A Parasite in Paradise: Marinomyxa halophilae Infects Halophila decipiens and Halophila hawaiiana, With Observations of Infected Fruits

As seagrasses decline, parasites continue to threaten remaining populations. Upon observing galls in Hawaiian seagrasses, efforts were undertaken to identify their cause, resulting in the first identification of infections by the seagrass parasite Marinomyxa halophilae in Halophila hawaiiana and in Hawaiian populations of H. decipiens . In both hosts, M. halophilae could be found year-round and was relatively common. Samples were taken from three sites per host, and sequencing of the ribosomal 18S gene revealed two strains, each specific to the host species. New gall morphology was identified for Marinomyxa infections in Halophila , namely, infections of H. decipiens with reduced internodes and infections of H. hawaiiana extending beyond petioles into fruits, representing a potential threat to seed-based restoration efforts.