Pseudochthonius, Balzan, 1892

Key to Brazilian Pseudochthonius View in CoL species

1 Presence of a pair of eyes or eyespots in one or both sex...................................................... 2

- Eyes absent......................................................................................... 12

2 Carapace almost rectangular, with no or little constriction on the posterior margin.................................. 3

- Carapace calix shaped, with a strong constriction on the posterior margin....................................... 11

3 Presence of a pair of well-developed eyes.................................................................. 4

- Presence of a pair of eyespots or weak developed lens........................................................ 7

4 Epistome flat, almost absent............................................................ Pseudochthonius lundi

- Epistome projected, dentated or with accessory projections.................................................... 5

5 Chelal fixed finger with 18–23 acute teeth.................................................................. 6

- Chelal fixed finger with approximately 36 teeth..................... Pseudochthonius itakuatiara Prado & Ferreira 2024

6 Teeth of chelal fixed finger with heterodonty (more than one row of teeth)...... Pseudochthonius heterodentatus Hoff 1946 View in CoL

- Teeth of chelal fixed finger with homodonty (single row of teeth)........ Pseudochthonius homodentatus Chamberlin 1929 View in CoL

7 Teeth of chelal movable finger numerous, small, constricted and generally projected backwards....................... 8

- Teeth of chelal movable finger few, well-spaced, acute at the middle section and rounded at the base............................................................................................... Pseudochthonius orthodactylus View in CoL

8 Chelal movable finger with approximately 24 small, constricted and projected backwards teeth............................................................................................. Pseudochthonius tuxeni Mahnert 1979 View in CoL

- Chelal movable finger bearing approximately 30 or more teeth................................................. 9

9 Movable chelal finger heterodentate (alternate dentition).................. Pseudochthonius gracilimanus Mahnert, 2001 View in CoL

- Teeth of movable chelal finger within a single row.......................................................... 10

10 Slender chelae, presence of a cluster of about 6 small teeth at the tip of fixed finger............. Pseudochthonius ricardoi View in CoL

- Robust chelae, absence of cluster of small teeth at the tip of fixed finger.......... Pseudochthonius brasiliensis Beier, 1970 View in CoL

11 Rallum with 7 pinnate blades......................... Pseudochthonius ramalho Assis, Schimonsky & Bichuette, 2021

- Rallum with 9 pinnated blades...................................................... Pseudochthonius biseriatus View in CoL

12 Trichobothrium et closer to it than to dx................................ Pseudochthonius pali Prado & Ferreira, 2023

- Trichobothrium et closer to dx than to it.................................................................. 13

13 Trichobothrium ist closer to est than to esb (shown by the ratio of the trichobothria ist–est / ist–esb <1.0.......................................................................... Pseudochthonius koinopoliteia Prado & Ferreira, 2023

- Trichobothrium ist closer to esb than to est or halfway (shown by the ratio of the trichobothria ist–est / ist–esb>= 1.0...... 14

14 Trichobothrium ist halfway between esb and est (shown by the ratio of the trichobothria ist–est / ist–esb = 1.0; body size larger than 2.0 mm;................................................ Pseudochthonius diamachi Prado & Ferreira, 2023

- Ratio of the trichobothria ist–est / ist–esb different> 1.0, body size shorter than 2.0 mm............................. 15

15 Most of the teeth of the chelal movable finger highly constrict and projected backwards............................ 16

- Most of the teeth of the chelal movable finger acute and sparse........................... Pseudochthonius limettioides

16 Approximately 26 teeth on movable chelal finger, trichobothrium ist three times closer to esb than est (shown by the trichobothrial ratio ist–est / ist–esb of 3.0).......................................................... Pseudochthonius olegario

- Approximately 30 or more teeth on movable chelal finger, trichobothrial ratio ist–est / ist–esb less than 3.0............. 17

17 Rallum with 5 pinated blades................... Pseudochthonius lubueno Assis, Schimonsky, Gallão & Bichuette, 2023

- Rallum with 7 pinated blades........................................................................... 18

18 Movable chelal finger with 32 to 35 teeth................................................ P. maquinensis View in CoL sp. nov.

- Movable chelal finger with between 36 and 40 teeth......................................................... 19

19 Body length ranging from 1.43 mm to 1.77 mm, with a trichobothrial ratio (ist–est / ist–esb) of 2.2.. P. urubuquaqua sp. nov.

- Trichobothrial ratio (ist–est / ist–esb) between 2.34–2.61 and body length ranging from 1,236 to 1,459 mm .............................................................................. Pseudochthonius aware Prado & Ferreira, 2024