Lithodid crabs constitute a valuable natural resource with commercial interest; however, their health status in South America is scarcely studied. The presence of pathogens may have a negative impact on affected populations, endangering the fishery. This study surveys the symbionts present in populations of the king crab, Lithodes santolla, and the stone/false king crab, Paralomis granulosa, using histology, transmission electronic microscopy, and molecular analyses to characterise various symbionts. The histological and molecular data revealed a wide range of infections in L. santolla, including prokaryotic microorganisms, Areospora rohanae (Microsporidia), apicomplexan gregarines, ciliated protozoans, ectoparasitic crustaceans, and various epibiotic associations. In the case of P. granulosa, apicomplexan gregarines, ciliated protozoans, and various ectoparasites were observed. Molecular analyses confirmed the presence of the microsporidian A. rohanae, occurring at high prevalences (30%) in L. santolla, and some bacterial associations. We use metagenomic tools to extract a partial genome of this parasite to aid in its identification and taxonomic position, which leads us to erect the taxonomic orders Astathelohaniida and Areosporida and further clarify the previously assigned: "Glugeida+". The results of this study represent the first broad survey for symbionts in both king crab species and take us another step forward to a more accurate microsporidian taxonomy.
Frizzera et al. (Sat,) studied this question.