Tetrapulmonata
Tetrapulmonata Shultz, 1990 is a non-ranked supra-ordinal group of
arachnids. It is composed of
Thelyphonida,
Schizomida,
Amblypygi and
Araneae.
It receives its name from the presence of paired
book lungs occupying the second and third opisthosomal segments, although the posterior pair is absent in Schizomida. Previous
synonyms of this lineage are rejected;
Caulogastra (Pocock, 1983) refers to
pedicel, which is
symplesiomorphic for the lineage and
convergent with
Solifugae, and
Arachnidea (van der Hammen, 1977) is easily confused with
Arachnida. Other
synapomorphies of Tetrapulmonata include a large postcerebral pharynx (reduced in Uropygi), prossomal endosternite with four segmental components, subchelate
chelicerae, a complex coxotrochanteral joint in the walking legs, a pretarsal depressor muscle arising in the patella (convergent with Dromopoda, lost in Amblypygi), a pedicel formed, in part, by ventral elements of the second opisthomal segment and a
spermatozoan axoneme a 9+3 microtubule arrangement (Schultz, 1990).
Shultz, J. W. 1990. Evolutionary morphology and phylogeny of Arachnida. Cladistics 6:1-38.
