Cryptovalsa rabenhorstii (Nitschke) Sacc., Myc. Ven.

Mehrabi, Mehdi, Hemmati, Roghayeh, Vasilyeva, Larissa N. & Trouillas, Florent P., 2016, Diatrypella macrospora sp. nov. and new records of diatrypaceous fungi from Iran, Phytotaxa 252 (1), pp. 43-55 : 48-49

Cryptovalsa rabenhorstii (Nitschke) Sacc., Myc. Ven. 135, tab. XIV. Fig. 3

Basionym: Valsa rabenhorstii Nitschke Pyr. Germ.

Synonym: Sphaeria spiculosa var. robiniae Rabenh. , in Exsicc. Klotzsch, Herb. myc.

Saprobic on decaying wood. Sexual morph: Stromata in the bark of dead branches (2 cm diam), effuse, covered by the epidermis which is not discolored. Perithecia buried in the inner bark, black and shin inside, either scattered in groups of 5–25 perithecia or rarely in larger groups, circinately or linear arranged, 400–600 μm diam, delimited by a black zone in the host tissues, ostioles mostly sheltered around a white to yellowish ectostroma, ostioles poorly emerging. Asci clavate, long and slender pedicellate, polysporous, 115–175 (–200) × 13–20 μm. Ascospores hyaline when immature turning yellowish to light-brown at maturity, sub-allaintoid to cylindrical, smooth, aseptate (12−)13−15 (−16)×(2.5−)3−4(−5) μm.

Asexual morph: immersed in bark, pycnidiainterspersed amongst stromata, rare, 0.5–2 mm diam, subconical, delimited by a black zone in the host tissues, hymenium labyrinthiform, light yellow, surface white to grey, powdery, with yellow stratum of spores. Conidia filiform and arcuate, 17–22(–25) × 0.8–1 μm.

Cultural characteristics:—Colonies irregular, with abundant aerial mycelia reaching the lid of Petri-dishes, white to primrose (23 ,, b) at the surface and primrose to amber (19, b) at the reverse after 2 weeks in the dark at 24 °C, covering 75 mm Petri-dish after 5 days at 24°C.

Specimen examined:— IRAN, Mazandaran Province, Sari City, on dead branches of Citrus sp. , 5 November 2014, M. Mehrabi, MNC72 ( IRAN 16683F, IRAN 2346C).

Notes:—This species resembles closely C. rabenhorstii on Vitis vinifera in Australia ( Trouillas et al. 2011). However, this fungus has a black zone that surrounds the globose perithecia within the host tissue. The pathogenicity of this species on grapevine has been confirmed ( Pitt et al. 2013). The results of the phylogenetic analyses of the ITS sequences supported the morphological identification (bootstrap value= 100% in MP and 99% in NJ, Fig. 1 ). To our knowledge, no members of the genus Citrus have been reported as substrate for this species. The present record is the first report of this species in Iran.

Figures

FIGURE 1. One of the 48 most parsimonious trees obtained from the ITS sequence data. MP/NJ Bootstrap support values from 1000 replicates higher than 50% are reported at the nodes.The original strain numbers are noted after the species names. The ex-type strains are in bold. The new sequences obtained in this study are indicated in highlight.

FIGURE 3. Cryptovalsa rabenhorstii from Citrus sp., (1) Habit of ascostromata on bark (2) Longitudinal section through the stroma shows ostioles and perithecia (3,4) Anamorph (5) Ascus with ascocpores (6) Ascospores (7) Conidia (8) Colony morphology on PDA.— Bars 1 = 1 mm. 2,3,4 = 500 μm. 5,6,7= 20 μm.