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An updated world key to the species of Acanthothecis s. lat. (Ascomycota: Graphidaceae), with ten new species from Brazil

Published online by Cambridge University Press:  31 March 2022

Shirley Cunha Feuerstein*
Affiliation:
Laboratory of Mycology, Universidade Federal do Rio Grande do Sul, CEP 91509-900, Porto Alegre, Rio Grande do Sul, Brazil
André Aptroot
Affiliation:
Laboratório de Botânica/Liquenologia, Instituto de Biociências, Universidade Federal de Mato Grosso do Sul, Avenida Costa e Silva s/n, Bairro Universitário, CEP 79070-900, Campo Grande, MS, Brazil
Rosa Mara Borges da Silveira
Affiliation:
Laboratory of Mycology, Universidade Federal do Rio Grande do Sul, CEP 91509-900, Porto Alegre, Rio Grande do Sul, Brazil
Robert Lücking
Affiliation:
Botanischer Garten, Freie Universität Berlin, Königin-Luise-Straße 6–8, 14195Berlin, Germany
Marcela Eugenia da Silva Cáceres
Affiliation:
Departamento de Biociências, Universidade Federal de Sergipe, CEP 49500-000, Itabaiana, Sergipe, Brazil
*
Author for correspondence: Shirley Cunha Feuerstein. E-mail: shirleycunha_@hotmail.com
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Abstract

As part of a revision of the genus Acanthothecis s. lat. (Graphidaceae) in Brazil, an updated world key to the known species of the genus is presented. From Brazil, the following ten new species are described: A. latispora, with single-spored asci, large, muriform ascospores, and norstictic and stictic acids; A. megalospora, with single-spored asci, very large, transversely septate ascospores, and norstictic and protocetraric acids; A. multiseptata, with 8-spored asci, medium-sized and narrow, transversely multiseptate ascospores, and lacking secondary substances except terpenoids; A. norstictica, with 1–2-spored asci, large, muriform ascospores, and norstictic acid; A. oryzoides, with 8-spored asci, medium-sized, transversely septate ascospores, and norstictic acid; A. rimosa, with 2-spored asci, small to medium-sized, muriform ascospores, and stictic acid; A. roseola, with 1–2-spored asci, large, muriform ascospores, and norstictic, stictic and subnorstictic acids; A. saxicola, with 8-spored asci, small, 3-septate ascospores, and norstictic acid; A. subfarinosa, with 8-spored asci, small, 6–8-septate ascospores, and norstictic acid; and A. submuriformis, with 8-spored asci, small, submuriform ascospores, and lichexanthone. In addition, three further species are formally validated, namely A. bicellulata, A. farinosa and A. subabaphoides, and the new combination A. bicellularis is proposed, based on Acanthotrema bicellularis.

Type
Standard Paper
Copyright
Copyright © The Author(s), 2022. Published by Cambridge University Press on behalf of the British Lichen Society

Introduction

Acanthothecis Clem. was one of the first genera to be reinstated in the course of a substantial reorganization of the lichenized family Graphidaceae (Staiger & Kalb Reference Staiger and Kalb1999). The genus is characterized by predominantly lirellate ascomata mostly lacking carbonization, and by apically spinulose paraphyses and/or periphysoids. Staiger & Kalb (Reference Staiger and Kalb1999) provided detailed descriptions and illustrations of the 16 species known at the time. Notably, long before this work, it was Kalb (Reference Kalb1982) who first took up the name Acanthothecis for two species, A. pachygraphoides (Vain.) Clem. (type) and the newly proposed combination A. caesiocarnea (Vain.) Kalb, both considered synonyms of A. hololeucoides (Nyl.) Staiger & Kalb (Staiger & Kalb Reference Staiger and Kalb1999).

In her broad revision of genus concepts in Graphidaceae, Staiger (Reference Staiger2002) added six more species to the genus, bringing the total to 22; however, since then the number of species assigned to Acanthothecis has more than doubled to 50, including several combinations and 25 further species described as new to science (Makhija & Adawadkar Reference Makhija and Adawadkar2003, Reference Makhija and Adawadkar2007; Archer Reference Archer2005, Reference Archer2007; Archer & Elix Reference Archer and Elix2007, Reference Archer and Elix2008; Dal-Forno & Eliasaro Reference Dal-Forno and Eliasaro2009; Kalb et al. Reference Kalb, Buaruang, Papong and Boonpragob2009; Kantvilas Reference Kantvilas2010; Sharma et al. Reference Sharma, Makhija and Khadilkar2010; Tripp et al. Reference Tripp, Lendemer and Harris2010; Cáceres & Lücking Reference Cáceres and Lücking2013; van den Boom & Sipman Reference van den Boom and Sipman2013; Lendemer & Harris Reference Lendemer and Harris2014; Sipman Reference Sipman2014; Weerakoon et al. Reference Weerakoon, Lücking and Lumbsch2014; Gupta & Sinha Reference Gupta and Sinha2015; Muscavitch & Lendemer Reference Muscavitch and Lendemer2016; Joshi et al. Reference Joshi, Upreti, Thanh and Nguyen2017; Seavey et al. Reference Seavey, Seavey, Gagnon, Guccion, Kaminsky, Pearson, Podaril and Randall2017; Herrera-Campos et al. Reference Herrera-Campos, Bárcenas-Peña, Miranda-González, Mejía, González, Colín, Téllez and Lücking2019). Eight previously recognized species were also placed in synonymy (Staiger Reference Staiger2002; Tripp et al. Reference Tripp, Lendemer and Harris2010; Muscavitch & Lendemer Reference Muscavitch and Lendemer2016). Muscavitch & Lendemer (Reference Muscavitch and Lendemer2016) were the first to provide an updated key to the genus Acanthothecis, including similar species of Fissurina with warted paraphyses.

Even with this substantial increase in species documenting the high level of previously unrecognized diversity in the Graphidaceae (Lücking et al. Reference Lücking, Johnston, Aptroot, Kraichak, Lendemer, Boonpragob, Cáceres, Ertz, Ferraro and Jia2014), the discovery of an additional ten new species only in Brazil is remarkable. It demonstrates that this vast territory is still much understudied for this family, particularly in the biomes of Amazonia, the Cerrado and the Atlantic Forest.

Overall, the new species were documented based on collections from seven states in three of the five macroregions of Brazil (North, Northeast and South). In this paper, the new species are described and discussed in detail and, given the high number of novelties, a further updated world key for Acanthothecis s. lat. is provided, now including 63 species. The genus is treated here in a broad sense given that a group of species with distinctly corticate thalli form a clade unrelated to the core group (Rivas Plata et al. Reference Rivas Plata, Parnmen, Staiger, Mangold, Frisch, Weerakoon, Hernández-M, Cáceres, Kalb and Sipman2013; Lumbsch et al. Reference Lumbsch, Kraichak, Parnmen, Rivas Plata, Aptroot, Cáceres, Ertz, Feuerstein, Mercado-Díaz and Staiger2014). These species will be treated in detail in a forthcoming study.

