Lecanora indigoana E. Tripp & J. Watts, 2025

Lecanora indigoana E. Tripp & J. Watts , sp. nov.

TYPE. USA, Colorado. Delta County. Gunnison National Forest, CR265, lower montane stand of Populus tremuloides and Picea pungens , corticolous on P. pungens , 8710 ft. elev., 39.124 568, -107.54828, 13 May 2024, E. Manzitto-Tripp & J. Watts 10446 ( Holotype: COLO!). Figures 1–2 View FIGURE 1 View FIGURE 2 & 7 View FIGURE 7 .

Mycobank #. 860001

Description. Thallus light gray to pale greenish gray, not continuous, irregularly areolate to bullate, the areoles sometimes producing small lobules, epruinose. Apothecia sessile and constricted at the base, prominent, 0.5–1.2 mm in diameter, occurring in irregular clusters, less commonly solitary. Discs distinctly indigo blue, invariably densely pruinose, slightly concave to plane. Margins white, mostly entire to occasionally incised/cracked, corticate, much lighter in color compared to the thallus, strongly raised above disk. Parathecium hyaline, inconspicuous. Amphithecium 74–112 μm thick, apical portions of cortex (26–)29–37(–47) μm thick, lower portions of cortex extremely well-developed and prominent, (40–)53–75(–90) μm thick, the upper and lower cortices as well as algal layer containing fine POL+ crystals, not dissolving in K, dissolving in N. Epihymenium brownish gray, containing fine POL+ crystals, not dissolving in K, C, or N, also with a conspicuous indigo-colored pigment interspersed among paraphyses tips, indigo pigment not dissolving in K but dissolving in C, reacting pale red in N, (10–)13–30(–37) μm tall, with fine POL+ crystals, not dissolving in K or N. Hymenium hyaline, densely inspersed with oil droplets, (43–)69–88(–100) μm tall. Hypothecium hyaline, (30–)55–65 μm tall. Asci with 8 spores per ascus, 32–38(–42) × cylindrical, frequently branched toward the apex, 1.5–2.5 μm wide apically, 1.0–1.5 μm basally. Ascospores simple, hyaline, subspherical to broadly ellipsoidal, (8–)9–11.5 × (5–)6–7, 1.4 to 1.7(–2.1) times longer than wide, sometimes surrounded by a thin, hyaline ring ca. 0.2–0.3 μm thick. Pycnidia not seen. Photobiont chlorococcoid, spherical 7–15(–18) μm in diameter.

Etymology. The new species is named in honor of Indigo Girls , a now five-decade musical duo and legend that has inspired millions of listeners with their lyrical contributions, commitment to environmental protection, and social activism. Emily Saliers and Amy Ray of Indigo Girls have been major proponents of climate justice and, for years, led grassroots-style campaigns to increase awareness and promote change in social atmospheres. Songs by Indigo Girls have universally conveyed an interconnectedness between environmental health and social rights, which reminds us of lichen biodiversity and our parallel need to continue advancing initiatives that promote education and awareness of these remarkable symbiotic organisms. The new species further reminds us of Indigo Girls because it is both lustrous and assertive, introspective yet audacious, and reflective of voices that have not yet been heard, until now.

Chemistry. Spot Tests: K,- C-, KC-, P- UV- (thallus and apothecia). Thin Layer Chromatography: No substances detected.

Distribution. Current data document the presence of Lecanora indigoana only from Delta and Pitkin Counties, Gunnison National Forest, in central-western Colorado. We expect that additional collection efforts throughout Colorado and the southern Rocky Mountains, as well as further study of existing herbarium materials, will in time reveal a broader geographical distribution of this remarkable species.

Substrate & Habitat. Lecanora indigoana has been found in lower montane forests occurring on two of Colorado’s most iconic tree species: Quaking Aspen ( Populus tremuloides ) and Blue Spruce ( Picea pungens ). Future lichenological fieldwork throughout the southern Rocky Mountains in similar habitats is likely to expand the known range of this species into comparable habitats, and potentially on additional substrates.

