Phyllosticta pterospermi Z.X. Zhang, X.Y. Liu, Z. Meng & X.G. Zhang, Z. X. Zhang, X. Y. Liu, Z. Meng & X. G. Zhang, 2022

Zhang, Zhaoxue, Liu, Xiaoyong, Zhang, Xiuguo & Meng, Zhe, 2022, Morphological and phylogenetic analyses reveal two new species and a new record of Phyllosticta (Botryosphaeriales, Phyllostictaceae) from Hainan, China, MycoKeys 91, pp. 1-23 : 1

Phyllosticta pterospermi Z.X. Zhang, X.Y. Liu, Z. Meng & X.G. Zhang sp. nov.

Fig. 3

Type.

China, Hainan Province: Bawangling National Forest Park, on diseased leaves of Pterospermum heterophyllum , 19 May 2021, Z.X. Zhang (holotype, HSAUP210104; ex-holotype living culture SAUCC210104) .

Etymology.

The specific epithet " pterospermi " refers to the genus name of the host plant Pterospermum heterophyllum .

Description.

Leaf endogenic and associated with leaf spots. Asexual morph: Conidiomata pycnidial, mostly aggregated in clusters, black, erumpent. On MEA, pycnidia exudes yellow conidial masses, within 15 days or longer. Pycnidial walls multilayered, textura angularis, brown, up to 30 μm thick; inner walls of hyaline. Conidiophores indistinct, often reduced to conidiogenous cells. Conidiogenous cells, cylindrical, hyaline, smooth, 7.5-11.0 × 2.5-4.5 μm. Conidia 8.0-12.0 × 4.5-8.5 μm, mean ± SD = 9.8 ± 0.9 × 7.3 ± 0.7 μm, hyaline, aseptate, thin and smooth-walled, coarsely guttulate or with a single large central guttule, obovoid, ellipsoidal to subglobose, enclosed in a thin mucoid sheath, 1.0-2.0 μm thick and bearing a hyaline, apical mucoid appendage, 4.0-6.8 × 1.5-3.0 μm, flexible, unbranched, tapering towards an acutely rounded tip.

Culture characteristics.

Colonies on PDA 80-90 mm in diameter after 14 days at 25 °C in darkness, with a growth rate of 5.7-6.5 mm/day, undulate at edge, grey white to greyish-green in obverse and reverse. Colonies on MEA 82-86 mm in diameter after 14 days at 25 °C in darkness, with a growth rate of 5.8-6.2 mm/day, undulate at edge, grey white to yellow in obverse and reverse, with moderate aerial mycelia on the surface, with black, gregarious conidiomata.

Additional specimen examined.

China, Hainan Province: Bawangling National Forest Park, on diseased leaves of Pterospermum heterophyllum . 19 May 2021, Z.X. Zhang, paratype HSAUP210106, ex-paratype living culture SAUCC210106.

Notes.

Two isolates from leaf spots of Pterospermum heterophyllum phylogenetically clustered into a well-supported clade (1.00/100), which is closely related to P. ardisiicola (0.90/62) and P. mangiferae (0.99/91; Fig. 1 ). However, P. pterospermi differs from P. ardisiicola by 30 nucleotides (13/603 in ITS, 3/553 in LSU and 14/248 ACT) and from P. mangiferae by 29 nucleotides (7/567 in ITS, 2/763 in LSU, 3/215 in tef1, 3/226 in ACT and 14/643 in GPDH). In morphology, they are distinguished by hosts and conidial size (8.0-12.0 × 4.5-8.5 μm in P. pterospermi vs. 7.0-11.0 × 5.0-7.5 μm in P. ardisiicola vs. 10.0-12.0 × 6.0-7.0 μm in P. mangiferae ). Furthermore, P. pterospermi differs from P. ardisiicola and P. mangiferae by wider conidiogenous cells (7.5-11.0 × 2.5-4.5 μm vs. 5.0-12.5 × 1.2-2.5 μm) and from P. mangiferae in having longer conidiogenous cells (7.5-11.0 × 2.5-4.5 μm vs. 6.0-10.0 × 3.0-4.0 μm) ( Motohashi et al. 2008; Glienke et al. 2011). Therefore, we establish this strain as P. pterospermi sp. nov. ( Jeewon and Hyde 2016).

Figures

Figure 1. Phylogram of the Phyllosticta capitalensis species complex, based on a concatenated ITS, LSU, tef 1, ACT and GPDH sequence alignment, with Phyllosticta hubeiensis (CGMCC 3.14986, CGMCC 3.14987) of the P. cruenta species complex serving as outgroup. Bayesian Inference posterior probabilities and Maximum Likelihood bootstrap support values above 0.70 and 70 % are shown at the first and second position, respectively. Ex-type cultures are indicated in bold face. Strains obtained in the current study are in red. Some branches are shortened for layout purposes - these are indicated by two diagonal lines with the number of times. The bar at the left-bottom represents substitutions per site.

Figure 3. Phyllosticta pterospermi (holotype SAUCC 210104) a diseased leaf of Pterospermum heterophyllum b, c colonies (left-above, right-reverse) after 15 days on PDA (b) and MEA (c) d conidiomata e-h conidiogenous cells with conidia i-j conidia. Scale bars: 10 μm (e-j).