Pedipalp sclerite homologies and phylogenetic placement of the spider genus Stemonyphantes (Linyphiidae, Araneae) and its implications for linyphiid phylogeny

Abstract

Male secondary genitalia (pedipalps) are useful characters for species discrimination in most spider families. Although efforts have been made to establish pedipalp sclerite homologies, there are still many inconsistencies in their use. The majority of the morphological characters used to reconstruct the linyphiid phylogeny address male genitalic variation; these inconsistencies may affect the phylogeny and our understanding of linyphiid evolution. Stemonyphantes Menge, 1866, has been hypothesised to be sister to all remaining Linyphiidae. However, despite the basal position of Stemonyphantes, its pedipalp sclerite homologies are not well understood and, along with its monophyly, have never been thoroughly tested in a phylogenetic context. We tested the homology of tegular and radical structures of five Stemonyphantes species to the known linyphioid and araneoid sclerites. All minimum-length trees found under all analytical methods used support Stemonyphantes monophyly and its placement as the sister group to all other Linyphiidae. Our study suggests that Stemonyphantes, unlike any other linyphiids, does have homologues of the araneoid median apophysis and conductor. As Stemonyphantes is the sister group of all other linyphiids, resolving its pedipalp sclerite homologies is critical for understanding sclerite homologies and the phylogeny of the entire family.

Rounding up the usual suspects: a standard target‐gene approach for resolving the interfamilial phylogenetic relationships of ecribellate orb‐weaving spiders with a new family‐rank classification (Araneae, Araneoidea)

“…Hormiga, 2008;Hormiga and Tu, 2008). A recent interpretation of the male palp sclerites of Stemonyphantes (Gavish-Regev et al, 2013) suggests that in this linyphiid genus the tegular sclerites could be homologues of the conductor and median apophysis, but supported a sister group relationship of Weintrauboa and Pimoa (and thus, Pimoidae monophyly) and of Pimoidae plus Linyphiidae. We are currently studying the phylogeny of pimoids with additional morphological and molecular data and a much larger taxon sample, including undescribed taxa (Hormiga and Dimitrov, unpublished).…”

Repeated colonization, adaptive radiation and convergent evolution in the sheet‐weaving spiders (Linyphiidae) of the south Pacific Archipelago of Juan Fernandez

“…To further confirm the phylogenetic position of the endemic species in the context of the overall diversity of the family Linyphiidae, we combined the newly generated sequences with DNA sequences available in GenBank from former studies (Hormiga et al, 2003; Arnedo et al, 2009; Wang et al, 2015), and complemented it with newly obtained sequences for species of additional South American genera, namely Patagoneta Millidge, 1985, Rhabdogyna Millidge, 1985 and Millidgella Kammerer, 2006. In all analyses the resulting trees were rooted based on the sister group relationship between the subfamily Stemonyphantinae and the remaining species within Linyphiidae (Hormiga, 1994; Arnedo et al, 2009; Gavish‐Regev et al, 2013).…”

A completely resolved phylogenetic tree of British spiders

“…The framework for the proposed linyphiid phylogeny is provided by the molecular analyses of Wang et al (2015) and Dimitrov et al (2017). This is complemented by the increasingly comprehensive morphological analyses of the entire family or large subgroups in Duperré & Paquin (2007), Gavish et al (2013), Hormiga (1993, 1994, 2000), Hormiga & Scharff (2005), Miller & Hormiga (2004), Paquin et al (2008), and Sun et al (2012). Most importantly, the relative placement of genera required a much larger degree of personal interpretation of the traditional taxonomic and morphological literature.…”