Material and Methods

Identification and descriptive work on the newly collected material was carried out in the Laboratory of Mycology at UFRGS and also in Soest, using a Leica Zoom 2000 and Olympus SZX7 stereomicroscope, and Zeiss Axioskop and Olympus BX50 compound microscope with interference contrast, connected to a Nikon Coolpix digital camera. Sections were mounted in tap water, from which all measurements were also taken.

Chemistry was initially assessed using standard spot tests (10% KOH, para-phenylenediamine) and a UV light source, and was investigated in detail by thin-layer chromatography (TLC) using solvents A and C (Orange et al. Reference Orange, James and White2001).

Results and Discussion

The new species

Acanthothecis latispora Feuerstein & Silveira sp. nov.

MycoBank No.: MB 840482

Corticolous Acanthothecis with single-spored asci, large, muriform ascospores, and containing norstictic and stictic acids; differing from A. mosquitensis in the longer and much wider ascospores and the presence of stictic acid, in addition to the more robust ascomata with exposed disc.

Type: Brazil, Rio Grande do Sul, Derrubadas, Parque Estadual do Turvo, 27°14ʹ10ʺS, 53°58ʹ42ʺW, on branches, 6 October 2017, S. C. Feuerstein 2791 (ICN—holotype).

(Fig. 1A)

Fig. 1. Habitus pictures of new Acanthothecis species, all holotypes. A, A. latispora. B, A. megalospora. C, A. multiseptata. D, A. norstictica. E, A. oryzoides. F, A. rimosa. Scales = 1 mm. In colour online.

Thallus corticolous, corticate, whitish to greenish, with black prothallus, densely filled with large crystals of calcium oxalate below the layer of algae and hamathecium.

Ascomata elongate, unbranched to irregularly branched, 0.3–2.0 × 0.18–0.27 mm, immersed-erumpent, labia well developed, 0.09–0.11 mm wide, entire to striate with shallow lines, white, with lateral thalline margin. Margin not carbonized. Disc exposed, grey with white pruina, 0.04–0.11 mm wide. Hamathecium not inspersed, 87–150 μm high. Paraphyses unbranched, hyaline, 1.0 μm thick, with the apex spinulose. Periphysoids spinulose, few, 3–5 μm wide. Asci single-spored. Ascospores hyaline, densely muriform, 82–100 × 27–35 μm, c. 3 times as long as wide, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and ascoma UV−, KOH+ yellow forming red, needle-shaped crystals in microscopic section. TLC: norstictic and stictic acids.

Distribution and ecology

On branches in open area of the Atlantic Forest in Rio Grande do Sul. So far known only from Brazil.

Discussion

This new species most closely resembles A. mosquitensis (Tuck.) Tripp & Lendemer in having muriform, I−, rather large ascospores and in producing norstictic acid. However, the latter has smaller ascomata with the disc concealed, smaller and much narrower ascospores (45–85 × 9–17 μm, c. 5 times as long as wide), and lacks stictic acid.

The newly described A. roseola (see below) agrees with A. latispora in ascospore dimensions and partly in secondary chemistry (also producing norstictic and stictic acids), but its ascomata are more irregular, with the disc concealed and the labia with a pinkish hue, and the excipulum lacks spinulose periphysoids. Also similar is the newly described A. norstictica (see below), but this lacks spinulose periphysoids and stictic acid and produces slightly wider ascospores.

Acanthothecis megalospora Feuerstein & Lücking sp. nov.

MycoBank No.: MB 840483

Acanthothecis with single-spored asci, very large, transversely septate ascospores, and norstictic and protocetraric acids; differing from A. africana in the larger ascospores and protocetraric acid as an additional substance, and from A. clavulifera in the larger ascospores and the additional production of norstictic acid.

Type: Brazil, Tocantins, near Itaguatins, on tree bark in cerrado on São Paulo farm, 25 October 2009, S. C. Feuerstein 153 (ICN—holotype).

(Fig. 1B)

Thallus corticolous, corticate, whitish grey.

Ascomata oval to elongate, scattered, unbranched, prominent to sessile, 0.5–2.3 × 0.4–0.6 mm, labia convergent, well developed, entire. Margin not carbonized. Disc usually concealed, rarely somewhat exposed in shorter, rounded ascocarps, then salmon-pruinose. Hamathecium not inspersed, 175–250 μm high. Paraphyses unbranched, hyaline, 1.0–2.0 μm thick, with glabrous apex. Periphysoids spinulose, 5 μm wide. Asci single-spored. Ascospores hyaline, transversely 15–17-septate, cells more or less rectangular, 135–185 × 27–30 μm, ascospore wall 1 μm thick, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and ascoma UV−, KOH+ green → strong yellow, P+ yellow. TLC: norstictic, connorstictic, protocetraric acids and unidentified substances with approximate R f values of 15 and 50.

Distribution and ecology

On tree bark in cerrado in Maranhão and Tocantins. So far known only from Brazil.

Discussion

This new species is rather unique in having very large, transversely septate ascospores and both norstictic and protocetraric acids as major compounds. It differs from both A. africana Staiger & Kalb and A. clavulifera (Vain.) Staiger & Kalb in the larger ascospores and the more complex chemistry, as well as the apically smooth paraphyses. Morphologically very similar is A. oryzoides, described below, which differs in the much smaller ascospores occurring in numbers of 8 per ascus.

Additional specimens examined

Brazil: Maranhão: Governador Edison Lobão, on tree bark in cerrado, 2014, A. R. L. Nunes 16, 39 (ICN). Tocantins: near Itaguatins, on tree bark in cerrado on São Paulo Farm, 2009, S. C. Feuerstein 136, 517, 524 (ICN).

Acanthothecis multiseptata Aptroot, Lücking & M. Cáceres sp. nov.

MycoBank No.: MB 840484

Corticolous Acanthothecis with 8-spored asci, medium-sized and narrow, transversely multiseptate ascospores, and lacking secondary substances except terpenoids; differing from A. aquilonia in ascomata morphology and in the smaller ascospores with more numerous septa.

Type: Brazil, Santa Catarina, São Francisco do Sul, Parque Estadual do Acaraí, 26°17′20″S, 48°32′35″W, on tree bark in restinga, alt. 10 m, 6 October 2015, M. E. S. Cáceres & A. Aptroot 27740 (ISE—holotype; ABL—isotype).

(Fig. 1C)

Thallus corticolous, ecorticate, covering areas up to 15 cm diam., c. 0.1 mm thick, ochraceous white, surrounded by a whitish, arachnoid prothallus c. 2 mm wide.

Ascomata oval to elongate-lirelliform, occasionally irregularly branched, 0.4–1.9 × 0.5–0.7 mm, solitary or often a small number in a line (originating from one ascoma initial), not crowded, erumpent to prominent. Margin not carbonized, entire, white, strongly prominent, dull, cottony, c. 0.2 mm wide and high, without algae. Disc open, flesh-coloured to pale grey, whitish pruinose, c. 0.2–0.5 mm wide. Hamathecium not inspersed. Paraphyses unbranched, tips thickened, long spinulose. Periphysoids absent. Asci 8-spored. Ascospores hyaline, vermiform, 35–43-septate, 69–77 × 6.5–7.5 μm, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and ascoma UV−, KOH−. TLC: a terpenoid, probably zeorin. Maybe from the bark.

