Arachniotus ruber was first described by Philippe Édouard Léon Van Tieghem in 1877 and it was thought to belong to the genus, Gymnoascus, due to similarities he observed in the gametangial initials.
[3][2] At the time, Schroeter did not designate a type species for the genus, which resulted in some debate until a lectotype, A. candidus, was eventually identified by Clements and Shear in 1931.
[2] Arachniotus ruber have discrete ascomata present, usually confluent and mostly spherical, measuring 20-200 μm and are red, orange, and brown in colour.
[2][4] They have an equatorial groove along the longitudinal axis, giving them a shape similar to that of a pulley wheel, and they measure 2.8-4.4 x 4-6.6 μm.
[8] As A. ruber grows on this medium, it will initially form white hyphae that will turn orange red and the colonies are pasty with occasional concentric rings of mycelium.
[10] The experiment used dry banana peels as a basis for the substrate and prepared A. ruber in media, autoclaving the two together under various conditions.