Flooded jellyskin (Leptogium rivulare) COSEWIC assessment and status report: chapter 2

Executive Summary

Flooded Jellyskin
Leptogium rivulare

Species information

Leptogium rivulare (the Flooded Jellyskin) is a small foliose lichen characterized by blue-grey lobes with a smooth, unwrinkled surface, abundant small brown discs with thin, even margins, which are the fruiting bodies, and especially the spores, which are produced 4 in each spore sac rather than 8, as in most other species of the genus. It is also confined to a very distinctive habitat (see below).

Distribution

Scattered northern temperate to temperate localities in eastern North America and western Europe. In Canada, known from 6 localities in Ontario and Manitoba, in the Mixedwoods Plains and Boreal Shield ecozones.

Habitat

Restricted toperiodically inundated substrate, usually the bark of trees along the banks of ponds and waterways, and in wet lowland forests flooded every spring. It occurs almost exclusively on the bark of living deciduous trees, and always below the high-water mark.

Biology

Flooded jellyskin lichen reproduces readily, presumably by spores, and disperses over at least short distances. It is able to colonize newly developing substrates (tree bark), and once established is able to survive dry years. It persists long enough to form dense mats on some trees. Its spread may be limited by an ineffective means of dispersal.

Population sizes and trends

This species has been considered rare wherever it occurs, in North America or in Europe. In Canada, it is currently known almost entirely from trees in just a few small, seasonal ponds at each of two localities. At these sites, such trees number in the dozens to hundreds, and the lichen populations appear to be healthy and well established. Very small amounts of the lichen have also been found on seasonally submerged rocks at two additional localities under very different substrates: a turbulent stream and a rocky lakeshore.

Limiting factors and threats

Flooded jellyskin lichen is limited to a very narrow strip of land – and usually tree trunk – between the seasonal high and low water marks. The species is therefore especially vulnerable to changes in the normal pattern of annual flooding. A drier climate could deprive the species of much suitable habitat. The removal or death of the trees would eliminate most of the substrate.

Special significance of the species

The rarity of this species worldwide indicates its vulnerability. It is of scientific interest because of its requirement for and ability to thrive in a very unusual habitat.

Existing protection or other status designations

There is no specific protection, and the species has no status designation in Canada, other than an SH ranking in Ontario, signifying a lack of recent records.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2004)

Species
Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X)
A species that no longer exists.

Extirpated (XT)
A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)
A species facing imminent extirpation or extinction.

Threatened (T)
A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)Footnote1
A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)Footnote2
A species that has been evaluated and found to be not at risk.

Data Deficient (DD)Footnote3
A species for which there is insufficient scientific information to support status designation.

 

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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