Redescription of Axine belones Abildgaard, 1794 (Monogenea, Axinidae), a gill parasite of Belone belone (Linnaeus, 1760) (Teleostei, Belonidae) off the Algerian coast, Western Mediterranean

Abstract

      Axine belones Abildgaard, 1794 is a polyopisthocotylean monogenean, parasite of belonid fishes, and there are few accounts with morphological and morphometrical data. Here, we redescribe A. belones based on newly collected specimens from its type-host, the garfish Belone belone (Linnaeus, 1760) collected off Algeria, Western Mediterranean, a new locality for this species. Several anatomical and morphological features (genital apertures and clamps sclerites) are described and illustrated. We provide morpho-anatomical and morphometrical data, along with detailed illustrations of A. belones, and we discuss the host specificity of A. belones. Notes on hosts and localities of this species and other congeners are presented, and host specificity patterns of A. belones revealed stenoxenic specificity to Belonidae Bonaparte, 1835, whilst the genus Axine Abildgaard, 1794 seems to be restricted to fishes of the order Beloniformes. Our attempt to investigate morphometric variations between Mediterranean and oceanic specimens revealed that the two populations differed by the number of testes, body length, and clamp dimensions. However, the limited number of measured organs in the various accounts precluded any distinction between the populations. Molecular data for both Mediterranean and oceanic specimens are needed to determine the existence of cryptic species.