Order Haplosporidia is a taxonomic group that includes parasitic organisms like Haplosporidium nelsoni and Haplosporidium costale. Some synonyms for this order include Class Haplosporea and Subphylum Haplosporidia. These synonyms are used interchangeably in various scientific studies, and are often used to classify organisms based on their morphological and molecular characteristics. It is worth noting that the classification of Haplosporidia is still evolving, and new taxonomic names may emerge as more information becomes available about these organisms. Nonetheless, the existing synonyms provide researchers with a framework for understanding the diversity and evolution of this fascinating group of parasites.