Molecular insights into the identification and phylogenetics of the cosmopolitan marine fish blood parasite, Haemogregarina bigemina (Adeleorina: Haemogregarinidae)

摘要

Haemogregarina bigemina is one of the most prevalent haemogregarines of marine fishes and has long been considered an enigmatic and cosmopolitan species. However, to determine whether H. bigemina truly represents a single global species, or whether it should be partitioned into several species or subspecies, and to confirm its taxonomic status among the Haemogregarina , molecular analysis is required. Here, we provide the first molecular characterisation of H. bigemina from one of its type hosts, Lipophrys pholis , in the UK using 18S rDNA sequences. Phylogenetic and p -distance comparisons of the newly generated H. bigemina sequences with those published from other haemogregarine taxa and related apicomplexans suggest that H. bigemina falls outside of the “ Haemogregarina ” clade as well as the Adeleorina altogether, forming a separate apicomplexan marine clade, and appears to be in fact more closely related to other non-haemogregarine Apicomplexa genera. Further work including sequences of H. bigemina and H. bigemina -like parasites observed from fishes in other localities is now needed to investigate this further.