Opuscula Philolichenum, 16: 317-321. 2017. *pdf effectively published online 18October2017 via (http://sweetgum.nybg.org/philolichenum/)

Acarospora toensbergii (Acarosporaceae), a new species from Alaska, U.S.A.

KERRY KNUDSEN1 AND JANA KOCOURKOVÁ2

ABSTRACT. – Acarospora toensbergii is described from Alaska in North America. The new species grows on siliceous rock and is easily recognized by its dispersed, solitary apothecia with a thick brown thalline margin, its amyloid hymenium and subhymenium, its lack of secondary metabolites, and its large mature ascospores that often measure up to 7 × 3 µm. Reports of Acarospora gallica and A. variegata from North America (New Mexico) are misidentifications of Acarospora janae. Acarospora canadensis is removed from synonymy with Acarospora glaucocarpa.

KEYWORDS. – Lecanorine apothecia, rare species, taxonomy.

INTRODUCTION

Lecanorine apothecia are ascocarps with a thalline margin and are common in lichenized fungi (Brodo et al. 2001; Wirth et al. 2013). True lecanorine apothecia are rare in the genus Acarospora (Knudsen 2007). Only a small number of species in Europe and North America produce lecanorine apothecia directly from an endolithic hypothallus. Examples include A. janae K. Knudsen from North America (Knudsen et al. 2011) and A. rehmii H. Magn. from central Europe (Malíček 2017). Usually in Acarospora there are one to twelve immersed apothecia without a thalline margin in the centers of areoles or squamules, although many species of the genus have what we consider pseudo-lecanorine apothecia. In pseudo-lecanorine apothecia, solitary immersed apothecia expand and reduce an areole or squamule to a thalline margin. Typical of this ontogeny is A. cervina A. Massal. (see Wirth et al. 2013 for a photograph of A. cervina with the apothecia in the process of expanding to fill the squamules and form lecanorine apothecia). Acarospra cervina regularly produces pseudo-lecanorine apothecia, but many species, such as A. fuscata (Schrad.) Arnold, only occasionally produce pseudo-lecanorine apothecia (Magnusson 1929). During a trip to Kenai Fjords National Park in Alaska, the Norwegian lichenologist Tor Tønsberg collected a new taxon with lecanorine apothecia that had thick thalline margins emerging from an endolithic hypothallus. Here we describe this taxon as Acarospora toensbergii in honor of Tor Tønsberg’s contribution to European and North American lichenology.

MATERIALS AND METHODS

Hand-cut sections of specimens from BG, CANL, NY, and UCR were studied using standard microscopy (following Brodo et al. 2001). Measurements were made in water. Structures were studied with KOH. Amyloid reactions of thin squashed sections were tested with fresh, undiluted Merck Lugol’s (IKI). Macromorphological photographs were taken with a digital camera Olympus DP72 mounted on an Olympus SZX 7 stereomicroscope with image stacks processed using the software Olympus Deep Focus 3.1.

1KERRY KNUDSEN – Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Kamýcká 129, Praha 6 - Suchdol, CZ–165 21, Czech Republic. – e-mail: [email protected] 2JANA KOCOURKOVÁ – Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Kamýcká 129, Praha 6 - Suchdol, CZ–165 21, Czech Republic.

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Figure 1. Morphology of Acarospora toensbergii (holotype, Tønsberg 45624). Scale = 0.5 mm.

TAXONOMIC SECTION

Acarospora toensbergii K. Knudsen & Kocourk., sp. nov. FIGURES 1 & 2. MYCOBANK #MB823029.

Similar to Acarospora janae but differing especially in having a parathecium expanded around the apothecial disc and in not producing gyrophoric acid.

TYPE: U.S.A. ALASKA. KENAI PENINSULA CO.: Kenai Fjords National Park, Exit Glacier Park Campground, 60°11′10″N, 149°40′27″W, 795 m, 12.vii.2015, on siliceous rock marking path between campsites, T. Tønsberg 45624 (BG!, holotype; ALA!, PRM!, isotypes).

