Acarospora rorida F. H. Liang & L. Hu sp. nov.

Fig. 3

Type.

China • Shandong Province: Yantai City, Muping District, Kunyu Mountain Nature Reserve, Taiboding, on the path leading down the mountain, 37°15'06"N, 121°45'36"E, alt. 752 m, on silicious rock, 22 Nov. 2024, R. T. Li et al. 20242399 (SDNU, holotype).

Diagnosis.

Similar to Acarospora brodoana (Knudsen et al. 2016) but differs in having smaller compound apothecia (0.25–1 mm vs. 1–1.5 mm), lower hymenium (50–125 μm vs. 150–175 μm), hypothecium hyaline (vs. black), and occurrence in humid areas at an altitude lower than 800 m (vs. at elevations above 1400 m).

Etymology.

The specific epithet refers to the moist habitat where this species was found.

Description.

Thallus endolithic. Algal layer scattered in the rock beneath the base of the apothecia or not observed, discontinuous and dispersed, algal cells globose, 8–15 μm in diam. Apothecia immersed or superficial on substrate, often dispersed, sometimes continuous, round or irregular, 0.25–1 mm in diam. Disc black, with carbonized epihymenial accretions, sometimes knobby, epruinose, rough, matt or glossy, uneven, initially flat and below margin, but then usually becoming convex and higher than the margin. Margin carbonized, usually forming a series of often irregular marginal segments. Parathecium 25–50 μm thick, with black carbonized outer layer, brown inner layer, widths variable. Hymenium 50–125 μm high, hyaline, epihymenium reddish – brown, 10–25 μm thick, with dark brown to black carbonized accretions up to 50 μm thick on the disc surface, paraphyses narrow, often 1–2 μm wide, rarely more than 2.5 μm wide, septate, infrequently branching in lower half, becoming shorter in upper third, sometimes constricted at septa, apices sometimes expanded or unexpanded in darker brown to black pigment caps, hymenium gel IKI + usually immediately reddish orange, rarely light blue turning reddish orange, hemiamyloid. Asci clavate, 50–100 × 12–20 μm, ascospores mostly over 100 per ascus. Ascospores simple, hyaline, narrowly ellipsoid to ellipsoid, 3–4 × 1–2 μm, without oil drop. Subhymenium indistinct. Hypothecium hyaline, indistinct to 15 μm thick. Pycnidia not observed. Not producing secondary metabolites.

Habitat and distribution.

Acarospora rorida is currently known only from Shandong and Jiangsu provinces in eastern China. This new species occurs on siliceous rock at low altitudes in humid habitats, with the two collection sites separated by approximately 685 km.

Additional specimens examined.

China • Shandong Province: Yantai City, Muping District, Kunyu Mountain Nature Reserve, the sixth parvial field, Longxu Bridge, 37°17'33"N, 121°41'35"E, alt. 154 m, on silicious rock, 25 Nov. 2024, L. L. Zhang et al. 20242080 (SDNU); • Yantai City, Muping District, Kunyu Mountain Nature Reserve, the fifth parvial field, Huaquan Road, 37°17'38"N, 121°45'03"E, alt. 162 m, on silicious rock, 23 Nov. 2024, L. L. Zhang et al. 20242194 (SDNU); • Taiboding, on the path leading down the mountain, 37°15'06"N, 121°45'35"E, alt. 752 m, on silicious rock, 22 Nov. 2024, R. T. Li et al. 20242399 (SDNU). Jiangsu Province: Changzhou City, Liyang City, No. 96, Tianmu Lake Avenue, near Jinding Zen Temple, 31°29'35"N, 119°09'26"E, alt. 119 m, on siliceous rock, 2024, L. L. Zhang et al. 20250315 (SDNU).

Note.

The new species is characterized by compound apothecia with margins forming a series of irregular marginal segments, occurring at low altitudes in humid habitats. Acarospora rorida are morphologically similar to Sarcogyne cyclocarpa and A. subfuscescens. Acarospora rorida differs from S. cyclocarpa in having bigger ascus 50–100 × 12–20 µm (vs. 40–60 × 15–20 µm), smaller ascospores 3–4 × 1–2 µm (vs. (3.5 –) 4–5 (– 6) × (1 –) 2 (– 2.5) µm), indistinct subhymenium (vs. 40–80 µm), and growing on siliceous rocks (vs. on strongly calcareous rock) (Knudsen and Kocourková 2009; Knudsen et al. 2023 b). Acarospora rorida differs from A. subfuscescens in having smaller apothecia 0.25–1 mm in diam (vs. 1–3 mm), lower hymenium 50–125 µm (vs. (80 –) 100–140 (– 180) µm), and not being parasitic on other lichens (vs. parasitic on other lichens) (Knudsen and Kocourková 2008). Furthermore, this new species with verrucose margin is similar to Sarcogyne clavus but differs especially in not having a dark brown hypothecium (Knudsen and Standley 2007). The segmented margin with irregular marginal segments of this species is similar to S. hypophaea, but that species has smooth segments usually at angles to each other (Knudsen et al. 2013). In addition, S. paradoxa, described from Mojave Desert in California, which we collected in northwestern China, also produces carbonized hymenial accretions. But S. paradoxa differs from this new species by its reddish-brown carbonized accretions (vs. black), hymenial gel euamyloid, IKI + blue (vs. IKI + usually immediately reddish orange, rarely light blue turning reddish orange), and smaller ascospores (3 –) 4–4.5 (– 7) × 2–3 µm (vs. 3–4 × 1–2 μm) (Knudsen and Kocourková 2020).