Helminthosporium nabanhensis Jing W. Liu & Jian Ma, 2022

Liu, Jingwen, Hu, Yafen, Luo, Xingxing, Castaneda-Ruiz, Rafael F. & Ma, Jian, 2022, Three novel species of Helminthosporium (Massarinaceae, Pleosporales) from China, MycoKeys 94, pp. 73-89 : 73

Helminthosporium nabanhensis Jing W. Liu & Jian Ma sp. nov.

Fig. 2

Etymology.

Referring to the collecting site of Nabanhe Nature Reserve in Yunnan Province, China.

Holotypus.

HJAUP M2054.

Description.

Saprobic on dead branches. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies on natural substrate effuse, scattered, hairy, brown to black. Mycelium partly superficial, partly immersed in the substratum, composed of branched, septate, pale brown to brown, smooth hyphae. Conidiophores macronematous, mononematous, solitary or in groups of 2-4, simple, occasionally branched, erect, straight or flexuous, cylindrical, smooth, 8-21-septate, brown to dark brown, paler towards the apex, with well-defined small pores at the apex and rarely laterally beneath the upper 1-3 septa, 365-557 × 6.5-13.5 μm. Conidiogenous cells polytretic, integrated, terminal and intercalary, cylindrical, brown, smooth, with noncicatrized, distinct pores. Conidial secession schizolytic. Conidia acropleurogenous, solitary, dry, obclavate, pale brown to brown, 3-6-distoseptate, smooth, straight or curved, wider below than apex, truncate and dark at base, apically rostrate and pale, guttulate when young, non-guttulate at maturity, 26.5-46.5 μm long, 6.5-10 μm wide, tapering to 3-3.5 μm wide near the apex, 3-6 μm wide at the basal scar.

Cultural characteristics.

Colony on PDA reaching 50-55 mm diam. after 2 weeks in an incubator under dark conditions at 25 °C, irregular circular, surface velvety, with white and denser mycelium at the center, becoming olivaceous and sparser towards the edge; reverse pale brown at the center, dark brown at the periphery.

Material examined.

China, Yunnan Province: Xishuangbanna Dai Autonomous Prefecture, Nabanhe National Nature Reserve , on dead branches of an unidentified broadleaf tree, 12 July 2021, J.W. Liu, HJAUP M2054 (Holotype), ex-type living culture HJAUP C2054 .

Notes.

The phylogenetic tree shows that the strain of H. nabanhensis (HJAUP C2054) clusters with the ex-type strain of H. chlorophorae (BRIP 14521). The BLASTn analysis of ITS of our ex-type strain HJAUP C2054 showed 90% identity (425/471 bp, 10/471 gaps) with ex-type strain BRIP 14521 of H. chlorophorae . Moreover, H. nabanhensis morphologically differs from H. chlorophorae in bigger conidiophores (365-557 × 6.5-13.5 μm vs. 120-270 × 7-10 μm) occasionally branched, and smaller conidia (26.5-46.5 × 6.5-10 μm vs. 52-102 × 8-11 μm) with fewer septa (3-6 vs. 6-9), and from H. sichuanense ( Zhang et al. 2004) in narrower conidiophores (6.5-13.5 μm vs. 14-25 μm) and smaller conidia (26.5-46.5 × 6.5-10 μm vs. 41-86 × 10-14 μm) with fewer septa (3-6 vs. 5-11).

Figures

Figure 2. Helminthosporium nabanhensis (HJAUPM 2054, holotype) A, B culture on PDA from above and reverse C conidia D conidiophores with conidia E-G conidiophores with conidiogenous cells.