Arthrorhaphis farinosa Frisch & Y.Ohmura, 2022

Frisch, Andreas, Ohmura, Yoshihito, Holien, Håkon & Bendiksby, Mika, 2022, A phylogenetic survey of the ascomycete genus Arthrorhaphis (Arthrorhaphidaceae, Lecanoromycetes) including new species in Arthrorhaphis citrinella sensu lato, TAXON 71 (5), pp. 936-962 : 953

Arthrorhaphis farinosa Frisch & Y.Ohmura , sp. nov.

– Holotype: SWEDEN. Dalarna, Idre parish, Mt Knittarna , the diabase rock face Skäret , 61°45 ′ 38.94 ″ N, 12°34 ′ 03.06 ″ E, old mixed forest dominated by Picea abies and Pinus sylvestris, on boulder below the rock face, 739 m, 4 Jul 2016, Thor 33718 ( UPS!) .

Diagnosis. – Arthrorhaphis farinosa is characterised within A. citrinella s.l. by the typically well-delimited, distinctly areolate thalli with finely granular to farinose surface of the areolae.

MycoBank 842545

See Fig. 7D,E for images of the type and additional material.

Description. – Thallus lichenised, forming small, typically well-delimited colonies over saxicolous bryophytes and cyanobacteria, up to 1.8 cm in diam., (greenish) yellow, areolate; areolae discrete to mostly confluent, irregularly rounded to elliptical, moderately convex to bulging, 0.5–2 mm, the surface usually completely disintegrated into finely granular to farinose soredia of 0.02–0.08 mm; medulla absent; Ca-oxalate crystals absent. Apothecia (1 specimen) between the areolae, 0.5–0.8 mm, shortly and broadly stipitate, black, matt, the thick margin level with the flat, coarsely rugose disc. Epihymenium dirty to brownish olive green, HNO 3 green, 15– 25 μm. Hymenium unpigmented to pale olive green, densely inspersed, 110–120 μm. Subhymenium 40–60 μm, dirty to brownish olive green. Exciple 40–50 μm wide, dark dirty to brownish olive green, darker towards the outer edge. Paraphyses sparsely branched and anastomosed, 1–1.5 μm wide. Asci 105–120 × 10–13 μm. Ascospores acicular, parallel in the asci, 70–85 × 3.5–4.0 μm, 6–9-septate. Pycnidia absent.

Chemistry. – Rhizocarpic acid (major), epanorin (minor).

Distribution and ecology. – This species is known from the mountains of central Honshu, Hokkaido, Primorsky Territory in eastern Russia, and a restricted area of north-western Dalarna ( Sweden). The elevation ranges from 590 to 740 m in Sweden, 1610 m in Russia, and 1450 to 2360 m in Japan. Arthrorhaphis farinosa grows on acrocarpous mosses – mostly Andreaea spp. and Grimmiaceae – and colonies of cyanobacteria ( Stigonema ) on exposed to shaded base- and mineral-rich rocks including diabase in boulder fields and open forests, including spruce and pine dominated forests in Sweden. The species is often associated with Lepraria spp. Parasitic stages on other lichens have not been observed.

Etymology. – The name of the new species refers to the finely granular to farinose thallus surface.

Notes. – Arthrorhaphis farinosa is a distinctive species within A. citrinella s.l. It is characterised by small, usually well-delimited colonies growing over saxicolous bryophytes or tufts of cyanobacteria. The thalli are formed of typically confluent, convex to bulging areolae with a soft velvety to almost mealy appearance caused by the thallus surface being dissolved into finely granular to almost farinose soredia. A well-delimited medulla and Ca-oxalate crystals have not been observed. Specimens of A. citrinella s.str. growing in the same locality and elsewhere are readily distinguished by often poorly delimited thalli formed of coarser granular soredia (0.05–0.15(–0.2) mm) in loose to compacted coralloid aggregations. Discrete areolae or well-delimited thalli are absent. Almost all investigated specimens of A. farinosa are sterile, but two apothecia were found on the holotype from Sweden. The ascospores were mostly young and only few well-developed ones have been observed. Ascomatal characters agree with the other species of A. citrinella s.l. and no clear differences could be observed.

Contrary to the other species in Arthrorhaphis citrinella s.l., A. farinosa has been collected on base-rich substrates including diabase and unspecified calcareous rock.

Selected specimens examined (a total of 15 specimens seen). – JAPAN. Honshu. Yamanashi Pref., Minami-Alps-city, from Kitazawa Pass to Sensui Pass , 35°44 ′ 40 ″ N, 138° 13 ′ 38 ″ E, 28 Jun 2012, Ohmura 8975 ( TNS) . Iwate Pref., Mt Yakeishi , 26 Aug 1983, Inoue 16652 ( TNS) . Akita Pref., Higashinaruse-mura, Mt Yakeishi , 11 Aug 1982, Inoue 22978 ( TNS) . Hokkaido. Kato Distr., Kitaurimaku, Senjokuzure , 5 Jul 2014, Kashiwadani 51465 ( TNS) . RUSSIA. Primorsky Territory, Partizansky Distr. , c. 19 km ESE of Monakino, 43°20 ′ 43 ″ N, 133°39 ′ 26 ″ E, 12 Sep 2014, Ohmura 11644 ( TNS) . SWEDEN. Dalarna, Särna parish. Fulufjället National Park, Skärhamrarna , 61°37 ′ 14.34 ″ N, 12°47 ′ 32. 64 ″ E, 3 Jul 2016, Thor 33526 ( UPS) ; ibid., 61°37 ′ 12.78 ″ N, 12°47 ′ 43.32 ″ E, 3 Jul 2016, Thor 33551 ( UPS) . Idre parish, Mt Blocktjärnåsen, Gethammaren , 61°43 ′ 41.22 ″ N, 12°37 ′ 14.58 ″ E, 3 Jul 2016, Thor 33606 ( UPS) .

Figures

Fig. 7. A, Arthrorhaphis catolechioides (Moberg & Owe-Larsson NZ2:5, UPS); B, A. citrinella (Odelvik 10598, S); C, A. citrinella (Frisch 15/No100, TRH); D, A. farinosa (Ohmura 9312, TNS); E, A. farinosa (Thor 33718, UPS); F, A. bullata (Ohmura 10730, TNS). — Scale: A, B, E & F, 1 mm; C, 0.5 mm; D, 5 mm. Photos: A. Frisch.