Historical

Silva-Moreira, Thiago Da, Kulkarni, Siddharth & Hormiga, Gustavo, 2025, A total evidence phylogenetic analysis of the spider family Linyphiidae (Araneae, Araneoidea), Zootaxa 5685 (1), pp. 1-78 : 4-5

Historical background

The history of linyphiid classification is long and convoluted (for details, see Merrett 1963 and Hormiga 2000). With a few exceptions ( Bertkau 1878; Gerhardt 1923; Wiehle 1956, 1960), the consensus has been that the Linyphiidae represents a natural group of spiders with highly variable genitalic anatomy (e.g. Hormiga 1994b; Griswold et al. 1998; Miller & Hormiga 2004; Arnedo et al. 2009). Most linyphiid taxonomic classifications resulted from compilations of anatomical information followed by the choice of some particular character or characters deemed important for higher classification, such as the works of Hull (1920), Simon (1926, 1929), Petrunkevitch (1928), and especially Millidge (1977, 1984, 1986, 1988). Most of those studies predate Hennigian phylogenetic systematic theory ( Hennig 1957, 1966) and/or lack an explicit phylogenetic approach.Modern studies on linyphiid phylogenetics began in the last decade of the past century ( Hormiga 1994a, b; Hormiga 2000; Miller and Hormiga 2004).Although the use of molecular data in spider systematics is well established, the majority of linyphiid phylogenetic studies to date have used only morphological data. The only study to date ( Arnedo et al. 2009) that has used a “total evidence” approach to resolve linyphiid familial relationships had a taxon sample too small (49 taxa) to draw detailed conclusions about such a large family. Wang et al. (2015) provide the most comprehensive study up to this point in both data and taxa (211 taxa, five DNA markers, but no morphological characters). However, their taxon sample was primarily tailored to address questions about relationships within the subfamily Erigoninae and, thus, was insufficient to address broad questions about relationships within the family. Recently, Silva-Moreira and Hormiga (2021, 2022) addressed the internal arrangement of linyphiids, but only in the context of establishing the monophyly of the revised genera Jalapyphantes Gertsch & Davis , Selenyphantes Gertsch & Davis , and Diplothyron Millidge. Both studies hypothesized higher level intrafamilial relationships and established new lineages (e.g., the Pocobletus clade, Silva-Moreira & Hormiga 2021) or corroborate and expand previously established groups (e.g., Mounded Posterior Median Eye or MPME clade, a group of linyphiid spiders characterized by having posterior median eyes (PME) on a mound; Silva-Moreira & Hormiga 2015, 2022). Nonetheless, neither study had been designed with the required taxonomic breadth or enough character data to build a robust phylogenetic hypothesis for the family Linyphiidae .

Our minimal knowledge of most of the spider fauna, especially from tropical areas, is a major obstacle to understanding the diversity of linyphiids. Some estimates suggest that up to 70% of collected spider specimens from those areas already deposited in museum collections are composed of undescribed species ( Coddington & Levi 1991; Agnarsson et al. 2013). Furthermore, many of the genera and species described from the Neotropical region have not been included in modern revisionary studies, and many remain known only from the type specimens, and the only information available about them is their original descriptions, some of them dating from the 19 th century. This “taxonomic impediment” (see Evenhuis 2007) has severe consequences for understanding global patterns of diversification within this clade. Good examples in Linyphiidae of how the addition of unknown fauna can dramatically change the understanding of a group can be seen in both the Mynogleninae ( Lehtinen 1967; Blest 1979; Frick & Scharff 2014), the Erigoninae ( Miller & Hormiga 2004; Miller 2007), the MPME clade; ( Silva-Moreira & Hormiga 2015, 2022), and the Pocobletus clade ( Silva-Moreira & Hormiga 2021). Some of the lineages whose species are endemic from Afrotropical/Australian and Neotropical regions (sensu Holt et al. 2013), such as Mynoglenines and the MPME clade, have unique features within linyphiids and, so far, are consistently recovered as well-supported clades (Frick & Scharf 2014; Silva-Moreira & Hormiga 2022).

Even with all those caveats, some hypotheses of linyphiid phylogeny have stood the test of a diversity of analyses and can be considered well corroborated. First, the monophyly of Linyphiidae is well supported by both morphological ( Hormiga, 1994b; Griswold et al. 1998; Hormiga 2000; Miller & Hormiga, 2004) and molecular data ( Arnedo et al. 2009; Wang et al. 2015; Wheeler et al. 2017; Dimitrov et al. 2017; Hormiga et al., 2021).

This study aims to produce a new phylogenetic hypothesis of Linyphiidae using both morphological and molecular data. We test the monophyly, composition, and placement of all the seven classic subfamilies of Linyphiidae (as recognized in Tanasevitch 2025): Erigoninae , Dubiaraneinae , Ipainae , Linyphiinae , Micronetinae , Mynogleninae , and Stemonyphantinae ) as well as of three recently proposed clades: MPME clade ( Silva-Moreira & Hormiga 2015), Porrhommini ( Zhao & Li 2017), and Pocobletus clade ( Silva-Moreira & Hormiga 2021). This study is the broadest scale phylogenetic matrix for linyphiids assembled to date. Despite the large taxon sample of this study relative to the phylogenetic analyses published so far, we recognize that our sample of linyphiid genera is insufficient for a thorough revision of the classification of this family and thus a detailed revision of such classification falls outside the scope of the study. We hope that the resulting hypotheses will provide a solid phylogenetic background upon which further questions on linyphiid evolution, such as biogeography or comparative biology, can be studied, as well as a foundation for future studies to expand the cladistic classification of this large and diverse family.