Ascomycetes and their anamorphs occur on submerged wood in freshwater and serve to breakdown and recycle the components of wood (Vijaykrishna and Hyde, 2006; Vijaykrishna et al., 2006). In addition, several species of freshwater fungi have been found to produce a variety of enzymes (Yuen et al., 1999; Bucher et al., 2004; Simonis et al., 2008) and have anti-fungal activities (Ho et al., 2003). A number of studies on the diversity of freshwater fungi were conducted in temperate regions (Hyde and Goh, 1999; Raja and Shearer, 2006; Shearer et al., 2007), but recently there have been more studies in tropical and subtropical regions (Ho et al., 2001; Cai et al., 2003; Vijaykrishna and Hyde, 2006), including peat swamps (Pinnoi et al., 2006; Pinruan et al., 2007). In China, freshwater fungi have received less attention as compared to endophytic fungi and saprobic fungi in terrestrial environment (Liu et al., 2006; Wei and Dai, 2006; Cai and Hyde, 2007; Hu et al., 2007; Wei et al., 2007). In 2004, 121 species of freshwater ascomycetes and anamorphic fungi were reported in China (Luo et al., 2004a). Recent studies on freshwater fungi in Yunnan Province revealed numerous novel taxa and records for China (Cai et al., 2002; Luo et al., 2004b; Cai et al., 2006). However, freshwater fungi in this large geographical region are still undersampled.

With the need to establish freshwater fungi diversity and distribution data in China, we have conducted a survey of freshwater fungi on submerged woody material in Zhejiang Province. During our collection, two interesting freshwater hyphomycetes were found. Sporidesmiopsis zhejiangensis is proposed as a new species. In addition, the rare fungus Spadicoides americana Wang was recorded from China for the first time. Both taxa are, therefore, described and illustrated in this article.

Samples were processed and examined following the methods described by Jiang et al.(2008). The specimens are deposited in Herbarium Mycologicum of Zhejiang University (HMZ), China. All microscopic measurements were conducted at their widest point from materials mounted in water. The range between minimum and maximum values for measurements is given.

Colonies effuse, dark brown to black, hairy. Mycelium partly immersed and partly superficial, composed of branched, septate, verruculose, 1.5~4 µm wide, brown hyphae. Conidiophores mononematous, differentiated, erect, straight or flexuous, dark brown to black, verruculose, thick-walled, up to 460 µm tall, up to 30 µm wide at the swollen base, 6~8 µm wide at the apex, up to 15-septate; branched below septa in the upper half, without or rarely percurrent proliferations, thick-walled, 1-septate, verruculose, dark brown, (17~25) µm×(6~8) µm. Conidiogenous cells integrated, apical on main stipe and branching, narrowly doliiform, truncate at the apex after conidium secession, (10.5~16) µm×(6.5~8) µm. Conidia solitary, obclavate to fusiform, slightly curved, base truncate, apex rounded with a globose mucilaginous sheath, 5-6(7)-distoseptate, with dark brown central cells and paler polar cells, verruculose, (46~65) µm×(10.5~18) µm (average 57 µm×15 µm, n=30), 2~3 µm wide at base, 3~4 µm wide at apex.

Holotype: Submerged wood, Songyang County, Lishui City, Zhejiang Province, China; Oct. 24, 2007, No. HMZFW 00001.

Mycobank No.: MB 512233.

Teleomorph: Unknown.

Etymology: zhejiangensis, in reference to the province where the type was found.

Habitat: Saprobic on wood submerged in stream.

Distribution: China.

The genus Sporidesmiopsis Subram. and Bhat was established by Subramanian and Bhat (1987) and S. malabarica Subram. and Bhat is the type species. The genus is segregated from Sporidesmium Link ex Fries by the characteristics of the conidiophores which are mononematous with apical branches, and conidiogenous cells occur on both the stipe and branches. Bhat and Kendrick (1993) later published the second species, S. goanensis Bhat & Kendrick, and combined S. malabarica with Brachysporiella dennisii Crane and Dumont (Crane and Dumont, 1978; Mercado-Sierra, 1984) as S. dennisii (Crane and Dumont) Bhat, Kendrick and Nag Raj.

Sporidesmiopsis zhejiangensis accords well with the generic concept of Sporidesmiopsis in having macronematous conidiophores with branches at the apex and conidiogenous cells arising on both stipe and branches. This species most resembles S. goanensis in having distoseptate and similar shaped conidia. The conidia of S. goanensis, however, differ in the absent of apical mucilaginous sheaths, and have smooth walls and all cells have similar coloration. Moreover, S. zhejiangensis is distinguished in having rough-walled hyphae and conidiophores; the conidia have more septa (5~6 vs 3~5) and are larger [(46~65) µm×(10.5~18) µm vs (20~40) µm×(5~10) µm] (Bhat and Kendrick, 1993; Wu and Zhuang, 2005).

Fig. 1 Light micrographs of Sporidesmiopsis zhejiangensis

Material examined: Submerged Wood, Stream at Nine Creeks, Hangzhou City, Zhejiang Province, China; Apr. 20, 2008, No. HMZFW 00002.

Teleomorph: Unknown.

Habitat: Lignicolous, saprobic on wood and submerged wood.

Distribution: USA, Hungary and China.

The genus Spadicoides S. Hughes with the type species S. bina (Corda) S. Hughes is characterized by polytretic, terminal or intercalary conidiogenous cells with several conidiogenous pores (Hughes, 1958). It has similar conidial ontogeny to the related genus Diplococcium Grove. However, Spadicoides produces solitary conidia on unbranched or branched conidiophores, whereas Diplococcium conidia are formed in short or long chains (Sinclair et al., 1985).

Morphological characteristics of the present fungus agree well with the description of S. americana (Wang, 1976; Holubova-Jechova, 1982; Goh and Hyde, 1996). Spadicoides americana has been previously reported from the North America (USA) (Wang, 1976) and Europe (Hungary) (Holubova-Jechova, 1982). This rare species has not been found in China (Teng, 1996; Zhuang, 2001; 2005) and our discovery has increased its distribution to include Asia.

Fig. 2 Light micrographs of Spadicoides americana

Two lignicolous hyphomycetes were described in the present survey of freshwater fungi on submerged woody material in Zhejiang Province, China. Among them, Sporidesmiopsis zhejiangensis is new to science and Spadicoides americana is the new record to China.