Caloplaca yorkensis S. Y. Kondr. & Kärnefelt
Mycobank MB 517748
Thallus (0.3–)1–2 cm wide or aggregated into larger colonies forming grey to greyish brown, somewhat indistinct areas of different thickness, from indistinct, almost endolithic or very thin and immersed in the substrate, cracked together with the substrate forming areoles, 0.4–0.7 mm wide, to rather thick and well-developed, (to 0.3 mm thick), plane or subconvex, immersed to ± exfoliating; areoles grey or greyish white to brownish grey with sparse, often minute, biatorine, dull yellow orange apothecia. Apothecia to 0.3–0.6(–0.7) mm diam., 0.2–0.25 mm thick in section, biatorine, usually scattered and regularly rounded, rarely irregular due to mutual pressure; proper margin pale yellowish or concolorous with disc, becoming excluded; disc plane to subconvex, dull yellow orange to brownish yellow-orange, in section biatorine, true exciple 30–50 µm thick in uppermost lateral part and to 40 µm thick in lower lateral part, 30–70 m thick at the base, pseudoprosoplectenchymatous to somewhat mesodermatous paraplectenchymatous with a well-developed matrix in the centre; hymenium 50–60 µm high; subhymenium 20–25(–70) µm thick; epihymenium bright yellow; paraphyses 1.5–2 µm diam., distinctly swollen to 4–5 µm diam. towards the tips; asci 2–4–6–8-spored, often mature bipolar and simple undeveloped or abortive ascospores present; ascospores small and very narrow, slightly swollen at the septa, 9–11(–12) x 3.5–5(–6) µm in water and (8–)9–12 x (4–)4.5–6(–7) µm in K, with rather thin septum, (1.5–)2–3.5 µm wide in water and 2.5–3.5(–4) µm wide in K. Secondary chemistry: epihymenium K+ purple to crimson purple, becoming brownish crimson on standing.
Caloplaca yorkensis, with its grey to greyish brown thallus and yellow to orange apothecia with small ascospores resembles species in the Caloplaca lactea group. This new species is similar to C. lactea (A. Massal.) Zahlbr., but differs in having a thinner and more immersed thallus. The subhymenium is thinner in C. yorkensis, the ascospores considerably narrower (3.5–5.5 µm vs, 6–7 µm wide), and the apothecia lack a well-developed thalline margin. Caloplaca brachyspora Mereschk. has a similar morphology, and also grows on limestone However, the thallus is better developed and greenish-brown in C. brachyspora and the ascospores are broader (6–8 µm; Kondratyuk et al., 2004). Caloplaca yorkensis differs from Caloplaca lithophila by its grey, mainly immersed thallus and smaller, narrower ascospores. Caloplaca oxfordensis Fink and C. mereschkowskiana, described above, differ in having orange apothecia and larger or broader ascospores.
This new species is named after the type locality, Yorke Peninsula in South Australia.
Caloplaca yorkensis is known from scattered localities in Western Australia, South Australia, Victoria and Tasmania, where it occurs on limestone outcrops.
Type:—AUSTRALIA: South Australia: Yorke Peninsula, Coodowie, 5 km E of Editburgh along the coast; 35°03’S, 137°44’E; on calcareous rocks, growing together with Caloplaca johnwhinrayi; Jan 1999, Kärnefelt 995207 (holotype CANB).
Additional specimens examined (paratypes):—AUSTRALIA: Western Australia: Point Peron, ca. 80 km S of Perth, Marchant 5578 (MEL 234720). 5 km S of Dongara, Kärnefelt et al. 20041103 (LD). 0.25 km E of mouth of Bow River, S of Horrocks Beach, Kondratyuk et al. 20421 (CANB, LD, KW, PERTH). Victoria: Portland region, Cape Bridgewater, Kärnefelt 996101 (LD). Tasmania: Bass Strait, Hogan Group, Hogan Island; 4 m; Dec 1973, Whinray s.n. (MEL). Bass Strait, Furneaux Group, Kangaroo Island, ca. 90 m SSW of the summit; Feb 1972, Whinray s.n. (MEL).
Caloplacae lacteae similis, sed thallo tenuissimo–crassiusculo, albido-cinereo, apotheciis biatorinis, obscure luteis, subhymenio minus evoluto et ascosporis angustissimis ((3.5–5(–5.5[–6]) µm latis) differt.