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Research Article
Chlorovibrissea korfii sp. nov. from northern hemisphere and Vibrissea flavovirens new to China
expand article infoHuan-Di Zheng, Wen-Ying Zhuang§
‡ Chinese Academy of Sciences, Beijing, China
§ University of Chinese Academy of Sciences, Beijing, China
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Abstract

A new species, Chlorovibrissea korfii, is described and illustrated, which is distinct from other members of the genus by the overall pale greenish apothecia 0.8–2.0 mm in diam. and 0.6–1.5 mm high, J+ asci 70–83 × 4.5–5.5 μm, and non-septate ascospores 44–52 × 1.2–1.5 μm. This is the first species of Chlorovibrissea reported from northern hemisphere. Vibrissea flavovirens is reported from China for the first time. Sequence analyses of the internal transcribed spacer of nuclear ribosomal DNA are used to confirm the affinity of the two taxa.

Key words

morphology, sequence analysis, taxonomy, Vibrisseaceae

Introduction

Vibrisseaceae was erected by Korf in 1990 to accommodate the genera Vibrissea Fr., Chlorovibrissea L.M. Kohn and Leucovibrissea (A. Sánchez) Korf. Members of the family are characterized by aquatic or semi-aquatic habitat, apothecia sessile to long stipitate, disc color range from whitish, yellowish, brownish, olivaceous to blackish green, ectal excipulum composed of textura globosa, textura angularis to textura prismatica, and filiform ascospores (Korf 1990). The three genera are distinguishable by the color of apothecia, structure of ectal excipulum and ascal apex apparatus (Korf 1990; Sandoval-Leiva et al. 2014). Besides the above three genera, Acephala Grünig & T.N. Sieber and Phialocephala W.B. Kendr. known only by asexual states, are also included in the family (Kirk et al. 2008; Johnston et al. 2014). Acephala was erected for the non-sporulating species of Phialocephala that contain a small group of dark septate root endophytes (Grünig and Sieber 2005; Grünig et al. 2008; Grünig et al. 2009; Münzenberger et al. 2009; Wang et al. 2009; Day et al. 2012). About 80 species are currently accepted in the family, among which two species are in Acephala, six in Chlorovibrissea, one in Leucovibrissea, 33 in Phialocephala, and 36 in Vibrissea (Grünig et al. 2008; Kirk et al. 2008; Grünig et al. 2009; Münzenberger et al. 2009; Wang et al. 2009; Day et al. 2012; Johnston et al. 2014; Sandoval-Leiva et al. 2014; Index Fungorum 2017). The previous phylogenetic studies on the vibrisseaceous fungi showed that Chlorovibrissea and Vibrissea are not closely related, and the family was presumably polyphyletic (Wang et al. 2006; Sandoval-Leiva et al. 2014).

In China, only two Vibrisseaceous fungi were recorded, i.e. V. cf. sporogyra (Ingold) A. Sánchez from Hainan Province (Zhuang et al. 2002) and V. truncorum (Alb. & Schwein.) Fr. from Guizhou Province (He 1988). During our studies of the helotialean fungi from China, two newly collected specimens fit the circumscription of Vibrisseaceae and represent two species. Based on morphology and molecular data, one is proposed as a new species of Chlorovibrissea, and the other is identified as V. flavovirens (Pers.) Korf & J.R. Dixon which is new to China.

Materials and methods

Specimens were collected from Beijing and Yunnan Province in 2016, and apothecial gross morphology when fresh was photographed by a Canon PowerShot G16 digital camera. Dried apothecia were rehydrated with distilled water and sectioned at a thickness of 15 μm with a Yidi YD-1508A freezing microtome (Jinhua, China). Measurements were taken from longitudinal sections and from squash mounts in lactophenol cotton blue solution using an Olympus BH-2 microscope (Tokyo, Japan). Iodine reactions of ascus apparatus were tested in Melzer’s reagent and Lugol’s solution with or without 3% KOH solution pretreatment according to Baral (2009). Images were captured using a Canon G5 digital camera (Tokyo, Japan) attached to a Zeiss Axioskop 2 Plus microscope (Göttingen, Germany) for anatomical structure. Voucher specimens were deposited in the Herbarium Mycologicum Academiae Sinicae (HMAS). Name of the new species was formally registered in the database Fungal Names, one of the three official nomenclatural repositories for fungal names (Redhead and Norvell 2012).

