Phylogenomics and biogeography of leptonetid spiders (Araneae : Leptonetidae)

Abstract

Leptonetidae are rarely encountered spiders, usually associated with caves and mesic habitats, and are disjunctly distributed across the Holarctic. Data from ultraconserved elements (UCEs) were used in concatenated and coalescent-based analyses to estimate the phylogenetic history of the family. Our taxon sample included close outgroups, and 90% of described leptonetid genera, with denser sampling in North America and Mediterranean Europe. Two data matrices were assembled and analysed; the first ‘relaxed’ matrix includes the maximum number of loci and the second ‘strict’ matrix is limited to the same set of core orthologs but with flanking introns mostly removed. A molecular dating analysis incorporating fossil and geological calibration points was used to estimate divergence times, and dispersal–extinction–cladogenesis analysis (DEC) was used to infer ancestral distributions. Analysis of both data matrices using maximum likelihood and coalescent-based methods supports the monophyly of Archoleptonetinae and Leptonetinae. However, relationships among Archoleptonetinae, Leptonetinae, and Austrochiloidea are poorly supported and remain unresolved. Archoleptonetinae is elevated to family rank Archoleptonetidae (new rank) and Leptonetidae (new status) is restricted to include only members of the subfamily Leptonetinae; a taxonomic review with morphological diagnoses is provided for both families. Four well supported lineages within Leptonetidae (new status) are recovered: (1) the Calileptoneta group, (2) the Leptoneta group, (3) the Paraleptoneta group, and (4) the Protoleptoneta group. Most genera within Leptonetidae are monophyletic, although Barusia, Cataleptoneta, and Leptoneta include misplaced species and require taxonomic revision. The origin of Archoleptonetidae (new rank), Leptonetidae, and the four main lineages within Leptonetidae date to the Cretaceous. DEC analysis infers the Leptoneta and Paraleptoneta groups to have ancestral distributions restricted to Mediterranean Europe, whereas the Calileptoneta and Protoleptoneta groups include genera with ancestral distributions spanning eastern and western North America, Mediterranean Europe, and east Asia. Based on a combination of biology, estimated divergence times, and inferred ancestral distributions we hypothesise that Leptonetidae was once widespread across the Holarctic and their present distributions are largely the result of vicariance. Given the wide disjunctions between taxa, we broadly interpret the family as a Holarctic relict fauna and hypothesise that they were once part of the Boreotropical forest ecosystem.

DNA barcodes revealed population dependent cryptic diversity and various sympatry of Korean leptonetid spider (Araneae: Leptonetidae)

“…Europe, and all of the species in Leptoneta are morphologically, and geographically misplaced 5 (Ledford et al, 2021). Although Seo transferred many species of Leptoneta to Falcileptoneta (2015) 18 , more than ten species of Korean leptonetids are still remaining in this genus.…”

Advances in the reconstruction of the spider tree of life: A roadmap for spider systematics and comparative studies

“…An analysis of UCE-derived data suggested that the subfamily Archoleptonetinae (which includes only two genera, the cribellate Archoleptoneta and the ecribellate Darkoneta) do not nest within the clade containing other leptonetids (Ram ırez et al, 2021). This subfamily then was elevated to family rank as Archoleptonetidae by Ledford et al (2021). This phylogenetic placement seems to be sensitive to data class and/or taxon sampling because, the transcriptomic data treated as amino acids, with three genera sampled, suggest that Archoleptoneta (Archoleptonetidae), Calileptoneta and Leptoneta (both Leptonetidae) form a clade (Kallal et al, 2021a).…”

Towards better-informed dispersal probabilities in historical biogeography: Arachnids as a model lineage

“…Not only spiders, but all arachnids prominently feature in biogeographic studies. Given the old age of many arachnid lineages, empirical studies have helped to reconstruct past events as old as the breakups of Pangea and Gondwana (Boyer et al, 2007;Rix and Harvey, 2012;Xu et al, 2015;Clouse et al, 2017;Chousou-Polydouri et al, 2018) and diversification on major land masses (Chamberland et al, 2018;Esposito and Prendini, 2019;Turk et al, 2020;Ledford et al, 2021;Turk et al, 2021b). Arachnids have featured in research of evolutionary consequences of global climatic oscillations (Luo et al, 2020) and, at finer geographical scales, of glaciation events (Xu et al, 2016;Santibañez-Loṕez et al, 2021), tectonic movements (Opatova et al, 2016), formation of rivers and mountain chains (Hedin et al, 2013;Emata and Hedin, 2016;Xu et al, 2018;Schramm et al, 2021), aridification (Abrams et al, 2019), and other biotic/abiotic events (Bond et al, 2020) as well as processes involved with subterranean colonization and diversification (Harms et al, 2018).…”