Notes. The most immediately recognizable and distinguishing features of Lecanora indigoana ( Figure 2 View FIGURE 2 ) are its densely pruinose apothecial discs that are unwaveringly deep indigo in color. Because of these two traits, in North America Lecanora indigoana is likely only confusable for four other taxa that sometimes bear heavily pruinose discs appearing bluish to slate-colored: L. juniperina Śliwa , L. wetmorei Śliwa , L. invadens H. Magn. , and L. perpruinosa Fröberg. Of these, only L. juniperina and L. wetmorei are similarly corticolous like the new species (note: the latter two are also lignicolous). Phylogenetic analyses resolved our two accessions of L. indigoana as reciprocally monophyletic with strong support (99% bootstrap [BS]) and sister to L. juniperina , also with strong support (100% BS). Lecanora indigoana can be differentiated from L. juniperina by the former’s conspicuous areoles that sometimes produce small lobules, its prominent indigo pigment interspersed among paraphyses tips, its inspersed hymenium that is taller than that of L. juniperina , its brownish gray (vs. yellow granular) epihymenium, its spores that are slightly shorter and wider, and its complete lack of secondary metabolites (vs. unknown xanthones in L. juniperina ). Furthermore, whereas L. juniperina is currently known most predominantly from low elevations, primarily pinyon-juniper habitats of the Colorado Plateau, so far as understood, L. indigoana occurs in middle montane forests east of the Colorado Plateau at higher elevations such as those dominated by aspen and blue spruce. With L. wetmorei the new species shares relatively large apothecia, a strongly expanded basal portion of the amphithecial cortex, and a primarily western North American montane distribution. However, L. wetmorei cannot be mistaken for Lecanora indigoana because of the former’s complete lack of a thallus ( Śliwa 2007; examination of the holotype, C. Wetmore 16568, MIN! [MIN722988]). Additionally, L. wetmorei has entire (never occasionally incised) disc margins, and for the most part, a taller amphithecium.

Like Lecanora indigoana , both L. perpruinosa and L. invadens have clearly visible thalli. However, the new species can nonetheless be readily differentiated from both. Lecanora perpruinosa differs by having a primarily thin, continuous thallus with indefinite edges, black to very dark brownish black discs, discs that are for the most part smaller in diameter (~ 0.3–0.8 mm; Śliwa 2007), an indistinctly delimited lower cortex of the amphithecium, and occurrence on calcareous rocks. Lecanora perpruinosa moreover is known primarily from Europe with only a limited number of occurrences in North America. Lecanora invadens differs from the new species by having an indistinct thallus, for the most part smaller apothecia (0.4–1.0 mm; Śliwa 2007), primarily yellow to brown or black discs, a much taller amphithecium (~160–170 μm), its chemistry (typical presence of lichen substances), and occurrence on non-calcareous or calcareous rocks as well as occasionally parasitic on other lichens. Finally, it is possible that some could confuse the new species for L. hagenii (Ach.) Ach. , which is also corticolous and similarly sometimes has slightly incised apothecial margins, however L. hagenii differs by lacking a thallus, having evenly distributed apothecia, orangish brown discs, and an indistinctly delimited lower cortex of the amphithecium. The latter species also has smaller apothecia with typically thinner discs ( Śliwa 2007; examination of the conserved type, F. Arnold, Exs. Sic. No. 31, M! [M-00345420]).

Elsewhere (outside North America), Lecanora indigoana bears resemblance to two species recently described from China ( Payzulla & Mamut 2025) although both are phylogenetically less closely related to the new species ( Figure 1 View FIGURE 1 ): Lecanora gigantea (R. Mamut & T. Payzula) E. Tripp & J. Watts and Lecanora planata E. Tripp & J. Watts (both treated under Myriolecis View in CoL in Payzulla & Mamut 2025, new combinations provided in Part 3, below). Lecanora gigantea differs in numerous features including its very conspicuous thallus and presence of vinetorin; that species also occurs on calcareous rocks and is so far known only from China. Lecanora planata differs from by having a thallus that is primarily within the substrate (or at most, occurring only underneath the apothecia), by its apothecia with margins that are level and even with the discs, and its slightly narrower spores; that species also occurs on calcareous rocks and is so far known only from China.

As in Tripp et al. (2019), we here opt to place the new species within a broadly defined concept of the genus Lecanora vs. the alternative, more narrowed circumscription of the lineage, i.e., Myriolecis Clements ( Zhao et al. 2016) , which has been used recently to refer to members of the Lecanora dispersa (Pers.) Röhl. group to which the new species belongs. We refrain from treatment of L. indigoana in other genera until a more stable classification (i.e., one in which the recognition of multiple segregate genera no longer renders Lecanora massively non-monophyletic) can be put forward.

Conservation Assessment. Based on current knowledge, Lecanora indigoana is here assessed as Critically Endangered (CR) under criterion D of the IUCN Red List ( IUCN 2024), which was invoked as a result of only two known populations consisting of a total of two mature individuals each.

Additional Specimens Examined. USA, Colorado, Delta County. Gunnison National Forest, CR265, lower montane stand of Populus tremuloides and Picea pungens , corticolous on P. pungens , 8710 ft., 39.124 568 -107.54828, 13 May 2024, J. Watts & E. Manzitto-Tripp 1496 (COLO!). Pitkin County. White River National Forest, Placita Trailhead, semi-arid, west-facing slope dominated by Quercus gambellii Liebm. and Populus tremuloides , corticolous on P. tremuloides , 7586 ft., 39.135 45 -107.26985, 13 May 2024 ( E. Manzitto-Tripp & J. Watts 10436 (COLO!).