Helkesida

Helkesida, formerly known as Sainouroidea, is a group of microscopic protists within the supergroup Rhizaria, discovered through molecular phylogenetic analyses. These organisms are amoeboid flagellates with two flagella and are found either free-living in aerobic environments, often on fecal matter, or as endozoic inhabitants of animal guts.

Biológicamente, Helkesida species exhibit gliding motility using their posterior flagellum. They lack scales or a theca and possess flat or discoid mitochondrial cristae, which is unique among Rhizaria. Their kinetid structure includes short centrioles with dense roots, and their anterior flagellum lacks an axoneme. The group also features an apical centrosome connected to the nucleus via a rhizoplast.

In terms of ecology, these amoebae are bacterivores thriving in aerobic or microaerobic environments. Some species can live freely, while others reside within animal guts. They have been found in diverse hosts, but further research is needed to fully understand their distribution and interactions.

Evolutionarily, Helkesida was first identified as Sainouroidea in 2009 before being reclassified into its current taxonomic framework in 2018. The group comprises two superfamilies, with species distributed across three families: Guttulinopsidae, Helkesimastigidae, and Rosculidae. Environmental studies have revealed a diverse array of species previously overlooked due to their highly divergent DNA sequences.

This summary captures the key aspects of Helkesida's biology, ecology, and evolution based on the provided information.