A chromosome-level genome of the giant vinegaroon Mastigoproctus giganteus exhibits the signature of pre-Silurian whole genome duplication.

This article focuses on the generation and analysis of the first chromosome-level genome assembly for the vinegaroon Mastigoproctus giganteus, a member of the arachnid clade Pedipalpi, which had previously lacked genomic resources. The study demonstrates that M. giganteus retains signatures of an ancient whole genome duplication (WGD) event shared across Arachnopulmonata, evidenced by duplicated gene clusters (e.g., Hox, Nk, Iroquois) and macrosynteny analyses. Comparative genomic analyses with other chelicerates, including spiders, scorpions, ticks, mites, and horseshoe crabs, support the systemic nature of this WGD and highlight lineage-specific patterns of gene retention and loss. This genomic resource provides a critical reference for polarizing evolutionary genomic events within Arachnopulmonata and advancing understanding of arachnid genome evolution.