Bulbothrix subcoronata ( Mueller Argoviensis) Hale. Phytologia 28: 481. 1974.

Benatti, Michel N., 2012, A review of the genus Bulbothrix Hale: the species with medullary norstictic or protocetraric acids, MycoKeys 2, pp. 1-28 : 12-14

Bulbothrix subcoronata ( Mueller Argoviensis) Hale. Phytologia 28: 481. 1974. Figures 11-13

Basionym.

Parmelia subcoronata Müller Argoviensis. Revue Mycologique: 135. 1887.

Holotype.

South America, place and collector unknown (G!, holotype).

Description.

Thallus subirregularly to almost sublinearly sublaciniate, turning dusky green in the herbarium, fragments up to 1.2 cm diam., submembranaceous, corticolous (anatomy not observed in view of the scarce material). Laciniae anisotomically dichotomously branched, contiguous, 0.4-1.0 mm wide, weakly adnate and apparently loosely adpressed, with flat, truncate to subtruncate apices, the margins flat, slightly sinuous to subcrenate, entire, not lacinulate, the axils oval, upper cortex continuous and smooth, laminal bulbate cilia absent. Lacinulae absent, not even marginal adventitious ones. Maculae absent. Cilia black, usually with simple to rarely lacking apices, short, occasionally downward-bent, 0.05-0.40 (-0.60) × ca. 0.03 mm, with emerse bulbate bases 0.05-0.10 (-0.15) mm wide, frequently along the margins in small groups in the crenulations and axils of the laciniae, spaced 0.05−0.15 mm from each other, becoming absent or scarce only at the apices of the laciniae. Soredia, pustulae and isidia absent. Medulla white (but tainted by the degenerated medullary acid). Lower surface black, shiny, smooth, papillate to slightly rhizinate. Marginal zone brown, attenuate, up to 0.5 mm wide, shiny, smooth, naked to papillate, becoming occasionally slightly rhizinate in the transition for the center. Rhizinae black, simple, commonly with subtle to conspicuous bulbate bases, 0.10-0.50 × 0.02-0.05 mm, fr equent, randomly grouped. Apothecia (only one present) subplane, 2.1 mm diam., apparently sessile and laminal, margins smooth, coronate (with few bulbs), amphithecia smooth with some bulbate retrorse rhizinae. Disc brown, epruinose, imperforate, epithecium 5.0-12.5 mm high, hymenium 37.5−45.0 µm high, subhymenium 17.5−25.0 µm high. Ascospores rounded to subellipsoid, 5.0−7.5 × 4.0−5.5 µm, epispore ca. 0.5 µm. Pycnidia not found.

Spot tests.

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

TLC/HPLC.

cortical atranorin, medullary norstictic acid (see also Hale 1976).

Distribution.

Asia: India ( Sinha and Singh 1986). South America: Argentina ( Hale 1976, Calvelo and Liberatore 2002), Paraguay and Brazil: GO, MT, RJ ( Hale 1976), PA ( Brako et al. 1985), RS ( Fleig 1985), SP ( Marcelli 1993, Jungbluth 2006), MG ( Ribeiro 1998) and PR ( Eliasaro 2001).

Comments.

The holotype of Bulbothrix subcoronata (Fig. 11) consists merely of four very small fragments, only one being a whole laciniae, with the distal and proximal portions intact. Due to the very poor condition of the specimen it is difficult to describe it accurately, since many of the characters could not be observed. There is only a third of a mature apothecium left, glued to the card voucher. The medulla, which probably was white, is stained with a reddish brown tinge probably due the degeneration of norstictic acid. The hymenium of the single apothecium is brownish and contains few ascospores. Most asci contain only a shapeless mass. It was necessary to totally crush a cross section of the apothecium to observe the highest possible number of ascospores, because almost none emersed from asci when a simple section was put under the microscope (which is a quite common problem in specimens of this genus).

For many years, Bulbothrix specimens without vegetative propagation containing medullary norstictic acid with wider laciniae, a brown lower cortex and larger ascospores were identified as Bulbothrix subcoronata . Recently Jungbluth et al. (2008) and Spielmann and Marcelli (2008) proved that they actually belong to different species, Bulbothrix regnelliana and Bulbothrix viatica . Unlike the descriptions found in Hale (1976), Fleig (1985), Marcelli (1993), Ribeiro (1998), Eliasaro (2001), Jungbluth (2006) but in agreement with the original diagnosis ( Müller Argoviensis 1887), the ascospores of Bulbothrix subcoronata are very small, being among the smallest in the genus. Müller Argoviensis (1887) described the species separating it from Parmelia tiliacea by the shape and color of the laciniae, shape of the apothecium and the small subglobose ascospores "ca. 5 µm long". Among the 35 ascospores found in good condition, the minimum length was 5 µm and only two slightly exceeded 7.0 µm long. In his remarks, Hale (1976) mentioned that Müller Argoviensis (1887) had cited ascospores with ca. 5 µm long, but that all the specimens he studied had larger ascospores.

In the holotype of Bulbothrix subcoronata the laciniae are sublinear and quite narrow, with subtruncate apices 0.5-1.0 mm wide, while other specimens at first suspected to belong to Bulbothrix subcoronata referred to the species have larger, more subirregular laciniae with subrounded apices, usually 1.0-4.5 mm wide.

Apparently, Bulbothrix subcoronata is a very rare species known only from the type. Since the original description mentions only South America as information for locality, it is impossible to give more precise location information.

Bulbothrix viatica Spielmann & Marcelli can be differentiated by the larger laciniae (1.0-4.5 mm wide) with rounded apices, lower surface with variable colors tending to mixtures of brown with black, common occurrence of laminal ciliary bulbs, and by the larger ascospores (10.0-) 12.0-18.0 × 7.0-10.0 µm.

Bulbothrix regnelliana Jungbluth, Marcelli & Elix can be distinguished by the same characteristics (except that it do not form laminal ciliary bulbs), and by the ascospores 8.0-12.0 × 4.0-8.0 µm. Bulbothrix ventricosa (Hale & Kurokawa) Hale can also be differentiated by the same upper and lower cortex and ascospores characteristics of Bulbothrix viatica , and additionally by the cortical maculae and flaminal isidia.