Deciphering Arctic sponge diversity: genetic and morphological evidence reveals cryptic lineages in Suberites

Abstract

Suberites luetkenii Schmidt, 1870 is a polymorphic Arctic species with several distinct morphotypes, suggesting that it might represent a species complex. The aim of the present work was to verify, using an integrative approach, whether these morphs are conspecific or represent cryptic species. Using COI mitochondrial and 28S nuclear loci, two phylogenies of the family Suberitidae were constructed that were congruent with each other. We retrieved two highly supported sister clades: the Suberites s.s. clade I, which includes suberitid species from the North Atlantic and North Pacific boreal regions associated with the hermit crab, and the arctic clade. New findings of Suberites pagurorum Solé-Cava & Thorpe, 1986 from the Norwegian Sea represent the northernmost records of the species, marking the northern limit of the boreal Suberites s.s. clade I at the Atlantic–Arctic biogeographical border. Along the Scandinavian coasts, members of both clades are sympatric, while further to the north, arctic counterparts predominate. Our analysis shows that the arctic clade defined in this study is more closely related to North Pacific species and shares a single evolutionary origin with them.