Introduction
A very characteristic specimen of Buellia was found growing with Rinodina fuscoisidiata Giralt et al. (Reference Giralt, Kalb and Elix2010: 3, sub Buellia aff. proximata), an isidiate, muscicolous taxon recently described from high altitudes in the Paramo vegetation of Venezuela (Giralt et al. Reference Giralt, Kalb and Elix2010). The presence of additional specimens in the herbarium of the second author (hb. K. Kalb) allowed detailed morphological and chemical studies which have shown that they can be clearly distinguished from all other known triseptate Buellia taxa by the larger triseptate ascospores and the markedly enlarged apical cells of the paraphyses which give to the surface of the apothecia a particular granular appearance. These specimens are described as a new species below.
Materials and Methods
The specimens were examined by standard techniques using stereoscopic and compound microscopes. Only free ascospores lying outside the asci have been measured. Measurements were made on material mounted in water at ×1000 magnification. Mean value (M) and standard deviation (SD) were calculated and the results are recorded as (minimum value observed) M ± SD (maximum value observed). M, SD and n (the total number of ascospores measured) are given within parentheses. The terminology used for the asci follows Rambold et al. (Reference Rambold, Mayrhofer and Matzer1994), for the ascospore-types and ascospore ontogeny, Giralt (Reference Giralt2001) and for the proper exciple-type, Bungartz et al. (Reference Bungartz, Nordin, Grube, Nash, Ryan, Diederich, Gries and Bungartz2007).
Chemical constituents were identified by standardized thin layer chromatography and high performance liquid chromatography (HPLC) (Elix et al. Reference Elix, Giralt and Wardlaw2003).
The Species
Buellia nordinii Giralt, Kalb & Elix sp. nov
Thallus muscicola vel lignicola, et in et supra substrato crescens, fuscus, atranorinum in vestigiis continens. Specimina in ligno crescentia normaliter blastidios formantia. Apothecia lecideina, nigra. Excipulum proprium typo aethalea. Cellulae apicales paraphysum usque ad 9–10 μm diametro auctae, parte superne fuscae. Ascosporae (1–2)–3-septatae, (25–)28·4–35·8(–42) × (10–)11·8–15·5(–18) μm; paries interioris apicaliter et ad basim septorum incrassatus, ontogenia typo A. Conidia bacilliformia, (2–)3–4 × c. 1 μm.
Typus: Venezuela, Mérida, distr. Libertador, Pico Espejo, SE von Mérida, Loma Redonda, 4200 m, 8°35′N; 71°00′W, on very soft and decomposed wood, 8 & 10 August 1989, K. & A. Kalb (hb. Kalb 23952—holotypus; GZU, hb. Kalb 34813—isotypi).
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Fig. 1. Buellia nordinii, blastidiate thallus with apothecia (note the granular surface) growing on lignum (holotype). Scale = 1 mm.
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Fig. 2. Buellia nordinii, ascospore ontogeny of type A and ascospore variability (holotype). Scale = 10 μm.
Thallus lignicolous or muscicolous, developing beneath the uppermost layers of the substratum (endosubstratal) or episubstratal, brown, thin; in both cases formed of ±globose units of 70–120 μm diam. composed of a paraplectenchymatous tissue with cells of 3–5(–7) μm diam. intermixed with chlorococcoid algal cells, 8–15 μm diam. Outermost (cortical) cells surrounding the globose units brown pigmented, up to 9 μm diam.. When episubstratal the globose units develop into blastidia; blastidia scattered to usually contiguous, forming a continuous reddish to dark brown, shiny, granulose crust. The anatomy of the blastidia is identical to that of the ± globose units of the non-blastidiate, muscicolous thalli and of the endosubstratal part of the lignicolous thalli. All thallus structures are non-amyloid.