Distribution and ecology

On tree bark in low coastal rainforest (arboreal restinga) in Santa Catarina. So far known only from Brazil.

Discussion

Acanthothecis aquilonia and A. multiseptata are the only species with a clear hymenium, lacking secondary substances, and with rather large, multiseptate ascospores. Anatomically A. aquilonia chiefly differs in the larger ascospores, curiously with fewer septa (80–100 × 8–10 μm, 27–34-septate). Morphologically the two species are more distinct, the ascomata of A. aquilonia being somewhat chroodiscoid and those of A. multiseptata oval to elongate-lirelliform.

Acanthothecis norstictica Aptroot, Lücking & M. Cáceres sp. nov.

MycoBank No.: MB 840485

Corticolous Acanthothecis with 1–2-spored asci, large, muriform ascospores, and norstictic acid; differing from A. latispora in the wider ascospores, absence of periphysoids and the exclusive presence of norstictic acid.

Type: Brazil, Tocantins, near Itaguatins, 5°44′48″S, 47°33′46″W, on tree bark in cerrado remnant on farm, alt. 150 m, 23 October 2016, M. E. S. Cáceres & A. Aptroot 28842 (ISE—holotype; ABL—isotype).

(Fig. 1D)

Thallus corticolous, ecorticate but smooth and partly shiny, covering areas up to 5 cm diam., c. 0.2 mm thick, ochraceous to pinkish white, not surrounded by prothallus, densely filled with large crystals of calcium oxalate.

Ascomata oval to elongate, unbranched, 0.5–1.3 × 0.4–0.7 mm, solitary but crowded, erumpent. Margin not carbonized, entire, corticated and of the same colour as the thallus, strongly prominent, c. 0.2 mm wide and high, with algae. Disc exposed, brownish, white-pruinose, c. 0.1–0.3 mm wide. Hamathecium not inspersed. Paraphyses thin, tips agglutinated, not thickened, spinulose. Periphysoids absent. Asci 1–2-spored. Ascospores hyaline, densely muriform, 95–110 × 35–40 μm, I+ violet, ellipsoid, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and thalline margin of ascoma UV−, KOH+ yellow forming red, needle-shaped crystals in microscopic section. TLC: norstictic acid.

Distribution and ecology

On tree bark in cerrado forest in Tocantins. So far known only from Brazil.

Discussion

Acanthothecis latispora (see above) and A. norstictica agree in having ascomata with an exposed, white-pruinose disc, rather wide, muriform ascospores and the norstictic acid chemistry. However, A. latispora also produces spinulose periphysoids and stictic acid in addition to norstictic acid.

Acanthothecis oryzoides Aptroot, Lücking & M. Cáceres sp. nov.

MycoBank No.: MB 840486

Corticolous Acanthothecis with 8-spored asci, medium-sized, transversely septate ascospores, and norstictic acid; differing from A. aurantiaca in the larger ascospores and the robust, short and broad, prominent ascomata.

Type: Brazil, Rondônia, Porto Velho, Parque Natural Municipal, 8°41′10″S, 63°52′05″W, on twig bark in park near rainforest, alt. 100 m, 16 November 2012, M. E. S. Cáceres & A. Aptroot 15100 (ISE—holotype; ABL—isotype).

(Fig. 1E)

Thallus corticolous, not corticate, covering areas up to 5 cm diam., c. 0.1 mm thick, glaucous white, dull, not surrounded by prothallus.

Ascomata oval to elongate, usually unbranched, 0.6–2.3 × 0.4–0.7 mm, solitary, rather dispersed, prominent to sessile. Margin not carbonized, entire, pinkish white (due to decomposing norstictic acid, not anthraquinone), dull, c. 0.2 mm wide and high, without algae. Disc mostly slit-like and closed, pinkish grey, not or whitish pruinose. Hamathecium not inspersed. Paraphyses tips not thickened but spinulose. Periphysoids absent. Asci 8-spored. Ascospores hyaline, 9–13-septate, 69–80 × 25–35 μm, ellipsoid, constricted at the septa, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and thalline margin of ascoma UV−, KOH+ yellow forming red, needle-shaped crystals in microscopic section. TLC: norstictic acid.

Distribution and ecology

On tree bark in park near tropical rainforest in Rondônia. So far known only from Brazil.

Discussion

The closest species in terms of ascospore type and chemistry is Acanthothecis aurantiaca (Müll. Arg.) Staiger & Kalb; apart from the smaller ascospores, it differs clearly in the much smaller and narrower, immersed-erumpent ascomata. Morphologically similar is A. megalospora (see above), which differs in the much larger ascospores occurring singly in each ascus.

Acanthothecis rimosa Aptroot, Lücking & M. Cáceres sp. nov.

MycoBank No.: MB 840487

Corticolous Acanthothecis with 2-spored asci, small to medium-sized, muriform ascospores, and stictic acid; differing from A. pruinocarpa in the larger ascospores and the robust, short and broad, prominent ascomata.

Type: Brazil, Alagoas, Quebrangulo, Pedra Talhada private area, 9°15′S, 36°25′35″W, on tree bark in Atlantic rainforest, alt. 500–700 m, 21–23 October 2017, M. E. S. Cáceres & A. Aptroot 42407 (ISE—holotype; ABL—isotype).

(Fig. 1F)

Thallus corticolous, ecorticate but smooth and partly shiny, covering areas up to 5 cm diam., c. 0.1 mm thick, mineral grey, not surrounded by prothallus.

Ascomata elongate, often somewhat sinuous, usually unbranched, 0.8–3.5 × 0.5–0.7 mm, solitary, densely crowded, erumpent. Thalline margin not carbonized, entire, of thallus structure and colour, but with the inner rim bordering the slit much paler, c. 0.2 mm wide and high, with algae. Disc mostly slit-like and closed, pinkish grey, whitish pruinose. Hamathecium not inspersed. Paraphysis tips spinulose. Periphysoids not observed. Asci 2-spored. Ascospores hyaline, muriform, with 15–19 transverse and 3–4 longitudinal septa per segment, 45–53 × 13–16 μm, ellipsoid, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and thalline margin of ascoma UV−, KOH+ yellow. TLC: stictic acid and satellite substances.

Distribution and ecology

On tree bark in Atlantic rainforest in Alagoas. So far known only from Brazil.

Discussion

Only a small number of species in the genus have rather small, muriform ascospores combined with a stictic acid chemistry. Among these, A. dialeuca differs by its distinctly shorter ascospores and its more delicate, fissurinoid ascomata. Acanthothecis pruinocarpa has similar ascospores, although a bit longer on average, but differs in thallus and ascoma morphology. Acanthothecis corcovadensis is morphologically and chemically similar but has much larger ascospores and the paraphyses are mostly smooth, whereas the warty periphysoids are well developed.

Acanthothecis roseola Feuerstein sp. nov.

MycoBank No.: MB 840488

Corticolous Acanthothecis with 1–2-spored asci, large, muriform ascospores and norstictic, stictic and subnorstictic acids; differing from A. latispora in the irregular ascomata with concealed disc and pinkish margins.

