courtesy of @william6 from here
When checking tarsal segments of Solifuges, take care not to mistake the pedipalps (first long limbs at front of animal) for the first pair of legs. Solifuges also tend to tear bits off each other, so may have limbs entirely missing
Common or readily identifiable groups keyed out first.
1a - Squat animals, with very short, stout legs modified for digging; abdomen partially overhanging head-plate --- Hexisopodidae (Mole Romans) ***
1b - Not like this --- Go to 2
2a - Fourth tarsus with more than 4 segments (7 unless damaged) ---Solpugidae
2b - Four or less segments on fourth tarsus --- go to 3.
2c - Fourth leg's tarsi not clear - go to 7
3a - Fourth tarsus with four segments - long legged animals, often like this one --- Daesiidae (part) - Biton
3b - Fourth tarsus with 3 segments, Namibian record --- Daesiidae (part) - Eberlanzia and Namibesia *
3c - Fourth tarsus with 2 segments --- Go to 4
3d - Fourth tarsus with 1 segment ---Go to 6
4a - Second and Third tarsi with 2 segments ---Ceromidae
4b - Second and Third tarsi with 1 segment ---- Go to 5
5a - Pale, long-legged animals, typically nocturnal ---Daesiidae (part) - Blossia
5b - Usually darker, shorter-legged animals - to this extreme --- Melanoblossiidae (part) - Melanoblossiinae **
6a - Legs often with distinctly thickened femora, small species, bald to quite hairy, but NEVER like Hexisopodidae (coupled one) --- Daesiidae (part) - Gnossippinae.
6b - Small to medium-sized species, usually entirely bald, appear restricted to western parts of South Africa and Namibia, first tarsus with small claws, without thickened hind femora - Gylippidae (Terrible couplet. Will fix when I've seen a Gylippid).
7a - 2nd or 3rd tarsi with 4 segments --- Solpugidae
7b - 2nd or 3rd tarsi with 2 segments, abdomen more-or-less parallel sided, often hairy ---Daesiidae (if not in Namibia, then almost certainly Biton)
7c - 2nd and 3rd tarsi with 2 segments, abdomen more rounded but not like Hexisopodidae (couplet 1), often with three rows of dots --- Ceromidae
7d - 2nd and 3rd tarsi with 1 segment first tarsus with small claws, Namibia and western S.A. --- Gylippidae
7e - 2nd and 3rd tarsi with 1 segment, no claws on first tarsus --- go to 8.
8a - Males with membranous flagellum --- Daesiidae
8b - Males with minute or no flagellum, usually invisible among bristles of chelicerae --- Melanoblossiidae.
This key is not ideal; Melanoblossiidae and Gylippidae - both of which are largely restricted to Namibia and the Western parts of S.A. - are both poorly identifiable here, but it should be a start.
. * Biton frequently damage hind legs, and may key to this.
. ** Hemiblossia o'neili (and possibly other Hemiblossia) can appear to have a 2-segmented 4th tarsus, hence occasional separation in 'Heteroblossia', but these are distinctly inflexible.
. *** If by some horrific accident, you find only the intact legs and head of a Solifuge, the mole-romans of Hexisopodidae are also readily identifiable by the complete lack of claws on the fourth tarsal segment. Their rather modified legs make counting segments extremely difficult, and different sources give different accounts; the most reliable seems to be 1-3-3-2 tarsal segments, but due to the extremely small size of the terminal segments on legs II and III, this appears as 1-2-2-2.
