Testing species hypotheses for Fridericia magna, an enchytraeid worm (Annelida: Clitellata) with great mitochondrial variation

Global species delimitation of the cosmopolitan marine littoral earthworm Pontodrilus litoralis (Grube, 1855)

The marine littoral earthworm Pontodrilus litoralis (Grube, 1855) is widely distributed and is reported as a single species. This study utilized an integrative taxonomic approach based upon morphological examination, phylogenetic reconstruction, and molecular species delimitation, to test whether the taxon is a single species or a species complex. For this, a total of 114 P. litoralis specimens collected from North America, Africa, Australia and Oceania, Europe and Asia were used. The phylogenetic analyses revealed deeply divergent mitochondrial lineages and a high level of genetic diversity among P. litoralis populations. Both single and multi-locus species delimitation analyses yielded several molecular operational taxonomic units. Therefore, due to the homogeneity of morphological characteristics, it is likely that the morphospecies P. litoralis is a complex of four or more cryptic species, suggesting that more sampling is required and that the population structure genetic data and gene flow need to be investigated.

How complex is the Naineris setosa species complex? First integrative study of a presumed cosmopolitan and invasive annelid (Sedentaria: Orbiniidae)

We performed a comparative study of the specimens from the Naineris setosa complex from the Pacific and the Atlantic Oceans and re-described the syntype of N. setosa, including the selection of the lectotype. Molecular phylogenetic and species delimitation analyses based on two mitochondrial (COI and 16S) and one nuclear (28S) marker revealed the presence of three species. One clade with wide Amphi-Atlantic distribution was attributed as Naineris setosa s. str. The second Atlantic clade restricted to Southern and Southeastern Brazil was described as a new species, Naineris lanai sp. n. The third clade, reported from the Northwestern Pacific, was identified as a new species but was not formally described due to the presence of only juvenile-sized worms in the studied material. Detailed morphological descriptions of several diagnostic characters in the Naineris setosa complex are provided.

Cryptic Clitellata: Molecular Species Delimitation of Clitellate Worms (Annelida): An Overview

Methods for species delimitation using molecular data have developed greatly and have become a staple in systematic studies of clitellate worms. Here we give a historical overview of the data and methods used to delimit clitellates from the mid-1970s to today. We also discuss the taxonomical treatment of the cryptic species, including the recommendation that cryptic species, as far as possible, should be described and named. Finally, we discuss the prospects and further development of the field.