by Eric B. Peterson
Table of Contents
- Introduction (this web-page, below)
- Key to Genera
- Key to Algae
- Literature Cited
The purpose of this work is to enable identification of a group of lichens and associated fungi that remain incompletely known in most regions. Many species occur on multiple continents and significant range-extending discoveries are frequent, such that keys to locally known species would almost certainly be incomplete. Therefore this work attempts to span all taxa that are in use in contemporary literature (roughly since the mid 1960’s) world-wide.
This is an on-going project; the keys are not meant to serve as final word on the determination of a specimen. I recommend that all determinations be followed up by consulting additional published taxonomic works or verification by an expert in Calicioid taxonomy.
Although the old Caliciales [Ach.?] is an invalid phylogenetic group (_), most taxa that formed the group possess important characters that unite them ecologically. Most have stalked ascomata with loose spores remaining at the top (either a true mazaedium or spores piling up after active, but weak discharge). This structure suggests similar spore dispersal mechanisms. Also most taxa from the Caliciales occur in one of two specific types of habitats: (A) on twigs, usually with very strong host specificity, and (B) in sheltered sites on old wood or bark. Some genera utilize both habitats. For example in the lichenized genus Calicium, the species C. adaequatum inhabits twigs of a selection of hardwood trees and shrubs, while other species in the genus inhabit sheltered sites, particularly on old wood or bark; similarly in the Mycocaliciaceae, Stenocybe pulatula inhabits twigs of the hardwood genus Alnus, while Stenocybe clavata inhabits old bark on conifers. Thus the old group has been retained by ecologists as a functional group, the ‘calicioids’.
While ‘calicioids’ may form an ecologically justified group; there are similar looking fungi and slime molds that occasionally appear in calicioid habitats. Most are not as restrictive to these habitats, so continue to be excluded from the ecologically-based definition of ‘calicioid’. There are a few species which might be justifiably included, though the habitat restrictions seem to be just for one or a few species within their genera – not genus-wide as with the excepted ‘calicioids’.
Slime-molds (Plasmodial slime molds; mycomycetes) may occur on twigs and on old wood habitats similar to calicioids. Usually in the case of old wood, the microhabitat is more damp than calicioids tolerate. Slime molds can be easily distinguished from calicioids in that their stalk tends to taper strongly upwards; the sporangium is often quite shiny and disintegrates, briefly leaving a fine, open, web-like structure; and of course spores are not produced within asci. The stalk and sporangial characters are illustrated in Figure 1.
S… (PSME resin)