Phylogeny of Symphytognathidae s.l. (Araneae, Araneoidea)

Abstract

The paper presents a phylogenetic analysis of Symphytognathidae sensu lato (= sensu Forster 1959): Anapidae, Micropholcommatidae, Mysmenidae and Symphytognathidae sensu stricto. These taxa include the smallest known spiders. Several authors have suggested that their similarities are merely the convergent result of reduction and loss (simplifications, minimization of organs). The data matrix comprises 80 characters scored for 12 ingroup and two outgroup taxa. The value of reduction characters is discussed in general, and the evidence regarding symphytognathids in particular is reviewed. In this case, homology explains the data better than convergence. Although Symphytognathidae s.l. is, in fact, based mainly on characters that might have accompanied miniaturization, the taxon is most probably monophyletic. Anapidae as currently defined is paraphyletic. As it constitutes, together with Micropholcommatidae, a well supported monophyletic group, the latter is herewith synonymised with the former. Mysmenidae should be relimited by transferring four Old World genera to a new family, Synaphridae. Sympyhtognathidae s.s. is also monophyletic, even though the main synapomorphy, fused chelicerae, also occurs in Mysmenidae.