Palp homologies, monophyly and phylogenetic placement of the spider genus Stemonyphantes (Stemonyphantinaea, Linyphiidae, Araneae) and implications for higher-level linyphiid phylogeny

Spider male secondary genitalia (palps) evolved rapidly and divergently and are the most important morphological characters for discrimination between species and genera in most spider families. Considerable efforts have been made to establish palp homologies, yet there are still many inconsistencies in their use. As the majority of the morphological characters used to reconstruct the phylogenetic trees are of the male palp, these inconsistencies may affect tree topology and our understanding of the evolution of male palps in linyphiids. My research includes a complete morphological revision, description and illustration of unique morphological characters (synapomorphies) of the monotypic subfamily Stemonyphantinaea, and a species level phylogeny of the genus Stemonyphantes.Stemonyphantes consist of 15 species and is a basal linyphiid lineage, sister to all remaining Linyphiidae and to the family Pimoidae. Despite its basal position, palp homologies in Stemonyphantes were not resolved yet.Stemonyphantes is probably the most ancestral extant linyphiid genus; therefore resolving its palp homologies will affect palp conformation in the entire family Linyphiidae and assist resolving linyphiid phylogeny. In order to resolveStemonyphantes palp conformation I am testing different hypotheses for palp homologies of Stemonyphantes, specifically regarding tegular apophyses and embolic division. I am using those hypotheses to test the monophyly and validity of the subfamily Stemonyphantinae and determined its phylogenetic placement.

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