Carinina ochracea (Palaeonemertea: Tubulanidae) Reaches Its Southernmost Distribution: New Morphological and Molecular Data

Abstract

New data for Carinina ochracea Sundberg et al., 2009 are provided for the Iberian Peninsula, establishing the southernmost limit of its known distribution. This species was previously known from only two localities: the type locality in Tjärnö (Sweden) and Pouldohan (Brittany, France). The material examined here was obtained during a faunal survey in the Villaviciosa Estuary (Asturias, northern Iberian Peninsula). The identity of the new specimen was confirmed both by DNA barcoding and anatomical examination. The molecular divergence of all available sequences of this species for four molecular markers, cytochrome c oxidase subunit I (COI), 16S, 18S and 28S rDNA, is discussed. For COI, four polymorphic sites were found, indicating: 1) a nuclear pseudogene; 2) heteroplasmy; or 3) gene duplication of a region of the mitochondrial genome. Two previously overlooked morphological characters were found: the presence of a colour ring and a postfixation staining band (pigmented band), which is histologically characterized. This species is the 12th palaeonemertean and the 75th nemertean reported from Iberian waters