Morffe, J.; Guiglielmoni, N.; Wassey, N.; Gueddach, K.; Schuster, A.; Becker, K.; Schiffer, P.; Holovachov, O.

Nematodes of the superfamily Thelastomatoidea are found in the digestive system of various arthropods, feeding on their host microbiome. They are sometimes considered to be ecologically intermediate forms between free-living rhabditids and parasitic Spirurina, while phylogenetically they are nested within the latter. In addition to new morphological data on the male morphology, this manuscript presents the first nuclear genome assembly of a thelastomatid species, Cranifera cranifera, using long-read sequencing approach, making a total of three nuclear genomes available for superfamily Thelastomatoidea. The C. cranifera nuclear genome assembly presented here is 246 Mb long, consists of 7563 contigs, has an N50 of 43 kb and includes 94% of the BUSCO nematoda_odb12 genes. The mitochondrial genome is 24646 bases long, includes a complete set of protein coding, rRNA and tRNA genes, and a repetitive region 9731 bases long, which includes multiple copies of tRNA-Asn(gtt) and tRNA-Lys(ttt). The nuclear assembly also contained two sequence variants of the 28S rRNA gene, highlighting the presence of intragenomic variation within rRNA operon. The newly generated assemblies (nuclear and organelle) will add to a growing body of genomic resources for underrepresented and understudied animal parasitic nematodes from the Clade 3, enabling comprehensive studies in their phylogeny and trait evolution in the future.