Hermatomyces sphaericus (Sacc.) S. Hughes 1953.

Ren, Guang-Cong, Wanasinghe, Dhanushka N., Monkai, Jutamart, Mortimer, Peter E., Hyde, Kevin D., Xu, Jian-Chu, Pang, Aimin & Gui, Heng, 2021, Novel saprobic Hermatomyces species (Hermatomycetaceae, Pleosporales) from China (Yunnan Province) and Thailand, MycoKeys 82, pp. 57-79 : 57

Hermatomyces sphaericus (Sacc.) S. Hughes 1953.

Figure 4

Description.

Saprobic on woody litter of Dipterocarpus sp. ( Dipterocarpaceae ) and Ehretia acuminata ( Boraginaceae ). Sexual morph Undetermined. Asexual morph Colonies on natural substrate forming sporodochial conidiomata, superficial, circular or irregular, scattered or crowded, consisting of a velvety, dense, annular, gray brown, sterile mycelial outer zone and a black, glistening, abundantly sporulating granulose center, with conidia readily liberated when agitated. Mycelium 2-2.5 μm wide, superficial, composed of a tightly network of branched, septate, smooth or finely verruculose, hyaline or pale brown hyphae. Conidiophores 10-13 × 2-4 μm (x = 12 × 3 μm, n = 10) micronematous, cylindrical or forked, smooth, hyaline or pale brown, often corresponding to conidiogenous cells. Conidiogenous cells 5-8 × 3-5 μm (x = 7 × 4 μm, n = 20), monoblastic, integrated, terminal, cylindrical, hyaline to pale brown, smooth or finely verruculose. Conidia of one type, 27-29 × 26-28 μm (x = 28 × 27 μm, n = 30) μm, 19-24 μm thick, solitary, lenticular, globose, subglobose in front view, muriform, smooth, central cells brown, dark brown, outer ring of peripheral cells narrow, pale brown to brown, often constricted at septa, disk-shaped in lateral view, consisting of two rows, each row with 4-6 cells, hyaline to light brown at lower and upper cells, middle cells brown to black brown.

Known host and distribution.

Tropical and subtropical regions of Central and South America, Africa, Asia, Oceania and North America. The species were found as saprobes on Acanthaceae , Apocynaceae , Arecaceae , Asteraceae , Dipterocarpaceae , Euphorbiaceae , Fabaceae , Lamiaceae , Leguminosae , Mimosaceae , Nyctaginaceae , Oxalidaceae , Pandanaceae , Pinaceae , Rhamnaceae , and Sterculiaceae ( Zhang et al 2009; Koukol et al. 2018, 2019).

Culture characteristics.

Colonies on PDA, reaching 35-40 mm diam., after 3 weeks at 25-30 °C, with circular, umbonate, fluffy, velvety, entire edge, a circular raised band, gray white, in reverse dark gray, black toward the center.

Material examined.

Thailand, Tak Province, Tha Song Yang District , on woody litter of Dipterocarpus sp. ( Dipterocarpaceae ), 22 August 2019, G. C. Ren, T903 (HKAS 112725), living culture, MFLUCC 21-0036 ; China, Yunnan Province, Xishuangbanna (21°55.19'N, 101°15.24'E), on woody litter of Ehretia acuminata ( Boraginaceae ), 4 August 2020, G. C. Ren, JH39 (HKAS 112166), living culture, KUMCC 20-0231 .

Notes.

The characters of our new strain of Hermatomyces sphaericus (KUMCC 20-0231, MFLUCC 21-0036) are similar to the type collection (K(M)-IMI 37763) in having gray black to black sporodochia, mononematous, pale brown, smooth, monoblastic, integrated, terminal, cylindrical, hyaline to pale brown conidiogenous cells and globose to subglobose conidia ( Hughes 1953). A multigene phylogeny indicates that novel strains clustered within the H. sphaericus clade (Fig. 1 ). We name our strain (KUMCC 20-0231, MFLUCC 21-0036) as H. sphaericus , which has been reported from different plant families and genera ( Koukol et al. 2018). However, we consider this might be a species complex that need further detailed studies. Our study provides the new host records of H. sphaericus on Dipterocarpus sp. ( Dipterocarpaceae ) and Ehretia acuminata ( Boraginaceae ), and updates sequence data for the new collections of H. sphaericus .

Figures

Figure 1. Phylogenetic RAxML tree based on analysis of a combined LSU, ITS, tub 2, tef 1 - α and rpb 2 and dataset. Bootstrap support values for ML and MP equal to or higher than 75 % and Bayesian PP equal to or greater than 0.95 are shown at nodes. Hyphens (--) represent support values less than 75 % / 0.95 BYPP. The ex-type strains are in bold and the new isolate in this study is in blue bold. The tree is rooted with Anteaglonium globosum (ANM 925.2) and A. parvulum (MFLUCC 14 - 0821). The scale bar represents the expected number of nucleotide substitutions per site.

Figure 4. Hermatomyces sphaericus (HKAS 112725) a, b colonies on the natural substrate c mycelia d-g young conidia h-k mature conidia (h-j surface view k thickness view) l germinated conidium m, n culture characters on PDA. Scale bars: 1000 μm (a); 200 μm (b); 20 μm (c-i, l); 30 μm (j, k); 3 cm (m, n).