Phaeotubakia lithocarpicola Y.Q. Zhu & Ning Jiang, 2023

Jiang, Ning, Zhu, Ya-Quan, Xue, Han, Piao, Chun-Gen & Li, Yong, 2023, Phaeotubakia lithocarpicola gen. et sp. nov. (Tubakiaceae, Diaporthales) from leaf spots in China, MycoKeys 95, pp. 15-25 : 15

Phaeotubakia lithocarpicola Y.Q. Zhu & Ning Jiang sp. nov.

Fig. 2

Etymology.

Named after the host genus, Lithocarpus .

Description.

From leaf spots, circular to subcircular, margin distinct, brown to fuscous. Sexual morph: Unknown. Asexual morph in vitro: Conidiomata sporodochial, appeared after 10 days on PDA surface, slimy, black, semi-submerged, 50-350 μm diam. Conidiophores reduced to conidiogenous cells. Conidiogenous cells brown, smooth, guttulate, cylindrical to ampulliform, attenuate towards apex, phialidic, 6-15.5 × 3.5-5 μm. Conidia blastic, subglobose, broad ellipsoid to ellipsoid, seldom irregular, brown to dark brown, walls smooth, becoming thicker with age, base rounded or with truncate basal hilum, (13.5-)14-16.5(-18) × (5.5-)7-8.5(-9) μm (n = 50), L/W = 1.7-3.2.

Culture characters.

Colonies on PDA flat, spreading, with flocculent aerial mycelium, white to pale luteous, with age forming concentric zones, reaching a 90 mm diameter and forming abundant black conidiomata after 10 days at 25 °C; on MEA flat, spreading, with flocculent aerial mycelium and crenate edge, pale luteous to pale grey, reaching a 45 mm diameter after 10 days at 25 °C; on SNA flat, spreading, with flocculent aerial mycelium forming concentric rings and entire edge, pale luteous, reaching a 60 mm diameter after 10 days at 25 °C.

Specimens examined.

China, Guangdong Province, Qingyuan City, Yangshan County , Guangdong Nanling Nature Reserve , on diseased leaves of Lithocarpus glaber , 4 December 2019, Yong Li (holotype CAF 800071; ex-holotype culture CFCC 54422) . Guangdong Province, Qingyuan City, Yangshan County , Guangdong Nanling Nature Reserve , on diseased leaves of Lithocarpus glaber , 3 December 2019, Dan-ran Bian (culture RK7CX) .

Notes.

Phaeotubakia lithocarpicola is the sole species within the newly proposed genus, which is associated with leaf spot disease of Lithocarpus glaber . Two tubakiaceous species were reported from the host genus Lithocarpus before the present study, viz. Obovoideisporodochium lithocarpi from Lithocarpus fohaiensis in China and Tubakia californica from Lithocarpus densiflorus in the USA ( Braun et al. 2018; Zhang et al. 2021). Phaeotubakia lithocarpicola represents the third tubakiaceous species discovered from the host genus Lithocarpus . However, P. lithocarpicola differs from O. lithocarpi and T. californica by brown conidiogenous cells and brown to dark brown conidia ( Braun et al. 2018; Zhang et al. 2021).

Figures

Figure 2. Morphology of Phaeotubakia lithocarpicola (CFCC 54452) A colonies on PDA, MEA and SNA after 10 days at 25 ° C B conidiomata formed on PDA C conidiogenous cells giving rise to conidia D-G conidia. Scale bars: 200 μm (B); 10 μm (C-G).