Suborders Acotylea and Cotylea (Polycladida): Study on morphological, ecological and reproductive features of some representative species from Tunisian coasts (Mediterranean)

Abstract

The aim of this work is to provide some important morphological, ecological and reproductive features of 8 polyclad species from Tunisian waters belonging to Acotylea: Echinoplana celerrima Haswell, 1907, Leptoplana mediterranea (Bock, 1913), Discocelis tigrina (Blanchard, 1847) and Imogine mediterranea (Galleni, 1976) and Cotylea: Thysanozoon brocchii (Risso, 1818), Prosthiostomum siphunculus (Delle Chiaje, 1822), Yungia aurantiaca (Delle Chiaje, 1822) and Prostheceraeus moseleyi (Lang, 1884). New data on distribution of some species are added. Moreover, morphological data are provided for the first time in living specimens of D. tigrina. Based on our specimens, we confirm characterization of the two sub-orders Acotylea and Cotylea that have been already made in previous studies. Function of attachment organs in polyclads is discussed. On the other hand, data dealing with associated fauna are offered for all species. The two acotyleans E. celerrima and I. mediterranea were seen to cover their egg plates practicing thereby a parental care. This work could be a baseline for future taxonomic and behavioural investigations.