Bulbothrix cinerea Marcelli & Kalb. Mitteilungen aus dem Institut fuer Allgemeine Botanik Hamburg 30/32: 127. 2002.

Benatti, Michel N., 2012, A review of the genus Bulbothrix Hale: the species with medullary norstictic or protocetraric acids, MycoKeys 2, pp. 1-28 : 4-5

Bulbothrix cinerea Marcelli & Kalb. Mitteilungen aus dem Institut fuer Allgemeine Botanik Hamburg 30/32: 127. 2002. Figures 3-4

Holotype.

Brasil, Bahia, Serra do Tombador, between Mundo Novo and Morro do Chapéu, alt. 1000 m, leg. K. Kalb s.n., 18/20-VII-1980 (K. Kalb pers. herb. 20931!).

Description.

Thallus sublinearly laciniate, turning dusky gray in the herbarium, fragments up to 3.8 cm diam., subcoriaceous, saxicolous; upper cortex 12.5−17.5 µm thick, algal layer 25.0−37.5 µm thick, medulla 62.5−75.0 µm thick, lower cortex 12.5−22.5 µm thick. Laciniae irregularly or in part anisotomically dichotomously branched, 0.4-1.6 (−2.5) mm wide, slightly imbricate becoming more crowded in the center, strongly adnate and very appressed, with flat, truncate to subtruncate apices, the margins flat, crenate to subcrenate or somewhat subirregular, entire to slightly incised, sometimes sublacinulate, the axils oval, upper surface smooth and continuous occasionally with irregular cracks in older parts, laminal cilia bulbs absent. Lacinulae marginal, adventitious, scarce, randomly appearing in old parts, short, flat, simple to furcate or irregularly branched, truncate, underside pale brown concolorous with the lower marginal zone, 0.2-1.5 × 0.1-0.7 mm. Maculae absent. Cilia black, without apices or with very brittle, simple and downward-bent apices, 0.05-0.40 × ca. 0.03 mm, with semi-immerse to emerse bulbate bases 0.10-0.20 (-0.30) mm wide, frequently throughout the margins spaced ca. 0.05 mm from each other to occasionally contiguous, in small groups or solitary in the crenulations and axils, often reniform and withered, becoming absent or scarce at the apices of the laciniae. Soredia and pustulae absent. Isidia frequent, laminal, granular to smooth cylindrical ± irregular, occasionally slightly flattened or somewhat dilated (but not inflated), straight, 0.05-0.30 (-0.65) × ca. 0.05-0.15 (-0.30 when dilated) mm, simple to sometimes sparsely branched, erect, firm although brittle, quite shiny with brown or blackish apices, eciliate (sometimes swollen and resembling thick pycnidia, see comments). Medulla white. Lower surface almost uniformly pale brown, except for some darker marginal parts, shiny, smooth, slightly papillate, moderately rhizinate. Marginal zone brown to dark brown, almost indistinct from the center, shiny, 0.5-1.0 mm wide, smooth, papillate or slightly rhizinate. Rhizinae brown to dark brown, simple, generally with dark bulbate bases, 0.10-0.60 × ca. 0.05 (-0.10) mm, frequent, evenly distributed. Apothecia subconcave to concave, adnate to substipitate, 0.3-3.7 mm diam., laminal, margin crenate to dentate and incised, coronate, the bulbs frequently interrupting the continuity of the margin leaving them lobulate, amphithecia smooth without ornamentations when young becoming gradually more isidiate and sometimes forming ciliary bulbs with progressing development. Disc light or meaty brown, epruinose, imperforate, epithecium 7.5-12.5 µm high, hymenium 45.0−55.0 µm high, subhymenium 25.0−32.5 µm high. Ascospores ellipsoid to oval, 10.0-13.5 × 6.0-7.5 (-8.5) µm, epispore ca. 0.5 µm. Pycnidia laminal (a lichenicolous fungus resembling pycnidia may occur on the isidia), immerse, with brown or black ostioles. Conidia weakly bifusiform, 5.0−6.0 × 1.0 µm.

