{{Short description|Species of lichen}} {{Use dmy dates|date=July 2025}} {{Use Oxford spelling|date=July 2025}} {{Speciesbox | image = | taxon = Bulbothrix thomasiana | authority = Benatti & Marcelli (2011) }}

'''''Bulbothrix thomasiana''''' is a species of foliose lichen in the family Parmeliaceae.<ref name="CoL_NSM6"/> It is a corticolous species that grows on tree trunks in the northern and central parts of South America. The lichen was formally described as a new species in 2011 by lichenologists Michel Benatti and Marcelo Marcelli. The specific epithet honours American lichenologist Thomas Hawkes Nash III. The species is distinguished by its unusual vegetative structures (isidia), which are uniquely fringed with tiny hair-like projections. It has been found growing on tree bark in tropical forests across northern South America, from Venezuela and French Guiana to central Brazil and Bolivia.

==Taxonomy==

''Bulbothrix thomasiana'' was formally described in 2011 by Michel Benatti and Marcelo Marcelli, who based the new species on a well-developed thallus collected in 1969 on the Kweikin-ima Tepui, Bolívar State, Venezuela. The authors separated it from the superficially similar ''B.&nbsp;apophysata'' because its vegetative propagules (isidia) are themselves rimmed with tiny, bulb-based {{lichengloss|cilia}}—a feature otherwise known only in ''B.&nbsp;fungicola'' and ''B.&nbsp;sipmanii''. They also pointed to its uniformly pale-brown lower {{lichengloss|cortex}}, abundant rhizines the same colour as the cortex, ecoronate apothecia (with a plain, smooth margin rather than a ciliate or lobulate one), and medullary lobaric acid chemistry as reliable differentiators.<ref name="Marcelli et al. 2011"/>

The type material of ''B.&nbsp;laevigatula'' was long thought to possess ciliate isidia, leading to confusion between that species, ''B.&nbsp;apophysata'', and the unnamed taxon that is now ''B.&nbsp;thomasiana''. Benatti and Marcelli re-examined the mixed "Leprieur 504" collections cited by earlier authors and showed that the true ''B.&nbsp;laevigatula'' has smooth isidia and a black lower surface, whereas the ciliate-isidiate fragments represent ''B.&nbsp;thomasiana''. The specific epithet honours the American lichenologist Thomas Hawkes Nash III for his contributions to the study of {{lichengloss|parmelioid}} lichens.<ref name="Marcelli et al. 2011"/>

==Description==

The lichen forms small foliose rosettes up to about 4&nbsp;cm across. Its lobes ({{lichengloss|laciniae}}) are narrow (0.3–1.0&nbsp;mm wide), more or less linear, and loosely attached to the bark. Their margins are densely fringed with short (0.05–0.25&nbsp;mm), repeatedly forked {{lichengloss|cilia}} that sit on glossy black, sub-spherical bases. The upper surface is continuous, smooth and dusky grey-green, showing no pale blotches ({{lichengloss|maculae}}). On the lobe surface arise plentiful cylindrical isidia 0.05–0.25&nbsp;mm tall; these propagules share the thallus colour but often carry miniature bulbate cilia, giving the isidiate areas a slightly darker cast.<ref name="Marcelli et al. 2011"/>

The medulla is white and reacts KC+ (rose) because of lobaric acid, while the {{lichengloss|cortex}} contains atranorin and turns yellow with potassium hydroxide solution (K+ yellow). Beneath, the cortex is pale brown—almost cream—throughout, glossy and densely clothed in rhizines that match its colour except for their tiny dark basal bulbs. Apothecia (fruiting bodies) are uncommon but when present are flattened discs 1–3.5&nbsp;mm across with a smooth to faintly scalloped ({{lichengloss|crenulate}}) margin. The ascospores are small (5–7.5 × 3–5&nbsp;μm), rounded to ellipsoid, and thin-walled. Pycnidia are rare; they produce very slender, weakly spindle-shaped conidia 5–7&nbsp;μm long.<ref name="Marcelli et al. 2011"/>

==Habitat and distribution==

''Bulbothrix thomasiana'' is corticolous, occurring on the bark of living trunks in lowland to sub-montane tropical forest. Confirmed records come from the Guiana Shield (type locality on the Venezuelan tepui and a nineteenth-century collection from Cayenne, French Guiana) and from central Brazil, where two specimens were gathered on a windswept escarpment near Chapada dos Guimarães, Mato Grosso, at about 500&nbsp;m elevation.<ref name="Marcelli et al. 2011"/> It was recorded from Bolivia in 2015.<ref name="Flakus et al. 2015"/>

==References== {{Reflist|refs=

<ref name="CoL_NSM6">{{Catalogue of Life |id=NSM6 |title=''Bulbothrix thomasiana'' Benatti & Marcelli |access-date=3 July 2025}}</ref>

<ref name="Flakus et al. 2015">{{cite journal |last1=Flakus |first1=Adam |last2=Sipman |first2=Harrie J. M. |last3=Rodriguez Flakus |first3=Pamela |last4=Jabłońska |first4=Agnieszka |last5=Oset |first5=Magdalena |last6=Kukwa |first6=Martin |last7=Meneses Q. |first7=Rosa I. |title=Contribution to the knowledge of the lichen biota of Bolivia. 7 |journal=Polish Botanical Journal |volume=60 |issue=1 |year=2015 |doi=10.1515/pbj-2015-0001 |doi-access=free |pages=81–98 [82]}}</ref>

<ref name="Marcelli et al. 2011">{{cite journal |last1=Marcelli |first1=M.P. |last2=Canêz |first2=L.S. |last3=Benatti |first3=M.N. |last4=Spielmann |first4=A.A. |last5=Jungbluth |first5=P. |author-link6=John Alan Elix |last6=Elix |first6=J.A. |year=2011 |title=Taxonomical novelties in Parmeliaceae |journal=Bibliotheca Lichenologica |volume=106 |pages=211–224 |url=https://www.researchgate.net/publication/235224715}}</ref>

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Category:Parmeliaceae Category:Lichen species Category:Lichens described in 2011 Category:Lichens of South America