Parasites of the Lessepsian sprinter Fistularia commersonii (Osteichthyes: Fistulariidae): an update after 15 years since its arrival in the Mediterranean Sea

Fistularia commersonii is a Lessepsian sprinter recorded for the first time in the eastern Mediterranean Sea (Israel) in 2000. Within a few years, this species reached the central Mediterranean (2004, Sicily) and, subsequently, the western Basin (2007, Iberian Peninsula). Merella et al. (2007) and Pais et al. (2007) described its parasites in the Mediterranean Sea from one fish caught off the Sardinian coast and six from North Africa, finding native generalist species, but also two Indo-Pacific digeneans: Allolepidapedon fistulariae and Neoallepidapedon hawaiiense. From 2007 to 2014, the capture of 24 specimens of F. commersonii in Sardinian waters allowed to add information about its parasites in the Mediterranean, and to evaluate their dynamics throughout the host migration path. Twenty parasite species/taxa were found, adding 13 taxa to the former Mediterranean list. The results confirmed earlier data: A. fistulariae, Nybelinia africana and Phyllobothriidae (Cestoda), Hysterothylacium spp. (Nematoda) and Gnathiidae (Crustacea) were among the most frequent parasites (P>15%); besides, two other taxa showed prevalence higher than 15%: Pseudogrillotia sp. (Cestoda) and Breizacanthus cf. ligur (Acanthocephala). Neoallepidapedon hawaiiense, previously recorded in North Africa, was not found in the present specimens. The results suggest that a non-indigenous species is not always subjected to the release from its natural enemies. Actually, the parasite fauna of F. commersonii increased throughout the host migration path, acquiring new generalist species, but also conserving the natural parasite A. fistulariae, that seemingly has been able to close its life cycle in the Mediterranean Sea.