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Montana Field Guide

Montana Field Guides

Hydrothyria Lichen - Peltigera hydrothyria
Other Names:  Hydrothyria venosa, Hydrothyria venosa

Species of Concern

Global Rank: G4
State Rank: S1
* (see State Rank Reason below)

Agency Status
MNPS Threat Rank:

External Links

State Rank Reason (see State Rank above)
Known from a few sites in western Montana.
  • Details on Status Ranking and Review
    Hydrothyria Lichen (Peltigera hydrothyria) Conservation Status Review
    Review Date =
General Description
Thallus foliose, gelatinous (non-stratified), medium sized, dark bluish gray to dark gray or black, loosely appressed in ruffles; lobes to about 1 cm wide; lower surface dark, distinctly veined; apothecia common, the disk brownish, spores 3-septate; and the photobiont blue-green (McCune and Geiser 2009). Chemistry: All spot tests negative (McCune and Geiser 2009).

Diagnostic Characteristics
The only gelatinous lichen with distinct veins. It is also the largest strictly aquatic lichen in the Pacific Northwest. Look for the dark, ruffled masses in small spring-fed streams. While searching for P. hydrothyria you will encounter ear-like lobes of non-lichenized Nostoc attached to submerged rocks; these are more jelly-like than P. hydrothyria and are never veined (McCune and Geiser 2009).

Species Range

Range Comments
Known from each of the major mountain chains in the U.S. and southern Canada, but more common in the Cascade and Sierra Nevada Ranges than in the other ranges (McCune and Geiser 2009).

Observations in Montana Natural Heritage Program Database
Number of Observations: 3

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Aquatic, in mountain streams and springs, especially those without marked seasonal fluctuations. Grows on rock and gravel, rarely on wood.

Aquatic. An indicator of good water quality. Photobiont is cyanobacteria (Nostoc), a nitrogen-fixer.

Reproductive Characteristics
Reproduces sexually by spores from the apothecium.

Threats or Limiting Factors
Water pollution.

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Citation for data on this website:
Hydrothyria Lichen — Peltigera hydrothyria.  Montana Field Guide.  .  Retrieved on , from