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).

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.).

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).

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).

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.

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).

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

Known only from the localities of the type series.

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).

Holotype ♂: China, Yunnan, Menghai County, Mangun Stockaded Village, Xishuangbanna Natural Reserve, secondary forest; 22°02’12’’N, 100°23’28’’E; 1179 m; 20.III.2016; S. Li leg. (SYNU-385). Paratype. 1♀: same data as for holotype (SYNU-386).

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

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).

Male (holotype). Body: habitus as in Fig. 4A–C; body length 1.52. Carapace: 0.81 long, 0.61 wide; yellow, with egg-shaped patches behind eyes, surface of elevated portion of pars cephalica smooth, sides finely reticulate, lateral margin straight, smooth (Fig. 4D, E). Clypeus: height about 1.3 times ALE diameter (Fig. 4G). Eyes: see Fig. 4D, G. Sternum: pale orange (Fig. 4F). Mouthparts: chelicerae, endites and labium orange; chelicerae straight, base of fangs unmodified, fang groove with a few small denticles (Figs 4H, I, 22C, D); anteromedian tip of endites with one strong, tooth-like projection (Fig. 4F). Abdomen: 0.65 long, 0.49 wide; dorsal scutum well sclerotized, pale orange, covering 1/3 of the abdomen width and approximately 1/2 of the abdomen length, not fused to epigastric scutum; epigastric and postgastric scutum well sclerotized, pale orange, fused, postgastric scutum covering about 1/2 of the abdomen length (Fig. 4A–C). Legs: pale orange, femur I with 2 prolateral spines, tibia I with 4 pairs, metatarsus I with 2 pairs of long ventral spines. Legs II lost. 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 stout, with numerous lamella-like membranes, retrolateral lobe narrow leaf-shaped (Figs 5, 20D–F).

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.

Female (paratype, SYNU-386). Same as male except as noted. Body: body length 1.93. Carapace: 0.80 long, 0.64 wide. Mouthparts: chelicerae and endites unmodified. Abdomen: 1.20 long, 0.81 wide; dorsal scutum very small. Epigastric area: the postgastric scutum with a strongly sclerotized structure in the middle (Fig. 6F). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, simple, winding tube posteriorly, ending in a small rectangular shaped atrium (Fig. 23C, D).

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

Known only from the type locality.

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).

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).

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).

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).

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).

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.

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).

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

Known only from the type locality.

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).

5♂7♀: China, Yunnan, Xishuangbanna Tropical Garden; 21°54.999'N, 101°16.237'E; 561 m; 24.IV.2019; Y. Tong and J. Liu leg. (SYNU-414–425).

See Platnick et al. (2012).

Tropical Asia. Introduced to North, Central, South America, Britain, Gaboon, Seychelles, Madagascar, Hawaii.

Holotype ♂: China, Yunnan, Mengla City, Menglun Town, Xishuangbanna Natural Reserve, 55 Km, monsoon forest; 21°57.531'N, 101°11.961'E; 751 m; 13.VI.2013; Q. Zhao and Z. Chen leg. (SYNU-405). Paratypes. 1♂5♀: same data as for holotype (SYNU-406–411); 1♂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-412–413).

The new species is similar to I. auritus Tong & Li, 2012 in the long dorsal scutum of the abdomen and the helmet-shaped sclerotized process of the male cheliceral fang, but can be distinguished by the broad mushroom-like projection (Fig. 20J–L) of the palp (vs the ear-shaped apophysis in I. auritus; Tong 2013: fig. 43A, B) and the central oval shaped depression (Figs 12H, 23G) of epigastric area (vs without external features in I. auritus; Tong 2013: fig. 43C).

Figure 10. 

Ischnothyreus qidaoban 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).

Male (holotype). Body: habitus as in Fig. 10A–C; body length 1.58. Carapace: 0.84 long, 0.69 wide; dark brown, with egg-shaped patches behind eyes, surface of elevated portion of pars cephalica finely reticulate, sides strongly reticulate, lateral margin straight, smooth (Fig. 10D, E). Clypeus: height about equal to ALE diameter (Fig. 10G). Eyes: (Fig. 10D, G). Sternum: pale orange (Fig. 10F). Mouthparts: chelicerae, endites and labium brown; chelicerae straight, base of fangs with helmet-shaped sclerotized process, fang groove with a few small denticles (Figs 10H–J, 22G, H); anteromedian tip of endites with one strong, tooth-like projection (Fig. 10F). Abdomen: 0.74 long, 0.46 wide; dorsal scutum well sclerotized, pale orange, covering whole abdomen width and abdomen length, fused to epigastric scutum; epigastric and postgastric scutum well sclerotized, yellow, fused, postgastric scutum covering about 5/6 of the abdomen length (Fig. 10A–C). Legs: yellow, 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 one small ventral protuberance, distal end of bulb elongated, with one broad mushroom-like projection, retrolateral lobe narrow (Figs 11, 20J–L).

