The nudibranch genus Doto is taxonomically problematic in particular, and some species are described on the notion of strict monophagy. Here we perform species delimitation on NE Atlantic species, as well as placing them phylogenetically, using two markers: the mitochondrial COI and the nuclear H3. We also study the morphology of the species including radular ultrastructure and review food specificity. Specimens were first divided into potential species using ABDG on both markers, these groups were used as input species for species delimitation analyses using BPP, and analyses were performed with both markers combined and on H3 only. The analyses delimit 11 and eight species, respectively. With the exception of one species for which only COI was available, the differences are found in D. fragilis, which is split into three groups when COI is included and lumped into one with only H3. Doto hystrix is nested within these groups. We also found that specimens from Sweden seemingly close to D. maculata in external morphology have identical sequences as D. coronata. Analysis of food preferences of the species involved in the study contradicts the notion of strict monophagy within Doto.