Western Mediterranean goose barnacles (Lepadidae): diversity, distribution, and environmental boundaries of these resistant hitchhikers of the sea

Abstract

[eng] Clusters of several species of epipelagic goose barnacles (Lepadidae), attached on a glider (underwater drone) patrolling along the Balearic Sea and up to 950 meters were found, implying they tolerate wider environmental conditions than previously reported in the literature. Seizing this opportunity, this project aims: 1) to identify these epipelagic drifters from the Western Mediterranean region using an array of methods, 2) to assess their genetic diversity, and 3) to evaluate the environmental boundaries they can tolerate. A sample of 109 specimens were objective of morphological and molecular analyses in order to discern among species of the Lepadidae family in the Western Mediterranean. Individuals were visually inspected and photographed to identify the present morphospecies. The mitochondrial marker Cytochrome c oxidase subunit I (COI) was sequenced to conduct molecular analysis for species discrimination. Phylogenetic analyses and species delimitation methods (including genetic distance, maximum parsimony haplotype networks, single and multi-rate Poisson tree processes model) including 219 additional sequences from Genebank. Combined results have yielded sequences into five groups which contrast with the three morphospecies found, identified (Lepas anatifera, Lepas pectinata and Conchoderma virgatum). These results imply that Lepas anatifera and Lepas pectinata are complexes holding some hidden cryptic species which have not been detected until now. High genetic diversity has been measured within species but also, some shared haplotypes between geographically distant regions which may imply anthropogenic translocation of individuals outside their natural range. In addition, oceanographic data collected by the gliders has been used to re-define the environmental boundaries (depth, salinity, and temperature) that the species collected have been exposed to. With all this data and morphometric features (capitulum length and growth rate), it is intended to provide further knowledge of these epipelagic hitchhikers and to develop useful strategies for species delimitation analysis of this type of organisms.