A chromosome-level genome of the giant vinegaroon <i>Mastigoproctus giganteus</i> exhibits the signature of pre-Silurian whole genome duplication

Within the arachnids, chromosome-level genome assemblies have greatly accelerated the understanding of gene family evolution and developmental genomics in key groups, such as spiders (Araneae), mites and ticks (Acariformes and Parasitiformes). Among other poorly studied arachnid orders that lack genome assemblies altogether are members of the clade Pedipalpi, which is comprised of three orders that form the sister group of spiders and diverged over 400 Mya. We close this gap by generating the first chromosome-level assembly from a single specimen of the vinegaroon Mastigoproctus giganteus (Uropygi). We show that this highly complete genome retains plesiomorphic conditions for many gene families that have undergone lineage-specific derivations within the more diverse spiders. Consistent with the phylogenetic position of Uropygi, macrosynteny in the M. giganteus genome substantiates the signature of an ancient whole genome duplication.