Neohelicomyces hydei J. Ma, Y. Z. Lu & K. D. Hyde, 2024

Ma, Jian, Gomdola, Deecksha, Boonmee, Saranyaphat, Shen, Hong-Wei, Tang, Xia, Zhang, Li-Juan, Lu, Yong-Zhong & Hyde, Kevin D., 2024, Three new species of Neohelicomyces (Tubeufiales, Tubeufiaceae) from freshwater and terrestrial habitats in China, MycoKeys 105, pp. 317-336 : 317-336

Neohelicomyces hydei J. Ma, Y. Z. Lu & K. D. Hyde sp. nov.

Fig. 4

Etymology.

The epithet “ hydei ” is named in honour of Prof. Kevin D. Hyde for his contributions to mycology.

Holotype.

HKAS 134925 .

Description.

Saprobic on decaying wood in a freshwater habitat. Sexual morph Unknown from natural habitat. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, effuse, gregarious, white to pale brown. Mycelium semi-immersed, hyaline to pale brown, septate, branched hyphae, smooth, comprising glistening conidial mass. Conidiophores 262–410 μm long, 5.5–7 μm wide (x ¯ = 335 × 6 μm, n = 30), macronematous, mononematous, erect, flexuous, cylindrical, branched, up to 20 – septate, hyaline to pale brown, smooth, thick-walled. Conidiogenous cells 7.5–19.5 μm long, 3.5–6 μm wide (x ¯ = 16.5 × 4 μm, n = 35), holoblastic, monoblastic to polyblastic, integrated, intercalary or terminal, cylindrical, with a denticulate protrusion, truncate at apex after conidial secession, hyaline to pale brown, smooth-walled. Conidia solitary, acropleurogenous, helicoid, rounded at tip, up to 18.5 μm in diameter and conidial filaments 2–3 μm wide, 137.5–171.5 μm long (x ¯ = 158 μm, n = 25), indistinctly multiseptate, coiled up to 4 times, becoming loosely coiled in water, guttulate, hyaline, smooth-walled.

Culture characteristics.

Conidia producing germ tubes on PDA within 12 hours of incubation at 25 ° C. Colonies on PDA are circular with umbonate surface and entire edge, reaching 42 mm in diameter after 50 days of incubation at 25 ° C, top view of colony brown to black brown, reverse pale brown to black brown.

Material examined.

China, Guizhou Province, Qianxinan Buyi and Miao Autonomous Prefecture, Xianheping National Forest Park, 24 ° 97 ′ N, 105 ° 63 ′ E, on decaying wood in a freshwater habitat, 16 March 2022, Jian Ma, XHP 1 ( HKAS 134925 , holotype; GZAAS 23–0621 , isotype), ex-type living cultures GZCC 23–0727 ; Ibid., XHP 1.1 ( GZAAS 23–0622 , paratype), living culture GZCC 23–0728 .

Notes.

Our isolates, GZCC 23–0727 and GZCC 23–0728 cluster together and form a sister clade to N. aquaticus ( MFLUCC 16–0993 and KUMCC 15–0463 ) with 96 % ML / 0.95 PP support. Upon comparison of the nucleotide bases between our isolates and Neohelicomyces aquaticus ( MFLUCC 16–0993 ), the following differences were observed: 1 / 851 bp (0.1 %, including 1 gap) across LSU, 13 / 869 bp (1.5 %, including 1 gap) across tef 1 α and 46 / 945 bp (4.9 %, with no gaps) across rpb 2. Unfortunately, we were unable to compare the differences in nucleotide bases across ITS as our isolates ( GZCC 23–0727 and GZCC 23–0728 ) lack ITS sequence data. Despite several trials using different PCR conditions, we were unable to amplify the ITS locus for our strain ( GZCC 23–0727 and GZCC 23–0728 ) successfully. Morphologically, our isolates ( GZAAS 23–0621 and GZAAS 23–0622 ) differ from N. aquaticus ( MFLU 16–2543 ) as they have mostly branched and hyaline conidiophores, polyblastic, terminal and hyaline conidiogenous cells and acropleurogenous conidia ( Luo et al. 2017). Based on phylogenetic placement and morphology, we identify GZCC 23–0727 and GZCC 23–0728 as a single species, Neohelicomyces hydei .

Figures

Figure 4. Neohelicomyces hydei (HKAS 134925, holotype) a, b colonies on the host surface c – e conidiophores and conidiogenous cells f – h conidiogenous cells i – m conidia n germinated conidium o, p surface and reverse colonies on PDA after 50 days of incubation at 25 ° C. Scale bars: 50 μm (c – e); 10 μm (f – n).