Abstract
We present the chromosome-level genome assembly of Dysdera silvatica
Schmidt, 1981, a nocturnal ground-dwelling spider endemic from the
Canary Islands. The genus Dysdera has undergone a remarkable
diversification in this archipelago mostly associated with shifts in the
level of trophic specialization, becoming an excellent model to study
the genomic drivers of adaptive radiations. The new assembly (1.37 Gb;
and scaffold N50 of 174.2 Mb), was performed using the chromosome
conformation capture scaffolding technique, represents a continuity
improvement of more than 4,500 times with respect to the previous
version. The seven largest scaffolds or pseudochromosomes cover 87% of
the total assembly size and match consistently with the seven
chromosomes of the karyotype of this species, including the
characteristic large X chromosome. To illustrate the value of this new
resource we performed a comprehensive analysis of the two major
arthropod chemoreceptor gene families (i.e., gustatory and ionotropic
receptors). We identified 545 chemoreceptor sequences distributed across
all pseudochromosomes, with a notable underrepresentation in the X
chromosome. At least 54% of them localize in 83 genomic clusters with a
significantly lower evolutionary distances between them than the average
of the family, suggesting a recent origin of many of them. This
chromosome-level assembly is the first high-quality genome
representative of the Synspermiata clade, and just the third among
spiders, representing a new valuable resource to gain insights into the
structure and organization of chelicerate genomes, including the role
that structural variants, repetitive elements and large gene families
played in the extraordinary biology of spiders.