Key to Genera
Recent studies have greatly improved our understanding of the various phylogenies involved with the Calicioids. However, that has made the circumscription of genera rather fluid. I expect we have only begun to see the changes. I expect some further rearrangment of the Caliciaceae and Coniocybaceae (Chaenotheca and Sclerophora) plus a major reconfiguration of the non-lichenized Mycocaliciales.
1a. Ascomata with a distinct stalk.
2a. Spore mass brown, orange, or pale and often yellowish.
3a. Spore mass orange, stalk and excipulum with hyaline hairs, up to 0.3 mm tall, with a greenish reaction in KOH. Previously called "Cryptocalicium" but that name is now in use for another fungus (see Prieto et al. 2021)."Within-bark" 3b. Spore mass brown or pale and often yellowish.
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5a. On bark of Juniperous, found on the back-side of bark strips. Known from Mediterranean Europe.Cryptocalicium -
4b. Lichenized, not on resin.
6a. Spore mass distinctly brown. Various photobionts may be present, including Trentepohlia.Chaenotheca 6b. Spore mass distinctly pale, often combined with a white or yellow pruina. Photobiont exclusively Trentepohlia.Sclerophora
2b. Spore mass black or dark greenish, sometimes dusted with pruina but the underlying spore mass is detectably black.
7a. Forming a true mazaedium of loose spores from the premature disintegration of asci (leading to a thick mass of loose spores intermixed with remaining asci, which will contain only smaller, immature spores).
8a. Spore mass with a peculiar greenish color, mature spores narrow with parallel sides (elliptical only when young), abruptly rounded, with a strong spiral ornamentation.Microcalicium 8b. Spore mass without a peculiar greenish color, or if so, then spores spherical to elipsoidal; sides not parallel.
9a. Excipulum with a tightly constricted margin, spores non-septate or if septate then with a thin wall and lacking clear ornamentation.Sphinctrina 9b. Excipulum generally not constricted, if so, then spores septate and typically with a thick wall ornamented with cracks.
10a. Occurring on wood or bark of tree trunks; while some semi-tropical species grow in exposed sites, most temperate species are limited to areas protected from direct rainfall. Stalks typically black or dark brown. Spore ornamentaion variable, including some species with spiral cracks.Calicium 10b. Growing where clearly exposed to precipitation on tree branches, or if on trunks then very near the top. Stalks often pale and sometimes thalloid, but they can be nearly black. Known taxa are non-tropical (known from Mediterranean, temperate, and boreal zones). Spores ornamented with spiral cracks.
11a. Stalks very thick, generally thicker than the capitulum (head), whitish, up to 1 cm tall. Known only from the upper portions of conifers at higher elevations, especially krumholtz.Tholurna dissimilis 11b. Stalks narrower than the capitulum (or perhaps gradually widening toward the base to a roughly equivalent width); pale in well developed specimens but often dark to nearly black in small ascomata; usually much less than 1 mm tall but occasionally found up to about 2 mm. Typically found on hardwood trees and shrubs but also near the tops of Abies in lower elevations.Allocalicium adaequatum
7b. Non-mazaediate, or weakly mazaediate (spores remaining in the asci until mature, then extruded so as to leave a layer of loose spores over the hymenium). These are the Mycocaliciales... a group recognized to be artificial genera and likely to be reworked when sufficient phylogenetic information is known.
12a. Spores regularly multiseptate and capitulum not flattened. This is the traditional concept of Stenocybe, as opposed to the works of Titov. Several species currently placed in Phaeocalicium will key here, but are later distinguished in the genus key.Stenocybe 12b. Spores non-septate, or with a single septum (occasionally more in some Phaeocalicium), or regularly multiseptate and with a flattened capitulum.
13a. Mature spores more or less pale as seen in a compound microscope.Chaenothecopsis 13b. Mature spores with a heavy brown pigmentation as seen in a compound microscope.
14a. Mature spores with rounded ends, typically > 10μm long, growing mainly on branches.Phaeocalicium 14b. Mature spores allantoid (with pointed ends), typically < 10μm long, growing mainly on tree trunks.
15a. Ascus tip lacking an apical canal (try a cytoplasmic stain, such as cotton blue). Typically on hard dead wood and sometimes showing the immersed thallus as a pale zone.Mycocalicium -
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16a. Spore mass with a peculiar greenish color.
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16b. Spore mass without a peculiar greenish color.
18b. Rim of excipulum not tightly constricted.
19b. Thallus crustose, medulla not yellow to orange (or if so, then cortex is also).
20a. Ascomata fully immersed in the thallus such that the rim of the excipulum does not rise above thalloid tissues.
21a. On rock; ascomata immersed in thallus; thallus gray to brown, not intensely yellow.Thelomma -
20b. Ascomata sessile or only partially immersed such that the rim of the excipulum is distinctly visible above the thallus or substrate.
22a. Excipulum strongly thickened at base; thallus distinct, greyish, greenish, or brownish.Acolium 22b. Excipulum not strongly thickened at the base, thallus immersed or superficial and of various coloration.Calicium