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Family: Acarosporaceae
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MB#840435 Holotype: Germany, Sachsen-Anhalt, Mansfeld-Südharz, Hettstedt, Welfesholz, Zimmermann, SW of Welfesholz, 51°37'34.8''N/11°32'24.4''E, 195 m, on copper slate on spoil heap and parasitic morphing out of Lecidea inops, 18.5.2019, U. Schiefelbein 5323 (B, holotype). Diagnosis. Similar to M. scabrida but differing in having mature bullate areoles with up to 12 apothecia and often having a brown or orange upper surface with or without orange epicortical crystals, and in being a lichenicolous lichen. Etymology. Based on morphology of mature squamules. Description. Hypothallus endosubstratal. Thallus consisting of areoles or squamules, 1– 4 mm wide, 0.5 –1.0 mm tall, dispersed to contiguous, mostly 1 mm wide with 1 to 3 apothecia, becoming larger with age and bullate with up to 12 apothecia and then often splitting in half (Fig. 2A-C), replicating by division,covering areas up to several cm wide (Fig. 2A), or occurring as facultative lichenicolous lichen morphing out of the thallus of Lecidea inops (Fig. 2D), brown at first, becoming independent and developing as a lichen, often becoming orange. Upper surface dull brown to orange, epicortical orange crystals scattered or absent. Cortex (60 –)80 –100 μm thick, POL-, of hyphae 2 μm wide, sometimes becoming disarticulated, forming irregular cells usually 1–3 μm wide, upper layer reddish-brown or orange, mostly 10 μm thick, lower layer hyaline. Algal layer 100 –130 μm thick, continuous beneath apothecia, interrupted by narrow hyphal bundles, algal cells 3 – 8 μm wide. Medulla up to 800 μm thick, hyphae gelatinized and obscure, 1–2 μm wide, with scattered algal cells. Apothecia cupular, immersed or elevated, with distinct parathecial ring of the same color as thallus, disc up to 500 μm wide, reddish brown, rough, the surface uneven, with or without scattered orange crystals. Parathecium expanded 60 –100 μm wide to form a ring around the disc of narrow hyphae 1–2 μm wide, IKI-, usually elevated. Hymenium (130 –)150 –250 μm high, epihymenium ca. 20 μm tall, paraphyses 1 μm wide with unexpanded apices, hymenal gel IKI+ blue (euamyloid). Asci Acarospora-type, narrow, 100 –180 × 10 –20 μm wide. Ascospores several hundred per ascus, small, mostly 2–3(– 4) × 1–1.5 μm, variable. Subhymenium usually cup-shaped, 40 –100 μm tall at deepest point, IKI+ blue (euamyloid), lacking oil drops. Hypothecium 20 – 40 μm thick, of narrow hyphae 1 μm wide, IKI-. Pycnidia not observed. Chemistry spot tests negative. Cortex and medulla lacking crystals in polarized light (POL-). Ecology and Distribution. Currently known only in Germany at low elevations below 250 m from Sachsen-Anhalt on slate spoils in full sun and from Niedersachsen on medieval slag piles (Huneck 2006; Fig. 3). Myriospora bullata is a facultative lichenicolous lichen parasitic on Lecidea inops Th.Fr. and could be parasitic on other genera. At the type locality Mansfeld-Südharz, the slate had 20,000 –200,00 ppm of iron and 12,800 –77,900 ppm of copper (Knitzschke 1999). It occurs on this substrate with M. dilatata and M. scabrida. In Niedersachsen, Dr. Rainer Niemeyer collected M. bullata at Grane Reservoir (216 m) on medieval metal slag with 28.9 –33.5 % iron and 1.00 –1.25 % copper (Niemeyer, pers. comm.). Myriospora dilatata was abundant but M. bullata was rare; only few small, scattered orange areoles of M. bullata were found. Discussion. Myriospora bullata and M. hassei are the only species in the genus reported as facultative lichenicolous lichens (Diederich et al. 2018, Knudsen & Bungartz 2015). Like all lichenicolous lichens, M. bullata begins as a juvenile fungal parasite in the host, expropriating its algae, and morphing out of the host, eventually forming a different and independent lichenized thallus (for more on lichenicolous lichens and morphing see Knudsen et al. 2014). Like Myriospora scabrida, which was growing also at the type locality, M. bullata has a parathecial ring around its apothecia but differs in having mature bullate squamules with up to 12 apothecia and in having an orange or reddish-orange pigmented cortex with or without scattered orange epicortical crystals. When the upper surface of M. bullata is orange, it could be confused with M. tangerina but M. tangerina differs in having orange cortical crystals in upper cortex and punctiform apothecia not in a parathecial ring. Myriospora dilatata grows on iron-rich rock and is orange at the type locality of M. bullata (it can be reddish brown). It differs from M. bullata especially in having an epicortical layer of red crystals and a narrow cortex not exceeding 15 – 40 μm in height. Myriospora rhagadiza like M. bullata can have a brown or orange thallus. It has a different ecology than M. bullata occurring in the salt-spray zone around the northern Atlantic coasts of Europe and North America (Knudsen 2005, Westberg et al. 2011). It differs especially from M. bullata in forming areoles not squamules and in having a narrow cortex (15 –35 μm vs. (60 –)80 –100 μm). Myriospora signyensis differs from M. bullata in having hemiamyloid hymenial gel vs. euamyloid gel, having usually 1–2 apothecia vs. as many as 12, and ecologically in occurring in Antarctica region (Purvis et al. 2018). Myriospora smaragdula can grow on copper-rich rock and have a green color (Wedin et al. 2009). It differs especially from M. bullata in producing norstictic acid in its cortex, easily detected with spot tests. |