Genomic DNA was extracted from dried apothecia using Plant Genomic DNA Kit (TIANGEN Biotech. Co., Ltd., Beijing, China). Materials were crushed in liquid nitrogen before extraction. The internal transcribed spacer of nuclear ribosomal DNA (ITS) were amplified and sequenced using primer pair ITS1 and ITS4 (White et al. 1990) according to Zheng and Zhuang (2016). Newly generated sequences were deposited in GenBank, and other sequences used in the phylogenetic analyses were retrieved from GenBank (Table 1). Holwaya mucida (Schulzer) Korf & Abawi was selected as outgroup taxon. Alignment was generated and manually edited with BioEdit 7.0.5.3 (Hall 1999). Maximum parsimony (MP) and Neighbor-joining (NJ) analyses were carried out using PAUP*4.0b10 with parameters used by Zheng and Zhuang (2014). The topological confidence of the NJ and MP trees was assessed with bootstrap analysis using 1,000 replications, each with 10 replicates of random stepwise addition of taxa. The resulting trees were viewed in TreeView 1.6.6 (Page 1996).

Sequences used in this study.

Species Strain/specimen ITS
Acephala applanata Grünig & T.N. Sieber CBS 109314 AY078146
A. macrosclerotiorum Münzenb. & Bubner BB11_301_Ah_Pi_150506 (DNA46) HM189696
Ascocoryne cylichnium (Tul.) Korf VL272 JF440583
A. sarcoides (Jacq.) J.W. Groves & D.E. Wilson CBS:309.71 HM152550
Chlorovibrissea albofusca (G.W. Beaton) Sandoval-Leiva, A.I. Romero & P.R. Johnst. PDD 75692 AY789384
C. albofusca PDD:88457 JN809648
C. bicolor (G.W. Beaton & Weste) L.M. Kohn ICMP19895 KF924737
C. chilensis Sandoval-Leiva, A.i. Romero & P.R. Johnst. PDD 99891 NR_132892
C. phialophora Samuels & L.M. Kohn 1989 PDD:83226 KF429261
C. korfii H.D. Zheng & W.Y. Zhuang HMAS 275652 KY924871*
Chlorovibrissea sp. PDD70070 DQ257353
Hyaloscypha aureliella (Nyl.) Huhtinen M235 EU940229
H. vitreola (P. Karst.) Boud. M39 EU940231
Lachnum bicolor (Bull.) P. Karst. ARON3113.P AJ430394
L. virgineum. (Batsch) P. Karst. 3706 JF937586
Phialocephala aylmerensis J.B. Tanney & B. Douglas DAOM C 250106 NR_136124
P. catenospora J.B. Tanney & B. Douglas DAOM C 250108 NR_136122
P. dimorphospora W.B. Kendr. CBS 300.62 NR_135931
Vibrissea filisporia (Bonord.) Korf & A. Sánchez JLF2084 JX415338
V. flavovirens (Pers.) Korf & J.R. Dixon MBH39316 AY789427
V. flavovirens N/A KF429257
V. flavovirens HMAS 275653 KY924872
V. truncorum (Alb. & Schwein.) Fr. PDD 99892 KF429259
V. truncorum (Alb. & Schwein.) Fr. PDD 99893 KF429260
Uncultured Vibrissea WPD-OTU-39 KT581681
Uncultured Vibrissea WPW-OTU-33 KT581735
Chlorociboria aeruginosa (Oeder) Seaver ex C.S. Ramamurthi, Korf & L.R. Batra PDD 81292 AY755360
Chlorociboria sp. HMAS 273905 KY498614
Cudoniella clavus (Alb. & Schwein.) Dennis BM18#13 AY789374
Dicephalospora aurantiaca (W.Y. Zhuang) W.Y. Zhuang & Z.Q. Zeng HMAS 81363 DQ986483
Holwaya mucida (Schulzer) Korf & Abawi B 70 0009352 DQ257357
Hymenoscyphus scutula (Pers.) W. Phillips MBH29259 AY789432
Hyphodiscus hymeniophilus (P. Karst.) Baral TNS:F-31802 AB546951
Ombrophila violacea (Hedw.) Fr. WZ0024 AY789366
Roseodiscus rhodoleucus (Fr.) Baral ARON2329.P AJ430395