Spot tests.

upper cortex K+ yellow, UV-; medulla K+ yellow→orange or light red, C-, KC-, P+ orange, UV-.

TLC/HPLC.

cortical atranorin, medullary norstictic and connorstictic acids (see also Marcelli and Ribeiro 2002).

Distribution.

South America: Brazil - Bahia ( Marcelli and Ribeiro 2002) and Minas Gerais ( Ribeiro 1998, Marcelli and Ribeiro 2002).

Additional specimen examined.

Brazil, Minas Gerais State, Catas Altas Municipality, Serra do Caraça, Parque Natural do Caraça, on sun exposed rock at the trail at the edge of riparian, leg. M.P. Marcelli & C. H. Ribeiro 31971, 09-IX-1997 (SP).

Comments.

The holotype (Fig. 3) consists of several small fragments (between 0.5 and 4.0 cm diam.) in good condition, free of substrate, not being glued to a card voucher. The lower cortex is easily viewable. On most of the fragments there are several apothecia in various stages of maturation, but not all fragments have apothecia containing mature ascospores.

Until the discovery of this species, Bulbothrix decurtata (Kurokawa) Hale was the only other known species of the genus that appeared to be obligatory saxicolous. In view of the very fragmentary condition of the analyzed material, Bulbothrix cinerea seems to be a species whose thalli are very closely attached to the substrate and difficult to collect, as noted already by the authors ( Marcelli and Ribeiro 2002).

The accentuated gray tinge of the thalli seen in Bulbothrix cinerea is unusual among Parmeliaceae (Marcelli & Ribeiro 2002). Its isidia also have some peculiarities. Their dark apices are somewhat bright in young stages and can, at this stage, be confused with laminal ciliary bulbs [like those found in specimens of Bulbothrix ventricosa (Hale & Kurokawa) Hale], parasitic fungi, or pycnidia.

Cross-sections of the isidia reveal, however, the typical anatomical structure: they are only covered by a thin dark “skin” [similar to the isidia of the saxicolous species Bulbothrix decurtata (Kurokawa) Hale] and lack a compact cortex cover. This dark coverage is restricted to the apices of the isidia when they are mature.

Common among isidia on both specimens studied are large, globose, blackened structures about 0.10-0.30 mm wide. They are mainly visible in the more inflated isidia and might be of parasitic nature. Morphologically they are identical to laminal pycnidia, but conidia were not found in sections under the microscope.

As explained by the authors (Ribeiro and Marcelli 2002), Bulbothrix cinerea tends to have marginal cilia without apices or with simple apices curved downward toward the substrate, leaving only the bulbs visible when casually observed from above. Sometimes scars or remnants of brittle apices can be observed. Several of the bulbs, however, notably those who developed in parts of the thallus unlikely to “anchor” it to the substrate, do not show any signs of apex development.

Bulbothrix isidiza (Nylander) Hale differs by being corticicolous with a more light tinged cortex, having laciniae twice as large as those of Bulbothrix cinerea (2.0-5.5 mm wide), isidia that are never pycnidiate and not becoming swollen or lobulate, and having salazinic acid as medullary substance.

Bulbothrix ventricosa also differs from Bulbothrix cinerea by being corticicolous, having a lighter tinge with larger laciniae (1.5-4.5 mm wide), never having pycnidiate isidia that are concolor to the cortex which do not become swollen or lobulate, and the often variable mottled colored lower cortex, as well as the fairly common presence of laminal ciliary bulbs.

Bulbothrix decurtata differs from Bulbothrix cinerea by having both a black lower cortex and rhizinae, and salazinic acid as medullary substance. Although when undeveloped the isidia of both species are somewhat similar (curiously, only saxicolous species of the genus appear to form blackened isidia), its development is well differentiated. Isidia on Bulbothrix cinerea grow larger and thicker, often appearing to be inflated (but not really pustular) or getting flattened acquiring an aspect similar to lobules. The isidia of Bulbothrix decurtata are small and near always completely blackened, even in advanced stages of development. Pycnidia do not develop in the isidia of Bulbothrix decurtata .