The genus Libertella Desm is a member of Diatrypaceae family in the order of Xylariales (Smith et al. 2003). Libertella has often been reported in various vascular plants (Kirk et al. 2001). During December 2017, Libertella isolates were recovered from the trunk of plane trees (Platanus orientalis), showing decline symptoms in Kermanshah urban area. Conidiomata (acervuli) were observed on the surface of the infected trunk, immersed in the bark, scattered and flat to subconical. Conidiophores were crowded, acicular, somewhat straight, branched, and approximately the same length as the conidia. Tendrils were highly gelatinous, coiled and twisted form with orange color. Conidia were abundant, one-celled, hyaline, slender, and strongly arcuate, 17 −25 (21) × 0.7 −0.9 (0.8) μm (Fig. 1a–d). The identification was carried out comparing the information registered with those published in the specialized literature and our sample is identical with the description of L. platani provided by Grove (1937).
The voucher specimen (IRAN 16935F) was deposited in the Fungal Reference Collection of the Ministry of Jihad-e Agriculture (IRAN…F) at the Iranian Research Institute of Plant Protection, Tehran, Iran. Libertella species are listed as parasites or saprophytes on different species of woody plants (Ellis & Ellis 1985). Teleomorphs are mostly members of the genus Diatrypella, however, some of them are also members of other genera, namely Eutypa, Eutypella, Diaporthe, and Polystigma (Kirk et al. 2001). This genus has been reported from England, France, Germany, Romania, Ukraine, Switzerland and Hungary (Sutton 1980; Dudka et al. 2004; Pilotti & Ponzio 2004; Magyar & Toth 2003). To date, there is no available information about the occurrence of a decline of plane trees and associated Libertella species in Iran. To our knowledge, this is the first report of the L. platani for mycobiota of Iran. The tendril color of this species is same as Cytospora fungus. The distinction between Cytospora and Libertella is essential for the assumption of an appropriate management strategy.
Fig. 1. Libertella platani. a. Acervuli on a twig of Platanus orientalis and a red tendril of conidia exuded from acervuli, b, c. Flat and subconical acervulus, d. Filiform conidia. — Scale bars: a =5 mm, b-d = 20 µm.