Arthrorhaphis (Obermayer, 1994)

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 : 955-957

Artificial key to the genus Arthrorhaphis .

— The morphologically poorly characterised “ Arthrorhaphis septentrionalis ” ( Fig. 8F ) and Arthrorhaphis sp. 1 are not included in the key. Characters for the parasitic species have been compiled from Obermayer (1994), Santesson & Tønsberg (1994), Kocourková & Van den Boom (2005), and Etayo (2017).

1. Lichenised thallus absent; species strictly lichenicolous .....2

1. Lichenised thallus present; lichenicolous stages present or absent.........................................................................7

2. On the thallus of foliose or squamulose lichens.............3

2. On the thallus of crustose lichens...................................6

3. Causing aeruginose discolouration of the host thallus; on squamules and podetia of Cladonia spp ....................... ................................................... A. aeruginosa ( Fig. 6A )

3. Aeruginose discolouration of the host thallus absent; on other lichens...................................................................4

4. Asci predominantly 4-spored; hymenium 110–150 μm; on Phyllobaeis imbricata ......................... A. phyllobaeis

4. Asci predominantly 6- or 8-spored; hymenium ≥150 μm; on other lichens..............................................................5

5. Asci predominantly 6-spored; hymenium 200–250 μm; on Arctoparmelia incurva ... A. arctoparmeliae ( Fig. 6B )

5. Asci 8-spored; hymenium 150–180 μm; on Melanohalea olivacea ........................................ A. olivaceae ( Fig. 6C )

6. Hymenium (except epihymenium) ± clear; ascospores 3.5–4.5(–5) μm wide, 10–15-septate; on Dibaeis baeomyces ................................................ A. muddii ( Fig. 6D )

6. Hymenium strongly inspersed; ascospores 2.5–3.5 (–4.5) μm wide, 7–9(13)-septate; on Baeomyces rufus .... ............................................................ A. grisea ( Fig. 6E )

7. Ascospores of the alpina, jungens or vacillans type; Ca-oxalate crystals in the medulla usually present..............8

7. Ascospores of the citrinella type; Ca-oxalate crystals absent in the medulla or beneath the soredia ( A. citrinella s.l.)................................................................................ 10

8. Ascospores (vacillans type); soredia absent..... A. vacillans

8. Ascospores of the alpina or jungens type; soredia present or absent.........................................................................9

9. Ascospores alpina type ..................................................... ........................... A. alpina var. alpina s.l. ( Fig. 8A,C,E )

9. Ascospores jungens type .................................................. ............................ A. alpina var. jungens s.l. ( Fig. 8B,D )

10. Soredia or granules absent; thallus distinctly bullate-areolate; parasitic stages absent...........................................11

10. Soredia or granules present (occasionally indistinct); thallus areolae present or absent; parasitic stages present or absent...........................................................................12

11. Thallus surface ± smooth and shiny; areolae folded in ridges and with central cavity or resting in umbrella-like fashion on black hyphal strands; Australasia ................... .............................................. A. catolechioides ( Fig. 7A )

11. Thallus surface ± verrucose, matt to slightly shiny; areolae convex to distinctly bullate, not folded in ridges; pale yellow medulla present; East Asia... A. bullata ( Fig. 7F )

12. Thallus forming small compact colonies on saxicolous bryophytes and cyanobacteria; thallus surface entirely disintegrated into finely granular to farinose soredia; parasitic stages absent; East Asia and Scandinavia .......... .................................................... A. farinosa ( Fig. 7D,E )

12. Thallus otherwise; parasitic stages present or absent........13

13. Thallus entirely of small loose to compact aggregations of granular soredia on saxicolous bryophytes; parasitic stages absent; Europe and Iceland.................................... ................................................... A. citrinella ( Fig. 7B,C )

13. Thallus of discrete to confluent areolae on soil, terricolous bryophytes and plant remains, or parasitic on Baeomyces spp. (rarely on other terricolous lichens); areolae breaking into soredia, rarely completely disintegrated or esorediate; widespread in the Northern Hemisphere........ ........................................................ A. vulgaris ( Fig. 6F )

Figures

Fig. 8. A, Arthrorhaphis alpina (Schaer., Lichenes Helvetici Exsiccati 532, G, lectotype); B, A. alpina var. jungens (Lichenotheca Graecensis 23, E, isotype); C, A. alpina (Ohmura 10119, TNS); D, A. alpina var. jungens (Kalb, Lichenes Neotropici 577, M); E, A. alpina (Brusse 4515, UPS); F, “A. septentrionalis” (Hansen 026, C). — Scale: A–F, 1 mm. Photos: A. Frisch.

Fig. 6. A, Arthrorhaphis aeruginosa (TØnsberg 19019, BG, holotype); B, A. arctoparmeliae (Kocourková & Kocourek JK5484 dpl., C); C, A. olivaceae (Santesson 11677, BG, isotype); D, A. muddii (Woods s.n., E, holotype); E, A. grisea (Th.M. Fries s.n., UPS, holotype); F, A. vulgaris (Norrlin s.n., H). — Scale: A–C, 0.5 mm; D–F, 1 mm. Photos: A. Frisch.

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.