Biodiversity Data Journal : Taxonomy & Inventories
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Taxonomy & Inventories
Phaeoisaria laianensis (Pleurotheciales, Pleurotheciaceae), a new species from freshwater habitats in China
expand article infoYu Liu, Gui-Ping Xu, Xin-Yi Yan, Min-Hui Chen‡,§, Yang Gao‡,§, Hai-Jing Hu‡,§, Hai-Yan Song|, Dian-Ming Hu‡,§, Zhi-Jun Zhai‡,§
‡ College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, China
§ Bioengineering and Technological Research Centre for Edible and Medicinal Fungi, Jiangxi Agricultural University, Nanchang, China
| Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of the P. R. China, Nanchang, China
Open Access

Abstract

Background

Freshwater fungi play an indispensable role in the ecosystem and have great research value. Based on morphological and phylogenetic analyses of a concatenated dataset of ITS, LSU and SSU sequences, a new species, Phaeoisaria laianensis, was introduced as a freshwater hyphomycete from Anhui Province, China.

New information

Phaeoisaria laianensis was morphologically described as erect, rigid, dark brown to black, velvety synnemata which has macronematous, septate, branched, brown to dark brown, parallel adpressed conidiophores with polyblastic, integrated, terminal, hyaline to pale brown, smooth, denticulate, sympodial conidiogenous cells and ellipsoidal to obovoid, rounded at the apex, obtuse and tapering towards base, septate, guttulate conidia. Based on molecular and morphological characteristics, it is confirmed to be a new species. All illustrations and descriptions have been provided.

Keywords

Ascomycota, Phaeoisaria, morphology, phylogenetic anaysis, taxonomy

Introduction

Phaeoisaria (Pleurotheciales) was established by Höhnel (1909) to accommodate Phaeoisaria bambusae as the type species, a hyphomycetous taxon isolated from a bamboo substrate. This genus is characterised by indeterminate synnemata with parallel adpressed conidiophores with numerous sympodially extending denticulate conidiogenous cells and aseptate or septate ellipsoidal, obovoidal, fusiform-cylindrical to falcate, hyaline conidia (Höhnel 1909, Réblová et al. 2016, Hyde et al. 2018, Luo et al. 2018, Boonmee et al. 2021). Nevertheless, indeterminate synnemata have not been observed in some species, such as P. curvata (de Hoog and Papendorf 1976), P. glauca (de Hoog and Papendorf 1976), P. loranthacearum (Crous et al. 2015), P. fasciculata (Réblová et al. 2016), P. annesophieae (Crous et al. 2017) and P. dalbergiae (Crous et al. 2021).

In the past decades, an increasing number of new species was assigned to Phaeoisaria by distinguishing characters (Crous et al. 2017, Hyde et al. 2018, Hyde et al. 2019, Luo et al. 2019, Boonmee et al. 2021, Crous et al. 2021). Until now, 26 species have been accepted in the genus Phaeoisaria (http://www.speciesfungorum.org/Names/Names.asp). These species are relatively common and have a worldwide distribution, while only four of them have been recorded in China. Moreover, there are presently only 15 species having the molecular data in Phaeoisaria. In this study, we depicted a new species, Phaeoisaria laianensis, from submerged wood in Anhui Province of China, with both morphological examination and molecular phylogenetic analysis.

Materials and methods

Samples collection, specimen examination and isolation

Submerged rotting wood samples were gathered from Laian County, Anhui Province, China and were brought back to the laboratory to be incubated in plastic boxes at room temperature. Fungi on the host surface were observed with a Nikon SMZ-1270 microscope (Nikon Corporation, Japan) and morphologically photographed with a Nikon ECLIPSE Ni-U compound microscope (Nikon Corporation, Japan), which was equipped with a Nikon DS-Fi3 camera. The structure of fungi was determined by PhotoRuler 1.1.3.0 (The Genus Inocybe, Hyogo, Japan) and figures were processed by Adobe Photoshop 2020 (Adobe Systems, USA). According to the method of Li et al. (2021), single spore isolation and pure culture were carried out. Fungal specimens were deposited in the Fungus Herbarium, Jiangxi Agricultural University, Nanchang, China.

