Introduction
The generic name Sagediopsis was re-introduced by Triebel (Reference Triebel1989), and Alstrup and Hawksworth (Reference Alstrup and Hawksworth1990) discussed the nomenclature and typification of the genus. Triebel (Reference Triebel1993) later recognised five species in the genus, all restricted in host range, confined to one species or one genus. The five species were all easily distinguished by ascospore size. Four further species also differing in this respect have been added subsequently (Hoffmann and Hafellner Reference Hoffmann and Hafellner2000; Orange Reference Orange2002; Zhurbenko Reference Zhurbenko2009; Zhurbenko and Yakovchenko Reference Zhurbenko and Yakovchenko2014).
Therefore, the genus Sagediopsis comprises nine species (http://www.indexfungorum.org last accessed 25th December 2016). It seems that all species of this genus, except S. bayozturkii and S. dissimilis, have a distribution in the northern hemisphere (for example, Alstrup & Hawksworth Reference Alstrup and Hawksworth1990; Triebel Reference Triebel1993; Zhurbenko Reference Zhurbenko2009).
While examining collections of lichenicolous fungi from Antarctica, we discovered an undescribed Sagediopsis species that infects Acarospora macrocyclos Vain., a lichen endemic to Antarctica (Øvstedal and Lewis Smith Reference Øvstedal and Smith2001). As there was no key published for all known species of Sagediopsis, the discovery of the new species also prompted us to prepare an artificial key for the now ten known Sagediopsis species.
Materials and methods
The specimens of the new records are deposited in Erciyes University Herbarium (EUH) Kayseri, Turkey. They were examined by standard microscopic techniques. Hand cut sections were studied in water, potassium hydroxide (KOH) and Lugol's solution (I). Measurements were made in water. When measuring the ascospores, numbers of ascospores from five different ascoma were measured. The measurements are given as lower−upper mean. ‘n’ is the number of measurements. The identification key prepared for the genus Sagediopsis is artificial and the data are provided from the relevant literature.
The species
Sagediopsis bayozturkii Halıcı, Güllü & Parnikoza, sp. nov.
Sagediopsis bayozturkii (holotype). A. Habitus immersed in the host areoles. B. Perithecium in section. C. and D. Asci with an internal apical beak, eight-spored.
Sagediopsis bayozturkii (holotype). Ascospores.
MycoBank No.: MB 820414
Etymology
Named in honour of Prof Dr Bayram Öztürk (University of Istanbul, Turkey), who was the leader of first Turkish Antarctic Research Expedition.
Diagnosis
Fungus lichenicola supra thallum lichenis Acarospora macrocyclos immersis. Ascomata perithecioidea, globosa, 90–150 µm in diameter. Asci eight-spori, 38–50 × 8–12 µm. Ascosporae (10−)11−12.5−14(−15) × 4−5 µm, three-septate.
Typus
Antarctica: Graham Coast: Argentine Islands: Galindez Island, Carpathians Ridge, on A. macrocyclos on andesite rocks, 65.246090°S, 64.2248560°W, altitude 9 m, 5 April 2016, M.G. Halıcı & I. Parnikoza (EUH-ANT 0.010 – holotypus).
Description
Non-lichenised, lichenicolous, evidently commensalistic as not affecting the appearance of the host. Ascomata perithecia, arising singly, first mostly immersed then usually semi-immersed to superficial, collapsed, black, ± shiny, 90–150 µm diameter; ostiolate, the ostiole not papilliform or raised, 15–25 µm in diameter. Ascoma wall dark brown to almost black, 20–25 µm thick, composed of 8–10(–12) cell layers, paler at the base. Cells 3.5–5 µm in diameter, with irregularly thickened walls and small lumina, pseudoparenchymatous. Hymenial gel ILugol + blue. Hamathecium of paraphysoids, rarely branched and septate, ca. 1–1.5 µm thick; periphysoids not observed. Asci elongate–clavate, bitunicate, with an apical beak, 38–50 × 8–12 µm (n=24), eight-spored. Ascospores overlapping and distichously arranged in the ascus, ellipsoid, apices generally somewhat attenuated but occasionally more rounded, hyaline but rarely pale brown, three-septate, rarely constricted at the septa, the cells often with conspicuous rounded vacuoles, smooth-walled, with a gelatinous sheath, (10−) 11−12.5−14(−15) × 4−5 µm (n=40), l/b ratio (2.2−) 2.5−2.9−3.3(−3.7) µm.
