The recognition of cryptic species concealed in traditionally established species may reveal new biogeographical patterns and alter the understanding of how biodiversity is geographically distributed. This is particularly relevant for marine ecosystems

The polychaete Stygocapitella subterranea is found in upper shore stable coarse substrata and can be regarded as semi-terrestrial. It is known from similar habitats in widely distributed locations of continental Europe. The first two British records,

The recognition of cryptic species concealed in traditionally established species can reveal new biogeographical patterns and alter the understanding of how biodiversity is geographically distributed. This is particularly relevant for marine ecosystems

The advent of sequencing technologies enabled the discovery of hidden species lineages with considerable genetic diversity within originally described species (cryptic species). Considering the prominent role of species delimitation in biological sciences,

Morphologically similar species, that is cryptic species, may be similar or quasi-similar owing to the deceleration of morphological evolution and stasis. While the factors underlying the deceleration of morphological evolution or stasis in cryptic species