Type: Brazil, Rio Grande do Sul, Sarandi, Parque Estadual Papagaio Charão, 27°54′26″S, 52°49′23″W, on tree bark in Atlantic rainforest, 8 October 2017, S. C. Feuerstein 2872 (ICN—holotype).

(Fig. 2A)

Fig. 2. Habitus pictures of new Acanthothecis species, all holotypes. A, A. roseola. B, A. saxicola. C, A. subfarinosa. D, A. submuriformis. Scales = 1 mm. In colour online.

Thallus corticolous, corticate, cracked, whitish to greenish, black prothallus, densely filled with large crystals of calcium oxalate below the layer of algae and hamathecium.

Ascomata elongate, scattered, unbranched to irregularly branched, 0.9–1.9 × 0.27–0.32 mm, erumpent, entire to striate with shallow lines, whitish to flesh-coloured or pinkish, with lateral thalline margin. Margin not carbonized. Disc slit-like, concealed. Hamathecium not inspersed, 105–110 μm high. Paraphyses unbranched, hyaline, 1.0 μm thick, apically spinulose. Periphysoids absent. Asci 1(–2)-spored. Ascospores hyaline, densely muriform, 77–98 × 25–30 μm, c. 3 times as long as wide, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and ascoma UV−, KOH+ yellow forming red, needle-shaped crystals in microscopic section. TLC: norstictic, stictic and subnorstictic acids.

Distribution and ecology

On tree bark in Atlantic rainforest in Rio Grande do Sul. So far known only from Brazil.

Discussion

This new species most closely resembles A. mosquitensis (Tuck.) Tripp & Lendemer in having muriform, I−, rather large ascospores and in producing norstictic acid. However, the latter has smaller ascomata, smaller and much narrower ascospores (45–85 × 9–17 μm, c. 5 times as long as wide), and lacks stictic acid. The newly described A. latispora above agrees with A. roseola in ascospore type and secondary chemistry but its ascomata are rather straight, with the disc exposed and the labia whitish, and it produces spinulose periphysoids.

Acanthothecis saxicola Aptroot, Lücking & M. Cáceres sp. nov.

MycoBank No.: MB 840489

Saxicolous Acanthothecis with 8-spored asci, small, 3-septate ascospores, and norstictic acid; differing from A. silicicola in the smaller, 3-septate ascospores and the apically spinulose paraphyses.

Type: Brazil, Maranhão, Riachão, Poço Azul, 7°13′28″S, 46°27′10″W, on overhanging sandstone in cerrado, alt. 450 m, 27 October 2016, M. E. S. Cáceres & A. Aptroot 40089 (ISE—holotype; ABL—isotype).

(Fig. 2B)

Thallus saxicolous, ecorticate but with irregular surface, covering areas up to 5 cm diam., c. 0.1 mm thick, ochraceous white, not surrounded by prothallus.

Ascomata oval to elongate to somewhat sinuous, unbranched, 0.4–1.3 × 0.2–0.4 mm, solitary, rather crowded, erumpent. Margin not carbonized, entire, whitish, dull, c. 0.15 mm wide. Disc mostly slit-like and closed, pinkish grey, whitish pruinose. Hamathecium not inspersed. Paraphysis tips apically spinulose. Periphysoids not observed. Asci 8-spored. Ascospores hyaline, 3-septate, 9.5–10.5 × 5.5–6 μm, ellipsoid, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and thalline margin of ascoma UV−, KOH+ yellow forming red, needle-shaped crystals in microscopic section. TLC: norstictic acid.

Distribution and ecology

On overhanging sandstone cliff in river gully in cerrado forest in Maranhão. So far only known only from Brazil.

Discussion

This new species is rather unique due to its small, 3-septate ascospores. Acanthothecis silicicola (Redinger) Staiger & Kalb comes close, also in ecology, but has a thicker, cracked thallus, larger, usually 5-septate, ascospores, and its paraphyses and periphysoids are not spinulose. Another somewhat similar species is A. kalbii Dal-Forno & Eliasaro, which differs in the corticolous, corticate thallus and ascomata with a distinctly exposed disc, but it may belong in Fissurina.

Acanthothecis subfarinosa Feuerstein sp. nov.

MycoBank No.: MB 840490

Corticolous Acanthothecis with 8-spored asci, small, 6–8-septate ascospores, and norstictic acid; differing from A. rosea in the larger ascospores with more numerous septa and the white ascomata.

Type: Brazil, Paraná, Campo Mourão, resquício de cerrado, 24°00′52″S, 52°21′47″W, on tree bark in cerrado, 24 February 2017, S. C. Feuerstein 2164 (ICN—holotype).

(Fig. 2C)

Thallus corticolous, ecorticate, cracked, greenish, without prothallus, few crystals of calcium oxalate on the lower side of the ascoma.

Ascomata oval to elongate, occasionally irregularly branched, 0.3–0.8 × 0.18–0.23 mm, immersed, entire, white, with lateral thalline margin. Margin not carbonized, c. 25 μm beyond the disc, with algae. Disc usually concealed but some ascocarps have disc slightly exposed, with white pruina, 0.02–0.03 mm wide. Hamathecium not inspersed, 60–70 μm high. Paraphyses unbranched, hyaline, 1.0 μm thick, apically spinulose. Periphysoids spinulose, few, 3–5 μm wide. Asci 8-spored. Ascospores hyaline, transversely 6–8-septate, 22–30 × 5 μm, I−, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and ascoma UV−, KOH+ yellow forming red, needle-shaped crystals in microscopic section. TLC: norstictic acid.

Distribution and ecology

On branches in cerrado in Paraná. So far known only from Brazil.

Discussion

Due to the small, transversely septate, I− ascospores and the norstictic acid chemistry, this new species comes closest to Acanthothecis rosea (Vain.) Staiger & Kalb; however, the latter differs in the distinctly smaller, 3-septate ascospores (16–21 μm long) and the pinkish ascomata. Note that A. rosea is keyed out incorrectly in Muscavitch & Lendemer (Reference Muscavitch and Lendemer2016), with a much larger ascospore size. Acanthothecis floridensis Seavey & J. Seavey is also similar but has a corticate thallus and ascomata with an exposed, brown disc.

Acanthothecis submuriformis Aptroot, Lücking & M. Cáceres sp. nov.

MycoBank No.: MB 840491

Corticolous Acanthothecis with 8-spored asci, small, submuriform ascospores and lichexanthone; differing from A. tetraphora in the much smaller, submuriform ascospores and in the lack of norstictic acid.

Type: Brazil, Rondônia, Porto Velho, Parque Natural Municipal, 8°41′10″S, 63°52′05″W, on tree bark in primary rainforest, alt. 100 m, 19 November 2012, M. E. S. Cáceres & A. Aptroot 15598 (ISE—holotype; ABL—isotype).

(Fig. 2D)

Thallus corticolous, ecorticate, rather smooth, covering areas up to 5 cm diam., c. 0.1 mm thick, ochraceous white, not surrounded by prothallus.

