Molecular phylogeny and biogeography of the temperate Gondwanan family Triaenonychidae (Opiliones : Laniatores) reveals pre-Gondwanan regionalisation, common vicariance, and rare dispersal

Abstract

Triaenonychidae Sørensen in L. Koch, 1886 is a large family of Opiliones with ~480 described species broadly distributed across temperate forests in the Southern Hemisphere. However, it remains poorly understood taxonomically, as no comprehensive phylogenetic work has ever been undertaken. In this study we capitalise on samples largely collected by us during the last two decades and use Sanger DNA-sequencing techniques to produce a large phylogenetic tree with 300 triaenonychid terminals representing nearly 50% of triaenonychid genera and including representatives from all the major geographic areas from which they are known. Phylogenetic analyses using maximum likelihood and Bayesian inference methods recover the family as diphyletic, placing Lomanella Pocock, 1903 as the sister group to the New Zealand endemic family Synthetonychiidae Forster, 1954. With the exception of the Laurasian representatives of the family, all landmasses contain non-monophyletic assemblages of taxa. To determine whether this non-monophyly was the result of Gondwanan vicariance, ancient cladogenesis due to habitat regionalisation, or more recent over-water dispersal, we inferred divergence times. We found that most divergence times between landmasses predate Gondwanan breakup, though there has been at least one instance of transoceanic dispersal – to New Caledonia. In all, we identify multiple places in the phylogeny where taxonomic revision is needed, and transfer Lomanella outside of Triaenonychidae in order to maintain monophyly of the family.

Phylogenomics and biogeography of leptonetid spiders (Araneae : Leptonetidae)

“…The biological characteristics of limited dispersal ability and high microhabitat preference often lead to biogeographic histories that are dominated by vicariance, with sometimes rare dispersal events, as seen in many other arachnid lineages (e.g. Harrison et al 2016;Hedin and McCormack 2017;Baker et al 2020).…”

Complex patterns of Gondwanan biogeography revealed in a dispersal‐limited arachnid

“…In cases where genera are known from multiple regions or were paraphyletic based on preliminary or published analyses (e.g. Baker, Sheridan, et al, 2020; Mendes & Kury, 2008), more samples were included. Not all genera were sampled, but the majority of these unsampled genera are monotypic single‐site endemics, which were confidently assigned to lineages based on morphology (Derkarabetian et al, 2021).…”

“…Boyer & Giribet, 2009; Hedin & McCormack, 2017; Peres et al, 2019; Pinto‐da‐Rocha et al, 2005; Saraiva & DaSilva, 2016) to intercontinental or global distributions (e.g. Baker, Boyer, et al, 2020; Baker, Sheridan, et al, 2020; Boyer et al, 2007; Emata & Hedin, 2016; Giribet et al, 2012; Oberski et al, 2018; Schönhofer et al, 2013), largely due to their biological characteristics of limited dispersal ability and high microhabitat specificity. Given these characteristics we can hypothesize that vicariance is the main force explaining geographic distributions, which is apparent in the majority of studies cited above and common at all phylogenetic depths including shallow species‐ and population‐level analyses (e.g.…”

“…This family shows a classic Gondwanan distribution (Figure 1) with representatives found in the temperate forests of former southern Gondwanan terranes including southern South America, southern Africa, Madagascar, Australia, New Zealand, New Caledonia, plus the more recent Crozet Islands. Recently, Baker, Sheridan, et al (2020) explored the biogeography of Triaenonychidae based on traditional Sanger sequenced loci. While some conclusions could be made about well‐supported lineages, much of the backbone topology had low support limiting broader biogeographic conclusions.…”

“…In this way, we explicitly test hypotheses of pre‐continental breakup divergences and ‘common vicariance, rare dispersal’ at the continental scale across the complex geological and palaeoclimatic history of Gondwanan terranes. Triaenonychidae are an ideal system to test the ‘common vicariance, rare dispersal’ hypothesis at the intercontinental scale because of their ancient origins which predate Gondwanan breakup (Baker, Sheridan, et al, 2020), widespread distribution on both continental and oceanic landmasses, low dispersal ability with high microhabitat constraints, and high levels of endemicity and diversity within major landmasses. In this way, we extend the ‘common vicariance, rare dispersal’ paradigm of more recent regional lineages where localized demographic events are easily inferred, to more ancient globally distributed lineages.…”