Introduction
Xanthoria is a genus of lichenized fungi in the family Teloschistaceae, mostly distributed in the Northern Hemisphere. In modern classification, the genus comprises six species, namely X. aureola, X. calcicola, X. mediterranea, X. parietina, X. resendei and X. stiligera (Arup et al. Reference Arup, Søchting and Frödén2013). Specific affiliations of recently described taxa (e.g. Kondratyuk et al. Reference Kondratyuk, Yatsyna, Lőkös, Galanina, Haji Moniri and Hur2013) should be studied further. The generic type, X. parietina, is the most widely distributed species, being very common in the Northern Hemisphere, but also known in the Southern Hemisphere (Arup et al. Reference Arup, Søchting and Frödén2013). To date, 41 species of lichenicolous fungi have been reported from X. parietina (Etayo Reference Etayo1998; Etayo & Diederich Reference Etayo and Diederich1998; Kukwa Reference Kukwa2004; Brackel & Kocourková Reference Brackel and Kocourková2006; Brackel Reference Brackel2009, Reference Brackel2010, Reference Brackel2011; Fleischhacker Reference Fleischhacker2011; Lawrey & Diederich Reference Lawrey and Diederich2015; Khodosovtsev & Darmostuk Reference Khodosovtsev and Darmostuk2016). Seven of these are facultatively lichenicolous, namely Athelia arachnoidea, Catillaria nigroclavata, Cladosporium macrocarpum, Cosmospora flammea, Dinemasporium strigosum, Epicoccum nigrum and Periconia digitata (Yurchenko & Golubkov Reference Yurchenko and Golubkov2003; Duan et al. Reference Duan, Wu and Liu2007; Hertel et al. Reference Hertel, Nash and Ryan2007; Etayo & Berger Reference Etayo and Berger2009; Fleischhacker Reference Fleischhacker2011).
During an examination of lichens collected by students the first author found a lichenicolous pyrenocarpous fungus with brown 3-septate ascospores and setose ascomata growing on the thallus of corticolous Xanthoria parietina. The fungus appears to represent a new species of Capronia Sacc. (Chaetothyriales) and is described below. A key to the lichenicolous fungi occurring on Xanthoria s. str. is also presented.
Material and Methods
Morphology and anatomy were examined using Nikon SMZ 745 and Nikon Eclipse 80i microscopes. The anatomy was studied on material mounted in water, 10% KOH (K) and for ascus structure Lugol’s iodine solution without (I) or with KOH pretreatment (K/I). Measurement of ascospores and other structures was made on material mounted in water. Ascospore measurements are given as
$$\left( {{\rm min-}} \right)\,(\bar{x} \,{\minus}\,{\rm SD})\,-\,(\bar{x} \,{\plus}\,{\rm SD)}\left(\!{-{\rm max}} \right)$$
where min. and max. are extreme values and
$\bar{x}$
the arithmetic means and SD the corresponding standard deviation. Length/width ratios of ascospores are indicated as l/w followed by the number of measurements (n). All photographs were taken with a Nikon Eclipse 80i microscope. Material examined is deposited in GSU herbarium.
The New Species
Capronia suijae Tsurykau & Etayo sp. nov.
MycoBank No.: MB 815580
Similar to Capronia spinifera, which differs mainly in its host selection (hymenium of basidiomycetes vs. lichen Xanthoria), and in having larger ascomata, 70–112 μm wide, and longer ascospores, (10·0–)12·0–15·5×3·5–4·5 μm.
Type: Belarus, Gomel region, Leltchitsy District, Ostrozhanka Village, 51°59'30''N, 28°33'32''E, on corticolous Xanthoria parietina, 8 November 2014, V. Selenya (GSU—holotype); accompanied by Muellerella lichenicola.
(Fig. 1)

Fig. 1 Capronia suijae (holotype). A & B, habitus; C, squashed ascoma; D, seta; E & F, ascospores at different stages of maturity. C–F: in water. Scales: A & B=50 µm; C=20 µm; D–F=10 µm. In colour online.
Mycelium immersed in the host thallus, hyphae flexuous, septate, brown, smooth, 1·5–4·0 µm wide.
