Two new smut fungi on Ventenata (Poaceae): Tilletia elizabethae from Slovakia and T. ventenatae from Turkey

Abstract: Two new smut fungi on Ventenata (Poaceae), Tilletia elizabethae (Tilletiaceae) on V. dubia from Slovakia, and T. ventenatae on V. subenervis from Turkey, are described and illustrated. They differ from all other Tilletia species by specialization on Ventenata. Tilletia elizabethae is distinguished from T. ventenatae by having larger spores and a dark cinnamon spore mass, while the spore mass of T. ventenatae is very dark reddish brown. Citation: Denchev T. T. & Denchev C. M. 2018: Two new smut fungi on Ventenata (Poaceae): Tilletia elizabethae from Slovakia and T. ventenatae from Turkey. — Willdenowia 48: 177-183. doi: https://doi.org/10.3372/wi.48.48201 Version of record first published online on 2 July 2018 ahead of inclusion in August 2018 issue.

During an examination of grass specimens in the herbarium of the Naturalis Biodiversity Center, National Herbarium of the Netherlands, Leiden (L; herbarium code according to Thiers 2018+), two ovariicolous smut fungi belonging to the genus Tilletia Tul. & C. Tul. were found on specimens of Ventenata. These fungi were considered to represent unknown species of Tilletia. Currently, 185 species are recognized in Tilletia (Bao & al. 2010;Vánky 2011Vánky , 2013Denchev & Denchev 2013;Li & al. 2014). Most commonly, their sori are produced in the ovaries, which fill with a semi-agglutinated or powdery spore mass intermixed with sterile cells. In some species, the sori are formed on leaves and culms, as streaks. Exceptionally, the sori appear as swellings on the culms or cover the surface of the leaves, or form witches' brooms (Vánky 2013). On grasses in the subtribe Ventenatinae, species of Tilletia have been previously recorded only on species of Apera. None of the currently recognized species of smut fungi is known to infect Ventenata species.
In the present article, two new species of Tilletia on Ventenata are described and illustrated. A key to the species of Tilletia that infect Ventenata and Apera is also provided.

Material and methods
Dried specimens from the herbarium of the Naturalis Biodiversity Center, Leiden (L) were examined under a light microscope (LM) and a scanning electron microscope (SEM). For LM observations and measurements, spores and sterile cells were mounted in lactoglycerol solution (w : la : gl = 1 : 1 : 2) on glass slides, gently heated to boiling point to rehydrate the spores and sterile cells, and then cooled. The measurements of spores are given as min -max (extreme values) (mean ± 1 standard deviation). For SEM, spores and sterile cells were attached to specimen holders by double-sided adhesive tape and coated with platinum in an ion sputter. The surface structure of spores and sterile cells was observed and photographed at 10 kV accelerating voltage using a JEOL JSM 6610-LV scanning electron microscope (Natural History Museum Vienna, Austria). The descriptions below are based entirely on the specimens examined. The shapes of sterile cells and spores are arranged in descending order of frequency.  (2) sterile cells with thinner walls (0.6 -)0.8 -1.5(-1.8) μm thick compared to (1.3 -)1.5 -2.0(-2.3) μm thick in T. separata.
It is difficult to determine the exact date that the type specimen of Tilletia elizabethae was collected, but it can be assumed that this happened during the period 1861 -1909 when J. Holuby served as a Lutheran priest in Zemianske Podhradie and collected plants and fungi in that area.
Ventenata dubia (syn. Avena tenuis Moench, V. avenacea Koeler) is distributed from C and S Europe and Algeria to Crimea, the Caucasus, Turkey, Kazakhstan and Iran (Hamzeh'ee & al. 2008;Contu 2013;Clayton & al. 2018). As mentioned, a smut fungus on V. dubia has been 179 Willdenowia 48 -2018  Denchev & Denchev: Tilletia elizabethae from Slovakia and T. ventenatae from Turkey previously reported only once (Vánky 1985), despite the relatively extensive geographic range of the plant and the fact that the smut fungi of C Europe are among the best studied in the world. The specimen of Hazslinszky, cited by Vánky (as Tilletia bromi, see Introduction), was collected in the same locality from which T. elizabethae is described here, if not a part of the same gathering, due to the fact that at the time when J. Holuby studied the flora of Zemianske Podhradie, he had close professional relationships with F. Hazslinszky (see Holuby 1874: 310). It seems that the smut fungus on V. dubia is a rare species, not simply a rarely recorded one.
Eponymy -The epithet refers to the host genus.
The newly described Tilletia species were compared with a German specimen of T. separata, a smut fungus originally described on a specimen from Germany.
Remarks -Tilletia madeirensis Syd. on Aira praecox L. was treated by Vánky (2011) as a synonym of T. separata, but, considering the phylogenetic position of Aira, these smut fungi should be recognized as different species, which will be discussed further in another article.
The newly described Tilletia species and that on Apera may be distinguished by the following key.