The ancient, relictual Asian scorpion family Pseudochactidae Gromov, 1998, has a disjunct distribution. Five genera and seven species of living pseudochactids are assigned to one epigean subfamily, Pseudochactinae Gromov, 1998, from Central Asia and southern China, and two hypogean subfamilies, Troglokhammouaninae Prendini et al., 2021, and Vietbocapinae Lourenço, 2012, from caves of the Khammouan-Phong Nha-Kẻ Bàng Karst in the northern Annamite (Trường Sơn) Mountains of Laos and Vietnam. The extinct subfamily Chaerilobuthinae Lourenço and Beigel, 2011, comprises one genus and 15 species, hypothesized to be endogean, from mid-Cretaceous Burmese amber. The discovery and uncertainty regarding the phylogenetic placement of Qianxie solegladi Tang, 2022, from South China, together with the discovery that the Cretaceous amber Chaerilobuthinae, from the Burma Terrane, is the sister group of the extant pseudochactid subfamily Vietbocapinae provided an opportunity to revisit the phylogeny and biogeography of Pseudochactidae, and their adaptation to subterranean habitats in Southeast Asia. In the present contribution, pseudochactid phylogeny is reanalyzed using three mitochondrial markers (12S rDNA, 16S rDNA, Cytochrome c Oxidase Subunit I), three nuclear markers (18S rDNA, 28S rDNA, Internal Transcribed Spacer) and 143 morphological characters, for all extant pseudochactid taxa and seven exemplar species of the extinct Chaerilobuthinae. Divergence time and ancestral range estimation are conducted and the evolution of troglomorphic characters investigated to reassess how this lineage of “living fossils” dispersed and diversified. Recent changes to the systematics of Pseudochactidae are confirmed. The four subfamilies, genera, and species were monophyletic with high support and the following scheme of relationships: (Pseudochactinae (Troglokhammouaninae (Chaerilobuthinae + Vietbocapinae). Phylogenetic analyses, reinforced by a multivariate morphometric analysis and pairwise genetic distances, confirm the validity of the monotypic, epigean Chinese genus, Qianxie Tang, 2022, which formed a monophyletic group with the epigean Central Asian genus, Pseudochactas Gromov, 1998, rather than the hypogean Southeast Asian genus, Troglokhammouanus Lourenço, 2007. Qianxie solegladi is transferred to Pseudochactinae. A revised time tree of Pseudochactidae suggests that the Burmese Chaerilobuthinae diverged from the Indochinese subfamilies, Troglokhammouaninae and Vietbocapinae, in the Early Cretaceous (ca. 117 Ma), consistent with Early Devonian rifting of the Burma Terrane.
Acknowledgment: I would like to extend my sincere thanks to Gérard Dupré for providing the complete manuscript.
Prendini L, Xuan Q, Du S, Wang C, Ehrenthal VL, Loria SF. Phylogeny and divergence time estimation of relictual Asian scorpion family suggests Early Cretaceous connections between Burma Terrane and Eurasia, and corrects placement of Chinese taxon. Am Mus Novit. 2026;4051:1-55. Published February 27, 2026.
