Trechus

Key to the Trechus species from Mt. Choke with body length up to 4 mm

1 Microphthalmic species with compound eyes about half as long as tempora. Entire body yellowish brown. Male protarsomeres not dilated...................................................................... T. hauthi Schmidt & Faille

- Compound eyes longer than tempora. Body reddish to dark brown. At least basal protarsomere of male dilated........... 2

2 Only the first protarsomere of male dilated................................................................. 3

- Protarsomeres 1 and 2 of male dilated..................................................................... 6

3 Pronotum shape as in Zabrus, with sides not clearly convergent toward base, albeit sinuate, and basolateral angles large, rectangular or slightly acute.................................................. T. lobeliae (Quéinnec & Ollivier)

- Pronotal basolateral angles small, obtuse or rounded, its sides markedly constricted toward base....................... 4

4 Elytra with second discal seta absent............................................. T. amharicus Ortuño & Novoa

- Elytra with second discal seta present..................................................................... 5

5 First protarsomere of male moderately dilated with long apical tooth at the interior margin. Aedeagal median lobe with apical lamella well sclerotized, hook-like bent upwardly.............................. T. afroalpinus (Quéinnec & Ollivier)

- First protarsomere of male very slightly dilated with short apical tooth. Aedeagal median lobe with apical lamella very weakly sclerotized, with tip rounded.............................................. T. abyssinicus (Quéinnec & Ollivier)

6 Dorsal opening of the aedeagal median lobe extends basally across three quarters of the basal bulb..................................................................................................... T. apertus Schmidt sp. n.

- The dorsal opening of the aedeagal median lobe not reaching the basal bulb....................................... 7

7 Two basal protarsomeres of males markedly dilated, with the first tarsomere about two times as broad as the third......... 8

- Two basal protarsomeres of males moderately dilated, with the first tarsomere about 1.5 times as broad as the third....... 10

8 Aedeagal median lobe markedly bent downwardly before apical lamella (Quéinnec et al. 2021, Fig. 26B)........................................................................................ T. niloticus (Quéinnec & Ollivier)

- Ventral margin of aedeagal median lobe straight before apical lamella............................................ 9

9 Aedeagal median lobe proportionally longer (EL/AL <1.9), with ventral margin straight in middle and with apical lamella long........................................................................... T. yitbareki Schmidt sp. n.

- Aedeagal median lobe proportionally shorter (EL/AL> 2.0), with ventral margin concave in middle and with apical lamella short..................................................................... T. reebae (Quéinnec & Ollivier)

10 Sculpticells on disc of elytra somewhat irregularly shaped, almost isodiametric. Apex of the aedeagal median lobe well sclerotized..................................................................... T. kniphofia Schmidt sp. n.

- Sculpticells on disc of elytra transverse. Apex of the aedeagal median lobe very slightly sclerotized....................................................................................................... T. igori Schmidt sp. n.