DNA extraction, PCR amplification and sequencing

By using the improved CTAB method (Doyle and Doyle 1987), fungal total genomic DNA was extracted from fresh mycelium. Three gene regions (ITS, LSU and SSU), were respectively amplified by polymerase chain reaction (PCR) using the primers of ITS1/ITS4 (White et al. 1990), LROR/LR7 (Hopple and Vilgalys 1999) and NS1/NS4 (White et al. 1990), with 25 μl of the final volume including 9.5 μl ddH2O, 12.5 μl 2× Taq PCR MasterMix (Qingke, Changsha, China), 1 μl of DNA template and 1 μl of each primer (10 μM). Then amplifications were conducted under the PCR conditions described by Zhai et al. 2022. The PCR products were purified and the sequencing reactions were commercially conducted with the corresponding forward and reverse primers by QingKe Biotechnology Co. (Changsha, China). All sequences were edited with SeqMan v. 7.1.0 (DNASTAR, lnc, Madison, WI) and were deposited in the NCBI GenBank database.

Phylogenetic analysis

The sequences of 69 strains were retrieved from recent articles (Luo et al. 2018, Hyde et al. 2019, Boonmee et al. 2021) and downloaded from GenBank (Table 1). Each matrix of ITS, LSU and SSU was aligned using the online service of MAFFT v.7 (http://mafft.cbrc.jp/alignment/server/large.html, Katoh et al. 2019) and then the sequences of three regions were concatenated by PhyloSuite v.1.2.2 (Zhang et al. 2020). By using RAxML v.7.2.6 (Stamatakis and Alachiotis 2010), Maximum Likelihood (ML) analysis was performed, which used a GTRGAMMA substitution model with 1000 bootstrap replicates. The Markov Chain Monte Carlo (MCMC) method in MrBayes was used to estimate the posterior probabilities (PP) (Zhaxybayeva and Gogarten 2002) and it was set as four chains (2 hot chains and 2 cold chains) running 2,000,000 generations synchronously, resulting in 40002 trees in total. Based on the initial 25% of sampled data being cut off as burn-in, PhyloSuite v.1.2.2 (Zhang et al. 2020) was used to infer Bayesian inference phylogeny under the JC+I+G+F model of the concatenation of ITS, LSU and SSU. After visualisation by FigTree v.1.4.4 (Rambaut 2018), the phylogenetic tree was edited and illustrated using Adobe Illustrator 2020 (Adobe Systems Inc., USA). The aligned matrices and trees were submitted to TreeBASE (http://purl.org/phylo/treebase/phylows/study/TB2:S29791).

Table 1.

Sequences used in this study. Note: Ex-type strains are in bold. The sequences of new species are indicated as underlined and unavailable sequences in GenBank are indicated by hyphen "-".

Taxonomy Strain GenBank accession numbers
ITS LSU SSU

Adelosphaeria catenata

CBS 138679 KT278721 KT278707 KT278692

Ascotaiwania fusiformis

MFLUCC 15-0625 KX550894 KX550898

Ascotaiwania fusiformis

MFLU 15-1156 MG388215 NG–057114

Ascotaiwania lignicola

NIL 00005 HQ446341 HQ446364 HQ446284

Ascotaiwania sawadae

SS00051 HQ446340 HQ446363 HQ446283

Bactrodesmiastrum obovatum

FMR 6482 FR870264 FR870266

Bactrodesmiastrum pyriforme

FMR 10747 FR870263 FR870265

Brachysporiella setosa

HKUCC 3713 AF132334

Canalisporium exiguum

SS 00809 GQ390296 GQ390281 GQ390266

Canalisporium grenadoideum

BCC 20507 GQ390267 GQ390252

Canalisporium pulchrum

SS03982 GQ390292 GQ390277 GQ390262

Conioscypha lignicola

CBS 335.93 AY484513 JQ437439

Conioscypha minutispora

CBS 137253 MH878131

Conioscypha peruviana

CBS 137657 KF781539

Conioscypha varia

CBS 113653 AY484512 AY484511

Fuscosporella pyriformis

MFLUCC 16-0570 MG388217 KX550896 KX550900

Helicoon farinosum

DAOM 241947 JQ429145 JQ429230
Leotia lubrica AFTOLID 1 DQ491484 AY544644 AY544746

