A review of the genus Bulbothrix Hale: the species with medullary norstictic or protocetraric acids

This study presents data of eight Bulbothrix (Parmeliaceae, Lichenized Fungi) species containing norstictic or protocetraric acid in the medulla. The current species delimitations were confirmed. New synonyms are proposed, new characteriscts are detailed and range extensions are added.

During a revision of the genus Bulbothrix (Benatti 2010) the type specimens and additional material of Bulbothrix species were studied.These species have cilia with hollow basal bulbs, which contain differentiated cells and a characteristic oily substance (Hale 1975, Feuerer and Marth 1997, Benatti 2011).This paper discusses the seven species with medullary norstictic acid [Bulbothrix cinerea Marcelli & Kalb, B. lordhowensis Elix, B. haleana Sérusiaux, B. subcoronata (Benatti & Marcelli 2010) were already published after their exclusion due to the lack of true bulbate cilia.

Material and methods
Type material and additional species were studied from B, BM, CANB, DUKE, G, ICN, NY, SP, TUR, UPS, US and from Dr. Klaus Kalb's personal herbarium, originating from Oceania, Asia, North Pacific, Africa, North America, Central America, Caribbean and South America, as well as material collected in Brazil during the last 30 years, mainly by the author and the members of the Lichenological Study Group of the Instituto de Botânica (GEL) in Brazil.
The morphological and anatomical characters of the specimens were analyzed using standard stereoscopic and compound microscopes.Anatomical sections, including those of apothecia and pycnidia when present, were made with a razor blade by hand.Bulbs on cilia, rhizines, apothecia and other thallus parts were checked using the clarification method (Benatti 2011) The chemical constituents were checked by spot tests with potassium hydroxide (K), sodium hypochlorite (C) and para-phenylenediamine (P), and also examined under UV light (360 nm).Chemical constituents of the additional specimens examined were identified by thin-layer chromatography (TLC) using solvent C (Bungartz 2001), and compared with the data on labels left with the specimens.The types had their chemical constituents examined by high performance liquid chromatography (HPLC), following the methods described in Elix et al. (2003).
The presence of norstictic acid is evidenced by a K+yellow→orange or bright red spot test reaction.Its presence is easily confirmed by the formation of tiny star shaped crystals, observed under a light microscope after the transfer of hyphae onto a microscope slide and dropping the reagent on the fungal material, such as cutting a small piece of the thallus or of the apothecia.Protocetraric acid is detected by KC+ rose and P+ reddish orange spot tests reactions, and do not form crystals using K reagent.
The species selected for comparisons are those who show close morphological or chemical similarities, and those most often compared by other authors due to peculiar characteristics.
TLC/HPLC.cortical atranorin, medullary protocetraric and conprotocetraric acids (see also Hale 1972Hale , 1976)).Analysis made by Dr. John A. Elix showed also salazinic and consalazinic acids on the isotype.In view of the condition of the collection, I believe it is a possible contaminant from mixed fragments of other thalli, since they are much agglomerated.
Comments.The holotype (Fig. 1) and the isotype (Fig. 2) consist of two fragments; the original specimen was apparently separated in half.Both type fragments are in good condition, but are still attached to a small twig which is glued to a card, making it difficult to clearly see the lower cortex.Both fragments contain well-developed apothecia and many pycnidia with mature ascospores and conidia.
Compared to the original description (Hale 1972), the investigated type material showed some differences in the thallus anatomy.The thicknesses mentioned by Hale for the upper cortex (14.0−18.0µm), the algal layer (10.0−15.0µm), medulla (70.0−90.0µm) and lower cortex (12 µm) are smaller than those found here, especially for the medulla.The ascospores found were slightly larger.This is the only true species of Bulbothrix with medullary protocetraric acid currently known, since B. subinflata (Hale) Hale proved to be a Parmelinopsis species (Benatti and Marcelli 2010).
Although the ciliary bulbs of B. chowoensis are small and not as evident as in other species of the genus, they are noticeable even with the thickening of the marginal black line, and are even more easily seen when this line is brownish.The bulbs, even when subtle, have the typical anatomical structure containing idioblast cells and an oily substance (Hale 1975, Feuerer and Marth 1997, Benatti 2011).
