Key to species of Aquattuor Frederiksen, 2013

The key is based on adult males. The diameter and number of podous rings are not absolute characters – newly collected specimens may fall outside the ranges (and because of the positive correlation between number of rings and diameter, if a specimens falls outside in one parameter, it is likely to fall outside in the other as well). Differences between species are subtle, and specimens should be carefully compared with the diagnoses and illustrations. Specimens collected in new localities are likely to represent new species.

1. Palette (pa) of gonopods elongate, much longer than broad (Figs 6A, 7A); 50+ podous rings, diameter> 1.7 mm .............................................................................................................................2

– Palette as long as broad or slightly longer (Figs 5A, 8A, 9A, 10A, 11A); diameter <1.9 mm .....3

2. 53–54 podous rings, diameter> 1.9 mm; anterior margin of telomere with a triangular tooth (Fig. 6A, tt) ................................................... A. major Enghoff sp. nov. (Udzungwa: Mwanihana)

– 50–52 podous rings, diameter ≤ 1.9 mm; anterior margin of telomere without triangular tooth .................................................... A. longipala Enghoff sp. nov. (Udzungwa: W Kilombero Scarp)

3. Subdistal part of telomere almost straight, parallel to coxite, telomere tip bent abruptly lateral (Fig. 11); 50–52 podous rings, diameter 1.6–1.8 mm ........................................................................ .............................................................................. A. denticulatus Frederiksen, 2013 (E Usambara)

– Telomere describing a smoother curve (Figs 5A, D, 8 B–C, 9C, 10E)...............................................4

4. Telomere describing a c. 360° curve, curving in three dimensions; telomere tip with serrate margins, but surface not microspiculate ...... A. stereosathe Enghoff sp. nov. (Udzungwa: Udzungwa Scarp)

– Telomere describing a c. 270°curve, curving almost in one plane only; telomere tip with microspiculate surface...............................................................................................................................5

5. Lateral incision (li) of gonopod coxa deep, apical palette (pa) rounded-triangular (Fig. 8A); ≤ 50 podous rings, diameter ≤ 1.7 mm ....................................................................................... ............. A. udzungwensis Enghoff sp. nov. (Udzungwa: Udzungwa Scarp, W Kilombero Scarp)

– Lateral incision (li) indistinct...........................................................................................................6

6. Palette (pa) of gonopods subquadratic, with well-developed meso-basal lobe (mbl) (Fig. 10 A–B); 50–53 podous rings, diameter 1.4–1.6 mm ............ A. claudiahempae sp. nov. (Mt. Kilimanjaro)

– Palette more rounded, meso-basal lobe small (Fig. 5 A–B); 45–48 podous rings, diameter 1.5–1.9 mm ........................................ A. submajor Enghoff sp. nov. (Udzungwa: Mwanihana)