Occurrence on wood substrate: Whitish to yellowish plasmodium and mustard-yellow plasmodiocarp appears on dead wood, leaves, and plant litter; June through August. Dimensions: Network of veins and resultant spore- forming structure can cover many square centimeters. The outer walls break down, revealing a cottony, mustard-yellow spore mass. Comments: Although many slime mold species fruit on wood they do not form a penetrating and absorptive mass of hyphae in the wood substrate. Rather, slime molds form structures called plasmodia which are naked i.
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Etymology[ edit ] "Trichiida" comes from the Greek thrix or trichos, which refers to hair or hair-like structures. History of knowledge[ edit ] The Myxomycetes were originally placed within the Kingdom Fungi by many zoologists, despite originally being placed within the group Protista by Ernst Haekel in Trichida has also been classified with its sister group Liceida in an order called the Lamprosporales by Lister and Lister in ,  but the two were separated in subsequent works.
This included The Myxomycetes by G. Martin and Constantine Alexopoulos, published in , which has been and still is considered one of the most useful pieces of literature for studying the Myxomycetes. Again, these two families are distinguished primarily through differences in the capillitium. The members of Dianemaceae are those that exhibit capillitium threads that are attached to the base or walls of spore and never form a net, while the Trichiaceae are categorized as having capillitium threads that are free or attached to the base of the spore, often in a net formation.
The most recent treatment of the order has four families;   however, many researchers have noted that distinguishing these families from each other, as well as the genera, is exceedingly difficult due to the fact that many species have features and morphologies found in more than one family. Molecular research into the order Trichiida itself has only occurred very recently. The first molecular sequencing research done on the Mxyomycetes was performed in by Anne-Marie Fiore-Donno et al.
The phylogeny generated by Fiore-Donna supported the close relationship between Trichiida and Liceida as well as other taxonomy predicted by morphology. In more recent research, it has been the delineation between Trichida and Liceida that has come into discussion.
Liceida is a complex order that is not likely monophyletic due to its defining feature being the absence of a capillitium. Fiore-Donna proposed the formation of new clades between Trichida and Liceida to account for the different types of pseudocapillitiums seen1. Another possible suggestion has been the break down of the Liceida order into several new clades. This would include the formation of the Trichiod clade, which would contain all the members of the Trichida order, as well as closely related members of the Liceida order, while the rest of the Liceida order would be split amongst several other newly clades based on molecular data.
The Myxomycete life cycle consists of two trophic phases: the smaller, amoebic phase where the organism has a single nucleus and may or may not also have flagellum for motility. The other phase is the macroscopic plasmodium, which arises from the fusion of multiple cells in the amoebic phase.
It contains the sister groups Trichiida and Liceida. Liceida is characterized by a complete lack of any capillitium  although some members may exhibit a pseudocapillitum  while members of Trichiida always have a capillitium. The genera of Trichiida usually have brightly coloured spore masses, with fruiting bodies that are either fixed and immobile or forming growing stalks. The development of the capillitium in Trichida is formed through tubular vacuoles within the plasmodium that are organized into the desired shape of the final capillitium, including potential branches and spirals.
Proteins then accumulate within these vacuoles, hardening them to form the mature structure. The presence of lime, or calcium carbonate within the capillitium has often been used to discern separate species. Species of the genera Hemitrichia, Trichia and Arcyria are numerous and easy to locate in forests from spring to late fall.
It is known for its plasmodial form, which is seen as a distinct golden-yellow network of tubes. Due to its wide spread habitat, Hemitrichia serpula has been used to study the process of speciation and gene flow in the Myxomycetes.
Hemitrichia therefore refers to the condition of partially having hair. Josef Rostafinkski described Hemitrichia in the family Trichiaceae, along with another genera Trichia. Trichia was described as having numerous capillitium threads, which are free and tapered at the ends. The presence of a net-like capillitium is likely the most defining and recognizable feature of the genus Hemitrichia, as it has been mentioned by almost every author in his or her description of the genus.