Aspiciliella

The genus Aspiciliella consists of crustose lichens, which form crust-like growths that adhere closely to the substrate. The thallus, or body of the lichen, is typically cracked and divided into small, irregular sections (rimose-areolate), and is partially continuous across the surface it grows on. The lichen's photosynthetic partner, or photobiont, is a type of chlorococcoid green alga.

The reproductive structures of Aspiciliella, the apothecia, range in colour from pale brown to dark grey or black. These apothecia have a true exciple, which is a distinct outer rim surrounding the spore-producing area. In some cases, the exciple may be further enclosed by an additional margin made from the thallus itself, though this is rare.^[4]

The upper layer of the apothecium, called the epithecium, can vary in colour from green to olive green or greenish-brown. When treated with certain chemical tests, the epithecium turns light green (N+). Beneath the epithecium, the hypothecium and subhymenium layers are colourless, but they react to iodine (I+) by turning blue to rusty red, as does the hymenium, the layer where the spores develop.^[4]

The asci, which are the structures that produce the spores, typically contain eight spores and are of the Aspicilia-type, meaning they share certain structural characteristics with those found in the genus Aspicilia. The ascospores themselves are ellipsoidal, colourless, and lack internal divisions (aseptate). The lichen also produces conidia, which are asexual spores that are straight and measure 7–11 μm in length.^[4]

Chemically, the thallus of Aspiciliella reacts positively to potassium hydroxide solution (K+ red), but does not react to chlorine (C−) or ultraviolet light (UV−). Thin-layer chromatography tests have identified norstictic acid as the primary chemical compound in the thallus, with some species also containing connorstictic and stictic acids.^[4]

Aspiciliella can be distinguished from its close relative Aspicilia by several key characteristics. The most notable differences are its smaller conidia, measuring 7–11 μm in length, compared to the larger conidia (11–40 μm) found in Aspicilia. Additionally, Aspiciliella consistently produces ellipsoid ascospores, while Aspicilia may have ellipsoid or occasionally globose ascospores. Another distinguishing feature is the consistent presence of norstictic acid in Aspiciliella, which is only occasionally found in some Aspicilia species.^[3]

• Aspiciliella cupreoglauca (B.de Lesd.) Zakeri, Divakar & Otte (2017)
• Aspiciliella intermutans (Nyl.) M.Choisy (1932)
• Aspiciliella pakistanica K.Habib, Firdous, Sohrabi & Khalid (2021)^[5]
• Aspiciliella portosantana Sipman & Zakeri (2017)^[3]