Collodictyon triciliatum

Collodictyon is a basal genus of single-celled eukaryotes not closely related to any heretofore known kingdom of that domain. Three species are currently recognised in this genus. The type species is Collodictyon triciliatum. A second species—Collodictyon sparsevacuolatum—named by Skuja is also recognised; this species is found in freshwater in the United States and Europe. A third species Collodictyon sphaericum has been described but its description is in doubt. A fourth species—Collodictyon hongkongense—has been described by Skvortzow but this description is considered inadequate and this species is regarded as being of dubious validity. Along with the genus Diphylleia, this organism appears to be only distantly related to the other eukaryotes. They share some morphological features with the species currently placed within the Excavata. However this latter clade is considered to be polyphyletic and in need of resolution (reorganisation into different groups). For this reason inclusion of this genus within the excavates may not assist in understanding its phylogenetic position. Brugerolle has proposed a family, Collodictyonidae for this genus and Diphylleia. Another genus that is related to Collodictyon is Sulcomonas. Scientists speculate that further study of Collodictyon may yield insights into the prehistoric beginnings of life hundreds of millions of years ago. Scientists from Norway have been studying a particular type of Collodictyon found living in sludge in Årungen, a lake in the municipality of Ås in Norway. Kamran Shalchian-Tabrizi, the leader of the Microbial Evolution Research Group (MERG), has claimed that these organisms resemble the basal eukaryote. Collodictyon now appears to have emerged in Varisulca. The species in this genus range in size from 30 to 50 µm in length, can grow broad pseudopodia, and have four flagella and a ventral feeding groove or sulcus. They are devoid of cellulosic cell walls, chloroplasts or stigmata. There are two to several contractile vacuoles.