Figure 11. 

Ischnothyreus qidaoban 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: mlp = mushroom-like projection; rl = retrolateral lobe.

Female (paratype, SYNU-407). Same as male except as noted. Body: habitus as in Fig. 12A–C; body length 1.64. Carapace: 0.77 long, 0.67 wide. Mouthparts: chelicerae and endites unmodified. Abdomen: 0.88 long, 0.65 wide; dorsal scutum covering 5/6 of the abdomen length and about 5/6 of the abdomen width. Epigastric area: postgastric scutum with central oval-shaped depression (Fig. 12C, H). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, simple winding tube posteriorly (Fig. 23G, H).

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

Known only from the localities of the type series.

Figure 12. 

Ischnothyreus qidaoban 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: cd = central oval depression. Scale bars: 0.4 mm (A–G); 0.2 mm (H).

4♂3♀: China, Yunnan, Menghai City, Mangun Stockaded Village, Xishuangbanna Natural Reserve, secondary forest; 22°02’12’’N, 100°23’28’’E; 1179 m; 20.III.2016; S. Li leg. (SYNU-372–378).

This species is similar to I. balu Kranz-Baltensperger, 2011 in the circular atrium in the female, but can be distinguished by the finger-shaped sclerotized process of the male cheliceral fang (Fig. 13H–J) (lacking in I. balu; Kranz-Baltensperger 2011: fig. 1F–G), the size of the atrium (nearly 1/5 the length of postgastric scutum (Fig. 23I)) (vs more than 1/3 the length of postgastric scutum; Kranz-Baltensperger 2011: fig. 2F, H) and the greater sinuosity of the winding tube (Fig. 23J) (vs the short, simple winding tube in I. balu; Kranz-Baltensperger 2011: fig. 2G).

Figure 13. 

Ischnothyreus qiuxing, male (SYNU-372) A–C habitus, dorsal, lateral and ventral views D–G prosoma, dorsal, lateral, ventral and anterior views H–J left chelicerae, anterior, lateral and posterior views. Abbreviation: stp = strong, tooth-like projection. Scale bars: 0.4 mm (A–G); 0.1 mm (H–J).

Male (SYNU-372). Body: habitus as in Fig. 13A–C; body length 1.90. Carapace: 1.03 long, 0.81 wide; yellow, with egg-shaped patches behind eyes, surface of elevated portion of pars cephalica smooth, sides finely reticulate, lateral margin straight, smooth (Fig. 13D, E). Clypeus: height about equal to ALE diameter (Fig. 13G). Eyes: see Fig. 13D, G. Sternum: pale orange (Fig. 13F). Mouthparts: chelicerae, endites and labium orange; chelicerae straight, base of fangs with finger-shaped sclerotized process, fang groove with a few small denticles (Figs 13H–J, 21F, G); anteromedian tip of endites with one strong, tooth-like projection (Fig. 13F). Abdomen: 0.95 long, 0.54 wide; dorsal scutum well sclerotized, pale orange, covering approximately 2/3 of the abdomen width and 3/4 of the abdomen length, fused to epigastric scutum; epigastric and postgastric scutum well sclerotized, pale orange, fused, postgastric scutum covering about 3/4 of the abdomen length (Fig. 13A–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 one very small ventral protuberance, distal end of bulb elongated, with distal narrow membrane, and a retrolateral tuber-like projection (Figs 14, 20M–O).

Figure 14. 

Ischnothyreus qiuxing, male (SYNU-372), 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: tlp = tuber-like projection; vpr = ventral protrusion.

Female (redescription, SYNU-378). Same as male except as noted. Body: habitus as in Fig. 15A–C; body length 1.82. Carapace: 0.81 long, 0.66 wide. Mouthparts: chelicerae and endites unmodified. Abdomen: 1.24 long, 0.79 wide, dorsal scutum very small. Epigastric area: surface without external features (Fig. 15H). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, simple winding tube posteriorly, ending in a circular atrium (Fig. 23I, J).

China, Myanmar.

Figure 15. 

Ischnothyreus qiuxing, female (SYNU-378) 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–G); 0.2 mm (H).

Holotype ♀: China, Yunnan, Xishuangbanna Tropical Garden; 21°54.999'N, 101°16.237'E; 561 m; 24.IV.2019; Y. Tong and J. Liu leg. (SYNU-426). Paratype. 1♀: same data as for holotype (SYNU-427).

The new species is similar to I. tadfane Tong & Li, 2013 in the large dorsal scutum of the abdomen, but can be distinguished by the greater short winding tube of the endogyne (Fig. 24B) (vs long winding tube; Tong and Li 2013: fig. 4I, K) and the nipple-shaped atrium (Fig. 24A) (vs inverted bell shaped atrium; Tong and Li 2013: fig. 4H, J).

