Genomic insights unveil taxonomic incongruities and evolutionary origins of solifuges across the southern Levant

The Levant region is an important recognized biological corridor that unites three major continents, Africa, Asia and Europe. Due to its intersectional positioning, the region has facilitated flora and faunal exchange between four biogeographical elements: Palaearctic, Palaeoeremic, Ethiopian and Oriental. The Levant’s unique geological position, along with a distinguishable climate gradient and topographic heterogeneity, has likely contributed to the impressive solifuge biodiversity in a comparatively small area, making it an ideal and important gateway for beginning to interrogate the current solifuge diversity in the Old World. In this region, there are currently six families of solifuges and over 50 species described. However, solifuge taxonomy in the Old World has remained largely stagnant. While there exists a consensus that accurate taxonomic estimates are imperative for conservation efforts, such information is often in reference to undiscovered diversity, rather than the possible taxonomic inflation that may exist in understudied groups such as solifuges. The purpose of this study was to revisit the current standing taxonomic hypotheses using UCE phylogenomics, divergence dating, and analysis of SNPs recovered from solifuge genomes, using both newly generated genomic data derived from natural history collections and previously acquired genomic data. Our primary goal was to reevaluate the solifuge historical taxonomy of this region, with the intent of obtaining a better picture of shallow-level diversity patterns in the six native solifuge families of interest. Our molecular study provides evidence to suggest that the current reported solifuge diversity from this region should be synonymized to about one-third, as they represent junior synonyms of conspecifics. Our findings highlight longstanding taxonomic inaccuracies within Levantine Solifugae and illuminate the extent of unwarranted and excessive taxonomic splitting. Future taxonomic research should prioritize clarifying species boundaries and reorganizing the group based on a comprehensive understanding of what defines a meaningfully stable taxonomic unit, while remaining open to simplified scenarios with fewer taxonomic ranks.