Bulbothrix hypocraea (Vainio) Hale differs from B. chowoensis by the evidently maculate upper cortex, larger and more evident bulbate cilia, larger ascospores (8.0−14.0µm long) and by the presence of medullary salazinic acid.
Bulbothrix viatica Spielmann & Marcelli differs by the coronate apothecia, common and constant occurrence of laminal ciliary bulbs, larger ascospores (12.0−18.0µm long), variable coloration of the lower cortex and by the presence of medullary norstictic acid.
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, B. 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, B. 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 B. 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 B. 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 B. 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 0.10-0.30mm 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), B. 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 B. 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 B. 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 B. 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 B. 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 B. decurtata are small and near always completely blackened, even in advanced stages of development.Pycnidia do not develop in the isidia of B. decurtata.Holotype.Zaire, Massif du Kahuzi, un peu au nord de la piste du Kahuzi, sur le versant sud-ouest du mont, bloc rocheux (type porphyre) au ras du sol dans une lande à Erica bequaertii et Philippia benguelensis, alt.2780 m., leg.J. Lambinon 71/Z/1356, 30-XII-1971 (LG!, isotype US!).
Comments.Both the holotype (Fig. 5) and the isotype (Figs.6-7) are small fragments between 1.0 and 3.5 cm in diameter.Both are in good condition, only slightly damaged, and not glued to cards, which made the investigation of the lower cortex possible.Inside the packet are small envelopes, containing very small fragments and loose/detached apothecia.
Although the species was originally described as containing medullary salazinic acid, the substance confirmed by microchemical tests and chromatography was norstictic acid.It is the only species currently known within this chemical group with ecoronate apothecia.Sérusiaux (1984) mentioned laciniae 1.0-3.0mm wide, but the laciniae of the type material are larger, 1.5−5.0mm wide.As for the ascospores, the measurements obtained were 6.0-9.0 × 4.0-7.0µm, a little larger than in the original description.
Sérusiaux (1984) also described the upper cortex as "not maculate on young lobes, becoming more or less maculate elsewhere".I found that distal parts of the younger lobes show no signs of maculae, but in most of the thallus, especially the older parts, the maculae are punctiform and dense, like those observed in species such as B. hypocraea.
Most of the cilia present typical inflated bases, but it is not uncommon that cilia without inflated bases are occasionally found among groups of cilia with inflated bases.Interestingly, in some cilia the bulb is displaced from the base.However, it is hardly found above the first third of the cilia length.It is uncertain why some cilia have no bulbs; maybe they were aborted or maybe they are not formed until a later stage of development.
The lower cortex is almost entirely brown, and in a few small spots more restricted to the central portions of the thallus it becomes a little darker.Sérusiaux (1984) wrote that the cortex could become almost whitish in some parts, but due to colour change after longer stay in the herbarium it is difficult to confirm this assertion.Most of the rhizinae have basal or displaced bulbs.Sérusiaux (1984) commented on the presence of black dots he supposed to be pycnidia, but he did not found sterigmata or conidia.In fact, conidia are difficult to find in the type material, but when they are found the size and shape is typical for the genus.At the first sight the pycnidia were taken for laminal ciliary bulbs or parasitic fungi, but this was proven to be incorrect.Sérusiaux (1984)  Bulbothrix haleana is morphologically similar to B. hypocraea, but can be distinguished by the corticicolous habit, ascospores size (6.0−8.0 vs. 8.0−14.0µm long), and medullary chemistry (norstictic acid vs. salazinic acid).There is some lower cortex tone difference between the types, but it may be due to the degree of medullary norstictic and salazinic acids oxidation.The holotype of B. hypocraea has more strongly bent cilia and is even more maculate, while the rhizinae of B. haleana appear to be more frequently bulbate.All other characters are similar.
Bulbothrix decurtata (Kurokawa) Hale differs by the more linear laciniae, an emaculate and quite fissured upper cortex, the formation of blackish small isidia, a predominantly black lower cortex and rhizinae without basal bulbs.
Bulbothrix cinerea Marcelli & Kalb also has medullary norstictic acid, a similar pale brown lower cortex and cilia aspect, but differs from B. haleana by the sublinear and dichotomous branched laciniae, emaculate upper cortex, simple laminal isidia with brown or blackish apices, and by the coronate apothecia.
