Constrictolumina cinchonae
Constrictolumina cinchonae is a species of corticolous crustose lichen in the family Trypetheliaceae. This widespread tropical lichen forms thin, whitish crusts on tree bark and produces small, hemispherical fruiting bodies that are often surrounded by distinctive grey rings. It has a pantropical distribution, being found across warm, humid regions of the Americas, Africa, and Asia, making it one of the most widely distributed members of its genus. The species was originally discovered growing on cinchona bark, which is reflected in its scientific name.
Taxonomy
Constrictolumina cinchonae was first described in 1814 by Erik Acharius as Verrucaria cinchonae, based on material collected from the bark of Cinchona officinalis. It was subsequently transferred to Arthopyrenia by Johannes Müller Argoviensis in 1883. In 2016, Robert Lücking and colleagues reclassified the species in the genus Constrictolumina, where it is currently recognized. The holotype is preserved in Acharius's herbarium in Helsinki.Several other names are now regarded as synonyms of this species. These include Verrucaria prostans, described by Camille Montagne in 1843 from French Guiana; Verrucaria alboatra var. detergens, described by William Nylander in 1869 from Rio de Janeiro, Brazil; and Verrucaria concamerata, described by James Stirton in 1881 from Assam, India, later transferred to Porina by Zahlbruckner. Two further synonyms introduced by Müller Argoviensis are Arthopyrenia nieteriana and Arthopyrenia planipes. All are now treated as belonging to Constrictolumina cinchonae.
Description
Constrictolumina cinchonae has a thin, whitish thallus. Its fruiting bodies are solitary, 0.4–0.6 mm across, and range from partly immersed to raised above the surface. They are hemispherical to somewhat flattened, with apical openings, and are often surrounded by a distinct grey ring. The ascomatal wall is absent below.The asci are usually narrowly, sometimes nearly cylindrical, and measure 100–125 by 17–22 micrometres. Each ascus contains 4–8 ascospores arranged in two overlapping rows or sometimes nearly in a single line. The ascospores are narrowly egg-shaped, divided by a single septum, and the lower cell may occasionally show a slight constriction in the middle. They have a well-developed and measure 20–30 by 7–11 μm.
Asexual reproductive structures are often present. These produce rod-shaped conidia about 4–5 by 1 μm. Both the thallus and ascomata give negative reactions in standard chemical spot tests, and thin-layer chromatography has not detected any secondary metabolites.