Jacinto Perez

Ribbon worms (Nemertea) are a less-known group of invertebrates, specially challenging for taxonomic studies due to the scarcity of external morphological features. As a consequence, the number of known nemertean species might represent just a small fraction of the true diversity of the phylum. The present study increases the number of known ribbon worm species with the description of the accordion worm Pararosa vigarae sp. nov., a new genus and species of Heternonemertea from the northwest coast of Spain. We performed molecular phylogenetic analyses based on partial sequences of 16S rRNA, 18S rRNA, 28S rRNA, cytochrome c oxidase subunit I ( COI ) and histone H3 gene markers that indicated the newly identified specimens represent a new genus and species of heteronemertean in the family Lineidae. We also provide morphological data and images illustrating its unique behaviour, contracting its body into a series of rings similar to an accordion. Our results increase our knowledge on the diversity of an important but often overlooked invertebrate phylum and emphasize the need to combine morphological and molecular data to discover new ribbon worm species and better evaluate the true diversity of the phylum.

Studying the early stages of the introduction of non-indigenous species (NIS) is crucial as it allows immediate management actions aimed at preventing NIS spread at a time when these actions are more likely to be effective. Recent species introductions present unique opportunities to study key aspects of the invasion process. However, comprehensive information on how and when NIS are first introduced remains rare. We assessed the characteristics of the introduction of a member of the widespread Pyura stolonifera species group (Chordata, Tunicata) in Europe. These ascidians are important bioengineer species that can attain amongst the highest benthic biomass per surface area ever reported. We collected introduced individuals on the coast of the northwestern Iberian Peninsula, an area with high shipping traffic and one of the world’s most important mussel farming regions. The specimens were analysed using taxonomic and genetic tools. Both field surveys and taxonomic analysis showed that one of the African members of the species group, Pyura herdmani, has recently been introduced to Europe and, although it does not yet form the large aggregates found in the native range, it is already well-established. Genetic data revealed that only the northwest African lineage of P. herdmani has been introduced to Europe. Considering the low dispersal capabilities of the early life-history stages of P. herdmani, the introduction of this species into Europe can only be explained via human mediated transport of NIS. In order to prevent any detrimental effects on both native biota and/or economically-important anthropogenic activities, regular monitoring of recent NIS introductions is urgently required.

New morphological information, reconsiderations and the first combination of a generic name based on a previously established species are presented in the current revision of the family Pleioplanidae (Polycladida, Acotylea). Species belonging to this family are briefly presented and Laqueusplana bocki gen. et sp. nov. is described. An identification key to all valid species of Pleioplanidae is provided. Furthermore, results from phylogenetic analyses of the species treated herein are discussed.