Genetic characterisation of spp. (Nematoda: Gnathostomatidae) from marine hosts in Australia.

We genetically characterised larval and adult specimens of species of s Molin, 1858 (Gnathostomatidae) collected from various hosts found within Australian waters. Adult specimens of were collected from a dasyatid stingray [ (Macleay); n = 2] from Moreton Bay, Queensland and larvae from a hydrophiine sea snake [ (Duméril); n = 3] from Cape York Peninsula, Queensland, from an octopus ( Amor & Hart; n = 3) from Fremantle, Western Australia and from a lucinid bivalve [ (Iredale); n = 5] from Heron Island, Queensland Australia. All nematode samples were identified morphologically and genetically characterised using the small subunit nuclear ribosomal DNA (SSU). Some morphological differences were identified between previous studies of spp. and those observed herein but the significance of these differences remains unresolved. Molecular phylogenetic analyses revealed that larval sp. from and in Australia were very similar (with strong nodal support) to larval sp. infecting two fish species from Egypt, (Richardson) (Synodontidae) and (Linnaeus) (Sparidae). The SSU sequences of larval sp from and adults from formed a well-supported clade with that of adult Deardorff and Ko, 1983 from the Port Jackson shark, (Meyer), as well as that of the larval sp., from the common carp ( Linnaeus) from Egypt. This study extends the intermediate host range of larvae by including a sea snake for the first time. Findings of this study highlight the importance of genetic characterisation of larval and adult specimens of spp. to resolve the current difficulties in the taxonomy of this genus.