On the liphistiomorph trichobothria and the significance of their structure for tracking the bothria evolution in the order Araneae

Femoral trichobothria in liphistiomorph spiders are re-discovered and described for the first time. Present in both Liphistiidae and Heptathelidae, they turned out to be another synapomorphy of this suborder. The trichobothria of Liphistiomorphae, situated dorsally on the distal leg/palp joints (as usual in spiders), and ventrally on femora, possess sharply dissimilar bothria; two types of trichobothrial bases in the same species are a unique case among Arachnida. The morphology of the bothria in the liphistiomorphs has been compared with those in the mygalomorphs and araneomorphs, as well as those in the tetrapulmonate and non-tetrapulmonate arachnid orders. The evolution of the bothrial types in all three main lineages of the Araneae seems to have been parallel.