Comments.The holotype (Fig. 8) consists of six small fragments in good condition, along with a small and fragile fragment.Isidia are or were present on all specimens; the latter can be identified by the marks that are left where the isidia broke off.A fragment is covering a Sarcographa specimen, while another fragment is partially covered by a small, sorediate Physcia specimen.
There are frequent laminal ciliary bulbs in the holotype.Part of the observed laminal bulbs were first interpreted as poorly developed pycnidia or even parasitic fungi, which has been proven wrong.Besides being generally small in size also in the margins, some of the laminal bulbs are poorly developed.This is one of the species with the narrowest laciniae in the genus, barely exceeding 0.5 mm in width.The cilia are evidently bulbate, with very small bulbs.Bulbs were not seen in the rhizinae, and if they occur, they should be rare and very subtle.The isidia are very small and appear as unornamented, darkened grains.When detached, they can leave strong marks, resembling spilled medulla that comes out through the cortex.They are easily distinguishable from maculae.
Among the isidiate species with medullary norstictic acid, B. ventricosa  Description.Thallus subirregular sublaciniate, dusky gray in herbarium, fragments up to 4.6 cm diam., subcoriaceous, corticicolous; upper cortex 12.5−17.5µm thick, algal layer 20.0−25.0 µm thick, medulla 75.0−92.5µm thick, lower cortex 12.5−17.5µm thick.Laciniae irregularly ramified to occasionally anisotomically dichotomously branched, (1.0−) 1.6-2.5 (−3.7) mm wide, imbricate becoming crowded in the center, weakly adnate to loose and ascending, with flat to involute, subrotund apices, the margins flat to involute frequently giving the laciniae a subcanaliculate aspect, crenate to subirregular, entire to irregularly incised, not lacinulate, the axils oval to irregular, upper cortex continuous with rare, random irregular fissures, smooth, laminal ciliary bulbs absent.Lacinulae absent, not even marginal adventitious ones present.Maculae absent.Cilia black, apices frequently absent to less commonly simple and short, 0.05-0.25 × ca.0.03 mm, with emerse bulbate bases (0.05−) 0.10-0.35mm wide, frequently along the margins in the crenulations and axils of the laciniae spaced 0.05−0.10mm from each other, occasionally becoming contiguous, solitary or in small groups, becoming absent or scarce at the apices of the laciniae and adjacent parts.Soredia, pustulae and isidia absent.Medulla white.Lower cortex pale brown to brown, sometimes appearing to be darker in some parts due to groups of dark rhizinae, opaque, rugose, moderately to densely rhizinate.Marginal zone brown to pale brown, not distinct from the center, opaque to slightly shiny, rugose or weakly venate, papillate, becoming slightly rhizinate towards the center.Rhizinae brown to pale brown, occasionally dark, black or with whitish apices on random parts, simple or rarely irregularly branched, generally with blackish bulbate bases of dislocate bulbs, 0.10-0.50(−0.80) × 0.03-0.10mm, frequent to abundant, commonly agglutinated, evenly distributed.Apothecia concave to urceolate, adnate to substipitate, 0.3-7.5 mm diam., laminal, margins crenate becoming deeply crenate, fissured and folded as they age, coronate (bulbs irregularly appearing in the crenulations), amphithecia smooth to rugose without ornamentations.Disc brown, epruinose, imperforate, epithecium 10.Comments.The holotype (Fig. 9) and the isotype (Fig. 10) consist of two fragments in good condition, free of substrate, not glued to the voucher card, which made the observation of the characters of the lower cortex possible.Both have numerous apothecia, although it is difficult to find ascospores (hymenia often without asci).
Several authors determined specimens of B. regnelliana Jungbluth, Marcelli & Elix as B. subcoronata (Müller Argoviensis) Hale or B. viatica Spielmann & Marcelli (e.g.Eliasaro 2001, Ribeiro 1998).These three species form a closely related group, in which the species are distinguished mainly by the color of the lower cortex, the size of ascospores and the presence or absence of laminal ciliary bulbs.
