Lepraria cryophila Lendemer

Authority

Lendemer, James C. 2010. Notes on s. l. (Lecanoromycetes, Ascomycota) in North America: New species, new reports, and preliminary keys. Brittonia. 62 (3): 267-292.

Family

Stereocaulaceae

Scientific Name

Lepraria cryophila Lendemer

Description

Description - Thallus crustose, leprose, marginally "lobate," continuous and distinctly bi-layered, yered, initially forming small discrete thalli which expand marginally, overlap and become confluent to form a thick crust (0.5- 1.0 mm), off-white to light blue-white in color; hypothallus a well developed layer of loosely intertwined hyphae surrounding the granules and projecting outward from the edge of the thallus; hyphae anchoring the granules to each other, (2.5-)3.0-5.0 [µm wide, hyaline, obscurely septate, frequently branching at the septa, thick walled, obscured by a thick layer of crystals that eventually dissolve in KOH; rhizohyphae pale to dirty brown, branching, extending from the hypothallus to anchor the thallus to the substrate; granules medium, (30-)40-50(-60)µm in diameter, with a pseudocortex of one to several layers of gelatinized hyphae, globose, well organized and discrete, with a core of >10 aggregated algal cells, forming compound units of 4 or more individual granules, readily dividing; photobiont green, coccoid, cells globose, 6-9 µm in diameter.

Discussion

Mycobank #518306

Chemistry. - Divaricane acid (major), nor- divaricatic acid (major), ± atranorin (trace). Spot tests: K-, C+ pink, KC+ pink, P-, UV+ blue- white.

Etymology. - The epithet cryophila meaning "cold-loving" recognizes the frequent occurrence of the new species in high humidity habitats associated with cold air flows, such as talus slopes and narrow rocky stream ravines.

Ecology and distribution - The new species occurs primarily on non-calcareous rocks and organic matter in or near rock overhangs or on wet vertical rock faces. It is apparently restricted to high humidity habitats where the temperature remains cooler than the surrounding area for most or all of the year. Such "cold traps" or "cold air flows" are typically associated with talus slopes or vertical rock faces in narrow stream ravines and have been discussed in detail by Lendemer et al. (2009).

The species is presently known only from the Appalachian Mountains of eastern North America where occurs at nearly all elevations and from several disjunct populations in the Ozark Ecoregion. The majority of collections from the southern Appalachians are from middle to high elevations (e.g., >900 m.) while those from the central and northern Appalachians are from lower elevations (e.g. <600 m). It is possible that the lack of collections from lower elecations in the southern Appalachians is an effect of collector bias (Lendemer & tripp, 2008).

As is discussed below the new species is most similar to Lepraria crassissima Lettau. Saag et al. (2009) reported the substrate preference of L. crassissima as "on siliceous rock and epilithic mosses, also sometimes on bark or calcareous rock." This report contradicts most of the available literature in which the species is described as being a calciphile. When the species was first recognized as distinct from L. incana (L.) Ach. by van den Boom et al. (1994) it was noted to show an affinity for sandstone with "some calcium content." Later studies of the species in Norway (Tonsberg, 1992) reported it from calcareous rock walls while studies in Poland (Czarnota & Kukwa, 2001; Kukwa, 2002, 2006; Kukwa & Sliwa, 2005) found it to be essentially restricted to limestone. Further, the type collection is from calcareous rocks (isotype, FH!). It is noteworthy that Baruffo et al. (2006) reported the species as being restricted to non-calcareous rocks but also reported that the concentration of zeorin was variable ("zeorin (in variable amount) ±." Further study of the Italian populations of L. crassissima, preferable with molecular methods, is needed.

Discussion. - In eastern North America the name Lepraria crassissima (Hue) Lettau has been used for the populations described here as L. cryophila. These populations belong to L. crassissima s. lat. and are chemically similar to L. crassissima s. str. in the production of a high concentration of nordi- varicatic acid in addition to divaricatic acid. However, they differ chemically from L. crassissima s. str. in consistently lacking zeorin. The absence of zeorin in the eastern North American populations of L. crassissima s. lat. also correlates with a difference in ecology. While L. crassissima s. str. is primarily a species of calcareous rocks, it has also been reported from the bark of trees in Estonia (Saag & Saag, 1999), the populations described here as L. cryophila consistently occur on non-calcareous rocks.

Since the eastern North American popula- tions that have been referred to Lepraria crassissima differ from that species in both chemistry and ecology they are recognized here as a distinct taxon. It is important to note that to date I have not examined any material of L. crassissima s. str. from eastern North America.

Lepraria incarta (L.) Ach., another species with divaricatic acid differs from both L. crassissima and L. cryophila in occurring primarily on the bark of trees (hardwoods), producing only a low concentration of nordivaricatic acid as an accessory to divaricatic acid (thus the thallus is C-), and in having a thinner thallus that lacks rhizohyphae. This species also produces zeorin- another chemical dissimilarity between it and L. cryophila.

Another species of Lepraria that is chemically similar to L. cryophila is L. yunnaniana (Hue) Zahlbr. That species, like L. incarta, produces nordivaricatic acid as a minor accessory to divaricatic acid. While it is morphologically comparable to L. cryophila in having a well developed hypothallus, the hypothallus is distinctly dark in color rather than pale (Aptroot et al., 1997; Laundon, 2008; Saag et al., 2009). Lepraria yunnaniana is also reported to be corticolous and muscicolous (Saag et al., 2009) while L. cyrophila is typically saxicolous.