BLAST analyses with LSU sequences revealed that Microthyrium is the closest related taxon to our isolates but with relatively low percentage of identities. The combined analysis of the two loci (ITS and LSU), which was analyzed by BI and ML approaches, confirmed the status of our isolates in the family Microthyriaceae. In this tree, YMF 1.04626 and YMF 1.04517 grouped into the Microthyriaceae with good support. YMF 1.04626 was clustered together with the sexual genus Microthyrium with good support (MLBP/BIPP = 92%/1.0), and the clade was close to the asexual genus Neoanungitea Crous. YMF 1.04517 formed an isolated clade, which close to Hamatispora L.T.H. Yen, K. Yamag. & K. Ando, Neoanungitea, Microthyrium, and YMF 1.04517 with well support (MLBP/BIPP = 80%/0.98). Combined with morphological differences, we described YMF 1.04626 and YMF 1.04517 as two new asexual genera and species in Microthyriaceae, named as Keqinzhangia aquatica and Pseudocoronospora hainanense.
Keqinzhangia Z. F. Yu, M. Qiao & R. F. Castañeda, gen. nov.
Etymology: Name in honors to Prof. Keqing Zhang of the Yunnan University for his contribution to the biological sciences.
MycoBank number: MB 840430
Asexual morph hyphomycetous. Vegetative hyphae cylindrical, branched, microguttulate, septate, hyaline, smooth-walled. Fertile hyphae cylindrical-obclavate, extended inflated subulate to the tip grow, macroguttulate, dark septate, hyaline, smooth-walled. Conidiophores prostrate, not differentiated. Conidiogenous cells holothallic, narrow cylindrical to cylindrical, discrete, indeterminate, forming conidia by random thallic-arthric conidial ontogeny. Conidial secession schizolytic. Conidia thallic-arthric, solitary, polymorphic, cylindrical, cylindrical-obclavate, obclavate, bacilliform, fusiform, sub-oblecythiform or cuneiform, unicellular to septate, hyaline. Chlamydospores globose, terminal, solitary or short catenulate, subhyaline. Sexual state: Unknown.
Type species: Keqinzhangia aquatica Z.F. Yu, M. Qiao & R.F. Castañeda.
Keqinzhangia aquatica Z.F. Yu, M. Qiao & R. F. Castañeda, sp. nov. (Fig. 2–4).
Etymology: Epithet refers to it growing in water.
MycoBank number: MB 840432
Asexual morph hyphomycetous. Colonies flat, growing slowly on CMA, attaining about 2.4 cm diam. after 20 days at 25°C. Pale mouse grey, reverse mouse grey. Mycelium mostly immersed, composed of cylindrical, branched, densely micro-guttulate, septate, subhyaline to hyaline vegetative hyphae and cylindrical-obclavate, extended inflated subulate to the tip grow, macroguttulate, dark septate, hyaline, smooth-walled fertile hyphae. Conidiophores prostrate, undifferentiated. Conidiogenous cells holothallic, narrowly cylindrical, frequently undifferentiated, hyaline, forming conidia by random thallic-arthric disarticulation. Conidia thallic-arthric, solitary, polymorphic, cylindrical-obclavate, long obclavate, cylindrical, bacilliform, fusiform, narrow doliiform, subdolabriform, suboblecythiform or cuneiform, truncate at the ends or truncate at the base and obtuse or rounded at the apex, 0–6(–7)-septate, slightly or strongly constricted at the dark septa, sinuate, macroguttulate, smooth, hyaline, 12–76.5 × 3–6.2 µm, arise after random disarticulation of fertile hyphae at the darker septa. Clamydospores solitary or catenate, broad globose, subglobose to ellipsoidal, terminal, slightly or densely guttulate, smooth, subhyaline, 8–12.6 × 4.1–5.4 µm. Sexual state: Unknown.
Holotype: YMF 1.04262, isolated from leaves of an unidentified dicotyledonous plant submerged in a stream, E’mei National Conservation Area, Sichuan Province, China, 29°35′1′′N, 103°17′3′′E, ca. 1750 m elev., Jun 2014, Zefen Yu, preserved in a metabolically inactive state (deep freezing) in the Conservation and Utilization of Bio‐Resources in Yunnan. Ex-type culture CCTCC AF 2021070.
