In the present paper we used a molecular data set (including mitochondrial partial 16S rRNA and COI gene sequences) to examine the genetic structure of Lepidopleuruscajetanus (Poli, 1791) (Polyplacophora, Leptochitonidae) - a distinctive shallow water chiton and member of the basal branching Lepidopleurida, which is widespread in and adjacent to the Mediterranean. The analyses of the two mt-standard marker fragments resolved two main discrete clusters reported as L.cajetanus s.s. and L.aff.cajetanus, respectively. Lepidopleuruscajetanus s.s. is widespread throughout the area under study, while the second distinct lineage apparently co-occurs on the eastern Spanish mainland coast of the Balearic Sea. This result is discussed comparing our data with those reported, in 2014, by Fernández and colleagues who described L.cajetanus as exhibiting "a 'chaotic patchiness' pattern defined by a high genetic variability with locality-exclusive haplotypes, high genetic divergence, and a lack of geographic structure". Although genetic data alone are not sufficient to draw any definitive conclusions, nevertheless we believe that present results shed new light on L.cajetanus which apparently shows more geographically patterned genetic structure than supposed so far.
Keywords: 16S rRNA; COI; chitons; phylogeny; standard mitochondrial markers.
Mariastella Colomba, Julia D. Sigwart, Walter Renda, Armando Gregorini, Maurizio Sosso, Bruno Dell’Angelo.