Melanconiella betulicola Fan

Fan, Xinlei, Du, Zhuo, Bezerra, Jadson D. P. & Tian, Chengming, 2018, Taxonomic circumscription of melanconis-like fungi causing canker disease in China, MycoKeys 42, pp. 89-124 : 103

Melanconiella betulicola Fan sp. nov. Fig. 7

Etymology.

betulicola (Lat.): referring to the host genus on which it was collected, Betula .

Diagnosis.

This species is distinguished by hyaline ascospores, (16.5 –)18–22(– 24) × (3 –)4– 6 μm, with slightly constricted at the septum and with hyaline broad cap-like appendages at both ends.

Holotype.

CHINA. Shaanxi Province: Ningshan County, Huoditang Forest Farm, Huodi Valley, 33°26'36.32"N, 108°26'46.48"E, 3 August 2015, on twigs and branches of Betula albosinensis , Q. Yang (BJFC-S1347 holotype; living culture, CFCC 52482).

Descriptions.

Pseudostromata inconspicuous, immersed in host bark, slightly erumpent from surface of host branches, 1.5-3 mm diam. Ectostromatic disc indistinct, usually circular, buff to hazel. Central column circular, mouse grey to iron grey. Ostioles numerous, violaceous black to black, scarcely projecting, 70-150 μm diam. Perithecia flask-shaped to spherical, arranged circularly or irregularly, 7-12 per disc, often appearing as rounded bumps beneath the bark surface surrounding the ectostromatic disc, (320 –)350–550(– 610) µm diam. (av. = 480 μm, n = 30). Asci hyaline, clavate to fusoid, (50 –)55–65(– 70) × (7 –)8.5–14(– 16) μm (av. = 60 × 11 μm, n = 20). Ascospores hyaline, ellipsoid, broadly ellipsoid or broadly fusoid, 2-4 guttulate, symmetric to slightly asymmetric, straight, rarely slightly curved, slightly constricted at the septum, (16.5 –)18–22(– 24) × (3 –)4– 6 μm (av. = 20 × 4.5 μm, n = 50), with hyaline broad cap-like appendages at both ends. Conidiomata acervular, immersed in host bark, erumpent from surface of host branches, scattered or occasionally confluent, 1.3-2.5 mm, covered by fawn to dark brick discharged conidial masses at maturity, usually conspicuous. Ectostromatic disc inconspicuous. Central column beneath the disc more or less conical, olivaceous grey to iron grey. Conidiophores hyaline, smooth, cylindrical to lageniform, simple, rarely branched at the base. Conidiogenous cells hyaline, phialidic. Conidia unicellular, hyaline, narrowly ellipsoid, elongate to slightly allantoid, (9.5 –)10–13.5(– 15) × (2 –)3–4.5(– 5.5) μm (av. = 13 × 3.5 µm, n = 50), with 0.5 µm wide gelatinous sheath.

Culture characteristics.

On PDA, cultures are initially white, becoming greyish-sepia after 3 d and distensible radially after 10 d. The colonies are felty with an irregular edge; texture uniform; sterile.

Additional material examined.

CHINA. Shaanxi Province: Ningshan County, Huoditang Forest Farm, Huodi Valley, 33°26'37.53"N, 108°26'44.14"E, 3 August 2015, on twigs and branches of Betula albosinensis , Q. Yang (CF 20150847; living culture, CFCC 52483);

Notes.

Melanconiella betulicola is associated with canker disease of Betula albosinensis in China. It is similar to M. ellisii but differs by larger ascospores (18-22 × 4-6 vs.> 12.5-16 × 4.0-5.5 μm) with hyaline, broad cap-like appendages at both ends ( Voglmayr et al. 2012), distribution (China vs.> eastern North America) and a different host, Betula albosinensis vs.> Carpinus caroliniana . Melanconiella decorahensis also occurs on Betula (in Europe and North America) and it can be distinguished from M. betulicola based on dark brown ascospores without appendages and dark brown conidia (Vogl mayr et al. 2012). The clear phylogenetic position confirmed a distinction from all other available strains included in this study and we therefore result in our decision to describe this species as new, based on DNA sequence data and morphology.