'A posteriori' searching for phenotypic characters to describe new cryptic species of sponges revealed by molecular markers (Dictyonellidae : Scopalina)

Cryptic speciation is repeatedly reported in sponge taxonomic studies. Most of the cryptic species, which were revealed by molecular markers, have never been formally described owing to the difficulty in finding diagnostic phenotypic characters. A previous molecular study revealed four genetically distinct species that had been misidentified as Scopalina lophyropoda Schmidt. One species was S. lophyropoda sensu stricto, whereas the other three were new species. Here, the three new species are formally described after careful searching for discriminatory phenotypic characters. The new species are Scopalina blanensis, sp. nov. from the north-western Mediterranean, S. ceutensis, sp. nov. from the Mediterranean coasts of Africa ( Atlantic waters) and S. canariensis, sp. nov. from the Canary Islands, Atlantic Ocean. All of them are at first sight morphologically similar and inhabit shallow environments with resuspended sediment. However, a closer examination allowed us to find some differential features: e. g. the amount of spongin embedding the spicules, the degree of complexity of the skeletal tracts, the size and curvature of the styles, the growth habit and the colour tinge. Furthermore, an identification key to the Atlanto-Mediterranean Scopalina species is presented. The differences between the genera Scopalina, Ulosa and Dictyonella are also discussed.