First phylogenetic assessment and taxonomic synopsis of the open-holed trapdoor spider genus Namea (Mygalomorphae: Anamidae): a highly diverse mygalomorph lineage from Australia’s tropical eastern rainforests
Authors: Rix Michael G. , Wilson Jeremy D. , Harvey Mark S. 
Published: September 2020

The tropical and subtropical rainforests of Australia’s eastern mesic zone have given rise to a complex and highly diverse biota. Numerous old endemic, niche-conserved groups persist in the montane rainforests south of Cooktown, where concepts of serial allopatric speciation resulting from the formation of xeric interzones have largely driven our biogeographic understanding of the region. Among invertebrate taxa, studies on less vagile arachnid lineages now complement extensive research on vertebrate taxa, and phylogenetic studies on mygalomorph spiders in particular are revealing significant insights about the biogeographic history of the Australian continent since the Eocene. One mygalomorph lineage entirely endemic to Australia’s tropical and subtropical eastern rainforests is the open-holed trapdoor spider genus Namea Raven, 1984 (family Anamidae). We explore, for the first time, the phylogenetic diversity and systematics of this group of spiders, with the aims of understanding patterns of rainforest diversity in Namea, of exploring the relative roles of lineage overlap versus in situ speciation in driving predicted high levels of congeneric sympatry, and of broadly reconciling morphology with evolutionary history. Original and legacy sequences were obtained for three mtDNA and four nuDNA markers from 151 specimens, including 82 specimens of Namea. We recovered a monophyletic genus Namea sister to the genus Teyl Main, 1975, and monophyletic species clades corresponding to 30 morphospecies OTUs, including 22 OTUs nested within three main species-complex lineages. Remarkable levels of sympatry for a single genus of mygalomorph spiders were revealed in rainforest habitats, with upland subtropical rainforests in south-eastern Queensland often home to multiple (up to six) congeners of usually disparate phylogenetic affinity living in direct sympatry or close parapatry, likely the result of simultaneous allopatric speciation in already co-occurring lineages, and more recent dispersal in a minority of taxa. In situ speciation, in contrast, appears to have played a relatively minor role in generating sympatric diversity within rainforest ‘islands’. At the population level, changes in the shape and spination of the male first leg relative to evolutionary history reveal subtle but consistent interspecific morphological shifts in the context of otherwise intraspecific variation, and understanding this morphological variance provides a useful framework for future taxonomic monography. Based on the phylogenetic results, we further provide a detailed taxonomic synopsis of the genus Namea, formally diagnosing three main species-complexes (the brisbanensis-complex, the dahmsi-complex and the jimna-complex), re-illustrating males of all 15 described species, and providing images of live spiders and burrows where available. In doing so, we reveal a huge undescribed diversity of Namea species from tropical and subtropical rainforest habitats, and an old endemic fauna that is beginning to shed light on more complex patterns of rainforest biogeography.