Figure 16. 

Ischnothyreus sijiae 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–G); 0.2 mm (H).

Female (holotype). Body: habitus as in Fig. 16A–C; body length 1.49. Carapace: 0.68 long, 0.54 wide; yellow-brown, without any pattern, surface finely reticulate, lateral margin straight, smooth (Fig. 16D, E). Clypeus: height about 0.8 times ALE diameter (Fig. 16G). Eyes: see Fig. 16D, G. Sternum: pale orange (Fig. 16F). Mouthparts: chelicerae, endites and labium orange; chelicerae straight, base of fangs unmodified (Fig. 16G); endites unmodified (Fig. 16F). Abdomen: 0.86 long, 0.53 wide; dorsal scutum well sclerotized, brown, covering 2/3 of the abdomen width and approximately 4/5 of the abdomen length, not fused to epigastric scutum; epigastric and postgastric scutum well sclerotized, pale orange, unfused (Fig. 16A–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. Epigastric area: surface without external features (Fig. 16H). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, simple winding tube, ending in a small nipple-shaped atrium (Fig. 24A, B).

Male. Unknown.

The species is named after Miss Sijia Liu, one of the collectors of the holotype.

Among the known species of the genus Ischnothyreus of China, I. qianlongae Tong & Li, 2008 and I. tergemintus Liu, Xu & Henrard, 2019 are known only from males. I. sijiae sp. nov. can be distinguished from I. tergemintus by the brown colour on the abdomen and sides of carapace (vs yellow abdomen and carapace in I. tergemintus; Liu et al. 2019: fig. 1A); and from I. qianlongae by the smaller size of the eyes (compare Fig. 16D with Tong and Li (2008: fig. 4A)).

Known only from the type locality.

Holotype ♂: China, Yunnan, Mengla County, Xiaolongha, Xishuangbanna Biodiversity Conservation Corridor, Qidaoban, valley forest; 21°24.832'N, 101°37.906'E; 721 m; 18.VI.2013; Q. Zhao and Z. Chen leg. (SYNU-428). Paratypes 1♀: same data as for holotype (SYNU-429); 1♂3♀: same data as for holotype; 21°24.253'N, 101°36.324'E; 761 m; 15.VI.2013; Q. Zhao and Z. Chen leg. (SYNU-430–433).

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

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).

Male (holotype). Body: habitus as in Fig. 17A–C; body length 1.48. Carapace: 0.80 long, 0.61 wide; yellow, with egg-shaped patches behind eyes, surface of elevated portion of pars cephalica smooth, sides finely reticulate, fovea absent, lateral margin straight, smooth (Fig. 17D, E). Clypeus: height about equal to ALE diameter (Fig. 17G). Eyes: see Fig. 17D, G. Sternum: pale orange (Fig. 17F). Mouthparts: chelicerae, endites and labium orange; chelicerae straight, base of fangs with tongue-shaped sclerotized process, fang groove with a few small denticles (Figs 17H–J, 21D, E); anteromedian tip of endites with one strong, tooth-like projection (Fig. 17F). Abdomen: 0.64 long, 0.48 wide; dorsal scutum pale orange, very small, covering approximately 1/4 of the abdomen width and 1/3 of the abdomen length, not fused to epigastric scutum; epigastric and postgastric scutum well sclerotized, pale orange, fused, postgastric scutum covering about 1/2 of the abdomen length (Fig. 17A–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 stout, with one narrow needle-shaped prolateral projection and a lamella-like membrane, retrolateral lobe broad leaf-shaped (Figs 18, 21A–C).

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.

Female (paratype, SYNU-429). Same as male except as noted. Body: habitus as in Fig. 19A–C; body length 1.70. Carapace: 0.76 long, 0.63 wide. Mouthparts: chelicerae and endites unmodified. Abdomen: 0.95 long, 0.64 wide. Epigastric area: surface without external features (Fig. 19H). Endogyne: from the middle of the slightly thickened margin of the postgastric scutum runs a dark, simple winding tube posteriorly, ending in a small bell-shaped atrium (Fig. 24C, D).

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

Known only from the type locality.

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 21. 

A–E I. xiaolongha sp. nov. F, G I. qiuxing A left male palp, prolateral view B left male palp, dorsal view C left male palp, retrolateral view D, F left male chelicerae, anterior view E, G left male chelicerae, posterior view. Abbreviations: fsp = finger-shaped process; tsp = tongue-shaped process. Scale bars: 0.2 mm (A–C).

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.

Figure 24. 

Endogyne of Ischnothyreus spp., A, B I. sijiae sp. nov. C, D I. xiaolongha sp. nov. A, C ventral view B, D dorsal view. Abbreviations: a = apodemes; bsa = bell-shaped atrium; nsa = nipple-shaped atrium; wt = winding tube. Scale bars: 0.2 mm.