Systematics and evolution of ground spiders revisited (Araneae, Dionycha, Gnaphosidae)

Gnaphosidae Pocock are a very diverse spider family with remarkable spinning organ morphology. Although the family has received intense taxonomic attention in recent years, its intergeneric relationships remain obscure. A phylogenetic analysis of Gnaphosidae genera was performed to untangle the evolutionary history of the family. A matrix of 324 morphological characters, scored for 71 gnaphosid genera and 29 outgroup taxa, was analysed through parsimony and Bayesian phylogenetic inference. Gnaphosidae are not recovered as a monophyletic group, neither were most of the previously proposed intrafamiliar groupings. In accordance with the phylogenetic results obtained, Vectius Simon and Hemicloea Thorell are transferred to Trochanteriidae, and Xenoplectus Schiapelli & Gerschman de Pikelin to Liocranidae. Micaria Westring, Nauhea Forster and Verita Ramírez & Grismado (and some related genera) are probably not gnaphosids, although their phylogenetic placement is uncertain. Gnaphosidae s.s. are defined as spiders with enlarged piriform gland spigots, longer and wider than the major ampullate gland spigots. Within Gnaphosidae s.s., well-supported clades allow the redefinition, on the basis of quantitative phylogenetic evidence, of Gnaphosinae Pocock, Zelotinae Platnick, Herpyllinae Platnick, Drassodinae Simon, Prodidominae Simon rank res. and the newly proposed Leptodrassinae subfam. nov. Many genera are not assigned to subfamily given their poorly supported and unstable relationships. The homology and evolution of structures such as the claw tuft clasper, the spinning organs and the modification of cheliceral promargin are discussed.