1	Epiproct of telson projecting into a short process	2
–	Epiproct of telson not projecting	5
2	Male legs without tarsal pads. Eyes consisting of 20 or less ommatidia. Anal valves with a deep groove between anterior half and sharp-edged lips	3
–	Male legs 3–7 with tarsal pads. Eyes with more than 25 ommatidia. Anal valves with neither a groove, nor sharp-edged lips	4
3	Specimens 35–43 mm long. Colour laterally black, dorsally with a thick, light brown stripe. Telopodite of posterior gonopod laterally with one large and second small finger-shaped process	R. mandenensis Wesener, 2009
–	Specimens shorter than 25 mm. Colour laterally black, dorsally with a thick, red stripe. Telopodite of posterior gonopod laterally with two large finger-shaped processes of equal size	R. minutus Wesener, 2009
4	Apical membrane on posterior gonopod weakly developed. Telopodite at mesal margin with a conspicuous horn. Process ‘x’ on lateral margin without recurved tip	R. aridus Wesener, 2009
–	Apical membrane on posterior gonopod present as a sail (Fig. 10G: ‘z’). Mesal margin without a horn. Process ‘x’ on lateral margin with a recurved tip bending mesally (Fig. 10G). Efferent duct ending free	R. makayi sp. nov.
5	Posterior telopod, telopodite with two or more slender, sharp projections (Fig. 3E)	6
–	Posterior gonopod, telopodite, projecting in a simple ‘flag’ (Fig. 9C)	9
6	Males > 40 mm, > 45 segments plus telson. Posterior gonopod separated into three parts (Fig. 3E)	7
–	Male ca. 25 mm long, 41 segments plus telson. Posterior gonopod only separated into coxite and telopodite (Fig. 8F)	R. bovinus sp. nov.
7	Antennae and legs red (Fig. 3A). Posterior gonopod, lateral process slender. Membranous mesal area spanning whole mesal side of tip (Fig. 3E: ‘z’)	8
–	Antennae and legs dark grey (FIg. 7A). Posterior gonopod, lateral process wide, straight, well-rounded (Fig. 7E). Membranous mesal area globular (Fig. 7E: ‘z’)	R. lavanono sp. nov.
8	Posterior gonopod with two lateral processes (Fig. 3E)	R. tsimelahy sp. nov.
–	Posterior gonopod with single lateral process (Fig. 4I)	R. mangatsiaka sp. nov.
9	Males > 45 mm long, dorsally with a red stripe. Antenna short, protruding back to segment 3. Male legs 3 to at least midbody legs with tarsal pad. Anterior gonopod, coxal process inconspicuous, not reverted. Posterior gonopod, apical part with membranous flag	R. anomalus Wesener, 2009
–	Males only 33 mm long, dorsally without any stripe. Antenna long, protruding back to segment 5. Male legs without a tarsal pad. Anterior gonopod, coxite process, apical margin reverted (Fig. 9A). Posterior gonopod, apical part of telopodite, flag with a sclerotised projection (Fig. 9C)	R. antafoky sp. nov.