Graphilbum xianjuensis G. H. Zheng & Q. Lu, 2022

Zheng, Guiheng, You, Minqi, Li, Xuening, Zhou, Qinzheng, Wang, Zheng, Wang, Huimin & Lu, Quan, 2022, Diversity of fungi associated with Monochamus alternatus larval habitats in Bursaphelenchus xylophilus - infected Pinus massoniana and identification of two new ophiostomatalean species (Ascomycota, Ophiostomatales), MycoKeys 92, pp. 1-25 : 1

Graphilbum xianjuensis G. H. Zheng & Q. Lu sp. nov.

Fig. 9

Etymology.

The epithet xianju (Latin) refers to the type locality.

Type.

China, Zhejiang, Xianju County, from Monochamus alternatus galleries and pupal chambers of Pinus massoniana infested by Bursaphelenchus xylophilus , December 2020, collected by G. H. Zheng, culture ex-holotype CFCC55738 = CXY4010 .

Description.

Sexual morph: not observed.

Asexual form: Hyalorhincladiella -like. Conidiogenous cells were simple or loosely branched, (9.12-) (15.44) - (48.64) (-62.49) × (1.25-) (1.53) - (2.21) (-2.45) μm. Conidia hyaline, smooth, cylindrical, aseptate, (4.76-) (6.07) - (9.87) (-13.41) × (0.99 -) (1.32) - (2.1) (-2.65) μm.

Culture characteristics.

Colonies on 2% MEA reaching 44.9 mm diameter, after incubation in the dark at 25 °C for 3 d, growth rate up to 14.98 mm/d at the fastest and colony margin irregular. Mycelium superficial to flocculose or floccose, hyaline, reverse grey-white. The optimal temperature for growth at 30 °C; no growth was observed at 5 °C.

Habitat and distribution.

Larval galleries and pupal chambers of Monochamus alternatus in Pinus massoniana , infested by Bursaphelenchus xylophilus , in Zhejiang Province, China.

Additional specimens examined.

China, Zhejiang, from Monochamus alternatus galleries and pupal chambers of Pinus massoniana infested by Bursaphelenchus xylophilus , December 2020, collected by G. H. Zheng, CFCC55739 = CXY4011, CXY4018 .

Note.

Only the Hyalorhincladiella -like asexual form was observed in Graphilbum xianjuensis . This is closely related to the G. acuminatum , G. anningense and G. translucens , based on the ITS, BT and TEF1-α phylogenetic trees (Figs 1 , 3 , 4 ). Four species differed according to the size of their conidia. The conidia of G. xianjuensis (6.07-9.87 μm) are longer than those of G. anningense (4.5-6.4 μm), G. acuminatum (3.5-6 μm) and G. translucens (2.4-3.5 μm) ( Wang et al. 2019; Jankowiak et al. 2020). Besides, G. xianjuensis was found to be associated with M. alternatus and PWN-infested P. massoniana , whereas G. anningense was reported in galleries of T. yunnanensis and T. minor associated with P. yunnanensis in southwest China ( Wang et al. 2019), G. acuminatum has been reported in galleries of Ips acuminatus and Pityogenes bidentatus associated with P. sylvestris in Europe ( Jankowiak et al. 2020) and G. translucens was first reported in Cryphalus piceae associated with P. densiflora . In conclusion, four species of Graphilbum differ not only in geographical distribution, but also in hosts and vectors. The optimum growth temperature of G. xianjuensis , G. anningense and G. translucens is 30 °C and only G. acuminatum had an optimum growth temperature of 25 °C ( Wang et al. 2019; Jankowiak et al. 2020).

Figures

Figure 1. ML tree of the ITS region of Ophiostoma, Sporothrix, Graphilbum, Ceratocystiopsis. Bootstrap values of ML / MP ≥ 70 % are recorded at nodes as ML / MP and bold branches indicate posterior probability values ≥ 0.9. ML and MP, Bootstrap values <70 % are indicated by the symbol *. The tree is drawn to scale (see bar) with branch length measured in the number of substitutions per site. Strains representing ex-type sequences are marked with " T. " ML, Maximum Likelihood; MP, Maximum Parsimony; BI, Bayesian Inference and the final alignment of 734 positions, including gaps.

Figure 3. ML tree of the BT region of Graphilbum. Bootstrap values of ML / MP ≥ 70 % are recorded at nodes as ML / MP and bold branches indicate posterior probability values ≥ 0.9. ML and MP, Bootstrap values <70 % are indicated by the symbol *. The tree is drawn to scale (see bar) with branch length measured in the number of substitutions per site. Strains representing ex-type sequences are marked with " T. " Abbreviations: ML, Maximum Likelihood; MP, Maximum Parsimony; BI, Bayesian Inference and the final alignment of 548 positions, including gaps.

Figure 4. ML tree of the TEF region of Graphilbum. Bootstrap values of ML / MP ≥ 70 % are recorded at nodes as ML / MP and bold branches indicate posterior probability values ≥ 0.9. ML and MP, Bootstrap values <70 % are indicated by the symbol *. The tree is drawn to scale (see bar) with branch length measured in the number of substitutions per site. Strains representing ex-type sequences are marked with " T. " Abbreviations: ML, Maximum Likelihood; MP, Maximum Parsimony; BI, Bayesian Inference and the final alignment of 725 positions, including gaps.

Figure 9. Morphological characteristics of Graphilbun xianjuensis sp. nov. (CFCC = 55738, Taxon 2). a, b thirty-day-old cultures on 2 % MEA c-f Hyalorhincladiella - like asexual morph: conidiogenous cells and conidia. Scale bars: 10 μm (c-f).