Ascomata elongate to sinuous, usually sparingly and irregularly branched, 0.6–1.5 × 0.2–0.3 mm, solitary, immersed to erumpent. Margin not carbonized, entire, whitish, dull, not distinctly prominent, but higher than the disc, c. 0.1 mm wide. Disc mostly slit-like and closed, pinkish brown, not pruinose. Hamathecium not inspersed. Paraphyses slightly thickened at the tips, spinulose. Periphysoids absent. Asci 8-spored. Ascospores hyaline, submuriform, 7–9 × 0–1-septate, with only c. 2 cells having a longitudinal septum, 29–31 × 6–8 μm, I−, ellipsoid, not surrounded by a gelatinous layer.

Pycnidia not observed.

Chemistry

Thallus and thalline margin of ascoma UV+ yellow, KOH−. TLC: lichexanthone.

Distribution and ecology

On tree bark in tropical rainforest in Rondônia. So far known only from Brazil.

Discussion

This new species is only the second to produce lichexanthone, after Acanthothecis tetraphora (Nyl.) Staiger & Kalb. The latter differs clearly in the much larger, muriform ascospores and the additional production of norstictic acid. Both correspond in the morphology of the thallus and ascomata.

Further nomenclatural novelties

Acanthothecis bicellulata Staiger & Kalb sp. nov.

MycoBank No.: MB 840492

Acanthothecis bicellulata Staiger & Kalb, Mycotaxon 73, 114 (1999); nom. inval., ICN Art. 36.1 (‘ad int.’).

Corticolous Acanthothecis with 8-spored asci, small, 1-septate ascospores; differing from A. bicellularis (see below) in the larger ascospores.

Type: Brazil, Minas Gerais, Serra do Espinhaço, Serra do Caraça, Bocaina, c. 4 km E of the monastery, alt. 1450 m, K. Kalb & G. Plöbst 31345a, July 1978 (WIS-L-0089204—holotype).

Reference to full description

Staiger & Kalb (Reference Staiger and Kalb1999: 114).

Acanthothecis farinosa Staiger & Kalb sp. nov.

MycoBank No.: MB 840493

Acanthothecis farinosa Staiger & Kalb, Mycotaxon 73, 115 (1999); nom. inval., ICN Art. 36.1 (‘ad int.’).

Corticolous Acanthothecis with 8-spored asci, small, transversely septate ascospores, paraphysis tips lacking warts, and norstictic acid; differing from A. subfarinosa which produces apically warty paraphyses.

Type: Brazil, Amazonas, Rio Preto, c. 80 km E of Manaus, 03°10′S, 59°50′W, alt. 40 m, K. Kalb & A. Kalb 27792, August 1993 (WIS-L-0089213—holotype).

Reference to full description

Staiger & Kalb (Reference Staiger and Kalb1999: 115).

Acanthothecis subabaphoides Staiger & Kalb sp. nov.

MycoBank No.: MB 840494

Acanthothecis subabaphoides Staiger & Kalb, Mycotaxon 73, 115 (1999); nom. inval., ICN Art. 36.1 (‘ad int.’).

Corticolous Acanthothecis with 4–6-spored asci, large, transversely septate ascospores, and containing protocetraric acid and lichexanthone; differing from A. submuriformis and A. tetraphora in the transversely septate ascospores and the chemistry.

Type: Brazil, Mato Grosso, between Jaciara and São Vicente, c. 100 km ESE from Cuiaba, in cerrado, alt. 750 m, K. Kalb 28850, May 1980 (hb. KALB—holotype).

Reference to full description

Staiger & Kalb (Reference Staiger and Kalb1999: 115).

Acanthothecis bicellularis (Sipman & Lücking) Lücking comb. nov.

MycoBank No.: MB 840495

Acanthotrema bicellulare Sipman & Lücking [as ‘bicellularis’] in Sipman et al. Phytotaxa 55, 1–214 (2012).

Notes

This species was originally described in the genus Acanthotrema but recognized as different due to the endoperidermal thallus. The latter feature is more typical of Acanthothecis s. str. and species with more or less rounded ascomata are known in that genus, particularly the type itself. Therefore, placement in Acanthothecis seems more appropriate. Within the latter, A. bicellulata, provisionally established by Staiger & Kalb (Reference Staiger and Kalb1999) and validated here, largely agrees morphologically and anatomically, but the differences in ascospore dimensions (7–10 × 3–4 μm in bicellulata vs 4–6 × 2–3 μm in bicellularis) are too substantial at this size for them to be considered the same species.

World key to species of Acanthothecis

  1. 1 Excipulum carbonized………2

    Excipulum uncarbonized………3

  2. 2(1) Excipulum laterally carbonized; hymenium inspersed; ascospores muriform with 11–13 transverse and 2–3 longitudinal septa, 35–50 × 9–12 μm; Neotropics (Brazil)………A. obscura Staiger & Kalb

    Excipulum apically carbonized; hymenium clear; ascospores 3-septate, 16–21 × 3–4 μm; eastern Paleotropics (India)……… ………A. collateralis Makhija & Adaw.

  3. 3(1) Hymenium inspersed………4

    Hymenium clear………6

  4. 4(3) No substances (K−, P−); thallus corticate, brownish, lirellae prominent, with striate labia (resembling a species of Pallidogramme); eastern Paleotropics (India)………A. subconsocians Pooja Gupta & G. P. Sinha

    Norstictic acid present (K+ yellow forming red crystals, P+ orange-red); thallus ecorticate, lirellae erumpent………5

  5. 5(4) Ascospores 12–14 × 3–4 μm, 3-septate; paraphyses apically warty; disc reddish when wet, on bark; eastern Paleotropics (India) ………A. coccinea B. O. Sharma et al.

    Ascospores 19–22 × 6 μm, 5-septate; paraphyses apically smooth; disc flesh-coloured when wet, on rock; Neotropics (Brazil, Paraguay)………A. silicicola (Redinger) Staiger & Kalb

  6. 6(3) Ascospores transversely septate………Group 1

    Ascospores submuriform to muriform………Group 2

Group 1: excipulum uncarbonized, hymenium clear, ascospores transversely septate

  1. 1 Ascospores 1-septate; ascomata more or less rounded, chroodiscoid; thallus endoperidermal………2

    Ascospores multiseptate; ascomata and thallus variable………3

  2. 2(1) Ascospores 7–10 × 3–4 μm; Neotropics (Brazil)………A. bicellulata Staiger & Kalb ex Staiger & Kalb

    Ascospores 4–6 × 2–3 μm; Neotropics (Costa Rica)………A. bicellularis (Sipman & Lücking) Lücking

  3. 3(1) Lichexanthone present (thallus UV+ yellow); ascomata rather short, prominent; thallus ecorticate; Neotropics (Brazil)……… ………A. subabaphoides Staiger & Kalb ex Staiger & Kalb

    Lichexanthone absent (thallus UV−); ascomata and thallus variable………4

  4. 4(3) No substances (thallus K−, P−)………5

    Norstictic, stictic, salazinic, psoromic and/or protocetraric acids, and/or isohypocrelline (K−, K+ yellow or K+ yellow forming red crystals or K+ green or P+ yellow or P+ orange-red)………11

  5. 5(4) Ascospores < 45 μm long and ≤ 10-septate………6

    Ascospores > 45 μm long and > 14-septate………8

  6. 6(5) Ascospores 8–10-septate, 35–43 × 7–10 μm; ascomata densely white-pruinose, somewhat irregular, with concealed disc; thallus ecorticate; eastern Paleotropics (India)………A. celata B. O. Sharma et al.

