The Hypogymnia Species of North America

Hypogymnia incurvoides

Click on Characteristic name for explanation. Click on image for larger version.


Synopsis: Labriform soralia beneath lobe tips, lattice-like branching, appressed, black-margined lobes that are neatly dichotomously branched; differing from H. physodes in the occasional perforations in lobe tips, absence of 3-hydroxyphysodic acid, and growth form; medulla K-, KC+ orange red, P+ orange red.
Distribution: Archangle region (Poelt 1969) = Arkhangelsk region, Russia. This is in northwestern Russia; Sweden, Norway, Newfoundland, Nova Scotia, Maine, Tennessee, North Carolina. H. incurvoides is known from only one locality in Greenland, where it grows on branches of Betula pubescens. Elsewhere known from the Arkhangelsk Region, Sweden, Norway, the coast of eastern Canada (Newfoundland and Nova Scotia), and the U.S.A. (Maine and the highest peaks of the Appalachian Mountains south to North Carolina).
Habitat: sparse to dense conifer forest
Range: Arctic, Subarctic, Alpine
Other Diagnostics: Differs from H. physodes in the absence of 3-hydroxyphysodic acid (K- rather than K+ reddish brown), a lattice-like growth form, and sparsely perforate lobe tips and axils. "The black-margined lobes and neatly dichotomous branching (Fig. 1) are often easily seen, but not completely consistent for separating H. incurvoides from H. physodes. The most definitive characters separating H. incurvoides from H. physodes are that the former has holes in many of the lobe tips and axils (Figs. 4_5) and it lacks 3-hydroxyphysodic acid. Hypogymnia physodes is never perforate, except where the lobes burst into soredia, and it always contains 3-hydroxyphysodic acid. " (McCune et al. 1995). Hypogymnia incurvoides similar to some forms of H. physodes, but is readily distinguished from that species by the presence of holes in the lobe tips and axils, black-margined lobes forming a regular lattice, and the absence of 3-hydroxyphysodic acid. This substance gives a K+ slow reddish brown reaction, which is consistently seen in H. physodes but not H. incurvoides. Although the soredia are similar in form to H. physodes, DNA evidence shows that H. incurvoides is most closely related to the North American endemic H. krogiae.
Substrate Notes: On conifers (Abies, Larix, Picea) and hardwoos (Betula), rarely on rock
Abundance in North America: Locally common
Substrate: Typically
Host: Betula, Abies, Larix, Picea
On Rock: Rarely
On Moss/Detritus/Sod: Never
Authority: Rass.
References: Rassadina (1967), McCune et al. (1997, 2006)
Synonymy: None
Hypogymnia incurvoides - Habit

Vegetative Structures

Habit Appressed: Almost always
Habit Pendulous: Never
Habit Erect to Suberect: Rarely
Size (cm): Mean: 10 SD: 5
Upper Color- White to Greenish Gray: White to greenish gray
Upper Surface Brown when Solarized: Blackish or unknown
Dark Mottles: Sometimes present
Black Border: Conspicuous
Lobes Separated: Contiguous to +/- separate
Lobe Outline: Even
Upper Surface Texture: Smooth to weakly rugose
Branching: Isotomic dichot.
Budding: Absent or rare
Lobe Width (mm): Mean: 1.25 SD: 0.125
Lobe Tips, Axils, and/or Lower Surface Perforated: Sometimes
Lobe Tips Perforated: Sparsely perforate
Lower Surface Perforated: Rarely perforate
Cavernulae: Never
Thallus Texture: Cartilaginous
Medulla: Almost always
Ceiling Color: White or dark
Floor Color: Dark
Hypogymnia incurvoides - Lobes
Hypogymnia incurvoides - Lower surface
Lower surface
Hypogymnia incurvoides - Lobe cavity
Lobe cavity

Reproductive Structures

Soredia: Labriform
   Soredia Texture: Commonly
   Soredia Terminal or Laminal: Almost always
   Soredia Shape Lip-Shaped: Almost always
   Schizidia: Rarely
   Isidia: None
Lobules: None
Apothecia: Rare
Spore Length (µm): Mean: 6 SD: 0.25 Max: 6.5 Min: 5.5
Spore Width (µm): Mean: 5.15 SD: 0.175 Max: 5.5 Min: 4.8
Pycnidia: Rare
Hypogymnia incurvoides - Soredia