Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Basidiomata: resupinate, thin or thick, often irregular, frequently poorly delimited, gall-like swellings of the host thallus, waxy-gelatinous, pale brown (more orange-brown than the host thallus and therefore easily distinguishable) to black (in R. cuspidata), 0.3-2 mm in diam.; fertile hyphae: thick-walled, 2.5-5 µm in diam., at least some with clamp connections haustorial branches: present, with clamp connections; mother cell: subspherical or ellipsoid, 3.5-5.5 µm in diam., haustorial filament: 1-1.5 µm thick, up to at least 11 µm long hymenium: hyaline, containing numerous probasidia; probasidial initials: ellipsoid, proliferations occurring through the basal clamp; hyphidia and cystidia: absent basidia: when mature, 2-celled, with one longitudinal or rarely oblique septum, 10.5-15.5 µm in diam., near the septum 12-17 µm long, both cells elongating at maturity, up to 30 µm long (epibasidium not included), in the upper part 4.5-7 µm in diam.; epibasidia: shrunken in herbarium material, probably subcylindrical and 2-4 µm thick, at least 30 µm long basidiospores: subspherical to shortly ellipsoid, with a distinct lateral apiculus, (5.5-)7.5-9(-11) x (4-)6.5-8 µm Anamorph: unknown. Hosts: thalli of Ramalina sinensis on conifers in a spruce-fir forest, in Europe also on R. cuspidata World distribution: oceanic, western Europe and southwestern North America Sonoran distribution: not yet confirmed but known from a habitat in New Mexico similar to Arizona. Notes: This species is characterized by its longitudinally 1-septate basidia, in which each cell elongates when mature and becomes much longer than the septum. Two lichenicolous species with similar basidia are known. Basidiomata of Tremella christiansenii Diederich induce the formation of brown to dark brown, convex, irregular and often tuberculate or cerebriform galls on the thallus or apothecia of Physcia species; its basidiospores are distinctly larger, 9-12 x 8.5-10.5 µm, and its haustorial cells smaller, 2.5-3 µm in diameter. Tremella hypocenomycis Diederich has black, irregular, often tuberculate or cerebriform basidiomata, smaller basidiospores, 5.5-6.5 µm in diam., and a different host, Hypocenomyce scalaris. Tremella tuckerae is readily distinguished from Tremella ramalinae, known from the same host genus. The latter species typically has pyriform, (3-)4-celled basidia with two transverse septa, and its upper third is divided by one longitudinal septum. Atypical specimens of T. ramalinae with many longitudinally septate basidia differ from T. tuckerae by its 4-celled basidia whose individual cells do not elongate at maturity.