Phylogenomics supports a single origin of terrestriality in Isopods.

Terrestriality, the adaptation to life on land, is one of the key
evolutionary transitions, occurring numerous times across the tree of
life. Within Arthropoda, there have been several independent transitions:
in hexapods, myriapods, arachnids and isopods. Isopoda is a
morphologically diverse order within Crustacea, with species adapted to
almost every environment on Earth. The order is divided into 11 suborders
with the most speciose, Oniscidea, including terrestrial isopods such as
woodlice and sea-slaters. Recent molecular phylogenetic studies have
challenged traditional isopod morphological taxonomy, suggesting that
several well-accepted suborders, including Oniscidea, may be
non-monophyletic. This implies that terrestriality may have evolved
multiple times. Current molecular hypotheses, however, are based on
limited sequence data. Here, I collate available genome and transcriptome
datasets for 36 isopods and four peracarid crustaceans from public
sources, generate assemblies, and use 970 single-copy orthologues to
estimate isopod relationships and divergences times with molecular dating.
The resulting phylogenetic analyses support monophyly of terrestrial
isopods and suggest conflicting relationships based on nuclear ribosomal
RNA sequences may be caused by long-branch attraction. Dating analyses
suggest a Carboniferous-Permian origin of isopod terrestriality, much more
recently than other terrestrial arthropods.