    Ascospores 3–4-septate, < 25 μm long; ascomata epruinose, with narrowly gaping disc; thallus variable………7

  7. 7(6) Ascospores 8–11 × 3–4 μm; ascomata becoming prominent; thallus corticate; northern temperate (USA)……… ………A. fontana Muscavitch & Lendemer

    Ascospores 16–20 × 6–8 μm; ascomata erumpent; thallus largely ecorticate; northern temperate (USA)……… ………A. paucispora Lendemer & R. C. Harris

  8. 8(5) Ascospores 69–100 μm long, > 26-septate; thallus ecorticate, whitish………9

    Ascospores 45–80 μm long, ≤ 22-septate; thallus distinctly corticate, olive green to yellowish brown………10

  9. 9(8) Ascospores 80–100 × 8–10 μm, 27–34-septate; ascomata irregularly chroodiscoid; thallus largely endoperidermal; Australasia (Australia)………A. aquilonia A.W. Archer & Elix

    Ascospores 69–77 × 6.5–7.5 μm, 35–43-septate; ascomata lirelliform, with narrowly…gaping disc; thallus largely epiperidermal; Neotropics (Brazil)………A. multiseptata Aptroot, Lücking & M. Cáceres

  10. 10(8) Ascomata robust, becoming prominent, solitary, with striate excipula; ascospores 45–80 × 9.5–12 μm, c. 5–7 times as long as wide; Neotropics (Panama)………A. maritima van den Boom & Sipman

    Ascomata small, immersed in distinct, erumpent pseudostromata; ascospores 50–80 × 7–9 μm, c. 7–9 times as long as wide; Neotropics (Brazil)………A. sarcographoides M. Cáceres & Lücking

  11. 11(4) Ascospores > 20 μm wide………12

    Ascospores < 15 μm wide………14

  12. 12(11) Ascospores single, 135–185 × 27–30 μm; norstictic, protocetraric and other acids; ascomata short to almost rounded, becoming prominent; Neotropics (Brazil)………A. megalospora Feuerstein & Lücking

    Ascospores 2–8 per ascus, ≤ 110 μm long; norstictic acid only………13

  13. 13(12) Ascospores 2–4 per ascus, 19–25-septate, 85–100 × 20–26 μm; ascomata lirelliform, erumpent; Paleotropics (Kenya)……… ………A. africana Staiger & Kalb

    Ascospores 8 per ascus, 9–13-septate, 69–80 × 25–35 μm; ascomata short to almost rounded, becoming prominent; Neotropics (Brazil)………A. oryzoides Aptroot, Lücking & M. Cáceres

  14. 14(11) Ascomata red or pinkish (K+ green); resembling species of Thalloloma or Cruentotrema………15

    Ascomata not pigmented (K−, K+ yellow or K+ yellow forming red crystals or P+ yellow or P+ orange-red)………17

  15. 15(14) Ascospores 9–12-septate, 22–31 × 4–6 μm; thallus ecorticate; Neotropics (Brazil)………A. mirabilis Staiger & Kalb

    Ascospores 3-septate, 17–20 × 6–8 μm; thallus corticate………16

  16. 16(15) Ascomata lirellate (≤10 mm long), fissurine, pinkish; Neotropics (Dominica)………A. rosea (Vain.) Staiger & Kalb

    Ascomata rounded, oval or branched and curved with broad lobes, dark red; Neotropics (Brazil)……… ………A. sanguinoloba (Redinger) Staiger & Kalb

  17. 17(14) Psoromic acid (K−, P+ yellow); ascospores (4–)5–7(–8)-septate………18

    Norstictic, stictic, salazinic and/or protocetraric acids (K−, K+ yellow or K+ yellow forming red crystals or P+ orange-red); ascospores variously septate………19

  18. 18(17) Ascomata rounded to irregular, barely contrasting with the whitish to yellowish, ecorticate thallus; ascospores 13–18 × 4–5 μm; Australasia (New Caledonia)………A. consocians (Nyl.) Staiger & Kalb

    Ascomata narrowly lirellate and branched, strongly contrasting with the olive-brown, corticate thallus; ascospores 9–16 × 3–4 μm; eastern Paleotropics (India)………A. nivalis Makhija & Adaw.

  19. 19(17) Norstictic acid present (K+ yellow forming large, needle-shaped, red crystals)………20

    Stictic, salazinic and/or protocetraric acids (K−, K+ yellow or K+ yellow forming mostly small red crystals or P+ orange-red) ………28

  20. 20(19) Ascospores > 30 μm long………21

    Ascospores ≤ 30 μm long………23

  21. 21(20) Ascospores 30–53 × 6–9 μm, 9–16-septate; lirellae immersed, thallus ecorticate; norstictic, connorstictic and stictic acids; northern subtropical (USA) and Neotropics (Brazil)………A. aurantiaca (Müll. Arg.) Staiger & Kalb [= A. intertexta (Müll. Arg.) Staiger & Kalb]

    Ascospores 45–90 × 6–12 μm, 15–23-septate; lirellae and thallus variable; norstictic acid only………22

  22. 22(21) Lirellae immersed-erumpent, with gently sloping margins separated from the thallus by a slit, and mostly concealed disc; ascospores 7–8 times as long as wide; northern temperate (USA)……… ………A. poitaeoides (Nyl. ex Tuck.) E. A. Tripp & Lendemer

    Lirellae erumpent to prominent, with steeply sloping margins and partially exposed, pruinose disc; ascospores 5–6 times as long as wide; Neotropics (Mexico)………A. alba Herrera-Camp. et al.

  23. 23(20) Ascospores ≤ 15 μm long………24

    Ascospores 16–30 μm long………25

  24. 24(23) Thallus saxicolous; disc mostly slit-like and closed; ascospores 9–11 × 5–6 μm, 3-septate; Neotropics (Brazil)……… ………A. saxicola Aptroot et al.

    Thallus corticolous; disc distinctly exposed; ascospores 9–15 × 4–5 μm, 4–6-septate; Neotropics (Brazil)……… ………A. kalbii Dal-Forno & Eliasaro

  25. 25(23) Paraphyses apically warty………26

    Paraphyses apically smooth………27

  26. 26(25) Thallus ecorticate; ascospores I+ blue; Neotropics (Brazil)………A. farinosa Staiger & Kalb ex Staiger & Kalb

    Thallus corticate; ascospores I−; northern subtropical (USA)………A. floridensis Seavey & J. Seavey

  27. 27(25) Ascospores 22–30 × 5 μm, c. 6–8-septate; norstictic acid only; ascomata whitish; thallus corticate, somewhat shiny; Neotropics (Brazil)………A. subfarinosa Feuerstein

    Ascospores 16–21 × 3–4 μm, 3-septate; norstictic and stictic acids; ascomata with dark slit; thallus ecorticate, matt; eastern Paleotropics (India)………A. collateralis Makhija & Adaw.

