Arthrorhaphis citrinella (Ach.) Poelt

Bestimmungsschl. Eur. Flechten: 126, 1969. Basionym: Lichen citrinellus Ach. - K. Vetensk.-Akad. Nya Handl., 16: 135, 1795.
Synonyms: Arthrorhaphis flavovirescens (A. Massal.) Th. Fr.; Bacidia citrinella (Ach.) Branth & Rostr.; Bacidia flavovirescens (A. Massal.) Anzi; Bacidia flavovirescens var. citrinella (Ach.) Vain.; Lecanactis citrinella (Ach.) H. Olivier; Lecidea citrinella (Ach.) Ach.; Lecidea flavovirescens (A. Massal.) Borrer; Lichen flavovirescens Dicks. non Wulfen; Mycobacidia flavovirescens (A. Massal.) Rehm; Raphiospora flavovirescens A. Massal.; Scoliciosporum flavovirescens (A. Massal.) Jatta; Skolekites citrinellus (Ach.) Norman
Distribution: N - Frl (Obermayer 1994, Tretiach & Hafellner 2000), Ven (Obermayer 1994), TAA (Obermayer 1994, Bilovitz & al. 2014), Lomb, Piem (Isocrono & al. 2004, Isocrono & Piervittori 2008), VA (Piervittori & al. 2001). C - Abr Gheza & al. 2021), S - Cal (Puntillo 1996), Si (Obermayer 1994).
Description: Thallus crustose, areolate, forming a compact crust. Areoles bright yellow-green, thin, 0.5-1(-2) mm wide, rounded, flat to mostly convex, contiguous, very fragile, without an epinecral layer, with diffuse, granular soredia. Medulla poorly developed. Apothecia rather rare, lecideine, rounded, sessile, to 1.5 mm across (usually less) with a black, flat to finally convex, smooth disc and a thin, smooth, black proper margin. Proper exciple black and almost carbonized in outermost part, dark grey-green within; epithecium dark grey-green to blue-green, N+ green; hymenium colourless, inspersed with oil droplets, I-; paraphyses lax, slender, densely branched and anastomosing, the apical cells not thickened; hypothecium colourless to pale brown. Asci 8-spored, bitunicate, clavate, I-, scarcely thickened at apex, with a small ocular chamber. Ascospores (5-)7-9(-16)-septate, hyaline, acicular with pointed ends, thin-walled, (40-)50-95(-110) x 2.5-3.5(-4) µm. Photobiont chlorococcoid. Spot tests: thallus and medulla K-, C-, KC-, P-, UV+ orange. Chemistry: rhizocarpic acid, epanorin, and sometimes traces of atranorin.
Note: an arctic-alpine, circumpolar species found on mosses and acid soil rich in humus in sheltered situations near and above treeline. Older thalli are lichenised, younger ones are lichenicolous on Baeomyces. Most frequent in the Alps, but also present in the mountains of Abruzzo, Calabria and Sicilia. To be looked for throughout the Apennines.
Growth form: Crustose
Substrata: soil, terricolous mosses, and plant debris
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)
paras Baeomyces rufus

Commonnes-rarity: (info)

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


pH of the substrata:

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Poleotolerance:

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Altitudinal distribution:

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Einar Timdal CC BY-SA-NC - Source: http://www.boldsystems.org/index.php/TaxBrowser_Taxonpage?taxid=561325



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (24570)
2001/12/13



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (24570)
2001/12/13



P.L. Nimis; Owner: Department of Life Sciences, University of Trieste
Herbarium: TSB (21138)
2001/12/13



Domenico Puntillo; Owner: Domenico Puntillo
Italy


Leif Stridvall - Source: http://www.stridvall.se/la/galleries.php (Courtesy: Anita Stridvall)


Leif Stridvall - Source: http://www.stridvall.se/lichens/gallery/
Courtesy: Anita Stridvall



Pier Luigi Nimis - CC BY-SA 4.0
TSB 38876


Einar Timdal CC BY-SA-NC - Source: http://www.boldsystems.org/index.php/TaxBrowser_Taxonpage?taxid=561325