Apothecia lecideine, black, with a fine granular surface (a somewhat soft and spongy appearance, Fig. 1), (0·2–)0·3–0·6(–0·8) mm diam., discrete to rarely crowded and coalescing, sessile and constricted at the base from the beginning when belonging to endosubstratal or muscicolous thalli or adnate when the thallus is an entirely blastidiate crust. Proper margin thick, prominent in young apothecia, becoming thinner, finally excluded. Disc concave at first, then flat and finally convex, epruinose. Proper exciple aethalea-type (Bungartz et al. Reference Bungartz, Nordin, Grube, Nash, Ryan, Diederich, Gries and Bungartz2007), laterally 10–30(–50) μm thick, expanded to 40–60(–75) μm below, inner part hyaline to brownish, outermost part brown with cells with dark brown caps and markedly enlarged, like the apical cells of the paraphyses. Hymenium colourless, 100–120 μm high, not inspersed with oil droplets. Epihymenium brown.Hypothecium 100–150 μm deep, dark brown, upper part with an olivaceous tinge. Paraphyses slender, 1–1·2 μm wide, the apical cells markedly enlarged, up to 9–10 μm wide, with dark brown cap. Asci Bacidia-type (Rambold et al. Reference Rambold, Mayrhofer and Matzer1994), 8-spored but very often with only (2–)3–4 ascospores fully developed. Ascospores (1–2)–3-septate, (25–)28·4–35·8(–42) × (10–)11·8–15·5(–18) μm (M= 32 × 13·5 μm; SD= 3·7 / 1·8 μm; n = 73), with inner walls slightly thickened at the apices and very pronounced at septa, when mature slightly constricted at septa; outer wall faintly microrugulate (visible at ×1000). Longitudinal septa never present. Ontogeny of type A (Giralt Reference Giralt2001) (Fig. 2).
Pycnidia rare, subimmersed, globose, unilocular, < 0·1 mm diam., ostiole dark brown with cells like the apical cells of the paraphyses; conidiogenous cells mainly apical but also intercalary (cf. conidiophore-type V, Vobis Reference Vobis1980). Conidia bacilliform, 2–3(–4) × c. 1 μm.
Chemistry. K−, C−, KC−, Pd−, UV−. The two specimens analysed (GZU, hb. Kalb 34813—isotype, hb. Kalb 34831) contain traces of atranorin.
Etymology. The species is named in honour of Dr Anders Nordin, Uppsala, Sweden, for his excellent revision of the pluriseptate species of Buellia.
Ecology and distribution. The new species is known only from two localities in Merida province in Venezuela growing on very decomposed lignum and on mosses. At the type locality a sterile, sorediate taxon containing xanthones grows intermixed with the new species. Other accompanying species included Tetramelas regiomontanus Marbach, Rinodina stictica Sheard & Tønsberg and R. fuscoisidiata Giralt, Kalb & Elix. These species grow in very humid situations near the ground in open paramo vegetation at elevations of 3500 and 4200 m.
Observations. Buellia nordinii is characterized by the endosubstratal to episubstratal thin, brown thallus which usually becomes entirely blastidiate (when growing on lignum), the presence of traces of atranorin, the markedly enlarged apical cells of the paraphyses which give to the apothecia their soft and porous appearance, and the large, triseptate ascospores (M = 32 × 13.5 μm), with inner apical and septal wall thickenings and an ontogeny of type A.
Among all the other known triseptate Buellia s. lat. species (Nordin Reference Nordin1996, Reference Nordin2000), Buellia nordinii together with the terricolous Tetramelas graminicola (Øvstedal) Kalb and T. geophilus (Sommerf.) Norman have the largest ascospores. The two Tetramelas Norman species are clearly distinguished by the presence of xanthones (6-O-methylarthothelin) and ascospores which lack internal wall thickenings. Similarly, T. triphragmioides (Anzi) A. Nordin & Tibell has much smaller triseptate ascospores while T. insignis (Nägeli ex Hepp) Kalb has large ascospores, but they very rarely become triseptate (Marbach Reference Marbach2000; Kalb Reference Kalb2004; Nordin Reference Nordin2004; Nordin & Tibell Reference Nordin and Tibell2005). The species of Hafellia Kalb, H. Mayrhofer & Scheid. species belong to Buellia s. str. since the type species of Buellia is Buellia (= Hafellia) disciformis (Fr.) Mudd. (cf. Gams Reference Gams2004). Hafellia bispora Sheard, H. disciformis (Fr.) Marbach & H. Mayrhofer and H. sanguinolenta (T. Schauer) Hafellner & Türk are distinguished from B. nordinii by the Callispora-type ascospores and the hymenia inspersed with oil droplets (Sheard Reference Sheard1992; Giralt et al. Reference Giralt, Barbero and Elix2002a; Etayo & Marbach Reference Etayo and Marbach2003).