  28. 28(19) Ascospores > 70 μm long………29

    Ascospores ≤ 60 μm long………31

  29. 29(28) Salazinic acid and traces of norstictic acid (K+ yellow forming small red crystals); ascomata prominent, with concealed to slightly gaping disc and entire labia; thallus ecorticate; eastern Paleotropics (Vietnam)………A. yokdonensis S. Joshi & Hur

    [≡ A. salazinica S. Joshi & Hur, nom. illeg.]

    Protocetraric acid (K− to K+ weak yellow); ascomata and thallus not as above…30

  30. 30(29) Ascomata short to irregular, with partially exposed disc and entire to irregular labia; ascospores 35–47-septate; thallus ecorticate, whitish to pale yellowish; Neotropics (Brazil)………A. clavulifera (Vain.) Staiger & Kalb

    Ascomata lirellate, with concealed disc and striate labia; ascospores 19–29-septate; thallus distinctly corticate, olive green to yellowish brown; Neotropics (Brazil)………A. subclavulifera Staiger & Kalb

  31. 31(28) Ascospores 36–56 μm long, > 10-septate; ascomata erumpent; thallus partly endoperidermal, whitish………32

    Ascospores 15–30 μm long, ≤ 9-septate; ascomata and thallus variable………33

  32. 32(31) Ascospores 40–56 × 7–8 μm, 15–17-septate, I−; protocetraric acid; Australasia (Australia)………A. borealis A. W. Archer & Elix

    Ascospores 36–45 × 6–7 μm, 11–13-septate, I+ blue; stictic acid; Neotropics (Brazil)………A. albescens (Vain.) Staiger & Kalb

  33. 33(31) Labia entire; ascospores 15–18(–21) × 4–5 μm; stictic acid only (only in the lirellae); thallus endoperidermal; northern temperate (USA)………A. leucoxanthoides Lendemer

    Labia striate; ascospores usually larger than 20 × 5 μm; stictic acid, additionally with peristictic or constictic and hypoconstictic acids; thallus mostly epiperidermal………34

  34. 34(33) Ascocarps very irregular, 1–2 × 0.4–0.8 mm; stictic and peristictic acids; Neotropics (Brazil)……… ………A. leucoxantha (Müll. Arg.) Staiger & Kalb

    Ascocarps regularly lirelliform, straight, 0.3–3 × 0.1–0.2 mm; stictic, constictic and hypoconstictic acids; temperate Australasia (Tasmania)…A. virgulicola Kantvilas

Group 2: excipulum uncarbonized, hymenium clear, ascospores submuriform to muriform

  1. 1 Lichexanthone present (thallus UV+ yellow); ascomata shortly lirelliform, erumpent; thallus corticate………2

    Lichexanthone absent (thallus UV−); ascomata and thallus variable………3

  2. 2(1) Ascospores muriform, with 19–29 transverse and 2–3 longitudinal septa per segment, 4–6 per ascus, 65–95 × 13–18 μm; norstictic and constictic acid (K+ yellow forming red crystals); Neotropics (Brazil and Colombia) and Paleotropics (Kenya)………A. tetraphora (Nyl.) Staiger & Kalb

    Ascospores submuriform, with 7–9 transverse and 0–1 longitudinal septa per segment (only c. 2 cells with a longitudinal septum), 8 per ascus, 29–31 × 6–8 μm; no additional substances (K−, P−); Neotropics (Brazil)……… ………A. submuriformis Aptroot, Lücking & M. Cáceres

  3. 3(1) No substances (thallus K−, P−)………4

    Norstictic, stictic, salazinic, psoromic and/or protocetraric acids (K− or K+ yellow or K+ yellow forming red crystals or P+ yellow or P+ orange-red)………10

  4. 4(3) Ascospores ≤ 25 μm long, submuriform………5

    Ascospores > 30 μm long, muriform………6

  5. 5(4) Ascospores 22–24 × 7–9 μm; ascomata erumpent; thallus ecorticate; northern subtropical (USA)……… ………A. floridana Lendemer & R. C. Harris

    Ascospores 8–11 × 3–4 μm; ascomata becoming prominent; thallus corticate; northern temperate (USA)……… ………A. fontana Muscavitch & Lendemer

  6. 6(4) Ascocarps rounded to irregular, with thin thalline margin often in several layers, appearing chroodiscoid; ascospores 45–60 × 20–30 μm; Neotropics (El Salvador)………A. adjuncta Welz & Sipman

    Ascocarps shortly elongate to lirelliform; ascospores variable in size………7

  7. 7(6) Ascospores ≤ 20 μm wide; thallus pale, ecorticate to indistinctly corticate………8

    Ascospores > 20 μm wide; thallus olive green to olive-brown or yellowish brown, distinctly corticate………9

  8. 8(7) Ascospores 4–6 per ascus, I+ blue; ascomata shortly elongate to lirellate and partly branched, with largely concealed disc; Paleotropics (South Africa)………A. dialeucoides Kalb & Staiger

    Ascospores 8 per ascus, I−; ascomata oval to shortly elongate, with exposed, pruinose disc; Australasia (Solomon Islands) ………A. asprocarpa (A. W. Archer) A. W. Archer

  9. 9(7) Ascospores 75–120 × 22–37 μm; widespread ornamentation on paraphyses; ascomata prominent to sessile, with entire labia, strongly contrasting with the olive green to olive-brown, corticate thallus; eastern Paleotropics (India)……… ………A. archeri B. O. Sharma et al.

    Ascospores 35–78 × 18–36 μm; few paraphyses with apical ornamentation; ascomata erumpent to prominent, with striate labia, weakly contrasting with the olive green to yellowish brown thallus; northern subtropical (USA) and Neotropics (Mexico) ………A. peplophora (M. Wirth & Hale) E. A. Tripp & Lendemer

  10. 10(3) Norstictic or salazinic acids (P+ orange-red, K+ yellow forming red crystals, large or small)………11

    Stictic or psoromic and/or protocetraric acids (P+ yellow or P+ orange-red, K− or K+ yellow, but never forming red crystals) ………19

  11. 11(10) Ascospores ≤ 20 μm wide………12

    Ascospores > 20 μm wide………16

  12. 12(11) Ascospores ≤ 45 μm long; ascomata immersed-erumpent, often separated from the thallus by a split………13

    Ascospores > 45 μm long; ascomata variable………14

  13. 13(12) Ascospores muriform, 28–42 × 10–15 μm, 2–6 per ascus; norstictic acid; Paleotropics (South Africa)……… ………A. socotrana (Müll. Arg.) Staiger & Kalb

    Ascospores submuriform, 20–32 × 6–8 μm, 8 per ascus; norstictic and connorstictic acids; northern subtropical (USA), Paleotropics (Réunion) and Australasia (Australia)………A. subaggregans (Müll. Arg.) A. W. Archer [= A. gracilis Staiger & Kalb]

  14. 14(12) Ascospores submuriform, 70–120 × 7–14 μm, 27–29-septate; salazinic and norstictic (trace) acids; ascomata prominent, with concealed to slightly gaping disc and entire labia; thallus ecorticate; eastern Paleotropics (Vietnam)……… ………A. yokdonensis S. Joshi & Hur

    Ascospores muriform, 45–85 μm long and ≤ 25-septate; norstictic acid only; ascomata and thallus variable………15

  15. 15(14) Disc exposed, cinnabar-red; ascospores, 45–50 × 12–15 μm, 6 × 0–2-septate; thallus corticate; eastern Paleotropics (Sri Lanka) ………A. aurantiacodiscus Weerakoon et al.

