length (Fig. 1A-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 numerous lamella-like membranes, retrolateral lobe broad, rectangular-shaped (Figs 2 , 20A-C ).

Female (paratype, SYNU-380). Same as male except as noted. Body: habitus as in Fig. 3A-C ; body length 1.76. Carapace: 0.72 long, 0.67 wide. Mouthparts: chelicerae and endites unmodified. Abdomen: 1.05 long, 0.67 wide; dorsal scutum covering 1/3 of the abdomen length, about 1/4 of the abdomen width. Epigastric area: postgastric scutum with strongly sclerotized structure in the middle (Fig. 3H ). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, simple winding tube, ending in a large bowl-shaped atrium (Fig. 23A, B ).

Etymology.

The specific name is a Latin adjective and refers to the large cockscomb-shaped sclerotized process of the cheliceral fang.

Distribution.

Known only from the localities of the type series.

Figures

Figure 1. Ischnothyreus cristiformis 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 2. Ischnothyreus cristiformis 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: llm = lamella-like membrane; rl = retrolateral lobe; rol = round lobe; tsm = thread-shaped membrane; vpr = ventral protuberance.

Figure 3. Ischnothyreus cristiformis 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: css = central strongly sclerotized structure; Scale bars: 0.4 mm (A-G); 0.2 mm (H).

Figure 4. Ischnothyreus mangun sp. nov., male holotype A-C habitus, dorsal, lateral and ventral views D-G prosoma, dorsal, lateral, ventral and anterior views H, I left chelicerae, anterior and posterior views. Abbreviation: stp = strong, tooth-like projection. Scale bars: 0.4 mm (A-G); 0.1 mm (H, I).

Figure 5. Ischnothyreus mangun 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: llm = lamella-like membrane; nsm = needle-shaped membrane; rl = retrolateral lobe; rol = round lobe; vpr = ventral protuberance.

Figure 6. Ischnothyreus mangun sp. nov., female paratype A-D prosoma, dorsal, lateral, anterior and ventral views E abdomen, dorsal view F epigastric region, ventral view. Abbreviation: css = central strongly sclerotized structure. Scale bars: 0.4 mm (A-E); 0.2 mm (F).

Figure 17. Ischnothyreus xiaolongha 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 18. Ischnothyreus xiaolongha 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: llm = lamella-like membrane; nsm = needle-shaped membrane; rl = retrolateral lobe; rol = round lobe; vpr = ventral protrusion.

Figure 19. Ischnothyreus xiaolongha 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. 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.