Results

Phylogenetic analyses

The ITS alignment consisted of 574 characters including gaps, of which 292 were constant, 52 were variable and parsimony-uninformative, and 230 were parsimony-informative. Forty-five equally most parsimonious trees were yielded by MP analysis (Tree length = 1085, Consistency index = 0.4719, Homoplasy index = 0.5281, Retention index = 0.6739, Rescaled consistency index = 0.3180) and one of them was shown in Fig. 1. MP and NJ bootstrap proportions (BP) greater than 50% were labeled at the nodes. In the phylogenetic tree (Fig. 1), species of Acephala, Chlorovibrissea, Phialocephala and Vibrissea formed four well-supported clades corresponding to each genus, and three of them further clustered together with high supporting values except for Chlorovibrissea, which showed a distant relationship with others. The undescribed species appeared as a distinct terminal lineage within Chlorovibrissea. ITS sequences of V. flavovirens from the Chinese, North American and New Zealand materials were of high similarity (99%) and formed a well-supported terminal branch.

Figure 1. 

Phylogenetic affinity of Chlorovibrissea korfii and Vibrissea flavovirens inferred from maximum parsimony analysis of ITS sequences. Bootstrap values (≥50%) of MP and NJ are shown at nodes from left to right.

Taxonomy

Chlorovibrissea korfii H.D. Zheng & W.Y. Zhuang, sp. nov.

Figure 2

Type

CHINA, Yunnan Province, Maguan County, 23°6.22'N, 104°19.75'E, alt. 1450 m, on moist rotten twig, 14 August 2016, X.H. Wang, S.H. Li, H.D. Zheng & S.C. Li YN16-151 (holotype: HMAS 275652).

Etymology

The specific epithet is in memory of the late distinguished mycologist Dr. R.P. Korf.

Figure 2. 

Chlorovibrissea korfii H.D. Zheng & W.Y. Zhuang (HMAS 275652, holotype). a, b Fresh apothecia on natural substrate c Longitudinal section of apothecium d Structure of margin, flank and hymenium e Excipular structure of flank f Asci g IKI reaction of apical rings h Paraphyses i Ascospores. Mouting media: c–f, h, i lactophenol cotton blue, g Lugol’s solution. Scale bars: a = 5.0 mm, b = 2.0 mm, c = 200 µm, d = 40 µm, e = 20 µm, f, h, i = 10 µm, g = 5 µm.

Description

Apothecia scattered or in cluster, discoid to slightly convex, stipitate, light greenish yellow, with hymenium and receptacle surface concolorous when fresh, 0.8–2.0 mm in diam. and 0.6–1.5 mm high, dried apothecial tissues with exudation of light yellow pigment in water; stipe cylindrical, with base dark, 0.4–1.0 mm high. Ectal excipulum of textura prismatica, non-gelatinous, 30–100 µm thick, hyphae parallel or lying at a low angle to receptacle surface, cells hyaline, with walls slightly thickened, terminal cells of external hyphae thin-walled, 8–25 × 3–7 μm. Medullary excipulum of textura porrecta to textura intricata, 30–300 µm thick, hyphae hyaline, 3–5 µm wide. Subhymenium not distinguishable. Hymenium 95–110 µm thick. Asci arising from simple septa, 8-spored, cylindrical, J+ in Melzer’s reagent and Lugol’s solution without KOH pretreatment, visible as two short blue lines, 70–83 × 4.5–5.5 μm. Ascospores filiform, tapering slightly from rounded apex to pointed base, hyaline, smooth, multiguttulate, non-septate, in fascicle, 44–52 × 1.2–1.5 μm. Paraphyses filiform, hyaline, unbranched, 1.5–2.0 µm wide, not exceeding the asci.

