Parmeliella testacea

Belguidoum, Amina, Lograda, Takia & Ramdani, Messaoud, 2022, The Lichen Flora on Quercus in the Tamentout Forest of Algeria, Phytotaxa 566 (2), pp. 200-208 : 204

Description of Parmeliella testacea from the Tamentout Forest:

The species has a squamulose to minutely foliose thallus composed of pale chestnut-brown to gray-brown lobes, forming a rosette. It tightly adheres to its substrate with distinct peripheral lobes and its upper surface is fragile ( Fig. 4 ). When wet, the thallus turns dark blue-gray. The thallus is sorediate with dark gray, coarsely granular soredia formed in predominantly marginal, sometimes also laminar, button-shaped soralia. These soralia are initially concolorous with the thallus surface, their soredia sometimes brittle, on a ± uniform surface, which may become coarsely cracked along the margin. The thallus resides on an arachnoid hypothallus, blue-black in color. In the specimens collected in Algeria, apothecia were not observed; the photobiont is Nostoc .

Notes: Only a single corticolous specimen of Parmeliella testacea was found in the Tamentout Forest, growing on Q. suber . The species generally appears to be quite rare, and in France its threat status has been assessed according to IUCN red-list criteria as Vulnerable (VU) by Roux et al. (2017). In the past, the species had been reported from England, but it is considered extinct ( Cannon et al. 2021).

Specimen examined. ALGERIA. Setif Province: Tamentout Forest, Collection Site 5 (36° 30ꞌ 52ꞌꞌN, 5° 44ꞌ 05ꞌꞌE), 961 m altitude, 2021, Belguidoum, A. no. Cl 92 ( ABHCH) .

Figures

FIGURE 4: Parmeliella testacea from the Tamentout Forest (Belguidoum, A. no. Cl92, ABHCH) A. Thallus overview (h: black hypothallus; arrow: button-shaped soralia). B. close-up of humid, bluish green thallus (arrow: button shaped soralia). C. close-up of wet, olive thallus. Scale bars: 5 mm.