Peltigera canina is the type species for this genus, and many tomentose Peltigera utilizing Nostoc cyanobacteria as a photobiont have initially been classified here, either as this species or as a variety or subspecies thereof.
The cyanolichens of the genus Peltigera perform a vital function by fixing atmospheric nitrogen, which returns to fertilize the soil when they die and decompose. They are also important bio monitors, because they do not thrive where the nitrates in the air are concentrated enough to overload the nitrogen fixing capabilities of the Nostoc, which has the added downside of hindering it in photosynthesis.
This is the first time I have positively identified Peltigera canina. This is mostly due to the fact that it is uncommon west of the Cascades, and when I go east I’m usually looking for invertebrates of some sort. But I got lucky on the cliff above Drano Lake, because that middle Gorge area is transitional between eastside and westside flora and fauna.
I didn’t even need a book or a hand lens to identify this (although I used both to confirm it). After looking through the literature on Peltigera over the last few weeks this specimen might as well have been yelling on a bullhorn. And I wanted to yell too, in happiness at finding my 4th species of Peltigera on one cliff.
Description– Light to dark gray or brown lobed and loosely appressed thallus, which is tomentose, at least neat the margins; lobes fairly large (25-35mm), with downturned margins; the ventral veins are distinct and glabrous to sparsely haired; rhizines are mostly bushy and tufted, more so away from the margins; apothecia brown and saddle shaped, on raised lobes; lacking soredia and isidia; the combination of downturned, tomentose margins and bushy, tufted rhizines is diagnostic for this species.
Similar species– P. rufescens and P. ponojensis have smaller lobes with upturned margins; other Peltigera have single rhizines or glabrous dorsal surface.
Habitat-On logs, soil, or moss, or soil or moss over rock; often in open areas of forests, from low elevations to subalpine.
Range– Holarctic; region wide but most common east of the Cascades.
Etymology of names– Peltigera translates from Latin as ‘shield bearer’, and refers to the shape of the thalli in many members of this genus. The specific epithet canina refers to the perceived resemblance between the apothecia of this species and the teeth or ears of dogs.