Monomyxum ligophori n. sp. in a ParasiteBlitz: monopisthocotylans as myxozoan hosts in South Carolina and monophyly of a cosmopolitan hyperparasitic clade

Abstract

A ParasiteBlitz event offers a brief, intense opportunity to discover diverse parasite species and to reveal life cycles of heteroxenous parasite taxa. In this study, we describe Monomyxum ligophori n. sp., a hyperparasitic myxozoan (Monomyxidae) proliferating in two dactylogyrid mono-pisthocotylan flatworms (Ligophorus saladensis, Ligophorus mugilinus) infecting mugilid fishes (Mugil cephalus, Mugil curema) on the Atlantic coast of North America. Furthermore, we used DNA barcoding to infer the parasite's complex life cycle, matching its hyperparasitic myxospore stages with actinospore stages infecting the polychaete Streblospio benedicti found in the same locality during the ParasiteBlitz and also reported previously from the same region. Thus we report the first life cycle of a myxozoan that most likely does not require a vertebrate host. Hyperparasitic myxozoans are rare with only five species reported worldwide to infect flat-worms. This study provides more information on the previously discussed host specificity towards monopisthocotylan hosts of these monomyxid myxozoan hyperparasites. Notably, Monomyxum ligophori n. sp. was detected in two out of four gill-infecting parasitic flatworms (being absent in Ligophorus uruguayensis and Metamicrocotyla macracantha) found infecting the same fish individuals during the ParasiteBlitz. Our molecular data and phylogenetic analysis support the previously suggested common origin of Monomyxum species infecting monopistho-cotylan flatworms, and contribute to understanding the life cycle and host interactions of this unique hyperparasitic myxozoan lineage.