The genome of an enigmatic sea urchin parasite Echinomermella matsi Jones & Hagen, 1987 resolves its place among other invertebrate parasitic nematodes

Supplementary data for the article entitled "The genome of an enigmatic sea urchin parasite Echinomermella matsi Jones & Hagen, 1987 resolves its place among other invertebrate parasitic nematodes", 18S_phylogeny.tar.gz includes all input, intermediate and output files generated during phylogenetic analysis using single locus (18S rRNA gene)phylogenomics.tar.gz includes all input, intermediate and output files generated during phylogenomic analysis using multiple protein coding genes as well as a custom bash script written to run the analysis; note that the script will not run on any other machines by itself, without installing all the dependencies and without editing some of the pathsAbstract of the article: We present a genome of Echinomermella matsi (Nematoda: Plectida: Benthimermithidae), a body cavity parasite of the green sea urchin Strongylocentrotus spp. commonly found along the coast of Central and Northern Norway. Three assemblies were generated, one from multiple individuals using Oxford Nanopore long read data and two from two individuals using PacBio long read data. The genome of Echinomermella matsi is 65 Mb long consisting of 7 chromosomes, with nematode Benchmarking Using Single Copy Orthologue (BUSCO odb12) completeness reaching 96%. The E. matsi chromosome complement corresponds to the proposed Rhabditida ancestral linkage groups. Phylogenetic analyses using newly generated 18S rRNA genes and a multigene dataset consisting of BUSCO protein coding genes, supported by morphological observations of juveniles, firmly place Echinomermella within the nematode order Plectida, alongside nematode parasitoids of marine invertebrates, Trophomera or Neocamacolaimus. As a result, the generally free-living order Plectida includes at least three independently evolved lineages of nematodes symbiotic with various groups of aquatic and terrestrial invertebrates and with unicellular organisms. This, and the fact that Plectida is the closest sister lineage to Rhabditida as a whole, and one node away from the exclusively animal parasitic Spirurina, makes this lineage a valuable model for study of evolution of animal parasitism in the aquatic environment.