Protistidel

Protistidel is a proposed taxonomic group within the eukaryotes, encompassing certain parasitic protists. While not universally recognized as a formal phylum, it has been used in some classifications to group organisms sharing specific evolutionary and biological characteristics. The primary members of this proposed group are historically referred to as gregarines, which are a diverse assemblage of apicomplexan parasites that infect invertebrates, particularly arthropods and annelids. Gregarines are characterized by their large size, intracellular or extracellular parasitism, and the formation of a gametocyst for reproduction. They typically infect the digestive tract of their hosts.

The concept of Protistidel arose from attempts to organize the vast diversity of protists based on molecular phylogeny and ultrastructural evidence. However, the precise phylogenetic relationships and the boundaries of such a group remain subjects of ongoing research and debate within the scientific community. Traditional classifications have often placed gregarines within the phylum Apicomplexa, a group also known for including medically important parasites like *Plasmodium* (causing malaria) and *Toxoplasma*. The debate over formalizing Protistidel reflects the dynamic nature of protist classification as new data continually refine our understanding of eukaryotic evolution. Currently, many researchers prefer to discuss these organisms within the broader context of Apicomplexa.