Maullinia is a genus of intracellular, phytomyxid parasites found across the Southern Hemisphere though primarily in Chile, The Prince Edward Islands, South Africa, Australia, and New Zealand.

[1][3] These swollen regions will burst alongside the mature Maullinia plasmodia, releasing biflagellated zoospores to the inter- and extracellular space to disperse the infection further.

[3] As Maullinia can infect a wide range commercially important brown algal hosts, they present a significant threat to kelp farming and mariculture efforts.

[1] These infections could also cause significant harm on a global scale to natural populations, as they are able to disperse over long distances via rafting and tend to thrive in the cooler waters where kelp are often found.

[7][8][9] The cause of these galls was first investigated purely by chance, when a team of researchers from the University of Konstanz, led by Dr. Ingo Maier, were conducting an epiphytic algal study in Chile.

[1] Some specimens of Ectocarpus siliculosus in a Chilean mariculture plantation appeared to have parasitic infections,[1] which piqued the research team's interest.

[1] Close to a decade later, while investigating gall-forming infections on fronds of the kelp Durvillaea antarctica, researchers produced the first evidence of a second Maullinia species.

[1] These appendages are oblong to sub-spherical in shape, extending predominantly from the terminal cell on each main filament axis, but are also seen on the lateral branches.

[10] Maullinia infections of non-filamentous brown algae primarily target adult hosts, and are mostly absent during their reproductive periods.

[1] In recent years however, new evidence has been revealed supporting intracellular phagotrophy as the primary mode of nutrition, with osmotrophy as a secondary function.

[12] This preference could be due to several factors, namely active targeting by Maullinia, the widespread nature of plastids within brown algal cells, or simply a slower digestion process of these complex pigment-containing organelles.

Maullinia is found across much of the Southern Hemisphere, with infected brown algal populations in Chile, The Prince Edward Islands, South Africa, Australia, and New Zealand currently known.

[4] While many parasites prefer warmer environments, Maullinia appears to thrive in lower temperatures, having greatest infection rates during the winter months and at greater latitude.

[3][4] The two species of Maullinia appear to have some preference for habitat, based on the brown algal hosts which they each primarily infect.

With the hypertrophied cells forming galls, a greater buoyancy is achieved in infected individuals, allowing them a wider distribution capability.

[5] The role of rafting, alongside the widespread populations separated by thousands of kilometers, implies that Maullinia may be capable of achieving global distribution along cold-temperate coasts.

[1] This growth may alter the hosts metabolic functioning, collecting energy-rich compounds within the cell to help feed the Maullinia parasite,[10] although this theory is not proven.

[3] Mature plasmodia transform into a single sporangium, which develops near the host cell wall and becomes attached to it via deposition of a fine, but dense, fibrillar wall-like material.

[2] The plasmodium begins resting spore development by concentrating cytoplasm around the nucleus, allowing the thick, 3-layered wall to start forming.

[1] These kinds of infections could compound with the delivery of brown algal viruses alongside the parasite, decimating entire kelp cultures in the process.