Parmelia barrenoae

Parmelia barrenoae has a foliose (leafy) thallus with a tight to loose attachment to its substrate. It measures 5–10 cm (2–4 in) in diameter. The lobes are contiguous to overlapping, with short, rounded tips, measuring 2–7 mm wide. The older lobes tend to curve backwards. The upper surface of the thallus is greenish grey to whitish grey, with a texture that is initially finely foveolate (covered with small pits) before becoming reticulate (net-like) and cracked. The thickness of the thallus is somewhat variable; depending on whether the central areas or the margins are measured, ranging from 200 to 375 μm. Of this, the cortex is 25–37.5 μm thick, the photobiont layer about 30–40 μm thick, the medulla 120–200 μm thick, and the underlying darkened cortex 25–40 μm thick. The latter tissue layer, which gives the thallus underside its blackened colour, is paraplectenchyma—a type of tissue in which the fungal hyphae are oriented in all directions. …

First described from Ávila, and a few years later from the Castellón mountains and Asturias, the geographical range of Parmelia barrenoae has increased expansively as other researchers have reported its occurrence in other locations. In 2010, the lichen was reported to occur in North America and Africa. The North American distribution includes the western United States, based on specimens collected in the states of California, Idaho, Oregon, and Washington. The African distribution includes the Middle Atlas mountain range of Morocco. In 2016, it was reported from Poland, in 2017 from Macedonia, and in 2018 from Turkey and Asia for the first time. In 2021 it was reported to occur in Hungary, Slovakia and Sweden. In some areas its precise range is not yet well known because of historical confusion with P. sulcata. In the Mediterranean, Parmelia barrenoae is widely distributed on oak bark and conifers. It is occasionally on moss-covered rocks in open and sunny places. The species occurs in Mediterranean areas at moderate altitudes between 800–1,800 m (2,600–5,900 ft). In this region it often co-occurs with Parmelia serrana and various species of Lobaria. In Hungary and Slovakia, the lichen was found in oak-hornbeam and oak forests at elevations between 260 and 500 m (850 and 1,640 ft). …