The tropical, montane Buellia proximata H. Magn. and B. lauricassiaeoides Aptroot, and the Macaronesian, submontane, B. laurocanariensis Giralt, Etayo & van den Boom, are probably more closely related to B. nordinii. All three taxa have ascospores with internal wall thickenings, but in contrast to B. nordinii, the ascospores are significantly smaller [M = 24·3 × 8·8 μm; n = 80; 23·2 × 8·9 μm; n = 10; and 22·9 × 8·9 μm; n = 61, respectively] and those of the first two species show type-B ontogeny (cf. Imshaug Reference Imshaug1955; Aptroot et al. Reference Aptroot, Diederich, Sérusiaux and Sipman1997; Nordin Reference Nordin2000;Giralt et al. Reference Giralt, Etayo and van den Boom2002b). Further, they are corticolous, lack vegetative propagules and have less enlarged paraphyses tips. Additional distinguishing features are the presence of diploicin as well as atranorin in B. proximata (Nordin Reference Nordin2000) and B. lauricassiaeoides (J. A. Elix unpublished data), the sporadic presence of longitudinal septa in the ascospores of B. proximata, the often 4–5–septate ascospores of B. lauricassiaeoides and the strongly ornamented ascospore walls (rugulate) of B. laurocanariensis.
According to the literature, relatively few Buellia s. lat. species are known to develop vegetative propagules, namely, Amandinea efflorescens (Müll. Arg.) Marbach, Buellia arborea Coppins & Tonsberg, B. dissimilis (Nyl.) Müll. Arg., B. elizae (Tuck.) Tuck., B. exalbida (Kremp.) Zahlbr., B. griseovirens (Turner & Borrer ex Sm.) Almb., B. manamiana Diederich, B. subfrigida M. Inoue, B. sorediata (Tuck.) Magn., B. violaceofusca Thor & Murh and Tetramelas graminicola (Imshaug Reference Imshaug1955; Harris Reference Harris1988; Thor & Muhr Reference Thor and Muhr1991; Tonsberg Reference Tønsberg1992; Inoue Reference Inoue1993; Aptroot et al. Reference Aptroot, Diederich, Sérusiaux and Sipman1997; Marbach Reference Marbach2000; Nordin Reference Nordin2000; Øvstedal & Lewis Smith Reference Øvstedal and Lewis Smith2001; Kalb Reference Kalb2004; Bungartz et al. Reference Bungartz, Nordin, Grube, Nash, Ryan, Diederich, Gries and Bungartz2007). None of these species have features that are diagnostic of Buellia nordinii.
Additional specimens examined. Venezuela: Mérida: distr. Rangel, zwischen Laguna Mucubaji und Pico Mucuñuque, etwa 15 km SE von Apartaderos, in Paramo-Vegetation, 3500 m, 8°45′N; 70°45′W, on lignum, 1989, K. & A. Kalb & López-Figueiras (hb. Kalb 27015); distr. Libertador, Pico Espejo, SE von Mérida, Loma Redonda, 4200 m, 8°35′N; 71°00′W, on mosses, 1989, K. & A. Kalb (hb. Kalb 34821, 34831–topotypes).
The authors wish to thank Anders Nordin for checking part of the material used in this study and for his helpful comments on it. The first author thanks the ‘Comissionat per a la Recerca’ (Catalan Government) and the project CGL2007-66734-C03-02/BOS (Spanish Government) for financial support.