Melanotrigonum ovale

CBS 138815 KT278722 KT278711 KT278698

Melanotrigonum ovale

CBS 138744 KT278725 KT278710 KT278697

Melanotrigonum ovale

CBS 138743 KT278724 KT278709 KT278696

Melanotrigonum ovale

CBS 138742 KT278723 KT278708 KT278695
Microglossum rufum OSC100641 DQ470981 DQ471033

Mucispora obscuriseptata

MFLUCC 15-0618 MG388218 KX550892 KX550897

Parafuscosporella moniliformis

MFLUCC 15-0626 MG388219 KX550895 KX550899

Phaeoisaria annesophieae

CBS 143235 MG022180 MG022159

Phaeoisaria annesophieae

MFLU190531 MT559109 MT559084

Phaeoisaria aquatica

MFLUCC 16-1298 MF399237 MF399254

Phaeoisaria clematidis

MFLUCC 16-1273 MF399229 MF399246

Phaeoisaria clematidis

MFLUCC 17-1341 MF399230 MF399247 MF399216

Phaeoisaria clematidis

MFLUCC 17-1968 MG837022 MG837017 MG837027

Phaeoisaria clematidis

DAOM 226789 JQ429155 JQ429231 JQ429243

Phaeoisaria dalbergiae

CPC 39540 OK664703

Phaeoisaria fasciculata

CBS 127885 KT278719 KT278705 KT278693

Phaeoisaria fasciculata

DAOM 230055 KT278720 KT278706 KT278694

Phaeoisaria filiformis

MFLUCC 18-0214 MK878381 MK835852 MK834785

Phaeoisaria guttulata

MFLUCC 17-1965 MG837021 MG837016 MG837026

Phaeoisaria laianensis

CCTCC AF 2022069 ON937559 ON937557 ON937562

Phaeoisaria laianensis

CCTCC AF 2022073 ON937560 ON937561 ON937558

Phaeoisaria loranthacearum

CBS 140009 KR611888 MH878676

Phaeoisaria loranthacearum

BYCDW25 MG820097

Phaeoisaria loranthacearum

BYCDW24 MG820098

Phaeoisaria microspora

MFLUCC 16-0033 MF671987 MF167351

Phaeoisaria pseudoclematidis

MFLUCC 11-0393 KP744457 KP744501 KP753962

Phaeoisaria sedimenticola

CGMCC3.14949 JQ074237 JQ031561

Phaeoisaria sedimenticola

S-908 MK878380 MK835851

Phaeoisaria siamensis

MFLUCC 16-0607 MK607610 MK607613 MK607612

Phaeoisaria sparsa

FMR 11939 HF677185

Phaeoisaria synnematica

NFCCI 4479 MK391494 MK391492

Phragmocephala stemphylioides

KAS 4277 KT278730 KT278717

Plagiascoma frondosum

CBS 139031 KT278713 KT278701

Pleurotheciella centenaria

DAOM 229631 JQ429151 JQ429234 JQ429246

Pleurotheciella rivularia

CBS 125237 JQ429161 JQ429233 JQ429245

Pleurotheciella rivularia

CBS 125238 JQ429160 JQ429232 JQ429244

Pleurotheciella uniseptata

KUMCC 15-0407 MF399231 MF399248

Pleurothecium aquaticum

MFLUCC 17-1331 MF399245 MF399263

Pleurothecium aquaticum

MFLUCC 21-0148 OM654775 OM654772 OM654807

Pleurothecium floriforme

MFLUCC 15-0628 KY697281 KY697277 KY697279

Pleurothecium obovoideum

CBS 209.95 EU041784 EU041841

Pleurothecium pulneyense

MFLUCC 16-1293 MF399262 MF399228

Pleurothecium recurvatum

CBS 138747 KT278728 KT278714 KT278703

Pleurothecium recurvatum

CBS 131272 JQ429149 JQ429237 JQ429251

Pleurothecium recurvatum

CBS 101581 JQ429148 AF261070 JQ429248

Pleurothecium semifecundum

CBS 131482 JQ429158 JQ429239 JQ429253

Pleurothecium semifecundum

CBS 131271 JQ429159 JQ429240 JQ429254

Savoryella longispora

SAT 00322 HQ446359 HQ446380 HQ446302

Savoryella paucispora

