Date Published: June 20, 2018
Publisher: Public Library of Science
Author(s): Arne Nygren, Julio Parapar, Joan Pons, Karin Meißner, Torkild Bakken, Jon Anders Kongsrud, Eivind Oug, Daria Gaeva, Andrey Sikorski, Robert André Johansen, Pat Ann Hutchings, Nicolas Lavesque, Maria Capa, Tzen-Yuh Chiang.
We investigate mitochondrial (COI, 16S rDNA) and nuclear (ITS2, 28S rDNA) genetic structure of North East Atlantic lineages of Terebellides, a genus of sedentary annelids mainly inhabiting continental shelf and slope sediments. We demonstrate the presence of more than 25 species of which only seven are formally described. Species boundaries are determined with molecular data using a broad range of analytical methods. Many of the new species are common and wide spread, and the majority of the species are found in sympatry with several other species in the complex. Being one of the most regularly encountered annelid taxa in the North East Atlantic, it is more likely to find an undescribed species of Terebellides than a described one.
The revelation of cryptic species has increased exponentially since the use of molecular data in taxonomic studies became common practise, but our understanding of the magnitude and importance of this neglected biodiversity is still at an early stage [1–3]. To unravel, describe and explain this hidden and unexplored dimension of life on earth is one of the major challenges to practising taxonomists .
Cryptic species are of paramount importance because of their commonality, and they are routinely found in genetic surveys, also in well-known taxa in well-studied areas [2, 54]. It is clear that the small fraction of morphological species that has been investigated so far still only represents the tip of the iceberg as Knowlton stated in her visionary paper on sibling species almost 25 years ago . Considering that cryptic species literally are everywhere, in a taxonomic as well as in a geographic context, they can in no way be neglected if we want to correctly assess species diversity, understand biogeographic patterns or keep track of natural or man-made induced changes in the marine environment.