Pronectria gromakovae, a new lichenicolous fungus on Lecanora populicola and notes on other records from Kharkiv region (Ukraine)

Recent records of lichenicolous fungi from the Kharkiv region are provided. Twenty species were reported as new to the region. Pronectria gromakovae is described as a new species on Lecanora populicola. Didymocyrtis cladoniicola, D. epiphyscia, Epicladonia sandstedei, Katherinomyces cetrariae and Lichenoconium lichenicola are new to the forest-steppe zone of Ukraine. Physcia stellaris is reported as a new host species for Cladosporium licheniphilum. Notes on the currently known distribution of selected species in other Ukrainian regions are provided.

In recent years the interest in lichenicolous fungi in Ukraine is increasing . The lichenicolous flora in southern Ukraine and the Carpathians is well studied, and there has also been new findings from the Zhytomyr and Ternopil regions (Kapets andKondratyuk 2019, Darmostuk andSira 2020).
Kharkiv is one of the most important mycology historical centers in Ukraine. The research of fungi diversity in general as well as lichenicolous diversity has a long history. In early times, only isolated findings of lichenicolous fungi were presented. Opegrapha physciaria (= Celidium varium (Tul.) Körb.) is one of the few records of lichenicolous fungi which was recorded in Ukraine in the 19th century (Chernov 1895). A new era in research of lichenicolous fungi was started at the end of last century with one report of Arthonia parietinaria (as Arthonia destruens sensu ukr. auct.) from Gaidary village (Kondratyuk and Khodosovtsev 1997). Currently, only 17 species of lichenicolous fungi were reported from the Kharkiv region (Darmostuk andKhodosovtsev 2017, Gromakova 2018). Currently, 277 species of lichenicolous fungi were reported from Ukraine (Darmostuk unpubl.) instead more than 1600 species of lichens were contributed to Ukraine (Kondratyuk et al. 2010).
It is therefore useful to report lichenicolous fungi new for the region to level biodiversity knowledge gaps and understand how lichenicolous fungi are distributed in Ukraine. In this paper, I contribute twenty species as new to the region, among them Pronectria gromakovae described as new for science.

Material and methods
Specimens were examined by lens (× 10) in situ and by standard microscope techniques using LOMO microscopes Optica and MICROMED-2. Microscopical examination was done in water, 10% KOH and Lugol's iodine solution, directly or after pre-treatment with KOH or Brilliant Cresyl Blue. Measurements were made in water with an accuracy of 0.5 µm for ascospores, asci, conidia, conidiogenous cells, conidiophores, ascomatal and pycnidial wall cells, and 5 µm for ascomata and pycnidia. They were made in magnifications × 640 and × 1600. Sizes are given as (min.) x − SD -x + SD (max.), where x is the average and SD is the standard deviation. All examined specimens are deposited in the lichenological herbarium of Kherson State University (KHER), N.V. Karazin Kharkiv National University (CWU) and author's personal herbarium (herb. VD). Non-collected material is marked as 'non coll.' Lichenicolous fungi were collected during field trips in 2018-2020 to Kharkiv region. Field surveys were carried out at the following locations ( Fig. 1):
This species was reported from a few localities, but is probably overlooked elsewhere. It was known from Mykolaiv, Kherson and Ternopil region , Khodosovtsev et al. 2019a, Darmostuk and Sira 2020. Physcia stellaris is a new host species.

Didymocyrtis cladoniicola (Diederich, Kocourk. & Etayo) Ertz & Diederich
Specimens examined: Site 1: on Cladonia uncialis on sand (herb. VD 460); Site 13: on Cladonia sp. on soil (herb. VD 775). This species was reported only from the steppe zone of Ukraine (Darmostuk andKhodosovtsev 2017, Khodosovtsev et al. 2019b). This record is new for the forest-steppe zone. This lichenicolous fungus is a poorly known species in Ukraine. It was reported only from Kherson region and Autonomous Republic Crimea . Probably, Didymocyrtis epiphyscia is a common but rarely collected species in Ukraine.
This species was reported from a few localities in different regions of Ukraine. In the forest-steppe zone, Homostegia piggotii was found in Poltava region .
Katherinomyces cetrariae was described on Cetraria aculeata from Kherson region ). Further research has shown that the species is not host specific and can infect other Parmeliaceae species as well as Lecidea fuscoatra and Rhizoplaca chrysoleuca (Darmostuk andKhodosovtsev 2019, Zhurbenko et al. 2020). Illosporiopsis christiansenii is a common species in Ukraine, but there is no previous report from Kharkiv region (Darmostuk and , Khodosovtsev and Darmostuk 2017b, Darmostuk and Sira 2020.
Lichenochora obscuroides probably is a common species within the forest-steppe zone of Ukraine (Darmostuk andKhodosovtsev 2017, Pleskach and. This is a common species in Ukraine (Darmostuk 2019).
In forest-steppe zone this species was reported only from Poltava region .

Etymology
The epithet honours the Ukrainian lichenologist Dr Alla Gromakova at the occasion of her 55th birthday.

Ecology and distribution
The new species is known from two localities in Kharkiv region, where it grows on the thalli of Lecanora populicola on Populus tremula. The infection does not induce gall formation, but causes a discoloration of the host thallus and apothecia.
Pyrenochaeta xanthoriae is a common fungus dwelling on Xanthoria, which was reported from a few localities in Ukraine , Kapets and Kondratyuk 2019, Khodosovtsev et al. 2019a).
Refractohilum intermedium is a rare species growing on Pachyphiale species (Roux et al. 1997). In the forest-steppe zone of Ukraine it was reported from Sumy and Ternopil regions Darmostuk 2017a, Darmostuk andSira 2020).
Trichoconis hafellneri was described from Kherson and Poltava region on thallus and apothecia of Athallia pyracea and Xanthoria parietina (Braun et al. 2016). Currently, only records from Austria are known in addition to the type localities (Berger 2019).

Conclusion
Including the 21 species presented in this study, in total 38 species of lichenicolous fungi are currently known in the Kharkiv region. Pronectria gromakovae is described as new for science on thallus and apothecia margin of Lecanora populicola. It is the first Pronectria species described from Lecanoraceae. Didymocyrtis cladoniicola, D. epiphyscia, Epicladonia sandstedei, Katherinomyces cetrariae and Lichenoconium lichenicola are new to the forest-steppe zone of Ukraine. Currently, the Kharkiv region harbours the greatest diversity of lichenicolous fungi in the Left Bank Forest-Steppe of Ukraine. However, we suggest that the 38 species currently known are only a fraction of all species present, and further studies on lichenicolous fungi in the Kharkiv region will likely result in more new findings.