A total evidence phylogenetic analysis of the spider family Linyphiidae (Araneae, Araneoidea)
Abstract
Linyphiidae, with 634 genera and more than 4,800 species, is the most speciose family of Araneoidea, the ecribellate orb weavers. This study presents a phylogenetic hypothesis of linyphioids (Linyphiidae plus Pimoidae) using a large-scale total evidence approach. We include representatives of all traditional Linyphiidae subfamilies (Stemonyphantinae, Micronetinae, Mynogleninae, Linyphiinae, Erigoninae, Dubiaraneinae, and Ipainae) as well as newly proposed lineages (Mounded Posterior Median Eye (MPME) clade, Pocobletus clade). We integrated nucleotide sequence data from five different markers, two mitochondrial (cytochrome oxidase subunit I, 16S rRNA) and three nuclear (18S rRNA, 28S rRNA and Histone H3) with a set of morphological and behavioral characters. We allocated the character data into eleven different matrices to test the robustness of the phylogenetic signal in our dataset concerning data occupancy, data category, and data completeness across different optimality criteria. The molecular dataset has a total of 294 terminals and a total of 6,835 bps, and the phenotypic matrix has 105 terminals and 256 characters, totaling 305 terminals and 7091 characters. We analyzed our datasets using three different optimality criteria: parsimony, maximum likelihood, and Bayesian inference. We recovered linyphioids as a monophyletic group with strong support. We identified 15 suprageneric monophyletic groups within linyphiids (some of those corresponding to the established subfamilies) whose relationships vary according to the analytical conditions. The linyphiid subfamilies Stemonyphantinae, Erigoninae, and Mynogleninae are monophyletic and well-supported. We revised the circumscription of the subfamilies Lepthyphantinae, Linyphiinae, and the MPME clade to fulfill the monophyly requirement. The Pocobletus clade remains a strongly supported group with the same original composition and is formally recognized as a subfamily (Pocobletinae new subfamily). The subfamilies Dubiaraneinae, Ipainae, and Micronetinae are not monophyletic, and their components were placed into different clades. The remaining linyphiids are classified into the following newly proposed lineages: the ConoSur clade; Linyphiinae (new circumscription) composed of three lineages: Linyphia clade, Frontinella clade, and MPME clade; Clade A, composed of two lineages: the MCP (Marginal Cephalothoracic Pits) clade and Mynogleninae, plus an assorted grade of Australian taxa; and Clade B, composed of seven distinct lineages:, Centromerus clade, (Lepthyphantinae new circumscription), Agyneta clade, Microneta clade, and the subfamily Erigoninae. The genera Allomengea, Australolinyphia, Labulla, Labulinyphia, Laetesia, Laperousea, Palaeohyphantes, Solenysa, and Turinyphia are considered incertae sedis. Elaphopus is declared a nomen dubium and a type species is designated for Typhloneta. Significant differences between topologies and support values, including spurious trees, are interpreted as artifacts caused by the extreme disparity in fragment length on the 28S ribosomal marker in our dataset. Our new hypothesis allows the reinterpretation of the evolution of characters such as the cephalothoracic pits, Fickert’s gland and the tracheal system anatomy.
