Graphilbum translucens R.L. Chang & X.Y. Zhang, 2021

Chang, Runlei, Zhang, Xiuyu, Si, Hongli, Zhao, Guoyan, Yuan, Xiaowen, Liu, Tengteng, Bose, Tanay & Dai, Meixue, 2021, Ophiostomatoid species associated with pine trees (Pinus spp.) infested by Cryphalus piceae from eastern China, including five new species, MycoKeys 83, pp. 181-208 : 181

3. Graphilbum translucens R.L. Chang & X.Y. Zhang sp. nov.

Fig. 11

Holotype.

China. Shandong province: Zhujiajuan village, Huancui District, Weihai City, from the gallery of Cryphalus piceae on Pinus thunbergii , 10 Oct. 2019, R. L. Chang (HMAS 249925-holotype; SNM144 = CGMCC 3.20263 - ex-holotype culture).

Additional cultures checked.

China. Shandong province: Laojiangou village, Laoshan District, Qingdao City, from the gallery of Cryphalus piceae on Pinus densiflora , 2, Aug. 2020, R. L. Chang (SNM104).

Etymology.

The name refers to the translucent appearance of the colony on MEA.

Diagnosis.

Graphilbum translucens can be distinguished from other closely related species, Gr. puerense and Gr. acuminatum , by the shorter hyalorhinocladiella-like conidiophores, smaller conidia and no pesotum-like asexual state.

Description.

Sexual morph is unknown. Asexual state hyalorhinocladiella-like: the conidiophores directly arising from the vegetative hyphae, measuring (3.6-) 8.6-42.2 (-72.3) μm × (0.9-) 1.1-1.7 (-2.0) μm (Fig. 11b-e ); conidia hyaline, smooth, unicellular short oblong, with rounded ends or ellipsoidal to ovoid, measuring (2.1-) 2.4-3.5 (-4.1) × (0.8-) 1.3-2.0 (-2.7) μm (Fig. 11b-e ).

Culture characteristics.

The colonies are light brown in color on MEA (Fig. 11a ). Mycelia are partially submerged in the agar. The optimal temperature for growth is 30 °C, reaching 74.0 mm diam in 5 days. Growth slower at 35°C, 24 mm diam in 5 days. No growth was observed at 5 °C.

Distribution.

Currently known from Qingdao City and Weihai City in Shandong Province, China.

Note.

Based on morphology coupled with single-gene (ITS, EF, BT, and CAL) phylogenies, Graphilbum translucens is phylogenetically close to Gr. puerense and Gr. acuminatum . In the ITS tree, Gr. translucens grouped with Gr. puerense (Fig. 3 ) and Gr. acuminatum whereas it formed distinct clades in the BT and EF trees (Figs 4 and 5 ). The hyalorhinocladiella-like asexual state was observed in Gr. translucens and Gr. puerense , but it is absent in Gr. acuminatum ( Chang et al. 2017; Jankowiak et al. 2020). The conidiophores of Gr. translucens are shorter than the Gr. puerense ( Chang et al. 2017). Conidia of Gr. translucens and Gr. puerense form hyalorhinocladiella-like asexual states that are similar in shape, yet the conidia size of Gr. translucens is smaller than Gr. puerense (2.1-4.1 × 0.8-2.7 vs. 3.5-12 × 1-3 μm, Fig. 11b-e ) ( Chang et al. 2017). Unlike Gr. puerense and Gr. acuminatum , a pesotum-like asexual state was not observed among the isolates of Gr. translucens recovered in this study.

Figures

Figure 3. Maximum likelihood phylogeny of Graphilbum using complete ITS region. The isolates recovered in this study are highlighted in color and in bold font. ML and MP bootstrap support values ≥ 75 are indicated at the nodes as ML / MP. Bold branches indicate posterior probabilities values ≥ 0.9. T indicates ex-type cultures.

Figure 4. Maximum likelihood phylogeny of Graphilbum using partial BT and partial CAL gene regions. The isolates recovered in this study are highlighted in color and in bold font. ML and MP bootstrap support values ≥ 75 are indicated at the nodes as ML / MP. Bold branches indicate posterior probabilities values ≥ 0.9. T indicates ex-type cultures.

Figure 5. Maximum likelihood phylogeny of Graphilbum using partial EF gene region. The isolates recovered in this study are highlighted in color and in bold font. ML and MP bootstrap support values ≥ 75 are indicated at the nodes as ML / MP. Bold branches indicate posterior probabilities values ≥ 0.9. T indicates ex-type cultures.

Figure 11. Morphological characters of asexual structures of Graphilbum translucens sp. nov. a fourteen-day-old culture on MEA b-e conidiophores and conidia. - Scale bars: 10 μm.