Chthonius, C. L. Koch, 1843

Gardini, Giulio, 2020, Zaragozachthonius (Pseudoscorpiones, Chthoniidae), a new genus with species in Italy and the Balkan peninsula, Zootaxa 4894 (4), pp. 535-548 : 537

Key to adults of the Chthonius -related genera (coxae II and III with coxal spines)

[modified from Zaragoza (2017)]

1 Intercoxal tubercle absent............................................................................... 2

1’ Intercoxal tubercle present, bisetose....................................................................... 4

2 Trichobothrium sb of movable chelal finger placed approximately halfway between trichobothria b and st ............... 3

2’ Trichobothrium sb of movable chelal finger distinctly closer to st than to b, forming with st and t a separate group with respect to b ........................................................................ Spelyngochthonius Beier, 1955

3 Chela not lagyniform, fixed finger sigmoid in lateral view. Distal marginal seta on pedipalpal coxa distinctly longer than distal marginal seta on coxa I........................................................... Microchthonius Hadži, 1933

3’ Chela lagyniform, fixed finger straight in lateral view. Distal marginal seta on pedipalpal coxa markedly shorter than the distal marginal seta on coxa I...................................................... Cantabrochthonius Zaragoza, 2017

4 Male genitalia without median hiatus dividing each row of internal guard-setae.................................... 5

4’ Male genitalia with median hiatus dividing each row of internal guard-setae into two groups of two setae........................................................................................ Hesperochthonius Browning, 1970

5 Coxal spines of coxa II irregularly arranged in a rounded patch................................................. 6

5’ Coxal spines of coxa II arranged in a transverse row................................. Neochthonius Chamberlin, 1929

6 Chela not lagyniform, hand fusiform; chelal fingers usually with more or less close-set teeth, distinctly reclined backwards. Apodeme of movable chelal finger usually absent, rarely well developed......................................... 7

6’ Chela lagyniform; chelal fingers mostly with large, upright and well-spaced teeth. Apodeme of movable chelal finger usually well developed and strongly sclerotized.................................................................... 8

7 Apodeme of movable chelal finger absent. Antiaxial tooth (td) on tip of fixed chelal finger absent.................................................................................................... Chthonius C.L. Koch, 1843

7’ Apodeme of movable chelal finger well developed and strongly sclerotized. Antiaxial tooth (td) on tip of fixed chelal finger present.......................................................................... Zaragozachthonius n. gen.

8 Proximal portion of chelal hand with 4 setae in adults and tritonymphs, seta hp 3 present. Tip of fixed chelal finger of male, tritonymph and deutonymph usually without a deep hollow on paraxial face and subapical protuberance (sp) (sometimes present in Globochthonius ); without a medial protuberance (ip) between chelal condyles................................ 9

8’ Proximal portion of chelal hand with 3 setae in adults and tritonymphs, seta hp 3 absent. Tip of fixed chelal finger of male, tritonymph and deutonymph with a deep hollow on paraxial face and subapical protuberance (sp); medial protuberance (ip) present between chelal condyles................................................. Ephippiochthonius Beier, 1930

9 Chelal hand distad of trichobothria ib-isb with a rounded hump and a marked hollow before base of movable finger; base of chelal hand without a pronounced hump dorso-paraxially; third tooth of normal row (mt) of fixed chelal finger modified in shape and deviated in orientation with respect to the other teeth; movable chelal finger lacking lyrifissures ma 1 and ma 2 ............................................................................. Occidenchthonius Zaragoza, 2017

9’ Chelal hand without a hump distad of trichobothria ib-isb, gradually constricted distad of trichobothria ib-isb and without hollow before base of movable finger; base of chelal hand with a pronounced hump dorso-paraxially; third tooth of normal row (mt) of fixed chelal finger neither modified in shape nor deviated in orientation with respect to the other teeth; lyrifissures ma 1 and ma 2 present on movable chelal finger......................................... Globochthonius Finnegan, 1932