SAT 00866 HQ446381 HQ446303

Savoryella verrucosa

SS 00052 HQ446353 HQ446374 HQ446296

Sterigmatobotrys macrocarpa

DAOM 230059 JQ429154 GU017316

Sterigmatobotrys macrocarpa

PRM 915682 JQ429153 GU017317 JQ429255

Sterigmatobotrys rudis

DAOM 229838 JQ429152 JQ429241 JQ429256

Taxon treatment

Phaeoisaria laianensis Y. Liu, G.P. Xu, X.Y. Yan, D.M. Hu & Z.J. Zhai, sp. nov.

Material   Download as CSV 
Holotype:
  1. scientificName:
    Phaeoisaria laianensis
    ; acceptedNameUsage:
    Phaeoisaria laianensis Y. Liu, D.M. Hu & Z.J. Zhai
    ; kingdom:
    Fungi
    ; phylum:
    Ascomycota
    ; class:
    Sordariomycetes
    ; order:
    Pleurotheciales
    ; family:
    Pleurotheciaceae
    ; taxonRank:
    species
    ; verbatimTaxonRank:
    species
    ; genus:
    Phaeoisaria
    ; specificEpithet:
    laianensis
    ; scientificNameAuthorship:
    Y. Liu, D.M. Hu & Z.J. Zhai
    ; continent:
    Asia
    ; country:
    China
    ; stateProvince:
    Anhui
    ; county:
    Laian
    ; locality:
    Wawuzhuang
    ; verbatimElevation:
    35
    ; locationRemarks:
    Label transliteration
    ; verbatimCoordinates:
    32.66 N, 118.65 E
    ; verbatimLatitude:
    32.66
    ; verbatimLongitude:
    118.65
    ; samplingProtocol:
    collecting
    ; eventDate:
    06-05-2021
    ; year:
    2021
    ; month:
    5
    ; day:
    6
    ; habitat:
    Freshwater
    ; recordedBy:
    Yu Liu
    ; identifiedBy:
    Yu Liu and Zhi-jun Zhai
    ; dateIdentified:
    2021
    ; type:
    PhysicalObject
    ; language:
    en
    ; rightsHolder:
    Dian-Ming Hu and Zhi-jun Zhai
    ; institutionID:
    HFJAU10040
    ; collectionID:
    LKJ17
    ; institutionCode:
    the Herbarium of Fungi, Jiangxi Agricultural University (HFJAU)
    ; collectionCode:
    Fungi
    ; ownerInstitutionCode:
    HFJAU
    ; occurrenceID:
    99B9C819-CA87-5634-AB08-7E7A79E1ADE0

Description

Saprobic on decaying wood submerged in freshwater habitats. Sexual morph: Undetermined. Asexual morph: Colonies effuse, solitary, scattered, dark brown to black, hairy, covered by white conidial mass. Mycelium partly superficial, partly immersed. Synnemata 290–848 × 9.3–30.7 µm (x̅ = 532 × 18.6, SD = 159 × 5, n = 20), erect, rigid, dark brown to black, velvety, smooth, composed of compactly and parallel adpressed conidiophores. Conidiophores 116.2–491.1 × 2–3.2 µm (x̅ = 276.1 × 2.4, SD = 96.7 × 0.5, n = 10), macronematous, synnematous, septate, branched, brown to dark brown, smooth. Conidiogenous cells 8.3–27.5 × 2.3–3.8 µm (x̅ = 17.1 × 2.7, n = 10), polyblastic, integrated, terminal, hyaline to pale brown, smooth, denticulate, sympodial, each with several denticulate conidiogenous loci, 0.8–1.6 × 0.4–0.8 µm (x̅ = 1.3 × 0.7, n = 10). Conidia 5–7.2 × 1.7–2.9 µm (x̅ = 5.9 × 1.7, SD = 0.5 × 0.3, n = 50), ellipsoidal to obovoid, straight, rounded at the apex, obtuse and tapering towards base, hyaline, aseptate, guttulate, smooth-walled. (Fig. 1).

