Discovery of cryptic species in Plesionika (Crustacea: Pandalidae): shared taxa between Taiwanese and Mediterranean waters.

Abstract

The genus Plesionika Bate, 1888 is the most diverse of the whole Pandalidae family (up to 92 species according to De Grave et al., 2009) and plays a very important trophic and ecological role in benthic ecosystems, as both predators and prey. In the present study, we have compared material from different species of Plesionika collected from Taiwan and the Iberian Pensinsula. Specimens were analyzed using morphological, ecological and genetic data. The literature on the genus was reviewed in order to obtain the original descriptions of all the main species analyzed (including Plesionika edwardsii, P. martia and P. narval) and define type locality and bathymetric distribution. Moreover, we sequenced both the cytochrome oxidase 1 (CO1) and 16S rDNA genes from 2-3 individuals per species in order to estimate genetic divergence among samples from both Taiwan and Mediterranean regions. The presence of cryptic species was detected through phylogenetic and genetic distance analysis. Furthermore, we have compared our genetic results with the coloration and morphology of the specimens analyzed to highlight the main differences between Plesionika samples from Taiwan and Iberian Peninsula. Our results highlight the need to combine the study of freshly collected material with specimens from museum collections and show that, although there are very few morphological differences between species of Plesionika, sometimes they can be more easily separated according to size and coloration, which facilitates de visu identification during fieldwork