Sarcogyne knudsenii J. X. Wang, F. H. Liang & L. Hu sp. nov.

Fig. 4

Type.

China • Xinjiang Uygur Autonomous Region: Tashkurgan Tajik Autonomous County, Aksay Kazakh Autonomous County, Pamir Plateau Tourist Area, 38°06'25"N, 74°59'05"E, 3544 m, on calcareous rock, 25 Jun. 2022, X. Y. Wang et al. XY 22-675 (KUN, holotype).

Diagnosis.

Similar to the calciphyte Sarcogyne pusilla (Knudsen and Kocourková 2008) in its endolithic thallus and carbonized apothecia, but differs in having lower hymenium 50–100 μm (vs. 100–125 μm), larger ascospores 6–7 × 3–4 μm (vs. 4–5 × 2–3 μm), and is not parasitic on other lichen species.

Etymology.

This species is named in honor of the Czech lichenologist Kerry Knudsen, in recognition of his important contributions to the taxonomic and phylogenetic studies of the family Acarosporaceae in California and the southwestern United States.

Description.

Thallus epilithic, forming ecorticate, with scattered algal layer in the substrate or below the apothecia, occasionally absent, algal cells 6–12 μm wide. Apothecia 0.25–1 mm wide, 200 μm thick, rough and matt, immersed or superficial on rock, round to irregular, dispersed or contiguous, replicating by division. Disc black, rough, epruinose or light pruinose, concave, with carbonized accretions on surface and forming an umbo structure, sometimes disc lacking carbonized accretions. Margin carbonized, 250–300 μm thick, sometimes covering up disc, segmented, usually in long linear sections at joints, higher than the disc. Parathecium outer layer carbonized, 25–50 μm thick, inner layer light brown to hyaline, 25–75 μm thick. Hymenium 50–100 μm tall, epihymenium light brown, 10–25 μm tall, paraphyses thin, usually 1.5–2 μm wide, barely expended in dark pigment caps, hymenial gel IKI + blue, euamyloid. Asci clavate, 60–75 × 15–20 μm, ascospores more than 100 per ascus. Ascospores ellipsoid or broadly ellipsoid, 6–7 × 3–4 μm wide, simple and hyaline, without oil drops. Subhymenium hyaline, 25–50 μm thick, IKI + blue. Hypothecium 10–25 μm. Pycnidia not observed. Not producing secondary metabolites.

Habitat and distribution.

This new species is currently known only from the cold and arid Pamir Plateau in the Xinjiang Uygur Autonomous Region, and grows on calcareous rock.

Additional specimens examined.

China • Xinjiang Uygur Autonomous Region: Tashkurgan Tajik Autonomous County, Aksay Kazakh Autonomous County, Pamir Plateau Tourist Area, 38°06'25"N, 74°59'04"E, alt. 3573 m, on calcareous rock, 25 Jun. 2022, L. S. Wang et al. 22-71601 (KUN); • Tashkurgan Tajik Autonomous County, Aksay Kazakh Autonomous County, Pamir Plateau Tourist Area, 38°06'25"N, 74°59'05"E, 3544 m, on calcareous rock, 25 Jun. 2022, X. Y. Wang et al. XY 22-675 (KUN).

Note.

This new species is morphologically similar to Acarospora austrooccidentalis, but A. austrooccidentalis differs in having higher hymenium (100 –) 120–150 μm (vs. 50–100 μm),, variable asci from 100 × 10–40 µm to 40 × 15 µm in same hymenium (vs. 60–75 × 15–20 µm), smaller ascospores (1.5 –) 4.0–4.6 (– 5.1) × (1.0 –) 2 (– 2.8) µm (vs. 6–7 × 3–4 µm), and usually occurs on non-calcareous rocks (vs. calcareous rocks), (Knudsen et al. 2025 a). Sarcogyne knudsenii is also similar to A. destructans in having segmented margin of apothecia, but differs in having a hemiamyloid hymenium (vs. euamyloid hymenium), a smaller ascospores (3 –) 4.5 (– 5) × (1 –) 1.5–2.5 µm (vs. 6–7 × 3–4 µm), not parasitizing on other lichens, and growing on calcareous rock (vs. growing on siliceous rock) (Knudsen et al. 2022).