    Disc concealed, pale; ascospores 46–85 × 9–17 μm, 14–25 × 0–3-septate; thallus ecorticate; northern subtropical (USA)……… ………A. mosquitensis (Tuck.) Tripp & Lendemer

  16. 16(11) Salazinic acid (K+ yellow forming small, red crystals); ascomata erumpent to prominent, with striate labia; thallus distinctly corticate, olive green to yellowish brown; northern subtropical (USA) and Neotropics (Panama)……… ………A. salazinica van den Boom & Sipman

    Norstictic acid (K+ yellow forming large, red, needle-shaped crystals); ascomata and thallus variable………17

  17. 17(16) Disc concealed, margins weakly pinkish; ascospores 77–98 × 25–30 μm; norstictic, stictic and subnorstictic acids; Neotropics (Brazil)………A. roseola Feuerstein

    Disc partially exposed, white-pruinose; margins whitish………18

  18. 18(17) Ascospores 82–100 × 27–35 μm; periphysoids present; norstictic and stictic acids; Neotropics (Brazil)……… ………A. latispora Feuerstein & Silveira

    Ascospores 95–110 × 35–40 μm; periphysoids absent; norstictic acid; Neotropics (Brazil)……… ………A. norstictica Aptroot, Lücking & M. Cáceres

  19. 19(10) Ascospores ≤ 35 μm long………20

    Ascospores > 35 μm long………22

  20. 20(19) Paraphyses apically smooth; ascospores muriform, 22–35 × 9–14 μm; stictic and constictic acids; ascomata with striate labia; thallus corticate; eastern Paleotropics (India and Malaysia) and Australasia (Fiji)………A. dialeuca (Kremp.) Staiger & Kalb [= A. incondita (Nyl.) Staiger & Kalb] [= A. leucolyta (Nyl.) Staiger & Kalb]

    Paraphyses apically warty; ascospores submurifom, 14–26 × 5–10 μm; ascomata and thallus variable………21

  21. 21(20) Ascomata 0.1–0.2 mm wide, straight, not or sparsely branched; stictic, constictic and hypostictic acids; temperate Australasia (Tasmania)……A. virgulicola Kantvilas

    Ascomata 0.3–0.6 mm wide, very irregular and partly branched; stictic acid; temperate Australasia (Australia: Victoria)……… ……A. gyridia (Stirt.) A. W. Archer

  22. 22(19) Psoromic and subpsoromic acids (K−, P+ yellow); ascomata rounded to shortly elongate, strongly prominent to sessile, with thick thalline margin and white-pruinose disc (resembling the genus Stegobolus); thallus distinctly corticate, verrucose; eastern Paleotropics (Vietnam)………A. verrucosa S. Joshi et al.

    Stictic, constictic or protocetraric acid (K+ yellow or K− to very weakly K+ yellow, P+ orange-red); ascomata and thallus not as above………23

  23. 23(22) Paraphyses apically smooth or few paraphyses with apical ornamentation………24

    Paraphyses distinctly apically warty………25

  24. 24(23) Ascospores single, 90–120 × 20–36 μm; paraphyses apically smooth; ascomata with entire labia, whitish; thallus whitish; Neotropics (Brazil)………A. corcovadensis (Redinger) Staiger & Kalb

    Ascospores 4–8 per ascus, 35–78 × 18–36 μm; few paraphyses with apical ornamentation; ascomata with striate labia, pale yellowish; thallus olive green to yellowish brown; northern temperate (USA) and Neotropics (Mexico)……… ………A. peplophora (M. Wirth & Hale) E. A. Tripp & Lendemer

  25. 25(23) Protocetraric acid (K− to very weakly K+ yellow); ascomata rather short, prominent; thallus ecorticate………26

    Stictic acid (K+ yellow); ascomata short, immersed to erumpent; thallus ecorticate but smooth and partly shiny to corticate ………27

  26. 26(25) Ascospores 1–4 per ascus, 84–171 × 13–30 μm; disc concealed, margins entire; northern temperate (USA) and Neotropics (Paraguay and Brazil)………A. leucopepla (Tuck.) E. A. Tripp & Lendemer [= A. abaphoides (Nyl.) Staiger & Kalb]

    Ascospores 4–8 per ascus, 67–96 × 12–19 μm; disc at least partially exposed, margins irregular to fissured; Neotropics (Mexico, Costa Rica, Guatemala and Brazil)………A. hololeucoides (Nyl.) Staiger & Kalb [= A. pachygraphoides (Vain.) Clem.] [= A. caesiocarnea (Vain.) Staiger & Kalb]

  27. 27(25) Ascomata with concealed disc, 0.8–3.5 × 0.5–0.7 mm; thallus ecorticate; ascospores with 15–19 transverse and 3–4 longitudinal septa per segment; Neotropics (Brazil)………A. rimosa Aptroot, Lücking & M. Cáceres

    Ascomata with more or less exposed, white-pruinose disc, 0.5–1 × 0.4–0.5 mm; thallus corticate; ascospores with 10–15 transverse and 1–3 longitudinal septa per segment; Neotropics (Brazil) ………A. pruinocarpa Dal-Forno & Eliasaro

Acknowledgements

We thank CAPES (Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior) for the Ph.D. scholarship to SCF; IAP (Instituto Ambiental do Paraná) and SEMA (Secretaria Estadual do Meio Ambiente) for the collecting permits; and CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico (Processos 401186/2014-8 and 459155/2014-8) for funding the collecting trips and a research grant to MESC (207282/2015-3). AA was funded through a visiting professorship by CAPES (Finance Code 001). Some data used for this study were assembled as part of the NSF-funded project ‘ATM – Assembling a Taxonomic Monograph: the Lichen Family Graphidaceae’ (NSF DEB-1025861 to The Field Museum).

Author ORCIDs

Shirley Cunha Feuerstein, 0000-0003-4589-694X; André Aptroot, 0000-0001-7949-2594; Robert Lücking, 0000-0002-3431-4636.

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Figure 0

Fig. 1. Habitus pictures of new Acanthothecis species, all holotypes. A, A. latispora. B, A. megalospora. C, A. multiseptata. D, A. norstictica. E, A. oryzoides. F, A. rimosa. Scales = 1 mm. In colour online.

Figure 1

Fig. 2. Habitus pictures of new Acanthothecis species, all holotypes. A, A. roseola. B, A. saxicola. C, A. subfarinosa. D, A. submuriformis. Scales = 1 mm. In colour online.

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An updated world key to the species of Acanthothecis s. lat. (Ascomycota: Graphidaceae), with ten new species from Brazil
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