Rostania occultata (Bagl.) Otálora, P.M. Jørg. & Wedin

Fungal Divers., 64, 1: 289, 2013. Basionym: Collema occultatum Bagl. - Comm. Soc. Critt. Ital., 1: 1, 1861.
Synonyms: Collema quadratum J. Lahm ex Körb.; Leptogium occultatum (Bagl.) Zahlbr.; Rostania quadrata (Körb.) Trevis.
Distribution: N - VG (TSB 18684), TAA (Nascimbene & al. 2007b), Piem, Lig (S-F148069). C - Tosc (Benesperi & al. 2007, Košuthová & al. 2022), Umb (Genovesi & al. 2002, Ravera & al. 2006), Laz (Ravera 2001), Abr (Ravera 2002b), Mol (Caporale & al. 2008), Sar (Zedda 2002). S - Bas (Potenza & al. 2014, Brackel 2011), Si (Grillo 1998, Grillo & Caniglia 2004, Ravera & al. 2021c).
Description: Thallus subcrustose to indistinctly subsquamulose-subplacodioid, homoiomerous, gelatinous when wet, forming a thin, effuse crust of scattered to contiguous, 120-170(-200) μm wide granules. Lobes absent or few, small and short, 150-200 µm thick (when moist), smooth, more or less channelled but sometimes becoming coralloid and forming c. 1 mm wide rosettes. Upper surface dark olive-green to black, dull, epruinose, semi-translucent when wet. Apothecia lecanorine, often numerous, sessile, mostly terminal, 0.1-0.3(-0.5) mm across, globose and perithecioid when young, with an initially punctiform, later concave, dark red to rarely pale yellow-brown disc, an entire to lobulate, finally sometimes excluded thalline margin and often a paler, up to 15 µm wide parathecial ring. Thalline exciple with a simple pseudocortex; proper exciple euthyplectenchymatous, with small-ellipsoid to rectangular cells, c. 10 µm thick; epithecium brown; hymenium colourless, 80-140 µm high, K/I+ blue; paraphyses c. 2 µm thick at mid-level, the apical cells up to 5 µm wide; hypothecium colourless, 15-50 µm high. Asci 8-spored, cylindrical-clavate, the apex strongly thickened, the apical dome K/I+ pale blue, with a downwardly projecting K/I+ deep blue tubular structure. Ascospores subglobose when young, then more or less cuboid with rounded angles and truncate ends, muriform with (4-)8-12 cells in optical view, (11-)13-18(-22) x 9-15 µm. Pycnidia immersed, globose. Conidia bacilliform, 4-5 x c. 1 µm. Photobiont cyanobacterial (Nostoc, the cells in chains of up to 10). Spot tests: all negative. Chemistry: without lichen substances.
Note: a temperate lichen found on smooth, base-rich, but not very eutrophicated bark of more less isolated broad-leaved trees (Acer, Fraxinus, Juglans, Populus) in rather humid sites, especially on basal parts of old trunks; easy to overlook and widespread, but certainly not common in Italy. It is included in the Italian red list of epiphytic lichens as “Data Deficient” (Nascimbene & al. 2013c).
Growth form: Crustose
Substrata: bark
Photobiont: cyanobacteria, filamentous (e.g. Nostoc, Scytonema)
Reproductive strategy: mainly sexual

Commonnes-rarity: (info)

Alpine belt: absent
Subalpine belt: absent
Oromediterranean belt: absent
Montane belt: extremely rare
Submediterranean belt: extremely rare
Padanian area: absent
Humid submediterranean belt: extremely rare
Humid mediterranean belt: absent
Dry mediterranean belt: absent

pH of the substrata:

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Solar irradiation:

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Aridity:

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Eutrophication:

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Poleotolerance:

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Altitudinal distribution:

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Predictive model
Herbarium samples
INDEX FUNGORUM GBIF DOLICHENS


P.L. Nimis CC BY-SA 04
TSB 8252



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (8252)
2001/12/04



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (36982)
2008.02.25



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (36982)
2008.02.25



P.L.Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (36982)
2008.02.25


Pier Luigi Nimis - CC BY-SA 4.0
Herbarium: TSB 8252



Curtis Randall Björk – CC BY-SA 4.0
Northwest New Mexico Date: 2010-03-05 Photographed from specimen (T.T. McIntosh 9668b, Hb. McIntosh), on oak bark



Felix Schumm - CC BY-SA 4.0
[VZ2005], Suecia. Värmland: Södra Finnskoga, Avensasen, 390 m. Ad corticem arborum (Acer platanoides). Leg. Sigurd W. Sundell, 27.07.1979. - EX A. V ZDA: LICHENES SELECTI EXSICCATI NR. 2005.



Felix Schumm - CC BY-SA 4.0
[VZ2005], Suecia. Värmland: Södra Finnskoga, Avensasen, 390 m. Ad corticem arborum (Acer platanoides). Leg. Sigurd W. Sundell, 27.07.1979. - EX A. V ZDA: LICHENES SELECTI EXSICCATI NR. 2005.


Wolfgang von Brackel - CC BY-4.0
Germany, Bavaria, Elmaubachtal


Wolfgang von Brackel - CC BY-4.0
Germany, Bavaria, Elmaubachtal


Source: Košuthová A, Westberg M, Wedin M. A revision of the Rostania occultata (Collemataceae) complex in Fennoscandia. The Lichenologist. 2022;54(1):13-24. doi:10.1017/S0024282921000487 - CC BY 4.0
Rostania occultata (A, UPS L-003461; B, S F388790; C & E, UPS L-872297; D, UPS L-123018). A, habitus – granular thallus composed of globose granules and apothecia dominating the thallus (Ap). B, habitus – thallus composed of granules and small squamules and apothecia (Ap). C, section of apothecium; note the excipulum thallinum with a simple pseudocortex (Pc) and Nostoc cells in short chains (N). D, section of apothecium mounted in Phloxin; note the euthyplechtenchymatous excipulum proprium (Ep) below the hymenium and Nostoc cells (N) with short coiled chains. E, section of apothecium. Scales: A & B = 1 mm; C & D = 10 μm; E = 50 μm.


Degelius G. 1954. The lichen genus Collema in Europe: Morphology, Taxonomy, Ecology. Symbolae Bot. Upsal. 13, 2: 1-499.


Degelius G. 1954. The lichen genus Collema in Europe: Morphology, Taxonomy, Ecology. Symbolae Bot. Upsal. 13, 2: 1-499.


Source: Košuthová A, Westberg M, Wedin M. A revision of the Rostania occultata (Collemataceae) complex in Fennoscandia. The Lichenologist. 2022;54(1):13-24. doi:10.1017/S0024282921000487 - CC BY 4.0
C, R. occultata (UPS L-872297) – oblong mature spore with truncated ends Scale: 10 μm