The concept of the symplesiomorphy shows the danger of grouping species together purely on the basis of morphologic or genetic similarity without distinguishing primitive from derived traits.
Previous synonyms of this lineage are rejected; "Caulogastra Pocock, 1893" refers to pedicel, which is symplesiomorphic for the lineage and convergent with Solifugae, and "Arachnidea Van der Hammen, 1977" is easily confused with Arachnida.