Hidden Species Diversity was Explored in Two Genera of Catapyrenioid Lichens (Verrucariaceae, Ascomycota) from the Deserts of China

Abstract

Verrucariaceae is the third-largest lichen family with high species diversity. However, this diversity has not been well-explored in China. We carried out a wide-scale field investigation in the arid and semi-arid regions of Northwest China from 2017 to 2021. A large number of lichen groups, especially those commonly distributed in deserts, were collected. Based on molecular phylogeny using ITS and nuLSU sequences by Bayesian and maximum likelihood analyses, combining morphological characters, seven taxa of catapyrenioid lichens in Verricariaceae were found in this study, including one genus (Clavascidium) and one species (Clavascidium lacinulatum) new to China; one genus (Placidium) new to the mainland of China; and four species (Clavascidium sinense, Placidium nitidulum, Placidium nigrum, and Placidium varium) new to science. It enriched our understanding of the high species diversity in Verrucariaceae and the lichen flora of Chinese arid and semi-arid deserts.

Keywords: Clavascidium; Placidium; Verrucariaceae; catapyrenioid lichens; new species; taxonomy.

Figure 1

Collection sites. The detailed collection areas are marked in a solid red circle, and the corresponding four provinces involved are marked with varying degrees of a gray color.

Figure 2

The RAxML tree is based on the concatenated ITS + nuLSU data set representing both ML and BI trees. The number in each node represents bootstrap support (BS) and posterior probability (PP) values. BS values ≥ 75 and PP values ≥ 0.95 were plotted on the branches. The taxa in bold indicate that these sequences were newly generated for this study. Green and red clades show Clavascidium and Placidium, respectively. The character status of 1 ascospores arrangement, 2 pycnidia position, and 3 rhizines are listed at the right of the tree, corresponding to each sample of Clavascidium and Placidium. Scale in 0.04 substitution per site.

Figure 3

The thallus habit and the anatomic structure of Clavascidium lacinulatum (HMAS-L 153962). (A). Squamulose thallus. (B). Transversal section of thallus. (C). Immersed perithecium. (D,E). Uniseriate ascospores in cylindrical asci. (F). Biseriate ascospores in clavate asci. (G). Conidia. Bars: (A) =2 mm, (B,C) =50 µm, (D,E) =10 µm, (F) =50 µm, and (G) =10 µm.

Figure 4

The thallus habit and the anatomic structure of Clavascidium sinense sp. nov (holotype HMAS-L 153946). (A). Squamulose thallus and immersed apothecia with the appearance of black spots. (B). Transversal section of thallus. (C). Perithecium. (D). Pycnidium. (E). Thallus section. (F). Uniseriate ascospores in cylindrical asci. (G). Biseriate ascospores in clavate ascus. (H,I). Ascospores. Bars: (A) =100 µm, (B) =100 µm, (C) =50 µm, (D) =2 mm, (E) =50 µm, (F,G) =10 µm, and (H,I) =5 µm.

Figure 5

The thallus habit and the anatomic structure of Placidium nitidulum sp. nov (holotype HMAS-L 151947). (A). Squamulose thallus. (B). Transversal section of thallus. (C). Immersed perithecia. (D). Aggregated pyrithecia. (E). Pycnidium. (F). Cylindrical asci with uniseriate ascospores. (G–I). Ascospores. Bars: (A) =2 mm, (B) =50 µm, (C–E) =100 µm, (F) =10 µm, (G,H) =5 µm, and (I) =10 µm.

Figure 6

The thallus habit and the anatomic structure of Placidium nigrum sp. nov (HMAS-L 153950). (A). Squamulose thallus. (B,C). Thallus section. (D). Immersed perithecium. (E,F). Dermatocarpon-type pycnidia. (G,H). Asci with ascospores. (I). Conidia. Bars: (A) =2 mm, (B,C) =100 µm, (D) =200 µm, (E,F) =100 µm, and (G–I) =10 µm.

Figure 7

The thallus habit and the anatomic structure of Placicium varium sp. nov (holotype, HMAS–L 151970). (A). Squamulose thallus (HMAS–L 153948). (B). Squamulose thallus (HMAS–L 151967). (C). Thallus section. (D). Immersed perithecium. (E). Asci with biseriate and uniseriate ascospores. (F). Ascospores. (G). Pycnidium. (H). Conidia. Bars: (A,B) =2 mm, (C,D) =50 µm, (E,F) =10 µm, (G) =100 µm, and (H) =10 µm.