Tubakia lushanensis Z. X. Zhang, J. W. Xia & X. G. Zhang, 2021

Zhang, Zhaoxue, Mu, Taichang, Liu, Shubin, Liu, Rongyu, Zhang, Xiuguo & Xia, Jiwen, 2021, Morphological and phylogenetic analyses reveal a new genus and two new species of Tubakiaceae from China, MycoKeys 84, pp. 185-201 : 185

Tubakia lushanensis Z. X. Zhang, J. W. Xia & X. G. Zhang sp. nov.

Fig. 4

Type.

China, Shandong Province: Zibo Lushan National Forest Park, on diseased leaves of Quercus palustris Münchh ( Fagaceae ), 20 Sep 2020, Z. X. Zhang, (holotype HSAUP1923, ex-type living culture SAUCC 1923) .

Etymology

. Named after the type locality, Lushan National Forest Park.

Description.

Asexual morph: Leaf spots irregular, occurring on leaf veins and at leaf edges. Colonies on PDA incubated at 25°C in the dark with an average radial growth rate of 5-7 mm/d and occupying an entire 90 mm Petri dish in 14 d, forming some conspicuous concentric circles, aerial mycelium cottony, white initially, then becoming greyish-sepia. Conidiomata pycnidial, usually globose or subglobose when viewed from above, formed on agar surface, black, semi-submerged, up to 200 μm diam. Pycnidial wall composed of an outer layer of yellow-brown, thick-walled textura angularis and an inner layer with hyaline, thin-walled cells. Conidiophores reduced to conidiogenous cells lining the inner cavity, ampulliform or flask-shaped, smooth, hyaline, 9.0-15.0 μm × 2.0-4.0 μm. Conidia solitary, globose to irregular globose, ellipsoid to broad ellipsoid, 10.0-18.0 μm × 7.5-16.0 μm, length/width ratio 1.0-1.7, slightly lighter and wall thin when immature, slightly darker and wall thickened when ripening, smooth, apex rounded, base with peg-like hila, 1.3-2.3 μm diam. Microconidia not observed. Sexual morph not observed.

Culture characteristics.

Cultures incubated on MEA at 25°C in darkness, attaining 52.0-56.0 mm diam. after 14 d (growth rate 3.7-4.0 mm diam./d), creamy white to pale brown with regular margin, grey near the centre and hyphae clusters, reverse brown to dark brown rings, heterogeneous colour, with creamy-white edge. Conidial formation not observed.

Additional specimen examined.

China, Shandong Province: Zibo Lushan National Forest Park, on diseased leaves of Quercus palustris Münchh. ( Fagaceae ), 20 Sep 2020, Z. X. Zhang, HSAUP1921; living culture SAUCC 1921.

Notes.

The phylogenetic analysis of a combined three-gene alignment (ITS, tef1 and tub2) showed that T. lushanensis formed an independent clade and is phylogenetically distinct from its closest sister species T. seoraksanensis . This species can be distinguished from T. seoraksanensis by 65 different nucleotides in the concatenated alignment (21/628 in the ITS, 31/581 in the tef1 and 13/521 in the tub2). Morphologically, T. lushanensis differs from T. seoraksanensis in having smaller conidia (10.0-18.0 μm × 7.5-16.0 μm vs. 13.0-25.0 μm × 10.0-15.0 μm) ( Yun & Rossman 2011). Furthermore, the MEA’s colony colour of T. lushanensis is different from T. seoraksanensis (surface: creamy white, pale brown to grey vs. whitish to pale yellow; reverse: creamy white, brown to dark brown vs. olive brown, light olive brown to yellow; Yun & Rossman 2011). Therefore, we describe this fungus as a novel species.

Figures

Figure 4. Tubakia lushanensis (SAUCC 1923). a diseased leaf of Quercus palustris; b surface of colony after 15 days on MEA; c reverse of colony after 15 days on MEA; d conidiomata; e-i conidiogenous cells with conidia; j-k conidia. Scale bars: 10 μm (e-k).