First description of the male of Thaida chepu Platnick, 1987 (Araneae, Austrochilidae) with micro-computed tomography of the palpal organ

The male of the austrochilid spider Thaida chepu Platnick, 1987 is described for the first time. We analyzed the internal anatomy of the palpal organ by using micro-computed tomography to investigate the spermophor as well as the muscles and tendons in the cymbium and tibia in detail. As shown by our data, muscles 29 and 30 originate in the tibia and continue with tendons to the base of the bulb, which resembles the ancestral organization for the male palp of spiders; this condition has not been described for Araneomorphae until now. The 3D reconstruction of the spermophor confirms recent interpretations of the male palp sclerites within Austrochilidae.