The Parotoplana jondelii species-group (Platyhelminthes: Proseriata): a microturbellarian radiation in the Mediterranean

Seven new Parotoplana species (Proseriata: Otoplanidae) from the Mediterranean, belonging to the P. jondelii complex, are described. They are characterized by the presence of numerous (14-22) copulatory spines. These are characteristically broad, and arranged in a girdle around the distal portion of the ejaculatory duct. In most species, dorsal and ventral spines are distinctly different from the rest of the spines of the girdle. This morphology of the copulatory spines is apomorphic for the genus Parotoplana, and supports a close relationship among these species. The new species (P. axi sp. n., P. crassispina sp. n., P. carthagoensis sp. n., P. gracilispina sp. n., P. ichnusae sp. n., P. obtusispina sp. n., P. pulchrispina sp. n.) are distinguished by number and shape of the copulatory spines, and presence / absence of bursal spines. Species of the P. jondelii complex are at present only known from their type localities, and, at most, from adjacent areas. Only P. crassispina n. sp. is known to present a wider distribution in north-western Mediterranean, although populations across the range appear morphologically differentiated. The restricted, non-overlapping ranges of most species of the complex are suggestive of allopatric speciation.