Cresponea pallidosorediata
Cresponea pallidosorediata is a corticolous lichen in the family Opegraphaceae. It is a small crustose lichen that forms pale brownish patches on tree bark in subtropical forests of northern Argentina. It is distinguished by abundant powdery soredia, tiny granules that serve as reproductive propagules, which can spread to cover most of the lichen's surface. It was formally described in 2022 from material collected in in Chaco Province, and had not been recorded elsewhere as of the original publication.
Taxonomy
Cresponea pallidosorediata was described in 2022 by André Aptroot from bark-collected material gathered in semi-deciduous subtropical forest at, at about elevation. The holotype is deposited in the herbarium of the Instituto de Botánica del Nordeste. Within Cresponea, it is characterized by a pale thallus with abundant soredia produced in tiny, point-like, and by narrowly club-shaped ascospores with 5–7 septa. It was compared with the only other sorediate species then known in the genus, C. flavosorediata. That species has much larger, irregular soralia; the thallus features and ascospore characters together support recognition of C. pallidosorediata as distinct.
Description
The thallus is crustose and continuous, forming a dull, pale olivaceous-brown layer up to about 0.1 mm thick. It lacks a cortex and is not bordered by a distinct It bears abundant that develop in tiny, point-like soralia and soon become granular and widespread, often covering most of the thallus surface. The is . The ascomata are solitary and sit on the thallus surface, with a constricted base. They are round, 0.7–1.3 mm in diameter and about 0.3 mm high. The is black and usually coated with a thin golden-yellow ; the black margin is raised above the disc and about 0.2 mm wide. The and are, and the epihymenium is brownish. The is not and contains anastomosing 1–1.5 μm wide. Ascospores are produced eight per ascus. They are hyaline, narrowly club-shaped, 5–7-septate, and measure 33–37 × 4.5–5.5 μm, without any surrounding gelatinous sheath. Pycnidia have not been observed. In standard spot tests the thallus is UV–, C–, K–, KC– and P–. Thin-layer chromatography has not detected any distinctive secondary metabolites.
Habitat and distribution
Cresponea pallidosorediata grows on tree bark in semi-deciduous subtropical forest in Parque Pampa del Indio at about elevation. As of its original publication, it had not been reported from outside Argentina. The type locality lies close to the border with Brazil.