Abstract
Perkinsea is a phylogenetic group of protists that includes parasites of distantly related hosts. However, its diversity is still mainly composed of environmental sequences, mostly obtained from freshwater environments. Efforts to isolate and culture parasitoids of dinoflagellates have led to the description of several phylogenetically closely related species constituting the Parviluciferaceae family. In this study, two new parasitoid species infecting dinoflagellates during recurrent coastal blooms are reported. Using the ribosomal RNA (rRNA) gene phylogenies, we show that both cluster within Perkinsea, one of them at the base of Parviluciferaceae and the other in a distinct branch unrelated to other described species. The establishment of host-parasite lab cultures of the latter allowed its morphological characterization, resulting in the formal description of Maranthos nigrum gen. nov., sp. nov. The life-cycle development of the two parasitoids is generally the same as that of other members of the Parviluciferaceae family but they differ in the features of the trophont and sporont stages, including the arrangement of zoospores during the mature sporangium stage and the lack of specialized structures that release the zoospores into the environment. Laboratory cross-infection experiments showed that the parasitoid host range is restricted to dinoflagellates, although it extends across several different genera. The maximum prevalence reached in the tested host populations was lower than in other Parviluciferaceae members. The findings from this study suggest that Perkinsea representatives infecting dinoflagellates are more widespread than previously thought.
Highlights
The class Perkinsea was erected to encompass parasitic species of the genus Perkinsus, being characterized by having an incomplete conoid (Levine, 1978)
Using single-sporangium amplification of the ribosomal RNA (rRNA) gene obtained from an established culture, we demonstrate that the latter species is the first representative infecting dinoflagellates forming an undescribed distinct branch within Perkinsea
SSU rRNA gene sequences of the three cultured strains corresponding to M. nigrum had an identity of 100%, with only 1–3 differences, all corresponding to ambiguous (Ns) positions
Summary
The class Perkinsea was erected to encompass parasitic species of the genus Perkinsus, being characterized by having an incomplete conoid (Levine, 1978). Like Perkinsus, Parvilucifera species have an incomplete conoid, and the formation by the two genera of a clade independent of Apicomplexa led to the establishment of the phylum Perkinsozoa (Norén et al, 1999). Within this phylum, the class Perkinsea currently includes the family Perkinsidae, which encompasses Perkinsus species that infect bivalves (Andrews, 1988), the family Parviluciferaceae, comprising genera of closely related parasitoids (parasites that kill their hosts) of dinoflagellates (Reñé et al, 2017a), and the family Xcellidae whose member species infect fish (Freeman et al, 2017). Besides the abovenoted species and groups, Perkinsea contains a vast diversity and is mostly represented by environmental sequences with unknown correspondence
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
