Tectonically driven climate change and the spread of temperate biomes: Insights from dragon pseudoscorpions (Pseudotyrannochthoniidae), a globally distributed arachnid lineage

Abstract

AimUnderstanding the historical biogeography of the Earth's oldest terrestrial lineages provides insights into lineage diversification in relation to plate tectonics, climate change and biome shifts at maximum timescales. We investigate the biogeography of an ancient arachnid family, dragon pseudoscorpions, which are found today in mesic (mostly temperate) forests on all continents except Antarctica and Europe, have potential origins on Pangea and comprise species with extremely limited dispersal capacities. We evaluate the respective role of continental vicariance (abiotic) and biome shifts (biotic) deep in time and unravel the evolutionary history of this ancient group.LocationGlobal.TaxonPseudotyrannochthoniidae (Arachnida: Pseudoscorpiones).MethodsFive loci were sequenced for 75 Pseudotyrannochthoniidae samples collected across the globe. A matrix was compiled comprising 106 terminals and ~8800 bp, and phylogenetic analyses were performed to uncover relationships. Divergence time and ancestral range estimation analyses were used to reconstruct historical biogeography.ResultsPseudotyrannochthoniidae was monophyletic with high support but relationships among genera did not reflect current taxonomy and instead showed geographical structuring. Pseudotyrannochthoniidae originated in East Asia during the Middle Triassic and began diversifying in the Early Cretaceous.Main ConclusionsDiversity and distributional patterns of dragon pseudoscorpions can be explained by the interplay of continental vicariance through Pangaean breakup, and biome shifts via the spread of temperate habitats in the Cretaceous and their ongoing distributional fluctuations. Pseudotyrannochthoniidae diversification began in the Early Cretaceous as they dispersed with temperate forests across the Northern Hemisphere. Cretaceous vicariance, followed by widespread Holarctic extinction in the Late Tertiary–Quaternary, created their disjunct distribution at northern latitudes. Northern and Southern Hemisphere lineages diverged as Gondwana and Laurasia rifted, and Gondwanan breakup resulted in Afrotropical/Indomalayan and Austral clades. Austral lineages spread with temperate forests, however, cooling caused their disappearance from Antarctica and led to disjunct distributions at low latitudes.

Three new species of dragon pseudoscorpions (Pseudoscorpiones, Pseudotyrannochthoniidae) from China

“…Therefore, it is appropriate to place these two new species in the genus Spelaeochthonius , and it may be assumed that the species exhibiting these atypical spines are endemic to China. These atypical spines are similar to those found in the three North American species classified as “ Pseudotyrannochthonius ” and forming a monophyletic sister group to Spelaeochthonius ( Harms et al 2024 ); these are all characterized by tripartite spines with spatulate tips. However, the intermediate rami of these atypical spines are notably elongated ( Muchmore 1967 ; Benedict and Malcolm 1970 ).…”

“…The monophyletic pseudoscorpion family Pseudotyrannochthoniidae Beier, 1932, originated in East Asia during the Middle Triassic ( Harms et al 2024 ) and is one of the earliest branches of pseudoscorpion families. The group is small-bodied, usually less than 3 mm, but the chelicerae are disproportionately large and resemble the jaws of the mythical dragon.…”

“…The group is small-bodied, usually less than 3 mm, but the chelicerae are disproportionately large and resemble the jaws of the mythical dragon. Consequently, its group has earned the colloquial name dragon pseudoscorpions ( Harms et al 2024 ). Members of the family can be distinguished from all other pseudoscorpions in having trichobothria ib and isb located at the base of the fixed chelal finger and coxal spines present only on coxae I ( Harms and Harvey 2013 ).…”

“…The monophyly of both Allochthonius and Spelaeochthonius receives high support ( Harms et al 2024 ). The genus Allochthonius comprises 34 species, with 14 species documented from China and the remainder distributed across Russia, Japan, and South Korea.…”