Host
Growing immersed on the thalli of A. macrocyclos, a lichen which is endemic to Antarctica. It seems that there is no pathogenic effect of this lichenicolous fungi to the host, apparently commensalistic.
Distribution
The host lichen Acarospora macrocyclos is a common component of crustose lichens community, as well as invading stones within the community of the lichens Usnea antarctica, Umbilicaria antartica and the moss Andreaea regularis in Antarctica. It can grow on different types of rocks on relatively low islands and on the tops of the rocky plateaus on higher islands, as well as on artificial structures of the Ukrainian Vernadsky Base. Sometimes it covers large areas of rock. It seems that S. bayozturkii is very common on A. macrocyclos and it is probably also endemic to Antarctica. All A. macrocyclos specimens should be searched for the new species S. bayozturkii.
Additional specimens examined
Antarctica: Graham Coast: Argentine Islands: Forge Islands, Rudnicki Island (margin eastern island), on A. macrocyclos on andesite rocks, 65.232660°S, 64.287020°W, altitude 9 m, 6 April 2016, M.G. Halıcı & I. Parnikoza (EUH-ANT 0.061). Andesitic Island (margin eastern island), on A. macrocyclos on andesite rocks, 65.237240°S, 64.272900°W, altitude 11 m, 6 April 2016, M.G. Halıcı & I. Parnikoza (EUH-ANT 0.062).
Discussion
The lichenicolous genus Sagediopsis has two subgenera: Hawksworthiella with asci that have more or less distinct apical beak and ellipsoid ascospores and Sagediopsis with asci without an internal apical beak and narrowly ellipsoid to fusiform ascospores. Therefore, S. bayozturkii is a member of Hawksworthiella (Hafellner Reference Hafellner1993).
Ascospore septation is an important characteristic for the taxonomy of the genus Sagediopsis as some species have simple or one-septate ascospores (S. aspiciliae, S. dissimilis) (Triebel Reference Triebel1989; Hoffmann and Hafellner Reference Hoffmann and Hafellner2000; Orange Reference Orange2002) and some have three or more septate ascospores (S. aquatica, S. barbara, S. bayozturkii, S. campsteriana, S. fissuridensis, S. pertusariicola and S. vasilyevae) (Triebel Reference Triebel1989, Reference Triebel1993; Hafellner Reference Hafellner1993; Zhurbenko Reference Zhurbenko2009; Zhurbenko and Yakovchenko Reference Zhurbenko and Yakovchenko2014; present paper). There are four species in the subgenus Hawksworthiella with three-septate ascospores (S. campsteriana on Ochrolechia spp., S. fissurisedens on Aspicilia myrinii, S. pertusariicola on Pertusaria spp. and S. vasilyevae on Rhizocarpon spp.). Although there are few lichenicolous genera that have some species with quite wide host ranges and others restricted to single lichen hosts; it is known that all Sagediopsis species are confined to a particular host genus (Zhurbenko Reference Zhurbenko2009). There have been no previous reports of Sagediopsis species on the lichen genus Acarospora. In addition to different hosts, S. bayozturkii differs from S. vasilyevae by having much shorter ascospores ((37.5−)42−50(−53) µm versus (10−)11−14(−15) µm) (Zhurbenko & Yakovchenko Reference Zhurbenko and Yakovchenko2014) and from S. fissurisedens by having much smaller ascomata (400−700 µm versus 90−150 µm) (Hafellner Reference Hafellner1993). It seems that S. bayozturkii is most similar to S. campsteriana and S. pertusariicola but it has smaller ascomata and ascospores than both these species (Zhurbenko Reference Zhurbenko2009).
If this species is restricted to Acarospora macrocyclos, which is endemic to Antarctica, we can easily predict that S. bayozturkii is also endemic to Antarctica.
Key to the described species of Sagediopsis
This artificial key is based on data from original descriptions and other publications. Selected references to the literature on their morphology, distribution and ecology are also included.
Acknowledgements
This study was part of a collaboration between the First Turkish and 21st Ukrainian Antarctic Research Expeditions supported by the FBA-2015-5995 coded Erciyes University project. The Turkish expedition leader Prof Dr Bayram Öztürk (Istanbul University) and the National Antarctic Scientific Centre of Ukraine according to the national science–technical programme of Antarctic studies in 2011–2020 are thanked for this joint expedition and for their friendly help.