Although Jungbluth (2006) made an attempt to relate the shape of apothecia with the size of the ascospores in order to separate the species with norstictic acid, a close examination of the material of B. subcoronata, B. regnelliana and B. viatica demonstrated that this is not a reliable character for the species separation due to character overlap.In fact there are specimens interpreted as B. subcoronata with ascospores ca.7.0−12.0mm long (Hale 1976, Fleig 1985) and others with ascospores 10.0−20.0mm long (Marcelli1993, Eliasaro 2001, Ribeiro 1998).
Based on the color of the lower cortex and the ascospore size, the material examined by Hale (1976), which was described as B. subcoronata, should probably belong to B. regnelliana, as assumed by Jungbluth et al. (2008).It is also possible that the material examined by Fleig (1985), described with ascospores ≤ 10 mm, belongs to B. regnelliana.
In fact, the type specimen of B. subcoronata has a shiny black lower cortex with a well defined brown marginal zone, and a single, coronate apothecium, containing very small ascospores (5.0−7.5 × 4.0−5.5 µm).Bulbothrix subcoronata is further distinguished from B. regnelliana by the smaller width of the laciniae (ca.0.5−1.0mm), the more frequent marginal cilia often with simple apices, and the retrorse rhizinae on the amphithecium of the apothecia.
Bulbothrix viatica and B. regnelliana have several characteristics in common, which lead to the hypothesis that they were synonymous.Some specimens with overlapping characters were found; this concerned the absence of laminal ciliary bulbs, marginal cilia with and without apex, a brown lower cortex with small dark spots and ascospores 10.0-14.0µm long.However, when analyzing the characteristics of the specimens, verifying the collection sites and comparing the material side by side, a correlation of small features was noticed that include the total absence of laminal ciliar bulbs, an emaculate upper cortex, cilia often without apices, a strictly brown lower cortex and ascospores usually ≤ 12 µm long in B. regnelliana.which are apparently constant and related to the possible geographic distribution of the species.We therefore decided not to put them into synonymy.The region of the Tropic of Capricorn seems to represent the northern limit of distribution for B. regnelliana, while the latitude of Rio Grande do Sul State in Brazil may represent the southern limit of distribution for B. viatica.Thus, there is a common area of occurrence for both.Also some very few specimens mentioned (Ribeiro 1998) with large ascospores, that are know only from the north of Minas Gerais State, also in Brazil, that might represent an undescribed taxa maybe overlapping with the distribution of B. viatica.
Bulbothrix ventricosa (Hale & Kurokawa) Hale differs from B. regnelliana by having the same characteristics as B. viatica, and the presence of maculae as well as laminal isidia.The coloration of the lower cortex shows an even more frequent mixture variation (i.e., much more varied mixes of black and brown tones) in B. ventricosa than in B. viatica.
Comments.The holotype of B. 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 B. subcoronata.Recently Jungbluth et al. (2008) and Spielmann and Marcelli (2008) proved that they actually belong to different species, B. regnelliana and B. 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 B. 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 B. subcoronata the laciniae are sublinear and quite narrow, with subtruncate apices 0.5-1.0mm wide, while other specimens at first suspected to belong to B. subcoronata referred to the species have larger, more subirregular laciniae with subrounded apices, usually 1.0-4.5 mm wide.Apparently, B. 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.
Comments: The holotype (Fig. 14) consists of a small thallus in good condition, growing on a sliver of bark, indicating that the lower surface has never been examined yet.The lower cortex is difficult to see without removing the thallus from the substrate, but it is apparently black at the margins and dark brown otherwise.The type has only one mature apothecium with crenate margins containing ciliary bulbs.This kind of ciliary bulbs occurs also on other thallus parts.The amphithecium is maculate and has no isidia.The isotype in C mentioned by Hale (1976) was not found by the curator of that herbarium.
One of the most distinguishing characteristics of this species are the laminal ciliary bulbs, present in variable amounts (found in almost all thalli examined).These bulbs may appear all over the lamina, most often on young parts or those devoid of isidia, being bright and having an identical size and anatomy compared to those of the marginal cilia.Except in rare cases, they usually do not show formation of apices, much like those in the margins of the amphithecia.They are more massive and opaque than the pycnidia, which tend to have opaque brown or black ostioles, and are immersed in the thallus.
All bulbs have the same oily substance and idioblasts cells (Hale 1975, Feuerer and Marth 1997, Benati 2011), whether they are marginal, laminal or those that form the coronation of apothecia.No true pycnidia were found in the holotype.
