Climate Relicts: Asian Scorpion Family Pseudochactidae Survived Miocene Aridification in Caves of the Annamite Mountains

Abstract

Southeast Asia is a hotspot of karst systems in the tropics and many relictual taxa have been documented in caves across the region. The ancient, relictual scorpion family Pseudochactidae Gromov 1998 has a disjunct distribution and includes two hypogean subfamilies from caves in the Khammouan-Phong Nha-Kẻ Bàng Karst in the northern Annamite (Trường Sơn) Mountains of Laos and Vietnam, and one epigean subfamily from Central Asia. A recent revision identified six species in the family; however, how these taxa dispersed and diversified into Southeast Asian cave systems has not been tested. In the present contribution, the phylogeny of Pseudochactidae is reconstructed using three mitochondrial and three nuclear markers and 140 morphological characters, divergence time and ancestral range estimation analyses are conducted, and the evolution of troglomorphic characters is investigated. Results confirm a previous hypothesis that Pseudochactidae originated in Eurasia, most likely near the Tajik block in the Carboniferous, supporting the ‘Out of Eurasia’ hypothesis and contradicting the ‘Eurogondwana’ and ‘Out of India’ hypotheses for the origin of Southeast Asian scorpions. Pseudochactidae dispersed across Southeast Asia after the collision of the Cimmerian continent and Indochina with Eurasia in the Late Jurassic. Colonization of Southeast Asian caves began in the Late Cretaceous and was completed by the Miocene. The onset of aridification in Southeast Asia during the Late Miocene resulted in the extinction of epigean Pseudochactidae, whereas hypogean members of the family likely survived within caves in the limestone massifs of the Annamite Mountains, supporting the ‘Climate Relict’ hypothesis.

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

“…Tree files were combined in LogCombiner removing 50% burnin, and the maximum clade credibility tree was selected from combined trees in TreeAnnotator. For comparison, a second BEAST analysis (Table S4) was prepared using the same settings described above, except that a normal distribution was applied to the COI ucld.mean using the Brower (1994) rate for arthropods ( μ = 0.0115, σ = 0.0001), and broad uniform priors were applied to all nuclear loci ( ucld.min = 0.0001 and ucld.max = 0.01), following biogeographical studies on other arachnids (Loria et al., 2022; Loria & Prendini, 2020).…”

Congruence between ultraconserved element‐based matrices and phylotranscriptomic datasets in the scorpion Tree of Life

“…Tests of relationships using Sanger data were limited to analyses at the level of family, genus or regional fauna (e.g. Fet et al., 2003; Prendini et al., 2003; González‐Santillán and Prendini, 2015; Santibáñez‐López et al., 2017a; Loria et al., 2022; Parmakelis et al., 2022; Štundlová et al., 2022). Two competing hypotheses classified scorpions into either four parvorders (Soleglad and Fet, 2003) or 18 families (i.e.…”