Key to species of Metatarsonemus Attiah, 1970

1. Female without a pair of coxisternal fissures near bases of 1a, tegula short (less than 5 μm); male with dorsal opisthosomal setae c2 usually longer than c1 and d .......................................................................... 2

- Female with a pair of coxisternal fissures near bases of 1a, tegula long (more than 5 μm); male dorsal opisthosomal setae c1, c2 and d variable in length.............................................................................. 3

2. Female with prodorsal seta v1 (18–21) shorter than sc2 (30–34), short triangular fissure laterad the bases of seta 1a and 2a, presence of angulate fissures at the base of 3b; male with solenidion ω of tarsus II almost twice longer than the greatest width of the tarsus, apodeme 5 present............................................................ M. shirishi sp. nov.

- Female with prodorsal seta v1 (19–20) longer than sc2 (16–17), long curved fissures on lateral region of coxisternal plate 1, absence of fissure at the bases of 3b; male with solenidion ω of tarsus II almost equal the greatest width of the tarsus, apodeme 5 absent.................................................................. M. caissara Lofego and Cavalcante

3. Female with incomplete sensory cluster on tibia I, pl” absent on tarsus II, coxisternal fissures next to 3b posteriorly bifurcate; male with solenidion on tarsus II long (more than 10 μm)..................................................... 4

- Female with complete sensory cluster on tibia I, pl” present on tarsus II, coxisternal fissures next to 3b posteriorly subtriangular; male with solenidion on tarsus II medium (6-7 μm long)................................ M. simplicissimus Attiah

4. Female with dorsal tergite D uniformly convex posteriorly, longer than 60 μm, ventral setae 3a (16–18) almost twice the length of 3b (9–10), tc” more than twice longer than v’Ti on leg IV, both setae smooth; male with prodorsal seta v1 shorter than sc2, ventral setae 3a and 3b longer than 16 μm, apodeme 5 split conspicuously at the level of setae 3b, solenidion ω of tarsus II almost twice longer than the greatest width of the tarsus...................................... M. badurkani sp. nov.

- Female with dorsal tergite D convex medially, shorter than 50 μm, ventral setae 3a (8–15) almost equal in length with 3b (9–10), tc” less than twice longer than v’Ti on leg IV, both setae serrate; male with prodorsal seta v1 as long as sc2, ventral setae 3a and 3b shorter than 16 μm, apodeme 5 split slightly at distal end of coxisternites 4, solenidion ω of tarsus II almost 1.5 times longer than the greatest width of the tarsus...................................... M. megasolenidii, Lofego & Ochoa