In contrast to earlier publications (e.g., Hale 1976), the color of the lower surface was found to be not constantly black, but variable among specimens of B. ventricosa.It ranges from almost completely black to entirely brown, or to variable in color: (a) a brown to pale brown center with brown to dark brown margins, (b) a brown to dark brown center with dark brown margins, (c) a brown to black center with dark brown margins, (d) a brown to black center with pale brown margins, (e) a black to dark brown center with pale brown margins and (f) a black center with pale brown margins.
Small specimens apparently tend to have an almost black lower surface, with dark brown margins and occasional few parts in the center, with a tendency to lighten as the thallus expands and develops.The margins of the lower cortex are initially distinct and lighter than the center until the brown color predominates on the lower surface, which usually occurs in some of the larger and older thalli.
Even with this tendency for variation apparently linked to thallus development, some developed thalli were found with a predominantly black to dark brown lower cortex, as well as some small thalli with a predominantly brown to pale brown lower cortex.
Apparently, Eliasaro (2001) was the only author to perceive the occurrence of different colors in the lower cortex, citing specimens with a variation from dark brown to black.
The discovery of the laminal bulbs and the constant citation of a black lower surface in the literature (Hale andKurokawa 1964, Hale 1976) originally led to the hypothesis that there was a new undescribed species close to B. ventricosa, but the laminal bulbs and the variable colour of the lower cortex appeared to be characteristic for the species.
Bulbothrix ventricosa can be misidentified as B. tabacina when the lower cortex is black or as B. isidiza when it is more brownish.The three species are morphologically close and have similar spot test reactions (see differences below).Also Relicina abstrusa (Vainio) Hale has been confused with these, probably by the presence of a black lower surface, isidia, and medullary norstictic acid.Relicina abstrusa has, however, a yellowish upper cortex due to the presence of usnic acid, while the cilia have smaller bulbs in comparison to those of B. ventricosa and are more evenly spaced and distributed along the margins.The ascospores are also smaller and rounded, 5.0-6.0 × 4.0-5.0µm.Vainio (1915), in describing B. ventricosa as Parmelia isidiza var.domingensis, believed it to be a variety of P. isidiza Nylander [Bulbothrix isidiza (Nylander) Hale], which curiously has a brown lower surface, and whose medulla (which contains salazinic acid instead of norstictic) reacts similarly to the K test.He noted the apothecia "without pycnidia adorning its margins" (absence of the bulbs that form the corona), and the laminal ciliary bulbs, but understood them as pycnidia, stating that he did not find conidia.
Because the name Parmelia domingensis was already used by Acharius (1814) for a species of Anaptychia [= Heterodermia domingensis (Acharius) Trevisan], Hale and Kurokawa (1964) proposed a new name and a new status for the taxon.The authors mentioned that P. ventricosa would be a Caribbean species with a disjoint locality in southern Africa, while P. isidiza would be a typically African species.
Bulbothrix tabacina (Montagne & Bosch) Hale differs from B. ventricosa by the constantly black and shiny coloration of the lower cortex, the ecoronate apothecia and by the medullary chemistry due the presence of salazinic acid.Bulbothrix isidiza differs similar to B. tabacina, but has a overall brown lower cortex.Thalli of these species do not form laminal ciliary bulbs.