Figure 1.  

Phaeoisaria laianensis (HFJAU 10040, Holotype) a, b Colonies on wood; c, d Conidiophores; e, f Conidiogenous cells with conidia; g Germinating conidium; h Conidia; i, j Colony on PDA for 26 days from above and reverse. Scale bars: a, b = 100 µm, c, d = 50 µm, e–h = 10 µm.

Culture characteristics: Conidia germinated within 24 h in which germ tubes were produced from both ends or sides at 28℃ on PDA. The colony on PDA grows up slowly and reaches 24.5 mm in 26 days, periphery grey, surface folded, middle grey-green to black, raised with mycelium in the centre, covered with lots of white conidia, powdery, reverse grey to black.

Material examined: China, Anhui Province, alt. 35 m, near 32.66°N, 118.65°E, on decaying wood submerged in a freshwater stream, 6 May 2021, Y. Liu, G.P. Xu and Z.J. Zhai, LKJ17 (HFJAU 10040, holotype), ex-type living culture, CCTCC AF 2022069 = CCTCC AF 2022073.

Etymology

The name reflects the district where this fungus was found.

Notes

Phylogenetic analysis shows that Phaeoisaria laianensis is a phylogenetically-distinct species, most closely related to P. dalbergiae and then to P. clematidis (Fig. 2). However, P. laianensis is easily distinguished from P. dalbergiae by its ellipsoidal to obovoid, rounded at the apex and tapering towards base conidia (Crous et al. 2021). In addition, P. laianensis has synnemata, which is absent in P. dalbergiae (Crous et al. 2021), also in P. curvata, P. glauca (de Hoog and Papendorf 1976), P. loranthacearum (Crous et al. 2015), P. annesophieae and P. fasciculata (Réblová et al. 2016) (Table 2). The new species is similar to P. clematidis in having resembling synnemata or conidia (Hughes 1958, Luo et al. 2018), while the former has shorter synnemata (290–848 µm vs. 1000–1500 µm) and smaller conidia (5–7.2 µm wide vs. 4–10 µm wide) than P. clematidis (Table 2). Likewise, P. laianensis has longer synnemata than P. siameneis (290–848 µm vs. 330–380 µm), smaller conidiophores than P. guttulata (Hyde et al. 2018) and P. aquatica (116.2–491.1 × 2–3 µm vs. 480–700 × 2–5 µm and 1028–1262 × 3.5–4.5 µm) (Luo et al. 2018) and smaller conidia (5–7.2 × 1.7–2.9 µm) than P. annesophiae (4.5–9 × 2–3.5 µm) (Crous et al. 2017), P. synnematica (4–11 µm long) (Boonmee et al. 2021) and P. siamensis (3–4 µm wide) (Table 2). In addition, it can be differentiated from P. filiforms by the indeterminate asexual morph of the latter species (Luo et al. 2019).

Table 2.

Synopsis 1 of asexual morphological characteristics of Phaeoisaria species. Note: Hyphens “-” are indeterminate or unavailable data.

