Spoon-leaved moss (Bryoandersonia illecebra) COSEWIC assessment and status report: chapter 2

COSEWIC Executive Summary

Spoon-leaved Moss
Bryoandersonia illecebra

Species information

Bryoandersonia illecebra is a distinctively robust, shiny, julaceous (smoothly cylindric, like a rat’s tail) moss (Division Bryophyta, subdivision Musci, order Hypnales). The genus Bryoandersonia is monotypic, and belongs to the large and variable family Brachytheciaceae. “Illecebra” means “attractive, or alluring”. The species’ large size and distinctive form make it easy to see and identify in the field.

Distribution

Bryoandersonia illecebra is endemic to eastern North America, where it ranges widely throughout the deciduous forest, although it occurs most commonly in the south. It is distributed from southern Ontario to Connecticut, New York, Ohio, Indiana, Iowa, Florida, and Texas. Twelve contemporary (since 1970) Canadian collections of B. illecebra, representing 6-8 sites, are known from the counties of Essex, Middlesex, Elgin, and Welland in southern Ontario. All contemporary sites were searched in 2001 and 2002, and three extant populations of B. illecebra were recorded in Essex, Elgin, and Welland Counties in 2002.

Habitat

Bryoandersonia illecebra prefers soil substrates, particularly on banks, although it sometimes occurs on rocks or tree bases. Canadian collections are from a variety of habitats (e.g. wet deciduous woodlot, grassy clearing among planted pines, among cedars in a swamp), which may make it less vulnerable to destruction or modification of a specific habitat type. All confirmed (2002) Canadian extant populations of B. illecebra grow in flat, low-lying areas affected seasonally by standing water. Like many Canadian Carolinian (eastern deciduous forest) species, B. illecebra appears to be limited climatically to the warm, southern tip of Ontario. Heavy urban, agricultural, and industrial development characterizes southern Ontario, and has resulted in extensive destruction and fragmentation of forested habitats there. Conversations with past collectors have shown that plant communities at several B. illecebra sites have changed substantially since they were last visited (prior to 2002).

Biology

Little research concerning the biology of Bryoandersonia illecebra has been conducted. Like all mosses, B. illecebra requires at least periodic moisture for fertilization, establishment, and growth. B. illecebra is dioicous, meaning that separate male and female plants must grow within a distance negotiable by sperm cells (a few centimetres) for successful fertilization. Sub-optimal environmental conditions at the edge of the species’ range compounded by habitat fragmentation may increase the distance between populations, thereby contributing to difficulty in sexual reproduction and dispersal. No sporophytes (fruiting bodies) have been discovered on Canadian collections of B. illecebra to date, and the author has found only female plants among these specimens. B. illecebra lacks vegetative propagules, but its pleurocarpous (creeping) growth form allows colonies to spread within the limits of local substrate availability.

Population sizes and trends

Three extant populations of Bryoandersonia illecebra,of which one or possibly two were previously recorded, were discovered in 2002. They consist of one to a few colonies measuring 50 cm² to 12 , although all sites were too large to survey in entirety. Only one of these populations is thought to have been previously documented, and its size was not noted at that time. B. illecebra may have been collected in abundance near to where the largest extant population was found.

Limiting factors and threats

Factors limiting Bryoandersonia illecebra in Canada appear to include climate, human disturbance, successional habitat change, and species biology. These factors are suggested based on observations of extant populations, herbarium specimens, and locations from which specimens were collected in the past.

Special significance of the species

Bryoandersonia illecebra is significant in that it is the sole representative of its genus, and in that it is known from a few closely occurring locales in Canada. B. illecebrais endemic to eastern North America, and the Canadian occurrences mark the northern limits of the species’ global range. It is also part of a well-publicized suite of Carolinian species at risk in Canada.

Existing protection

This species is not protected in any jurisdictions.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC Membership

COSEWICcomprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Definitions

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)*
A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

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

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

* Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.
** Formerly described as “Not In Any Category”, or “No Designation Required.”
*** Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.

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.

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

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