Ascomata perithecioid, ostiolate, scattered, initially partly immersed in the host thallus, later almost superficial, globose to subglobose, black, 40–80 μm wide (excluding setae). Setae arising from the upper part, dark brown, non-septate, unbranched, straight or curved, with an obtuse apex, thick-walled, smooth, 20–38×2–3 μm at half height, sometimes gradually tapering towards the apex. Ascomatal wall composed of brown to olivaceous brown, K−, thick-walled angular pseudoparenchymatous cells, 3·5–10·0×3·0–5·5 μm. Hamathecium gelatinized; centrum I−, pseudoparaphyses absent. Periphyses clavate, hyaline, aseptate, and sometimes difficult to observe, 4·5–7·5×2 μm. Asci clavate, 8-spored, bitunicate, initially with a thick endotunica, later entirely thin-walled, I−, 28·5–38·0×6·0–11·5 μm, ascospores overlapping within asci. Ascospores ellipsoid to fusiform, with obtuse ends, smooth, first hyaline then pale brown, (0–1–)3-septate, constricted at the septa, no longitudinal septa observed, some with a single oil drop in each cell, (9·5–)9·9–11·2(–11·5)×(4·0–)4·2–4·6(–5·0) μm, l/w=(2·1–)2·2–2·6(–2·8), n=32.
Etymology
The new species is named after Dr Ave Suija (Tartu), an eminent Estonian lichenologist, in recognition of her important contribution to the knowledge of lichenicolous fungi.
Distribution and host
So far the species is known only from the type locality, growing on darkened lobes of healthy-looking Xanthoria parietina. As the darkened parts of the thallus were also infected with Muellerella lichenicola, we cannot confirm whether C. suijae is a pathogenic species. Muellerella lichenicola is a new species to Belarus.
Notes
The following non-lichenicolous Capronia species with 3-septate ascospores and 8-spored asci have been described: C. commonsii (Ellis & Everh.) M. E. Barr, C. coronata Samuels, C. obesispora Réblová, C. parasitica (Ellis & Everh.) E. Müll. et al., C. pilosella (P. Carsten) E. Müll. et al., C. porothelia (Berk. & M. A. Curtis) M. E. Barr, C. proteae Marincowitz et al., C. setosa (M. E. Barr) E. Müll. et al. and C. spinifera (Ellis & Everh.) E. Müll. et al. All these species differ in having larger ascomata and different ascospore dimensions, as well as a different life habit (Ellis & Everhart Reference Ellis and Everhart1890; Barr Reference Barr1959, Reference Barr1972, Reference Barr1976; Bigelow & Barr Reference Bigelow and Barr1963; Müller et al. Reference Müller, Petrini, Fisher, Samuels and Rossman1987; Réblová Reference Réblová1997; Untereiner Reference Untereiner1997; Marincowitz et al. Reference Marincowitz, Crous, Groenewald and Wingfield2008). The species mentioned above are compared in Table 1. Comparable lichenicolous species of Capronia are C. andina Etayo growing on Placopsis and C. minutosetosa Halici et al. growing on Chromatochlamys muscorum. The former differs from C. suijae in having (0–)3-septate setae and larger (13·0–19·0×4·5–6·0 µm) ascospores (Etayo Reference Etayo2003), and the latter in having some septate setae and 3–5-septate and larger ascospores, (19–)22–25(–28)×6·5–7·0 µm (Halici et al. Reference Halici, Hawksworth, Candan and Türk2010). Knufia peltigerae (Fuckel) Réblová & Unter., formerly known as Capronia peltigerae (Fuckel) D. Hawksw. (see Untereiner et al. Reference Untereiner, Gueidan, Orr and Diederich2011; Réblová et al. Reference Réblová, Untereiner and Réblová2013), grows on Peltigera, and has setose ascomata and similar 1–3-septate ascospores, but they are hyaline and larger, measuring 19–24× 6–8 µm (Hawksworth Reference Hawksworth1980).
Table 1 Comparison of Capronia suijae characters with those of similar Capronia species

* calculated using the figure provided in Müller et al. (Reference Müller, Petrini, Fisher, Samuels and Rossman1987)
Macroscopically, C. suijae could be confused with the setose coelomycete Pyrenochaeta xanthoriae, which grows mainly on the thallus and apothecia of Xanthoria parietina (Diederich Reference Diederich1990), but has also been reported from X. calcicola and weakened Physcia species adjacent to infected Xanthoria thalli (Brackel Reference Brackel2011). No Capronia species is known to have a Pyrenochaeta-type asexual stage (Müller et al. Reference Müller, Petrini, Fisher, Samuels and Rossman1987; Untereiner Reference Untereiner1997) and thus the two fungi are not expected to belong to the same holomorph. Furthermore, recent studies (Aveskamp et al. Reference Aveskamp, de Gruyter and Crous2008; de Gruyter et al. Reference de Gruyter, Aveskamp, Woudenberg, Verkley, Groenewald and Crous2009) revealed Pyrenochaeta as belonging to the Pleosporales (Dothideomycetes).
We are greatly indebted to Gernot Friebes (Graz) for help with the literature search and to Mikhail Zhurbenko, Paul Diederich and an anonymous reviewer for their critical comments, helpful corrections and advice for improving the manuscript.