Notes: In Keqinzhangia aquatica, the fertile hyphae are located at the margin of the colony arise laterally from vegetative hyphae forming aerial mycelium with narrow cylindrical, cylindrical, long cylindrical-obclavate, obclavate, inflated or globose, subulate cellular structures, that include the tip growth. The thallic-arthric conidia are formed by random fission at the darker septa of preexisting cells of the fertile hyphae in a similar holothallic mode described by Cole (1986) and Seifert et al. (2011).
Pseudocoronospora Z. F. Yu, M. Qiao & R. F. Castañeda, gen. nov.
Etymology: Name refers to it is similar to the genus coronospora in morphology.
MycoBank number: MB 840431
Asexual morph hyphomycetous. Conidiophores macronematous, mononematous, erect, septate, unbranched, brown. Conidiogenous cells polyblastic, denticulate, integrated, sympodial extended, terminal, indeterminate. Conidial secession rhexolytic. Conidia solitary, acropleurogenous obclavate, crowned, with mammiform protuberances arranged near the apex; septate, smooth or verruculose, hyaline, fringed at the base. Sexual state: Unknown.
Type species: Pseudocoronospora hainanense Z.F. Yu, M. Qiao & R.F. Castañeda.
Notes: The genus Coronospora was established by Ellis with C. dendrocalami M. B. Ellis as type species, in which after the conidiogenous events the cicatrized loci are produced following sympodial extensions of the polyblastic conidiogenous cells disposed in geniculate conidiophores and the conidia are liberated via schizolytic conidial secession (Seifert et al. 2011; Zhang and Zhang 2004; Ellis 1971), but in Pseudocoronospora hainanense the conidiogenous loci are tiny or conspicuous denticles and the conidial basal cells are fringed after the rhexolytic conidial secession. Matsushima (2001) observed the Coronospora in culture of Ascoronospora Matsush., so he thought that Coronospora is asexual state of Ascoronospora. Then Asthton et al. (2009) and Wijayawardene et al. (2018) accepted the link between two genera. So far, molecular sequences of two genera were not obtainable, so the connection between two genera was not confirmed by molecular data. However, Ascoronospora was treated as Pleosporales genera incertae sedis (Wijayawardene et al. 2018), which is morphologically different from members of Microthyriaceae.
Pseudocoronospora hainanense Z.F. Yu, M. Qiao & R. F. Castañeda, sp. nov. (Fig. 5,6)
Etymology: Epithet refers to the region Hainan where type strain isolated.
MycoBank number: MB 840433
Asexual morph hyphomycetous. Colonies on CMA attaining 3 cm diam. after 20 days at 25°C, effuse, white to pale flesh, reverse buff. Hyphae thin-walled, septate, hyaline, smooth. Conidiophores macronematous, mononematous, straight or slightly flexuous, somewhat geniculate toward the apex, septate, unbranched, mid brown or pale brown below, pale brown to subhyaline towards the apex, 16.5–49 µm long, 3.5–5.0 µm wide. Conidiogenous cells polyblastic, denticulate, denticle conspicuous, narrowly cylindrical, integrated, sympodial extended, terminal, sometimes intercalary, indeterminate, pale brown to subhyaline. Conidial secession rhexolytic. Conidia solitary, acropleurogenous, obclavate, crowned with 2–3 broadly mammiform protuberances, radially arranged near the rounded to obtuse apex; 2 septate, smooth or slightly verruculose at the basal and central cells, hyaline, 27.2–33 × 3.7–8.0 µm, with a minute basal frill. Sexual state: Unknown.
Holotype: YMF 1.04517, isolated from leaves of an unidentified dicotyledonous plant submerged in a stream, Diaoluoshan National Forest Park, Hainan Province, China, 18°42′11′′N, 109°53′16′′E, ca. 1124 m elev., Apr. 2014, Zefen Yu, preserved in a metabolically inactive state (deep freezing) in the Conservation and Utilization of Bio-Resources in Yunnan. Ex-type culture CGMCC 3.18823.