Morphological and phylogenetic analyses reveal a new genus and two new species of Tubakiaceae from China Author Zhang, Zhaoxue Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, 271018, China Author Mu, Taichang Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, 271018, China Author Liu, Shubin Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, 271018, China Author Liu, Rongyu Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, 271018, China Author Zhang, Xiuguo Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, 271018, China Author Xia, Jiwen https://orcid.org/0000-0002-7436-7249 Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, 271018, China zhenjunxue@126.com text MycoKeys 2021 2021-11-22 84 185 201 http://dx.doi.org/10.3897/mycokeys.84.73940 journal article http://dx.doi.org/10.3897/mycokeys.84.73940 1314-4049-84-185 5E34A44441E1590BBF27BCFB8DAF8961 Obovoideisporodochium lithocarpi Z. X. Zhang, J. W. Xia & X. G. Zhang sp. nov. Fig. 3 Type . China , Yunnan Province : Xishuangbanna Tropical Botanical Garden , Chinese Academy of Sciences , on diseased leaves of Lithocarpus fohaiensis ( Fagaceae ), 11 Sep 2020 , Z. X. Zhang , ( holotype HSAUP0748, ex-type living culture SAUCC 0748) . Figure 3. Obovoideisporodochium lithocarpi (SAUCC 0748). a infected leaf of Lithocarpus fohaiensis ; b surface of colony after 15 days on MEA; c reverse of colony after 15 days on MEA; d conidiomata; e-g conidiophores, conidiogenous cells and conidia; h-i conidia. Scale bars: 10 μm ( e-i ). Etymology. Name refers to the genus of the host plant Lithocarpus fohaiensis . Description. Asexual morph: mycelium consisting of septate, smooth and hyaline hyphae, thin-walled, 1.0-2.0 μm . Colonies on PDA incubated at 25°C in the dark with an average radial growth rate of 5-6 mm/d and reaching 75-80 mm diam. in 14 d, formed some conspicuous concentric circles, aerial mycelium cottony, white initially, then becoming greyish-sepia. Conidiomata sporodochial, appeared within 20 days or longer, formed on agar surface, slimy, pale bluish-green, semi-submerged. Sporodochial conidiophores densely and irregularly branched, 12.0-26.5 x 1.5-3.0 μm , bearing apical whorls of 2-3 phialides; sporodochial phialides monophialidic, subulate to subcylindrical, 9.5-20.0 x 1.5-3.0 μm , smooth, thin-walled, tapering towards apex, swelling at base. Conidia formed singly, obovoid to ellipsoid, 5.5-8.0 x 2.5-4.0 μm , length/width ratio 1.7-3.1, hyaline, smooth, thin walled, apex obtuse, base with inconspicuous to conspicuous hilum, 0.4-0.9 μm diam. Sexual morph: unknown. Culture characteristics. Cultures incubated on MEA at 25°C in darkness, attaining 52.0-58.0 mm diam. after 14 d (growth rate 3.5-4.0 mm diam./d), grey-white to creamy white with irregular margin, spread like petals from the inside and outside, reverse dark to light brown, distributed in an irregular circle. Conidial formation not observed. Additional specimen examined. China, Yunnan Province: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, on diseased leaves of Lithocarpus fohaiensis ( Fagaceae ), 11 Sep 2020, Z. X. Zhang, HSAUP0745; living culture SAUCC 0745. Notes. In the two phylogenetic trees (Figs 1 and 2 ), Obovoideisporodochium lithocarpi is related to Racheliella wingfieldiana , Oblongisporothyrium castanopsidis , Paratubakia subglobosa and P. subglobosoides , but forms a separate single species lineage with full support (PP = 1, ML-BS = 100%). Furthermore, the conidia of O. lithocarpi (5.5-8.0 μm x 2.5-4.0 μm ) are smaller than those of R. wingfieldiana (11.0-15.0 μm x 6.5-7.5 μm ), Ob. castanopsidis (14.0-17.0 μm x 7.0-9.5 μm ), P. subglobosa (10.0-13.0 μm x 8.0-11.0 μm ) and P. subglobosoides (10.0-12.5 μm x 5.5-10.0 μm ) and Racheliella , Oblongisporothyrium and Paratubakia spp. form crustose conidiomata and true pycnothyria.