The genus Parotoplana Meixner, 1938, which includes 15 species in the Mediterranean alone, is the most species-rich of the family Otoplanidae Hallez, 1892 (Platyhelminthes: Proseriata) (Delogu and Curini-Galletti, 2009). Thegenus appears heterogeneous as to the shape of body and pharynx, presence/absence of bursal nozzles and the proximal/distal fusion of the oviducts. Morphology of the copulatory spines in particular is extremely variable. The high number and morphological diversity of the species presently included in the genus suggest that careful re-examination is required.
Recently, under the sponsorships of the project ‘Biodiversity of Inconspicuous Organisms in Marine Protected Areas’ (BIOIMPA), a series of sampling campaigns were carried out along the Mediterranean coasts, aimed to gather data on the composition and distribution of a taxon of microturbellarians, viz the Platyhelminthes Proseriata. Description of the numerous new Parotoplana species found in the BIOIMPA samples, so far only marginally accomplished (Delogu and Curini-Galletti, 2007; 2009; Delogu et al., 2008), may thus help to throw light on the monophyly of the genus, and elucidate intra-group relationships.
The present contribution focusses on a group of Parotoplana species provided with a distinctive sclerotised apparatus, similar to that present in Parotoplana jondelii Delogu and Curini-Galletti, 2007 – henceforth called the P. jondelii species-group – of which seven new species are described.