Pseudodiplectanum syrticum n. sp. (Monogenea: Diplectanidae), a parasite of Synapturichthys kleinii (Teleostei: Soleidae) from off Tunisia Hela Derbel Lobna Boudaya Lassad Neifar Received: 10 August 2006 / Accepted: 27 February 2007 Ó Springer Science+Business Media B.V. 2007 Abstract Pseudodiplectanum syrticum n. sp. (Mono- genea: Diplectanidae) is described from the gills of Synapturichthys kleinii (Risso) collected from the Gulf of Gabe`s in the Mediterranean Sea off Tunisia. The new species differs from the congeneric species by the morphology of the penis and vagina. It resembles the Mediterranean species P. kearni Vala, Lopez-Roman & Boudaoud, 1980 from Solea vulgaris Quensel and P. gibsoni Oliver, 1987 from Michrochirus variegatus (Donovan) in its tubular penis, but it differs from these two species by having a vagina with a long tube presenting two loops and a male copulatory organ ending in a curved point. It also differs in the morphology and size of the transverse bars of the haptor. In P. syrticum the ventral transverse bar and dorso-lateral bars are longer than those of P. gibsoni (114 vs 69.5–89 mm and 48 vs 33–44 mm, respectively). Introduction The Gulf of Gabe`s, off the Tunisian coast in the southern Mediterranean, is characterised by an ichthyofauna with a subtropical affinity (Quignard & Tomasini, 2000). Several studies on the monoge- nean fauna of fishes from this area have led to the description of new species (Neifar et al., 2000, 2001, 2004). Synapturichthys kleinii (Risso) (Soleidae) has a subtropical distribution and is more common in the southern part of the Mediterranean Sea (Froese & Pauly, 2006). During a parasitological survey of this fish, we found on the gills a new species of the Diplectanidae Monticelli, 1903. This new species belongs to Pseudodiplectanum Tripathi, 1957. The structure of the squamodiscs, with sclerotised rodlets in concentric rows opening anteriorly places this species in the Diplectaninae Monticelli, 1903, in which only Pseudodiplectanum is characterised by the atrophy of the ventral anchors and the presence of a transversal furrow between the shaft and blade of the dorsal anchors. This genus is reported from pleuronectiform teleosts. Five species have been described: Pseudodiplectanum cynoglossum Tripathi, 1955 from Cynoglossus arel (Bloch & Schneidar) in the Indian Ocean (also reported by Nagibina (1977) from C. bilineata (Lace´pe`de) in the South China Sea); P. bychowskii Nagibina, 1977 from C. bilineata collected in the South China Sea; P. cabelleroi Nagibina, 1977 from Symphurus orientalis (Bleeker) in the South China Sea; P. kearni Vala, Lopez- Roman & Boudaoud, 1980 from Solea vulgaris in the Mediterranean Sea and P. gibsoni Oliver, 1987 from Michrochirus variegatus in the Mediterranean Sea H. Derbel  L. Boudaya  L. Neifar (&) Laboratoire d’Ecobiologie Animale, Faculte´ des Sciences de Sfax, BP 802, Sfax 3018, Tunisia e-mail: lassad.neifar@fss.rnu.tn 123 Syst Parasitol (2007) 68:225–231 DOI 10.1007/s11230-007-9108-4