DESCRIPTION. – Hypothallus endolithic, IKI-, algae not observed in substrate. Epilithic thallus lacking. Apothecia round, dispersed, or rarely replicating by division, 0.4–1.0 mm wide and 300–400 µm high, emerging from the endolithic hypothallus. Thalline margin brown, up to 200 µm wide. Upper cortex (20–)30–40 µm thick, cortical cells mostly round and 5–6 µm in diameter, upper layer brown ca. 10 µm thick, lower layer hyaline. Lateral cortex 30–60 µm thick, extending to base of apothecia, cortical cells mostly round and 5–6 µm, the outer layer brown or often blackened in holotype. Algal layer continuous beneath hypothecium and filling the margins, ca. 50–100 µm thick, not interrupted by hyphal bundles, algal cells 8–12 µm in diameter. Medulla up to 200 µm thick, of thin-walled hyphae 2–3 µm wide, mostly obscure and mixed with substrate crystals, IKI-, continuous with endolithic hypothallus. Disc round, reddish-brown, smooth, epruinose, lower than the top of margin. Parathecium expanded around disc usually to about 40 µm, not visible from above as parathecial crown, IKI-, hyphae mostly 2 µm in diameter, ending at surface with apices expanded to 6 µm and brown, intergrading with cortex. Parathecium sometimes expanding to 100 µm wide and excluding most or all of the upper cortex but not excluding the lateral cortex. Epihymenium 10 µm high, reddish-brown, coherent in thick gel, IKI-.

318 Hymenium (90–)100–120 µm tall, paraphyses mostly 2 µm wide at midlevel with oil drops, cells at mid- level 5–7 µm long, about 10 µm below apices the cells becoming 2–3 µm long, apices to 4 µm wide in gel cap, hymeninal gel IKI+ blue below epihymenium. Asci cylindrical, fully developed ca. 50 × 10 µm, 100 or less ascospores, often asci poorly developed. Ascospores 7 × 3 µm when fully developed, but often 5–6 × 2.0–2.5 µm. Subhymenium about 40 µm thick, IKI+ blue. Hypothecium 10 µm thick, IKI-. No pycnidia observed. No secondary metabolites with TLC (Tønsberg, pers. comm.)

ETYMOLOGY. – The species is named in honor of the Norwegian lichenologist Tor Tønsberg (b. 1948), collector of the type specimen, in honor of his important and continuing contributions to the study of lichenized fungi in Europe and North America.

ECOLOGY AND DISTRIBUTION. – Known only from Kenai Fjords National Park in Alaska, on siliceous rock. It is likely a pioneer species of hard exposed rock and a poor competitor with other saxicolous lichens. The type collection of A. toensbergii was made on a recently deglaciated alluvial terrace.

DISCUSSION. – The North American species with consistently lecanorine apothecia arising from an endolithic hypothallus that is most similar to Acarospora toensbergii is A. janae (Brodo 2016). Acarospora janae differs from A. toensbergii especially having an indistinct parathecium, smaller mature ascospores (3–4 × 2 µm vs. 7× 3 µm) and in producing gyrophoric acid (Knudsen et al. 2011). Though the data were not included in the protologue (Lumbsch et al. 2011), A. janae like A. toensbergii has blue amyloid hymenial gel. Some confusion surrounds A. janae. Magnusson (1930) reported two European species with pseudo-lecanorine apothecia new to North America, A. gallica H. Magn. and A. variegata H. Magn. These reports were however, based on taxon later described as A. janae from New Mexico. Magnusson identified specimens of A. janae with a lighter brown thalline margin as A. gallica. Whereas specimens with a darker brown thalline margin he identified as A. variegata. Neither A. gallica nor A. variegata occur in North America. In North America, because mature thalli in some populations are comprised of only apothecia with brown thalline margins, the calciphile Acarospora canadensis H. Magn. could be confused with A. toensbergii (Brodo 2016). The apothecia of A. canadensis do not arise from an endolithic hypothallus. Instead, it has an epilithic thallus of brown areoles with immersed apothecia that eventually expand and reduce the thallus to a thalline margin. Besides the ontogeny of its apothecia, A. toensbergii differs from A. canadensis especially in occurring on non-calcareous rocks, having larger cells in its cortex (5–6 µm vs. 1– 2 µm in A. canadensis), and a higher hymenium (90–120 µm vs. 65–85 µm in A. canadensis) (Magnusson 1929). Previously (e.g., Knudsen 2007), the first author considered A. canadensis to be a synonym of A. glaucocarpa (Ach.) Körber but with further study of the specimens we now consider it a distinct species. Though both species can look the same and have similar anatomical measurements, A. glaucocarpa differs in that it always has a distinct jagged algal layer interrupted by wide hyphal bundles forming algal palisades. Acarospora canadensis has an even algal layer uninterrupted by hyphal bundles. Acarosporaceae are relatively rare in Alaska, compared to farther south in North America (Bruce McCune, pers. com.) and we suspect that Acarospora toensbergii could occur in Canada or in Asia. It may also be a naturally rare species, a survivor of the radical changes of the Ice Age in North America (Ehlers et al. 2016). In addition to the specimens that we examined directly, two other specimens of A. toensbergii were determined by M. Schultz and verified via digital images by K. Knudsen.

