Micarea fennica Launis & Myllys, 2019

Launis, Annina & Myllys, Leena, 2019, Micarea fennica, a new lignicolous lichen species from Finland, Phytotaxa 409 (3), pp. 179-188 : 182-185

Micarea fennica Launis & Myllys sp. nov. Fig. 2

MycoBank number: MB 831733

GenBank numbers: ITS MK517712, MK517711, mtSSU MK517716, MK517715, Mcm7: MK520931, MK520930.

Etymology: Micarea fennica is so far known only from Finland.

Type: Finland, Pohjois-Häme, Rautalampi, Kalajanvuori, mixed old-growth forest dominated by Betula spp. , Picea abies , Pinus sylvestris and Populus tremula . On standing dead P. sylvestris (1.4 m tall), on soft lignum. Together with M. prasina , WGS-84: Lat. 62° 34,74664’, Lon. 26° 42,03070’, 11.6.2015, Launis 3220 holotype (H), isotype (E).

Diagnosis: Thallus pale olive green, bright green or greyish green, minutely granular; pycnidia stalked, dark grey to dark brown, 0.2–0.5 mm tall, tomentose, K+ violet and C+ violet (Sedifolia-grey), mesoconidia cylindrical or cylindrical-fusiform, (3.8–)4.0–5.5 × 1.2–1.8 μm; apothecia not known; produces micareic acid.

Description: Thallus effuse, uneven and wide-spreading, pale olive green, bright green or greyish green, minutely granular, composed of small goniocysts 17–25 μm in diam., often coalescing to form larger granules, K− and C−. Photobiont micareoid, algal cells 4.5–7 μm. Apothecia unknown. Pycnidia numerous and conspicuous, simple or branched, stalked with one or up to five borne terminally, dark grey to dark brown, K+ violet and C+ violet (Sedifolia-grey), covered with thin whitish tomentum, 0.2–0.5 mm tall or up to 1 mm tall when proliferating, 0.07–0.15 mm diam., usually with extruding white mass of conidia. Mesoconidia cylindrical or cylindrical-fusiform, (3.8–)4.0–5.5 × 1.2–1.8 μm.

Chemistry: Micareic acid

Habitat and distribution: Micarea fennica is known from two old-growth forests in southern and central Finland. In both localities the species was found in a similar strictly delimited microhabitat: on soft lignum in shaded parts of dead standing Pinus sylvestris (Fig. 3 D).

Notes: Micarea fennica is characterized by the granular pale olive to bright green to greyish green thallus, the development of stalked dark grey to dark brown pycnidia covered in thin white tomentum, the production of micareic acid, and the absence (or rareness) of apothecia. Our results show that M. prasina s. str. is the closest relative to M. fennica . Despite the similarities in the thallus structure and secondary metabolites (both produce micareic acid), the two species are easily separated by the pycnidia that are never conspicuously stalked in M. prasina s. str. In addition, M. prasina usually develops numerous apothecia and the thallus is darker olive green.

Micarea fennica resembles M. hedlundii though phylogenetic analysis shows that they are not very closely related ( Fig. 1 ). Both species occur on soft lignum of conifers, develop a granular thalli composed of goniocysts and produce numerous stalked pycnidia with Sedifolia-grey in the wall structures (K+ violet and C+ violet). However, M. hedlundii is characterized by a darker green thallus and paler pinkish brown pycnidia. In addition, M. hedlundii produces a dull orange pigment in the thallus, which appears as K+ violet oily droplets in microscopic examinations. Furthermore, no secondary metabolites detectable by TLC are known from M. hedlundii .

The new species resembles morphologically also M. botryoides especially in the development of pycnidia that are usually numerous in both species, dark in color and stalked up to 0.5 mm tall. Compared to M. fennica , however, the pycnidia in M. botryoides are often shiny and always lack the tomentum. Additionally, the pycnidial walls of M. botryoides lack Sedifolia-grey and are instead K± dulling in microscopic examinations. Furthermore, M. botryoides lacks secondary metabolites, has a thin and scurfy thallus and occurs on a wider spectrum of substrata, such as rocks, bryophytes, bark as well as lignum. Micarea botryoides was not included in our analysis, but according to Andersen & Ekman (2005) it does not belong to the M. prasina group.

Additional specimen examined: FINLAND. Etelä-Häme, Hämeenlinna, Evo Nature Reserve, Valkea-Kotinen, Pinus sylvestris , Picea abies and Populus tremula dominated old-growth forest, W side of the lake Valkea-Kotinen, on dead standing Pinus sylvestris , on soft lignum, in shade near ground. Together with M. prasina and M. melaena . WGS84: Lat. 52° 32,99048’, Lon. 71° 17,21219’, 22.9.2010, Launis 68 (H).

Figures

FIGURE 1. Phylogenetic position of Micarea fennica sp. nov. (shown in bold).A maximum likelihood phylogram obtained from RAxML analysis based on the combined ITS, mtSSU and Mcm7 data set. Branches supported with bootstrap values ≥75% in RAxML analyses are shown above nodes.

FIGURE 2. A, B & C Micarea fennica sp. nov. (holotype H). A, Stalked pycnidium extruding mesoconidia, scale bar 100 μm; B, Mesoconidia in water, scale bar 10 μm; C, Habit, scale bar 1mm; D, Collection locality of M. fennica in Kalajanvuori old-growth forest in central Finland.