Notes. Six species have been recorded in the genus Chlorovibrissea. Chlorovibrissea korfii is different from any known species of the genus in both morphological and phylogenetic evidences. Morphologically, the diagnostic characteristic of the new species is the overall light greenish yellow apothecia. Chlorovibrissea phialophora Samuels & L.M. Kohn has ascospores of similar shape and size, but differs in apothecia stipitate-capitate, larger (2–5 mm in diam.) and dark green to nearly black, stipe longer (1–2.5 mm), asci larger (100–123 × 5–6 μm), and apical cells of ascospores forming subglobose to cylindrical phialides within the asci. The new fungus resembles C. albofusca (G.W. Beaton) Sandoval-Leiva, A.I. Romero & P.R. Johnst. in having pale colored apothecia, but the latter has larger apothecia (up to 4 mm diam. when dry) with hemispherical cap, larger ectal excipular cells (up to 35 × 15 μm) lying at a high angle to the outer surface, larger asci (195–225 × 7.5–8.5 μm), and larger ascospores (95–115 × 1.5–2 μm). Phylogenetically, C. korfii appeared to be related to C. bicolor, C. phialophora and Chlorovibrissea sp. (DQ257353) in the ITS tree (Fig. 1). Chlorovibrissea bicolor is different from the new species in apothecia with yellow, subglobose or lobed head up to 4 mm in diam. and a dark green tomentose stalk, larger asci (132–155 × 5–6.5 μm) and ascospores (53–60 × 1.5–2 μm).

Vibrissea flavovirens (Pers.) Korf & J.R. Dixon, Mycotaxon 1(2): 134, 1974.

Figure 3

flavovirensPeziza flavovirens Pers., Mycol. Eur. (Erlanga) 1: 323, 1822.

Description

Apothecia scattered or in cluster, slightly convex, sessile, hymenium surface light yellow, 0.5–1.5 mm in diam., receptacle surface brownish. Ectal excipulum of textura angularis to textura prismatica, non-gelatinous, lying at a high angle to the outer surface, 30–140 µm thick, inner cells subhyaline to light brown and outer cells brown, 15–30 × 9–14 μm. Medullary excipulum of textura angularis to textura prismatica, 50–150 µm thick, cells hyaline, 5–16 × 4–6 μm. Subhymenium not distinguishable. Hymenium 280–290 µm thick. Asci arising from simple septa, 8-spored, cylindrical, J– in Melzer’s reagent and Lugol’s solution with or without KOH pretreatment, 227–241 × 5–6 μm. Ascospores filiform, hyaline, smooth, multiguttulate, multi-septate, break into several pieces, in fascicle, 192–208 × 1.5–2.0 μm. Paraphyses filiform, slightly enlarged at the apex, hyaline, branched at upper portion, 3.0–5.0 µm wide at apex and 2.0–2.5 μm wide blow, exceeding the asci by 20–35 μm.

Figure 3. 

Vibrissea flavovirens (Pers.) Korf & J.R. Dixon (HMAS 275653). a Fresh apothecia on natural substrate b Longitudinal section of apothecium c Structure of margin and upper flank d Excipular structure of lower part and near base e, f Asci g Fragments of ascospores h Paraphyses. Mouting medium: b–h lactophenol cotton blue. Scale bars: a = 5.0 mm, b = 200 µm, c–e = 20 µm, f–h = 10 µm.

Specimen examined

CHINA, Beijing, Yunmeng Moutain, 40°33.00’’N, 116°40.80'E, alt. 800 m, on herbaceous stem of unidentified plant submerged in water, 10 July 2016, H.D. Zheng, Z.Q. Zeng, X.C. Wang, K. Chen & Y.B. Zhang 10660 (HMAS 275653).

