Elongaticollum hedychii Tennakoon, C.H. Kuo & K.D. Hyde, 2020

Tennakoon, Danushka S., Thambugala, Kasun M., Wanasinghe, Dhanushka N., Gentekaki, Eleni, Promputtha, Itthayakorn, Kuo, Chang-Hsin & Hyde, Kevin D., 2020, Additions to Phaeosphaeriaceae (Pleosporales): Elongaticollum gen. nov., Ophiosphaerella taiwanensis sp. nov., Phaeosphaeriopsis beaucarneae sp. nov. and a new host record of Neosetophoma poaceicola from Musaceae, MycoKeys 70, pp. 59-88 : 59

Elongaticollum hedychii Tennakoon, C.H. Kuo & K.D. Hyde sp. nov. Figure 2

Etymology.

Name reflects the host Hedychium coronarium J. Koenig, from which the holotype was collected.

Holotype.

MFLU 18-2542.

Diagnosis.

Saprobic on dead leaves of Hedychium coronarium J. Koenig. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Conidiomata 120-140 µm high, 60-70 µm diam., pycnidial, solitary, scattered, superficial, visible as small black spots on host surface, dark brown to black, obpyriform, papillate. Neck up to 80-100 μm long, 20-30 µm diam., elongated, dark brown, usually straight, but sometimes slightly curved. Conidiomatal wall 10-20 µm wide, composed of 4-5 layers of light brown, thick-walled cells, arranged in textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 3-4 × 3-3.5 μm (x̄ = 3.6 × 3.2 μm, n = 10), arising from the inner cell wall of the apex, hyaline, aseptate, smooth, ampulliform. Conidia 4-5 × 1.8-2.2 μm (x̄ = 4.6 × 2.1 μm, n = 30), oval to oblong, smooth, thin-walled, hyaline, aseptate, with 1-2-minute guttules.

Culture characteristics.

Colonies on PDA reaching 30 mm diameter after 3 weeks at 20-25 °C, colonies medium sparse, circular, raised, surface slightly rough with entire edge, margin entire, colony from above: light brown to grey at the margin, dark brown at middle, dark brown to black at the center; reverse, light brown to yellowish at the margin, brown at middle, dark brown to black at the center; mycelium light brown to grey with tufts; not producing pigments in PDA.

Material examined.

Taiwan, Chiayi, Fanlu Township area, Dahu Forest, dead leaves of Hedychium coronarium J. Koenig ( Zingiberaceae ), 15 August 2018 (23°27.514'N, 120°36.302'E), D.S. Tennakoon, TLF031-A (MFLU 18-2542, holotype), ex-type living culture (MFLUCC 18-1638 = NCYUCC 19-0163); ibid. 20 August 2018 (23°27.530'N, 120°36.314'E), TLF031-B (NCYU19-0139, paratype), living culture (NCYUCC19-0286); ibid. 25 August 2018 (23°27.512'N, 120°36.301'E), TLF031-C (NCYU19-0140, paratype), living culture (NCYUCC 19-0287).

Notes.

The genus Elongaticollum differs from other asexual morphs in Phaeosphaeriaceae in dark brown to black, superficial, obpyriform, pycnidial conidiomata with distinct elongate necks (80-100 μm) and a globose base and oval to oblong, hyaline, aseptate conidia (Figure 2 ). Multi-gene phylogenetic analyses (LSU, SSU, ITS, tef1 -α), show Elongaticollum strains constitute a highly supported independent lineage nested between Setophoma sensu lato and Neostagonosporella (97% ML, 80% MP, 1.00 BYPP, Figure 1 ). However, the asexual morph of Setophoma can be distinguished from Elongaticollum in having setose conidiomata without elongate necks and oblong to ellipsoidal conidia, whereas, Elongaticollum have conidiomata with distinct elongate necks and lacking setae and oval to oblong conidia ( De Gruyter et al. 2010; Phookamsak et al. 2014). Despite some Setophoma species not having setae (i.e. S. antiqua , S. endophytica , and S. yunnanensis ) ( Liu et al. 2019), Elongaticollum species can be distinguished by its superficial conidiomata with elongate necks.

The asexual morph of Neostagonosporella differs from Elongaticollum in having multiloculate conidiomata without distinct elongate necks and two types of conidia (macroconidia: subcylindrical to cylindrical, transversely multi-septate, hyaline and microconidia oval, ellipsoidal or long ellipsoidal, aseptate, hyaline), whereas Elongaticollum has uni-loculate conidiomata with distinct elongate necks and oval to oblong conidia (Figure 2 , Yang et al. 2019).

Phylogenetic investigations herein provide insights into the taxonomy of Setophoma as well (Figure 1 ). Two major clades of Setophoma are recovered ( Setophoma sensu stricto and Setophoma sensu lato. The Setophoma sensu stricto clade includes S. brachypodii , S. poaceicola and S. terrestris (type species). Setophoma sensu lato comprises S. antiqua , S. chromolaenae , S. endophytica , S. pseudosacchari , S. sacchari , S. vernoniae , S. yingyisheniae and S. yunnanensis (Figure 1 ). Elongaticollum , differs from Setophoma sensu lato in having distinct superficial, obpyriform, pycnidial conidiomata with a globose base and distinct elongated necks (Figure 2 , Liu et al. 2019). Further work is needed to resolve relationships between Setophoma sensu stricto and Setophoma sensu lato.

Figures

Figure 1. RAxML tree inferred from combined dataset of ITS, LSU, SSU and tef 1 - α partial sequences of 168 strains of Phaeosphaeriaceae. Bootstrap support values for maximum likelihood (ML), maximum parsimony (MP) values ≥ 70 %, and Bayesian posterior probabilities (BYPP) ≥ 0.95 are given above each branch respectively. The new species are highlighted in red, and the new record in green. Ex-type strains are in bold. The tree is rooted by Leptosphaeria doliolum (CBS 505.75) and Paraleptosphaeria dryadis (CBS 643.86).

Figure 2. Elongaticollum hedychii (MFLU 18 - 2542, holotype) a specimen b appearance of conidiomata on host c close up of conidiomata on host d vertical section through conidioma e, f squash mount of conidioma g conidioma wall h, i elongated conidiomatal necks j conidiogenous cells k conidia l, m germinated conidia n colony from below o colony from above p, q pycnidia formed on PDA. Scale bars: 100 µm (c), 50 µm (d-h), 10 µm (g), 30 µm (i), 3 µm (j-m), 100 µm (p, q).