A New Mayorella Species Isolated from the Mariana Trench Area (Pacific Ocean)

In this paper, we describe a new naked amoeba species, Mayorella marianaensis sp. n., order Dermamoebida, isolated from the bottom of the Pacific Ocean (>3,000 m depth) in the vicinity of the Mariana Trench, based on morphological and molecular data. The newly discovered species was identified based on morphological and molecular data. This is the first time that a Mayorella species was discovered in the deep sea (>1,000 m). Mayorella marianaensis is an irregularly rectangular naked amoeba (30–120 × 11–60 µm), with a narrow frontal hyaline area. Four to 15 conical sub-pseudopodia, and three kinds of floating forms are identified. Trophozoites have a thick cell coat consisting of two distinct layers. The small subunit ribosomal RNA gene phylogeny showed that M. marianaensis is classified into Dermamoebida, and is a sister clade to other Mayorella species whose sequences are available. BLAST analysis revealed that M. marianaensis is most similar to Coronamoeba villafranca and Mayorella sp. JJP-2003, with sequence identities of 92.43% and 88.30%, respectively.