Micridium

Key to the species of Micridium (excluding M. angulicolle, M. lineatum, M. rhodeanum and M. vittatum)

1. Pronotum with two distinct linear depressions............................................................... 2

- Pronotum without linear depressions but sometimes with puncture depressions of variable size arranged in groups......... 7

2. Pronotal linear depressions +/– parallel (Figs. 17, 28).........................................................3

- pronotal linear depressions clearly narrowing anteriorly (Figs. 19, 23, 27, 30)......................................4

3. Male intercoxal process of metaventrum with four medial setae (Fig.97)............................. quadridens sp. n.

- Male intercoxal process of metaventrum without projecting setae (Fig. 95)......................... attenboroughi sp. n. (These two species are very similar and difficult to separate on other criteria)

4. Pronotal linear depressions sinuous and reaching past the midpoint..................................... oweni sp. n.

- Pronotal linear depressions shorter, barely reaching the midpoint................................................5

5. Dark species with long antennae (Fig. 44) (mesocoxae widely separated (Fig. 57)......................... elegans sp. n.

- Paler yellowish brown species, antennae shorter.............................................................6

6. Mentum sides +/– parallel (as Fig. 41)...................................................... halidaii (Matthews.)

- Mentum sides narrowed towards base (Fig. 35).................................................. boliviense sp. n.

7. Mesocoxae almost contiguous, separated by a narrow keel.....................................................8

- Mesocoxae not contiguous, more widely separated..........................................................11

8. Mentum sides =/– parallel (as Fig. 41).....................................................................9

- Mentum sides narrowed towards base (as Fig. 35)...........................................................10

9. Large species (Fig. 12)...................................................................... newtoni sp. n.

- Smaller species (Fig. 15).................................................................... proprium sp. n.

10. Pronotum with well marked circular pits (Fig. 21)................................................. foveatum sp. n.

- Pronotum with well marked reticulation but without circular pits (Fig. 24).............................. thayerae sp. n.

11. Mesocoxal separation narrower (Fig. 58)........................................................ hilli (Johnson)

- Mesocoxal separation wider (Figs. 47, 53).................................................................12

12. Metepiventral suture short (as Fig. 62)........................................................ inornatum sp. n.

- Metepiventral suture long (Fig. 61)............................................................. johnsoni sp. n.