Flooded jellyskin (Leptogium rivulare) COSEWIC assessment and status report: chapter 11
Summary of Status Report
Leptogium rivulare is a globally rare lichen with very restrictive habitat requirements. In Canada, it has previously been known only from a few herbarium specimens. These have indicated nothing about the populations involved. Four localities are now known. Populations at two sites are relatively large but the two others are much smaller. The largest population is protected, albeit weakly, by federal regulations.
Both of the major localities are susceptible to degradation associated with the observed increase in use and development of the lands. More generally, potential habitat is easily diminished or even eliminated by interference with the extent or duration of spring flooding. This lichen also has a requirement for living tree bark as a substrate, and thus depends on the existence of a living flood-zone forest. The main threats to these forests are introduced pests and diseases. The lichen itself appears to be susceptible to competition from mosses, which overgrow it.
The central question is whether the lichen is truly as rare as the extremely sparse records indicate. On the one hand, there are innumerable patches of potential habitat across its range, and it is unikely that we have found all the Leptogium rivulare that exists.
On the other hand, the region where the species is now found has been well studied by lichenologists, and careful searching of the full range of habitat possiblities in more than 60 sites, in the vicinity and region of the existing and historical populations, has failed to turn up any sign of it.
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