Characterisation of Ascaridoid larvae from marine fish off New Caledonia, with description of new Hysterothylacium larval types XIII and XIV

Abstract

Here we report occurrence of six different morphotypes of ascaridoid type larvae from 28 species of fish collected from New Caledonian waters. The larvae were morphologically identified as Anisakis type I, Hysterothylacium type VI and new larval types XIII and XIV, Raphidascaris larval type and Terranova larval type II. Representatives of each morphotype were subjected to the amplification of the second internal transcribed spacers (ITS-2) of ribosomal DNA (rDNA) and those sequences were compared with ITS-2 sequences of other ascaridoid nematodes previously deposited in GenBank. ITS-2 sequences of Anisakis larval type I were identical to those of A. typica. ITS-2 sequences of Hysterothylacium larval type VI in the present study were identical to those previously found in Eastern Australian waters. No match was found for ITS-2 sequences of Hysterothylacium larval types XIII and XIV; therefore, the specific identities of these larval types remain unclear. ITS-2 sequences of Raphidascaris larval type were identical to those of R. trichiuri, which have previously been reported in Taiwanese waters. Terranova larval type II in the present study had identical ITS-2 sequences with Terranova larval types reported from Australian waters, however, the specific identity is unknown. This taxonomic work is essential if further research on these zoonotic parasites is to be effective. This includes investigations into such aspects as life cycle studies, impacts on human health and risk assessment for their transmission to humans.