Species

Synnemata (µm)

Synnemata characteristics

Conidiophores (µm)

Conidiophores characteristics

Conidia (µm)

References

Phaeoisaria laianensis

290‒848 × 9.3‒30.7

Erect, rigid, dark brown to black, velvety, smooth, composed of compactly and parallel adpressed conidiophores

116.2‒491.1 × 2‒3.2

Macronematous, synnematous, septate, branched, brown to dark brown, smooth

5‒7.2 × 1.7‒2.9

This study

P. aguilerae - - - -

18–29.5 × 4–5

Castañeda Ruiz et al. (2002)

P. annesophieae

- -

Conidiophores indeterminate

Sometimes grouping in strands of 2–4 hyphae, a rising from aerial hyphae, cylindrical, hyaline to pale brown

4.5–9 × 2–3.5

Crous et al. (2017)

P. aquatica -

Erect, rigid, dark brown to black, velvety, smooth

1028–1262 × 3.5–4.5

Macronematous, synnematous, brown to dark brown, smooth

6.5–7.5 × 2.5–3.5

Luo et al. (2018)

P. bambusae -

Erect, rigid, dark brown toblack, velvety, smooth

-

Macronematous, synnematous, brown to dark brown, smooth

-

Höhnel (1909), Hyde et al. (2019), Luo et al. (2019), Réblová et al. (2016)

P. caffra -

Synnemata composed of at least 10 adpressed hyphae

-

Conidiophores not tuberculate

7.5–12 × 2.5–3.5

Castañeda Ruiz et al. (2002), de Hoog and Papendorf (1976)

P. clavulata -

Stiff synnemata, composed of parallel hyphae, packed with slender, curved conidiogenous cells with very thin, fragile conidiogenous rachides

- - 1–2 long

Castañeda Ruiz et al. (2002), de Hoog and Papendorf (1976), Mason and Ellis (1953)

P. clematidis

1000–1500 × 20–80

Conidiomata scattered, indeterminate, erect, rigid, superficial, dark brown composed of compact appressed conidiophores

312–568 × 2.5–3.5

Macronematous, septate, branched, brown to dark brown, smooth

4–10 × 1.5–2.5

Castañeda Ruiz et al. (2002), Hughes (1958), Luo et al. (2018)

P. curvata - -

Conidiophores indeterminate

-

(4–)6–8(–11) × (1–)2–3

de Hoog and Papendorf (1976)

P. dalbergiae - -

10–50 × 1.5–2.5

Indeterminate, erect, subcylindrical, hyaline, smooth, 0–2-septate, unbranched or branched at apex

0.5 µm diam, (5 –)6–7 × (1.5–)2

Crous et al. (2021)

P. fasciculata -

Synnemata absent

25–65 × 3.0–3.5

Macronematous, arising from brown, thick-walled cells, cylindrical, pale brown, subhyaline towards the apex, unbranched, smooth-walled

6.0–8.0 (–9.0) × 2.0

Réblová et al. (2016)

P. filiformis - - - - -

Luo et al. (2019)

P. glauca - -

Conidiophores indeterminate

-

2.5–3.5 × 1.6–2.2

de Hoog and Papendorf (1976)

P. guttulata -

Erect, rigid, dark brown to black, velvety, smooth, composed of compactly and parallel adpressed conidiophores

480–700 × 2–5

Macronematous, synnematous, erect, septate, smooth, mid-brown to dark brown

3.5–5.5 × 2.5–4.8

Hyde et al. (2018)

P. infrafertilis -

Synnemata narrow, composed of only 5-6 brown adpressed hyphae

- -

19.5–22 × 2–3

de Hoog and Papendorf (1976), Sutton and Hodges (1976)

P. loranthacearum

- -

10–30 × 2–3

Arising from superficial hyphae, erect, solitary, branched at base or not, subcylindrical, straight to geniculate-sinuous, 1–3-septate, hyaline

(5)7– 8(9) × (1.5) 2(3)

Crous et al. (2015)

P. magnifica

-

Synnemata brush-like, synnemata with flaring hyphae at the tip

-

Growing well away from the column in the apical portion

5–6.5 × 4–4.5

de Hoog and Papendorf (1976), Deighton (1974)

P. microspora

35–238 µm long, 4–31 µm wide at the base, 5–35 µm wide at the apex

Erect, straight or flexuous, dark brown at base, pale brown at apex

25–225 × 1–3

Macronematous, synnematous, septate, branched at the apex, smooth, pale to dark brown