Bulbothrix cassa Jungbluth, Marcelli & Elix is morphologically similar to B. ventricosa, but does not form laminal ciliary bulbs and its isidia are frequently ornamented with pycnidia.Bulbothrix cassa has a uniformly black lower cortex from the center to the margins, and by not forming any medullary substances (all spot tests negative).Description.Thallus sublinearly or subirregularly laciniate to sublaciniate, turning dusky green in the herbarium, fragments up to 5.3 cm diam., subcoriaceous to submembranaceous, corticicolous or ramulicolous; upper cortex 7.5−15.0µm thick, algal layer 25.0−37.5 µm thick, medulla 37.5−72.5 µm thick, lower cortex 12.5−25.0µm thick.Laciniae anisotomically dichotomously to irregularly branched, (0.4−) 1.1-4.7 mm wide, contiguous to sometimes slightly imbricate or rarely crowded in the center, adnate and loosely adpressed, with flat to slightly involute or revolute, subtruncate to subrotund apices, the margins flat to slightly involute, sinuous to crenate or subirregular, entire to slightly incised, rarely sublacinulate, axils oval to irregular, upper cortex continuous with irregular fissures in old parts, smooth to subrugose, laminal ciliary bulbs common, absent to abundant, usually frequent, mainly on young distal parts.Adventitious marginal lacinulae scarce on older parts, short, 0.2-1.2× 0.1-0.4mm, flat, simple to furcate or irregularly branched, apices subtruncate, lower side concolorous with the lower marginal zone.Maculae absent.Cilia black, with usually simple, sometimes double or absent, frequently downwardbent apices, 0.05-0.35(−0.60) × ca.0.03 mm, with emerse bulbate bases 0.05−0.15(-0.35) mm wide, frequent along the margins in the crenulations and axils of the laciniae, spaced 0.05−0.10mm from each other, occasionally becoming contiguous, solitary or in small groups, absent or scarce at the apices of the laciniae and in some parts of the margins.Soredia, pustulae and isidia absent.Medulla white.Lower surface brown to dark brown, sometimes blackened in some small parts [black, mottled with brown in variable intermediary levels to completely brown], opaque to shiny, smooth to rugose, moderately rhizinate except at the margins.Marginal zone brown to pale brown, black or variegate, attenuated or indistinct from the center, shiny, 0.5-4.0mm wide, smooth to subrugose or subvenate, papillate, becoming rhizinate towards the center.Rhizinae black to dark or pale brown, occasionally with whitish apices, simple or rare irregularly branched, partially with bulbate bases, 0.10-0.50(−0.80) × 0.03-0.05mm, frequent but sometimes becoming more abundant at some spots, evenly distributed.Apothecia subconcave to concave or urceolate, occasionally subplane, adnate to substipitate, 0.5-5.4mm diam., laminal, margins smooth to crenate, coronate (bulbs appearing in the crenulations), amphithecium smooth

Bulbothrix viatica
The same color variations found in the lower cortex of specimens of B. viatica were also found in specimens of B. ventricosa (see there).The most common is different tinges of brown mixed with dark or blackish spots of variable sizes (as in the holotype), but some thalli, especially the smaller ones, tend to have a darker or black coloration.
The laminal ciliary bulbs were overlooked by Spielmann and Marcelli (2008).They are clearly present in part of the material cited by these authors, including the holotype.Admittedly, specimens without laminal bulbs do also occur and are more common in B. viatica than in B. ventricosa.The structure of the laminal bulbs is the same as in B. ventricosa (see above).The eventual appearance of these bulbs in these species might be conditioned to thallus development and environmental stimuli.
As shown by Marcelli and Canêz (2008), there are at least three morphologically similar species, with norstictic acid and simple cilia with globose bulbate bases, common in the southern and southeastern regions of Brazil which formerly included in B. subcoronata.They are differentiated by the size of the ascospores, the presence or absence of laminal ciliary bulbs and the coloration of the lower cortex.The ones currently known are B. regneliana, B. ventricosa and B. viatica and possibly true B. subcoronata.The specimens with a brown lower surface with ascospores 7−11 µm long reported by Hale (1976) as B. subcoronata are possibly B. regnelliana, while the specimens with ascospores (10−) 12−18 (−20) µm long and a black or brown lower surface cited in other works might be B. viatica.
The holotype of B. megapotamica Canêz & Marcelli has narrow and truncate laciniae (0.5−1.5 mm wide), lacks laminal ciliary bulbs (with many pycnidia), and a black lower surface with brown margins, and almost no formation of bulbs in the rhizinae (the few seen are subtle).However, there are specimens with intermediary characteristics who show that B. megapotamica is a synonym of B. viatica.
distinguished B. haleana from other species of the genus by the saxicolous habit, the light color of the lower surface and the small size of the ascospores.Bulbothrix bulbochaeta (Hale) Hale, B. chowoensis (Hale) Hale, B. confoederata (W.L. Culberson) Hale, and B. laevigatula (Nylander) Hale, which have also small ascospores (≤10 mm long), differ chemically and morphologically from B. haleana.Other Bulbothrix species containing medullary salazinic acid were differentiated by the author mainly by the larger ascospores, ranging from 8.0−12.0 to 14.0−20.0µm long.