A New Type of Echinactinomyxon (Myxozoa), Infecting a Marine Polychaete, Heteromastus filiformis (Polychaeta: Capitellidae) In the Alvor Estuary (Portugal)

The study of Actinosporea (a former class of the Myxozoa) was conducted for many years without the knowledge that they represented the definitive stage of the life cycle of myxosporean parasites [1–3]. The discovery of the life cycle of Myxobolus cerebralis altered this perspective [1], leading to the elucidation of several other life cycles in the past few years [2,3]. Most studies aim at the life cycles of freshwater Myxozoa infecting oligochaete hosts, while in the marine environment there are many species of Myxozoa whose life cycles are yet to unravel. In this work we present a new type of marine actinospore of the collective group Echinactinomyxon. Polychaetes were collected in the Alvor estuary, Portimão, Algarve, downstream to a fish farm. Specimens were examined using differential interference contrast (DIC) optics. Measurements of actinospores were taken from fresh material. Infected polychaetes were processed for molecular procedures, namely sequencing of the SSU rRNA gene. For inferring phylogenetic relationships, the Maximum Likelihood (ML) method was performed in MEGA 5.05, using Kimura 2-parameter as substitution model with uniform rates.