4.5–6.9 × 1.3–3.1

Hyde et al. (2017)

P. muscariformis

- - - -

12–22 × 4

Castañeda Ruiz et al. (2002), Siboe et al. (1999)

P. pseudoclematidis

200–500 µm long, 40–80 µm wide at the base, 40– 60 µm wide in the middle, 20–30 µm wide at the apex

Erect, rigid, dark brown, velvety, smooth, composed of compactly and parallel adpressed conidiophores

50–500 × 2–3

Macronematous, synnematous, brown to dark brown, septate, branched, smooth

5–8.5 × 3–4

Liu et al. (2015)

P. sedimenticola

up to 4000 µm high or sometimes longer, 70– 90 µm wide

Erect, cylindrical to subulate, consisting of very regular, parallel, brown hyphae

aseptate (3.5–)4.5–5.5(–7.5) ×

(2.5–)3–4(–4.5) 1-septate (4.5–)5.5–6.5(–9) × (2–)2.5–3.5(–4.5)

Cheng et al. (2014)

P. siamensis

330–380 × 20–25(–30)

Conidiomata scattered, indeterminate, erect, rigid, superficial, dark brown composed of compactly appressed conidiophores

2–2.5(–3) µm wide

Macronematous, in synnematous conidiomata, scattered, synnemata subulate or cylindrical, indeterminate, at the base 13–15 µm beneath the fertile portion with conidiogenous cells, composed of medium to dark brown, smooth, septate parallel hyphae, splaying out at the middle to apex

5–8 × 3–4

Hyde et al. (2019)

P. sparsa

-

Synnemata composed of at least 10 adpressed hyphae

-

Not tuberculate

10–15.5 × 2.5–3.5

de Hoog and Papendorf (1976), Sutton (1973)

P. sparsa var. cubensis

- - - -

(4–)7– 11(–17) ×(1.5–) 2– 3(–4)

Mercado-Sierra et al. (1997), Mel’nik (2012)

P. synnematica

399–960 × 12–30

Synnematal, erect, rigid, dark brown to olivaceous brown, composed of compactly parallel appressed conidiophores, cylindrical to clavate

1.5–960 × 1–3.5

Macronematous to semi- macronematous, highly geniculate, dark brown to olivaceous brown, synnematous, simple to dichotomously branched, emerging out at the apex and along the sides of the upper half or two thirds of each synnema, dark brown at the base, brown to pale brown

4–11 × 2–5

Boonmee et al. (2021)

P. tuberculata

-

Synnemata composed of at least 10 adpressed hyphae

-

Conspicuously tuberculate

8–13.5 × 1.5–2

Castañeda Ruiz et al. (2002), Sutton (1993)

P. uniseptata

- - - -

(3.5–) 5.5– 7.5 (–10) × 1.5–3

de Hoog and Papendorf (1976), Mercado-Sierra (1984), Mel’nik (2012)

P. vietnamensis

330–380 µm high, 20–25(– 30) µm wide at the base

-

2–2.5(–3) µm wide

Macronematous, in synnematous conidiomata, scattered, synnemata subulate or cylindrical, indeterminate composed of medium to dark brown, smooth, septate parallel hyphae

18.5– 23.5 × 4.5–5

Mel’nik (2012)

Figure 2.  

Phylogenetic tree of Bayesian analysis, based on a concatenated alignment of ITS, LSU and SSU sequences. Branch support is shown at the nodes, Maximum Likelihood bootstrap support (BS, black) ≥ 60% and Bayesian posterior probability (PP, red) ≥ 0.95. Leotialubrica (AFTOLID 1) and Microglossum rufum (OSC100641) are selected as the outgroup taxa. The new species is marked in red and ex-type strains are in bold.