Additional specimens examined. – U.S.A. ALASKA. KENAI PENINSULA CO.: Kenai Fjords National Park, near Harding Icefield Trail, ridge above Exit Glacier, alpine tundra with scattered low shrubs and metasedimentary outcrops, 60°11′10″N, 149°40′27″W, 795 m, 11.vii.2015, in rivulet on flushed boulders of metamorphic sedimentary rock, M. Schultz 16928f (ALA, HB); Kenai Fjords National Park, Exit Glacier Campground, near Exit Glacier Creek, floodplain forest with cobble openings and thickets of Populus balsamifera, Alnus and Salix, 60°11′27″N, 149°37′27″W, 112 m, 12.vii.2015, on cobbles of metamorphic sedimentary rock, growing with Thelignya lignyota and Placynthium asperellum, M. Schultz 16936b (ALA, HB)

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Figure 2. Morphology of Acarospora toensbergii (holotype, Tønsberg 45624). Scale = 0.5 mm.

Selected specimens of A. canadensis examined. – CANADA. MANITOBA. Winnipeg, Birds Hill Provincial Park, 50°0′52″N, 96°54′53″W, 266 m, 20.vii.2002, on limestone pebble in open, I.M. Brodo 31240 (CANL). ONTARIO. BRUCE CO.: Fathom Five National Marine Park, Flowerpot Island, 45°18′14″N, 81°36′43″N, 180 m, 22.ix.2008, on dolomite, R.C. Harris 55019 (NY); Bruce Peninsula, S end of Georgian Bay, 45°12′13″N, 81°18′32″N, 8 m, 16.vi.2014, on calcareous rock, J. McCarthy 2414 (NY, UCR, hb. Kocourková & Knudsen). U.S.A. CALIFORNIA. SAN BERNARDINO CO.: San Bernardino Mountains, 3N03, Smarts Ranch Rd., along seasonal stream bed, 34°15′39″N 116°43′36″W, 1961 m, 5.xi.2015, on limestone, K. Knudsen et al. 17024 (UCR).

ACKNOWLEDGEMENTS

We thank our reviewers. We thank the curators of BG, CANL, HB, NY and UCR for their assistance. The work of Kerry Knudsen and Jana Kocourková were financially supported by the grant ‘‘Environmental aspects of sustainable development of society’’ 42900/1312/3166 from the Faculty of Environmental Sciences, Czech University of Life Sciences Prague.

LITERATURE CITED

Brodo, I.M., S. Duran Sharnoff and S. Sharnoff. 2001. Lichens of North America. Yale University Press, New Haven and London. 795 pp. Brodo, I.M. 2016. Keys to Lichens of North America: Revised and Expanded. Yale University Press, New Haven and London. 427 pp. Ehlers, J., P. Hughes and P.L. Gibbard. 2016. The Ice Age. London, Wiley-Blackwell. 560 pp. Lumbsch, H.T. [+103 authors not cited here]. 2011. One hundred new species of lichenized fungi: A signature of undiscovered global diversity. Phytotaxa 18: 1–127. Knudsen, K. 2007[2008]. Acarospora. In: Nash III, T. H., Gries, C. & Bungartz, F. (eds). Lichen flora of the Greater Sonoran Desert Region, Volume 3. Tempe, Arizona State University. pp. 1–38. Knudsen, K., J.C. Lendemer and R.C. Harris. 2011. Lichens and lichenicolous fungi – no. 15: Miscellaneous notes on species from eastern North America. Opuscula Philolichenum 9: 45–75.

320 Magnusson A.H. 1929. A monograph of the genus Acarospora. Kungliga Svenska Vetenskaps Akademiens Handlingar, ser. 3, 7: 1–400. Magnusson A.H. 1930. The lichen genus Acarospora in New Mexico. Meddelelser fran Göteborgs Botaniska Trädgard 5: 55–72. Malíček, J. 2017. Lišejníky NPP Kaňk u Kutné Hory (Lichens of the protected area Kaňk near Kutná Hora). Bryonora 59: 30–36. Wirth, V., M. Hauck and M. Schultz. 2013. Die Flechten Deutschlands, Band 1. Stuttgart, Ulmer. 672 pp.

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