The Battle of Helminths Deep: Molecular Insights Into Oegopsid Squid Parasites in Aotearoa New Zealand

Abstract

Cephalopods play crucial roles in marine ecosystems due to their diverse and indispensable contributions to trophic webs. However, parasitological research on cephalopods remains limited in Aotearoa New Zealand (NZ), despite the commercial significance of certain squid species and the zoonotic potential of the parasites within them. This study aimed to enhance our understanding of parasitic infections in NZ deep-sea squid species. We examined 11 squid species, including the commercially harvested ‘arrow’ squids (Nototodarus sloanii and N. gouldi), alongside 5 additional large-bodied species: giant squid (Architeuthis dux), ‘hooked’ squids (Moroteuthopsis ingens and Onykia spp.), ‘flying’ squids (Todarodes angolensis and T. filippovae), Dana octopus squid (Taningia danae), and Pholidoteuthis sp., as well as a smaller-bodied glass squid (Teuthowenia pellucida), and cock-eyed squid (Histioteuthis sp.). Squid specimens were opportunistically collected during research surveys between 2016 and 2024. Their helminth parasites were sampled and sequenced for 28S rRNA, 18S rRNA, ITS1 and/or ITS2 rDNA. We identified 6 nematode taxa (Anisakis berlandi, A. pegreffi, Anisakis sp., Skrjabinisakis physeteris, Lappetascaris sp., and Crassicauda sp.), 3 cestode taxa (Tentacularia coryphaenae, Hepatoxylon trichiuri, and Clistobothrium sp.), and 1 trematode Accacoeliidae gen. sp. Furthermore, the genetic diversity of Anisakis spp. was analysed to explore potential influences of host geographic and phylogenetic patterns on parasite infections. This study contributes important baseline data to improve our understanding of parasite diversity in NZ cephalopods, with implications for ecological research and ecosystem management.