Molecular evidence of intraspecific variability in Lysidice ninetta (Polychaeta: Eunicidae) in the Mediterranean Sea

Abstract

A first study of the phylogeography of the polychaete Lysidice ninetta Audouin & MilneEdwards (Polychaeta: Eunicidae) in the Mediterranean Sea, based on analyses of the molecular markers ITS1 and COI, indicated the occurrence of strong intraspecific variability and possible sibling species. Here, we report further evidence of the presence of sibling species within L. ninetta, revealed by analysing a new molecular marker (16S rRNA) and supported by preliminary morphological observations. Specimens were collected in association with the seagrass Posidonia oceanica in 6 meadows of the Mediterranean basin; in one of the meadows in which putative siblings co-occurred (Cava meadow off the island of Ischia, Naples, Italy), additional samples were collected for genetic and morphological analysis. The mitochondrial region 16S rRNA of 78 specimens revealed 2 haplotypes (nA and nB); morphological characters, associated with these 2 molecular clades were also observed in a sub-set of the analysed specimens of L. ninetta, revealing the presence of 2 morphotypes. The morphotype termed 'dark', characterised by a typical dark colour pattern on the prostomium and first anterior segments, as well as by black aciculae all along the examined body portion, matching quite well with the description of L. ninetta from the Atlantic type locality, corresponded to haplotype nA. The morphotype termed 'light', with lighter colouration of the prostomium and first anterior segments, and both black and yellow aciculae on the examined body portion, corresponded to haplotype nB, suggesting the existence of a different species. The hypotheses that can be addressed are the following: (1) only a single new species (the light morph/genotype) is present, while the dark morph corresponds to the original L. ninetta species; (2) both morphs/genotypes (dark and light) are new taxa and need to be fully and properly described; and (3) one or both of the species corresponds to previously described species, synonymised by previous authors as L. ninetta. In all cases there is an urgent need for revision of the genus Lysidice and the nominal species in the Mediterranean Sea basin. This is a complex task far beyond the scope of this work.

Cryptic polychaete diversity: a review

“…; Iannotta et al . , ; Barroso et al . ) is to use the divergence rate from transisthmian geminate pairs of snapper shrimps that were separated at the time of the closure of the Panama Isthmus.…”

Polychaetes of Greece: an updated and annotated checklist

“…Frequently reported from Greece. However, Iannotta et al (2006) and Iannotta et al (2009) investigated molecular markers and provided evidence of sibling species within the Lysidice ninetta complex. Two morphotypes (dark and light), differentiated by colour patterns in anterior body and acicular chaetae, were identified.…”

Revision of the taxonomic status of Lysidice (Polychaeta, Eunicidae) in the Western Caribbean Sea with observation on species reproductive features and habitat preference

“…This feature is unique among all currently described Lysidice species. However, Iannotta et al (2009) described a morphotype, also with a distinct genotype, of 'L. ninetta' from the Mediterranean Sea, with both black and yellow acicula; unfortunately, no complete morphological descriptions of the Mediterranean specimens were given so complete comparison is not possible.…”

“…In the Mediterranean Sea, a recent genetic analysis of the genus type species, Lysidice ninetta Audouin & Milne-Edwards, shows the presence of at least two cryptic forms (Iannotta et al 2007(Iannotta et al , 2009, both associated with the seagrass Posidona oceanica as borers of the sheaths of this plant (bases of the old leaves that persist in the rhizomes; Gambi 2002). One of these cryptic forms was hypothesized to be the type-species of the genus L. ninetta, and the redescription of this form was highly recommended, but not undertaken by Iannotta et al (2009).…”

“…One of these cryptic forms was hypothesized to be the type-species of the genus L. ninetta, and the redescription of this form was highly recommended, but not undertaken by Iannotta et al (2009). Other Lysidice species, synonymized with L. ninetta, have been also recently been validated and redescribed in the Mediterranean (Iannotta et al 2007;Kurt Sahin & Cinar 2009).…”