Hermatomycetaceae » Hermatomycetaceae » Hermatomyces

Hermatomyces sphaericus

Hermatomyces sphaericus (Sacc.) S. Hughes, Mycol. Pap. 50: 100 (1953).


Basionym: Stemphylium sphaericum Sacc., Atti Accad. Sci. Ven.-Trent.-Istr. 10: 86 (1917).


Synonyms: Hermatomyces chromolaenae Jin F. Li et al., Index Fungorum 342: 1 (2017).


Hermatomyces saikhuensis Tibpromma et al., Phytotaxa 275: 134 (2016).


Hermatomyces tectonae Doilom et al., Fungal Div. 82: 117 (2016).



Description: Colonies on the natural substrate in the form of sporodochial, subiculate conidiomata, superficial, more or less circular, oval or lobed, scattered or crowded and confluent, brown-black or gray-black, consisting of a velvety, dense, thick, annular, brown or gray, sterile mycelial outer zone enclosing a black, glistening, abundantly sporulating granulose centre, circular, oval or lobed by confluence where conidia are easily liberated when touched, 300–800 μm diam when solitary, up to 1600 μm long when confluent. Mycelium superficial, composed of a tightly compact network of repent, branched, septate, smooth or finely verruculose, locally thick-walled, brown hyphae, 2–4 μm wide, subicular hyphae flexuous, undulate, strongly or irregularly geniculate, subhyaline or pale brown to brown, branched, smooth, finely verruculose or locally verrucose, branching and anastomosing to form a dense network. Conidiophores micronematous, mononematous, cylindrical or forked once, subhyaline or pale brown, up to 15 long and 2–4 μm wide, often corresponding to conidiogenous cells. Conidiogenous cells monoblastic, integrated, terminal, cylindrical, determinate, subhyaline to pale brown, smooth or finely verruculose, often arising directly on the superficial mycelium and closely packed together at the fertile centre, sphaerical, subsphaerical or ampulliform, 4–10 × 3–4 μm. Conidia of one type, solitary, dry, lenticular, globose, subglobose, disc-shaped or broadly ellipsoidal in front view, muriform, smooth or verruculose, central cells brown, dark brown to blackish brown, sometimes all cells brown and muriform septation visible, outer ring of peripheral cells narrow or wide, pale brown to brown, often constricted at septa, broadly ellipsoidal or oblong in side view where two distinct adpressed halves can be recognized, each half seen laterally as a row of 4–7 cells, end cells subhyaline to pale brown, middle cells brown to blackish brown, with a narrow, sometimes deep constriction between them, (21–)24–29(–32.5) × (18–)21–27(–31.5) μm, 16–23.5(–28) μm thick, L/W = 1.08, L/T = 1.22.


Cultures: Colonies moderately slow growing reaching on MEA 13–17 mm diam, on PCA12–16 mm, and on PDA 12–16 mm after 7 d at 25 °C. Sporulation on PDA late within 4 m at 25 °C and observed only in one (CCF 5911) of 12 strains. Lenticular conidia (24.5–)26.5–30(–31.5) × 22.5–29 μm and (18.5–)21–25.5 μm thick.


Notes: Hermatomyces sphaericus was the first species with one conidium type transferred into the genus (Hughes 1953). Our numerous collections match well with the type collection (K(M)–IMI 37763) and Hughes’ description based on his specimens from bark of Albizia gummifera (Mimosaceae), Averrhoa carambola (Oxalidaceae), Theobroma cacao (Sterculidaceae), and rachides of leaves of Elais guineensis (Arecaceae) collected in Ghana. He described the lenticular conidia as 26–31 × 25–30 μm and 20–25 μm thick. Other specimens described in the literature are reported as having similar or slightly smaller conidia. Holubová-Jechová & Mercado (1986) reported conidia as 24–28.8 × 24–27 μm and 16.6–21 μm thick for a specimen collected on a dead branch from Cuba (PRM 838101) and revised in this study, while Heredia et al. (1997) described conidia as 24–29 × 24–30 μm and 15–21 μm thick for specimens collected on fallen twigs and branches of angiosperms and on a palm petiole in Mexico. Zhang et al. (2009) provided conidial dimensions of 23–29 × 22–26 μm for specimens collected on a dead branch of Rauvolfia vomitoria (Apocynaceae) and dead wood of Tectona grandis (Lamiaceae) in China. Mel’nik (2000) reported conidia 26–31 × 25–30 μm and 25–30 μm thick for a specimen collected on dry thin branches of Larix sibirica (Pinaceae) in Russia, which is, however, questionable, because it represents the only record outside the tropics.