|The family Fionidae
contains mostly tiny species with patchy distributions. For that
reason, many are
seldom seen and poorly known even though some of them are among the
colorful aeolids. Most feed on hydroids and store nematocysts in
cnidosacs at the tips of their cerata. However, some feed on
scleractinian corals and do not have cnidosacs. Many species also
secrete defensive chemicals from glands in their cerata. This is
particularly prominent where it may compensate for the lack of
nematocysts. There are about 42 species known from Hawaii in at least four genera (Abronica, Eubranchus, Fiona, and Tenellia). The family was recently
revised to include the families Tergipedidae and Eubranchidae (Cella, et. al., 2016).
We've tentatively assigned undescribed and insufficiently studied Cuthona spp. to Tenellia as per Cella, et. al., 2016.