Pseudopeltula necrocorticata
Pseudopeltula necrocorticata is a species of cyanolichen in the family Lichinaceae. It forms small, yellowish-olive, scale-like lobes up to about 3.5 mm across on rock and gravel in desert habitats. The species is unusual in having a surface layer formed partly from dead cyanobacterial cells, which gives rise to its name. It is known from the Sonoran Desert region of northwestern Mexico, where it may be overlooked because it resembles small species of Peltula.
Taxonomy
Pseudopeltula necrocorticata was described as new in 2011 by Burkhard Büdel and Matthias Schultz from specimens collected in the Sonoran Desert region of Baja California. Although its yellowish-olive, thallus can look much like small species of Peltula, its internal anatomy is closer to Gloeoheppia, and it is placed in Pseudopeltula because its apothecia develop a characteristically subdivided hymenium. The species epithet necrocorticata refers to the "necrotic" -like outer layer formed when the uppermost cyanobacterial cells die and become incorporated into the thallus surface.Description
The thallus forms small, shield-shaped scales that are yellowish olive, often slightly concave, and up to about 3.5 mm across; the margins typically curve downward, and the upper surface is often cracked or wrinkled. The thallus is anchored to the substrate by rhizine-like strands and is roughly 186–286 μm thick in cross-section. A cortex-like upper layer is present and is covered by a thin dead layer ; this "" has a structure similar to the but includes dead cyanobacterial cells. The is a single-celled cyanobacterian, thought to be related to Chroococcidiopsis. A distinct, photobiont-free medulla is not developed.Apothecia are immersed to and can reach about 1.5 mm in diameter, with reddish-brown to dark-brown. In iodine, the hymenium and stain blue before shifting to red-brown, and the hymenium is commonly split into multiple partial hymenia by sterile tissue. Asci are 8-spored, and the ascospores are ellipsoid and non-septate. Pycnidia have not been observed.