Data from: A biting commentary: integrating tooth characters with molecular data doubles known species diversity in a lineage of sea slugs that consume “killer algae”

Predicting biotic resistance to highly invasive strains of “killer algae”
(Caulerpa spp.) requires understanding the diversity and feeding
preferences of native consumers, including sea slugs in family Oxynoidae.
Past studies reported low algal host specificity for Oxynoe (6 spp.) and
Lobiger (4 spp.), but these taxonomically challenging slugs may represent
species complexes of unrecognized specialists that prefer different
Caulerpa spp. Here, we assess global diversity of these genera by
integrating gene sequences with morphological data from microscopic teeth
and internal shells, the only hard parts in these soft-bodied
invertebrates. Four delimitation methods applied to datasets comprising
mtDNA and/or nuclear alleles yielded up to 16 species hypotheses for
samples comprising five nominal taxa, including five highly divergent
species in Lobiger and five in Oxynoe. Depending on the analysis, a
further four to six species were recovered in the O. antillarum-viridis
complex, a clade in which mitochondrial divergence was low and nuclear
alleles were shared among lineages. Bayesian species delimitation using
only morphological data supported most candidate species, however, and
integrative analyses combining morphological and genetic data fully
supported all complex members. Collectively, our findings double the
recognized biodiversity in Oxynoidae, and illustrate the value of
including data from traits that mediate fast-evolving ecological
interactions during species delimitation. Preference for Caulerpa spp. and
radular tooth characteristics covaried among newly delimited species,
highlighting an unappreciated degree of host specialization and
coevolution in these taxa that may help predict their role in containing
outbreaks of invasive algae.