The elephant in the room: first record of invasive gregarious species of serpulids (calcareous tube annelids) in Majorca (western Mediterranean)

Although there are several nuisance species of serpulids reported worldwide, the present study shows that some them have been overlooked even in geographic areas considered well studied. We report for first time Majorca invasive Ficopomatus enigmaticus and records Balearic Islands also non-native Hydroides dianthus, H. dirampha, elegans nigra. The most abundant were F. enigmaticus, found at higher densities Portixol (with up to 280 ind. m–2), elegans, highest port Palma 270 m–2). Species identified after morphological examination corroborated by mitochondrial DNA sequence data: cytochrome c oxidase subunit 1 (COI) b (Cytb). Molecular data show same haplotypes distant disjoint biogeographic which is only explicable unintentional translocation specimens through vectors (i.e. ship hulls or ballast water). delimitation analyses support previous findings complexes common both Hydroides. In fact, among Majorcan samples we able detect three complex, two complex dianthus complex. genetic distances between members 8.7% 16.7% COI sequences. hold 5.4% 47.6 % divergence