Lagynochthonius Beier 1951

Genus Lagynochthonius Beier, 1951 Type species: Chthonius johni Redikorzev, 1922, by original designation. Tyrannochthonius (Lagynochthonius) Beier, 1951: 61. Lagynochthonius Beier: Chamberlin, 1962: 314; Murthy & Ananthakrishnan, 1977: 16–17; Harvey, 1989: 21; Harvey, 1991: 182; Muchmore, 1991: 113; Harvey, 1999: 247; Edward & Harvey, 2008: 280. ......continued on the next page Key to the species of genus Lagynochthonius from China 1. Carapace with eyes or eyespots......................................... 2 - Carapace without eyes or eyespots.................................. 20 2. Eyes well-developed.......................................................... 3 - Eyes strongly reduced...................................................... 14 3. Tergites I and II each with two setae ................................. 4 - Tergites I and II each with four setae ................................ 6 4. Epistome present ............................................................... 5 - Epistome absent................ L. medog Zhang & Zhang, 2014 5. Fixed chelal finger with intercalary teeth............................ .......................................... L. duo Sun, Guo & Zhang, 2024 - Fixed chelal finger without intercalary teeth....................... ........................................ L. houi Sun, Guo & Zhang, 2024 6. At least one finger of chela with intercalary teeth............. 7 - Both chelal fingers without intercalary teeth................... 10 7. Both chelal fingers with intercalary teeth.......................... 8 - Only fixed chelal finger with intercalary teeth.................. 9 8. Carapace with a hump-shaped epistome; four eyes well-developed............. L. hepingensis Sun, Guo & Zhang, 2024 - Carapace with a flat, rounded epistome; posterior pair of eyes spot-like ........................... L. tonkinensis (Beier, 1951) 9. Carapace without epistome.................................................. ........................................ L. harveyi Zhang & Zhang, 2014 - Carapace with a hump-shaped epistome ............................. ..................................... L. gibbus Sun, Guo & Zhang, 2024 10. Epistome present ............................................................. 11 - Epistome absent............................................................... 12 11. Epistome triangular; pedipalpal chela length 0.75–0.93 mm, 5.17–6.25 times as long as broad ................................ ................................................. L. niger Hu & Zhang, 2012 - Epistome hump-shaped; pedipalpal chela length 0.68–0.73 mm, 6.80–7.30 times as long as broad ................................ ............................ L. sanhuaensis Sun, Guo & Zhang, 2024 12. Four eyes well-developed................................................13 - Anterior pair of eyes well-developed, posterior pair of eyes reduced to eyespots.............................................................. ........................... L. brachydigitatus Zhang & Zhang, 2014 13. Pedipalpal chela length 0.72 mm, 4.80 times as long as broad............................................. L. sinensis (Beier, 1967) - Pedipalpal chela length 0.95–1.00 mm, 5.56–6.33 times as long as broad.................. L. leptopalpus Hu & Zhang, 2012 14. Carapace with four strongly reduced eyes........................... .......................................................... L. baiguensis sp. nov. - Carapace only with two eyespots .................................... 15 15. Tergites I and II each with two setae ............................... 16 - Tergites I and II each with four setae .............................. 18 16. Epistome present .................................... L. zhaoae sp. nov. - Epistome absent............................................................... 17 17. The length of chela femur (0.78 mm) and pedipalpal chela (1.08 mm); chela femur 7.80 (♀) times longer than broad.. ........................................................ L. zhakouensis sp. nov. - The length of chela femur (0.61 mm) and pedipalpal chela (0.88 mm); chela femur 5.54 (♀) times longer than broad.. .................................................... L. longquanensis sp. nov. 18. Epistome triangular; pedipalpal chela length 1.61 mm (♂), 1.69–1.77 mm (♀) ................................ L. infirmus sp. nov. - Epistome obtuse and small, round; pedipalpal chela length not more than 1.60 mm (♂ ♀) .......................................... 19 19. Pedipalpal chela 7.00–7.14 (♂), 6.40–6.46 (♀) times as long as broad (length 1.54–1.57 (♂), 1.55–1.60 (♀) mm); palpal femur 8.21–8.50 (♂), 7.50–7.87 (♀) times as long as broad (length 1.15–1.19 (♂), 1.18–1.20 (♀) mm).............. .................................. L. crassus Hou, Gao & Zhang, 2022 - Pedipalpal chela 7.33–7.67 (♂), 6.71–6.82 (♀) times as long as broad (length 1.32–1.38 (♂), 1.41–1.50 (♀) mm); palpal femur 6.92–7.23 (♂), 6.80–7.29 (♀) times as long as broad (length 0.90–0.94 (♂), 1.02 (♀) mm)........................ .............................. L. latipectus Hou, Feng & Zhang, 2023 20. Carapace without antero-median setae; trichobothrium sb closer to b than to st ........................................................ 21 - Carapace with antero-median setae; trichobothrium sb closer to st than to b or midway between st and b .......... 22 21. Epistome pointed and small, triangular; pedipalpal chela 7.03 (♂) times as long as broad (length 2.04 mm) ............. ........................... L. xinjiaoensis Hou, Gao & Zhang, 2022 - Epistome small and obtuse, rounded; pedipalpal chela 6.44– 6.46 (♂), 5.87–6.04 (♀) times as long as broad (1.55–1.61 (♂), 1.69–1.76 (♀) mm) ..................................................... ....................... L. magnidentatus Hou, Gao & Zhang, 2022 22. At least one chela finger with intercalary teeth .............. 23 - Both chelal fingers without intercalary teeth.................. 32 23. Only fixed chelal finger with intercalary teeth............... 24 - Both chelal fingers with intercalary teeth....................... 26 24. Movable chelal finger teeth markedly retrorse and contiguous............... L. retrorsus Hou, Gao & Zhang, 2022 - Movable chelal finger teeth upright and contiguous ...... 25 25. Tergite Ⅹ with two setae; pedipalpal chela length 1.79–1.85 mm (♀), chela femur length 1.27–1.28 mm (♀), 8.47–8.53 (♀) times as long as broad; trichobothrium sb situated midway between st and b ................................................... ............................ L. zhijinensis Hou, Feng & Zhang, 2023 - Tergite Ⅹ with four setae; pedipalpal chela length 2.06–2.19 mm (♀), chela femur length 1.47–1.48 mm (♀), 7.40–7.74 (♀) times as long as broad; trichobothrium sb slightly closer to st than to b ...... L. spinulentus Hou, Gao & Zhang, 2022 26. Tergites II and III each with four setae........................... 27 - Tergites II and III each with two setae ........................... 28 27. Tergites I with four setae; pedipalpal chela length 1.84 mm (♂), 1.83–1.91 mm (♀), 8.76 (♂), 8.30–8.32 (♀) times as long as broad; chela femur length 1.36 mm (♂), 1.35–1.41 mm (♀), 10.46 (♂), 10.07–10.38 (♀) times as long as broad; trichobothrium sb situated midway between st and b .................. L. yaowangguensis Hou, Gao & Zhang, 2022 - Tergites I with two setae; pedipalpal chela length 1.33 mm (♂), 1.26 mm (♀), 6.65 (♂), 6.63 (♀) times as long as broad; chela femur length 0.93 mm (♂), 0.89 mm (♀), 7.15 (♂), 7.42 (♀) times as long as broad; trichobothrium sb slightly closer to st than to b .......................................... ...................... L. longedentatus Hou, Feng & Zhang, 2023 28. Tergites IⅤ and Ⅹ each with four setae ............................... ................................................. L. guangyangensis sp. nov. - Tergites IⅤ and Ⅹ each with two setae ........................... 29 29. Trichobothrium sb slightly closer to st than to b ............ 30 - Trichobothrium sb situated midway between st and b ... 31 30. Carapace markedly narrowed posteriorly; chela 8.38–8.84 (♂) times as long as broad, hand 3.38–3.58 (♂) times longer than broad; proximal half of movable chelal finger without vestigial teeth........... L. serratus Hou, Gao & Zhang, 2022 - Carapace gently narrowed posteriorly; chela 7.00 (♂) times as long as broad, hand 2.92 (♂) times longer than broad; proximal half of movable chelal finger with 6 vestigial teeth ................... L. xiaolinensis Hou, Gao & Zhang, 2022 31. Pedipalpal chela length 1.53–1.54 mm (♂), 1.53–1.55 mm (♀); chela femur length 1.06–1.07 mm (♂), 1.08–1.15 mm (♀); fixed chelal finger with 23–25 macrodenticles, slightly retrorse and pointed, plus 14– 15 intercalary microdenticles ...................................... L. fengi Hou, Gao & Zhang, 2022 - Pedipalpal chela length 1.88–1.99 mm (♂), 1.89–2.01 mm (♀); chela femur length 1.35–1.39 mm (♂), 1.36–1.41 mm (♀); fixed chelal finger with 31–36 macrodenticles, slightly retrorse and pointed, plus 27– 31 intercalary microdenticles ........................ L. guanniuensis Hou, Feng & Zhang, 2023 32. Tergites I and II each with two setae .............................. 33 - Tergites I and II each with four setae ............................. 38 33. Tergites Ⅹ with two setae .................................................... ............................. L. nigriculus Hou, Feng & Zhang, 2023 - Tergites Ⅹ with four setae............................................... 34 34. Tergites III and IⅤ each with two setae............................... ........................... L. daidaiensis Hou, Feng & Zhang, 2023 - Tergites III and IⅤ each with four setae ......................... 35 35. Epistome triangular ............................................................. ...................... L. laoxueyanensis Hou, Gao & Zhang, 2022 - Epistome hump-shaped .................................................. 36 36. Pedipalpal chelal length 0.78–0.83 mm (♂