Notes

This is the first report of V. flavovirens from China. The fungus was originally described from France and currently known in Denmark, Germany, Madeira, New Zealand, UK and USA (Korf 1974; Iturriaga 1995; Sandoval-Leiva et al. 2014). The Chinese collection agrees with the description of V. flavovirens by Iturriaga (1995). The ITS sequence of the Chinese specimen shared high similarity (99%) with those of North American and New Zealand materials, and the sequences of materials from different geographic regions formed a strongly supported terminal branch (Fig. 1).

Discussion

The three sexual genera in Vibrisseaceae are mainly differentiated by color of apothecia and structure of ectal excipulum. The excipular cells of Vibrissea are more or less angular to globose and lying at a high angle to the receptacle surface, while those of Chlorovibrissea and Leucovibrissea are rectangular and axes of cells are nearly parallel to the receptacle surface. Chlorovibrissea is different from Leucovibrissea in having greenish apothecia instead of the whitish ones. Differences between Chlorovibrissea and Vibrissea were found in ascal apex, which is round to somewhat truncate and with the apical ring placed subapically in the former genus, while that of the latter is acute with apical ring placed at the tip (Sandoval-Leiva et al. 2014). The ascal apex of C. korfii is somewhat conical and with apical ring placed apically, broader at tip and narrower downward (Fig. 2g), unlike that of other known Chlorovibrissea species. Further studies are needed to evaluate whether ascal apical apparatus is phylogenetically informative in Vibrisseaceae.

Chlorovibrissea was assumed to have a southern hemisphere distribution because species of the genus was never reported from north hemisphere (Kohn 1989; Sandoval-Leiva et al. 2014). The discovery of C. korfii from China expands the distribution of the genus to north hemispheres, which might break the assumption “the origin of the southern hemisphere vibrisseaceous fungi could be independent from the northern hemisphere representative” (Wang et al. 2006).

In the family Vibrisseaceae, sequence data of Leucovibrissea are not available. The two asexual genera Vibrisseaceae are Phialocephala and Acephala. Due to the heterogeneity of Phialocephala, only the type species, P. dimorphospora, and two closely related taxa were included in our phylogenetic analyses. Vibrissea, Acephala and Phialocephala clustered as a highly supported group (MPBP/NJBP = 100%/100%, Fig. 1), while Chlorovibrissea were distantly related (Fig. 1). The results coincided with those of the previous studies (Wang et al. 2006; Sandoval-Leiva et al. 2014), in which Chlorovibrissea and Vibrissea appeared as two separate clades. As to relationships among species of Chlorovibrissea, C. albofusca and C. chilensis were very closely related (MPBP/NJBP = 100%/100%), and C. korfii is associated with the rest species of the genus, which did not receive a reasonable support (MPBP = 81%). The inter-specific relationships of Vibrissea were hardly demonstrated (Fig. 1) since very few species were sampled.

The two asexual genera are recognizable and associated each other with low supports (Fig. 1). The two existing species of the genus Acephala were sisters (Fig. 1, MPBP/NJBP = 99%/99%). Acephala was thought to be congeneric with Phialocephala by some authors, and differentiated only by the lack of observed sporulation in culture (Grünig et al. 2009; Münzenberger et al. 2009; Tanney et al. 2016). Phialocephala species are commonly isolated as dark-septate endophytes from coniferous tree roots or from decomposing wood (Menkis et al. 2004), and attributed to Vibrisseaceae mainly based on sequence data (Wang et al. 2006; Kirk et al. 2008). Connections of some Phialocephala species with Mollisia or mollisioid sexual states were reported recently (Grünig et al. 2009; Tanney et al. 2016). It seems that a lot of work needs to be done to establish the generic concepts.

In conclusion, Vibrisseaceae established based on morphology is quite possibly polyphyletic. Sequence data of Leucovibrissea are desirable to get a more comprehensive outline of the family. Phialocephala s.l. is heterogeneous. Its generic concept needs to be clarified. As more sequences of vibrisseaceous fungi are available, the circumscription of the family will become monophyletic.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (nos. 31570018, 31300021). The authors would like to thank Dr. X.H Wang and Dr. S.H. Li for their invaluable help during the field work.

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