Analysis

Phylogenetic analysis

The aligned matrix for the combined analysis, ITS+LSU+SSU had 3105 bp, including ITS = 509 bp, LSU = 1172 bp and SSU = 1424 bp. No topological conflict exists between the tree generated by ML analysis and the Bayesian tree. The Bayesian tree is shown with BS and PP in Fig. 2. All 15 Phaeoisaria species in our analyses form a monophyletic group (BS/PP = 59/1.00). Most importantly, the two collections of Phaeoisaria laianensis form an independent lineage with strong support (BS/PP = 100/1.00). This lineage groups with P. dalbergiae into a highly supported clade (BS/PP = 98/1.00), which is sister to P. clematidis (BS/PP = 54/1.00). After searching of NCBIs GenBank nucleotide database based on a megablast, the ITS sequence of P. laianensis was found to share 97.46% similarity with P. dalbergiae (CPC 39540) and 96.35% similarity with P. clematidis (DAOM 226789). In addition, the sequence has nine different loci from that of P. dalbergiae and 15 different loci from that of P. clematidis.

Discussion

In our molecular phylogenetic tree, Phaeoisaria consists of 15 species and is supported as a monophyletic group (BS/PP = 59/1.00, Fig. 2). The low ML bootstrap might be due to a large number of unavailable sequences for 13 species in Phaeoisaria. However, the independent lineage of P. laianensis (BS/PP = 100/1.00, Fig. 2) is established and groups with P. dalbergiae into a highly supported clade (BS/PP = 98/1.00, Fig. 2). This clade is sister to the four collections of P. clematidis although with lower support (BS/PP = 54/1.00, Fig. 2). In addition, the morphological characters of P. laianensis can be effortlessly distinguished from P. dalbergiae and P. clematidis and other species in Phaeoisaria (Tables 2, 3). Notably, our results favour P. laianensis as a new species in the genus. However, molecular data for Phaeoisaria species require enriching to clarify more species relationships in the genus.

Table 3.

Synopsis 2 of asexual morphological characteristics of Phaeoisaria species. Note: Hyphens "-" are indeterminate or unavailable data.

Species Conidia septation Conidia characteristics Host District References
Phaeoisaria laianensis Aseptate Ellipsoidal to obovoid, straight, rounded at the apex, obtuse and tapering towards base, hyaline, guttulate, smooth-walled Decaying wood China, Anhui Province This study
P. aguilerae 1-septate, rarely 2–3-septate Clavate or cylindrical, curved, with obtuse, rounded apex, slightly uncinate, and truncate base, hyaline, smooth

Decaying twig submerged in river

Cuba Castañeda Ruiz et al. (2002)
P. annesophieae Aseptate Ellipsoidal to obovoid, straight or slightly curved, rounded at the ends or sometimes tapering towards the base, hyaline, guttulate, smooth-walled Isolated from soil The Netherlands, Geldermalsen Crous et al. (2017)
P. aquatica Aseptate Ellipsoidal to obovoidal, rounded at the apex, hyaline, with two guttules smooth-walled

Decaying wood submerged in Jinsha River

China, Yunnan Province Luo et al. (2018)
P. bambusae aseptate or septate Ellipsoidal to obovoidal, fusiform-cylindrical to falcate, hyaline, straight, guttulate, smooth-walled

Unidentified submerged bamboo

Indonesia Höhnel (1909), Hyde et al. (2019), Luo et al. (2019), Réblová et al. (2016)
P. caffra Aseptate, rarely 1-sepate Conidia straight, ellipsoidal to clavate, obovoid, not attenuated at the apex, pale yellow brown, smooth

On decaying leaf of Podocarpus

Cape Province Castañeda Ruiz et al. (2002), de Hoog and Papendorf (1976)
P. clavulata Aseptate Broadly ellipsoidal to ± spherical, subspherical, smooth, hyaline On rotten decorticated wood Great Britain Castañeda Ruiz et al. (2002), de Hoog and Papendorf (1976), Mason and Ellis (1953)
P. clematidis Aseptate Obovoidal, rounded at the apex, obtuse and tapering towards base, hyaline, smooth-walled

Decaying wood submerged in Lancang River

China, Yunnan Province Castañeda Ruiz et al. (2002), Hughes (1958), Luo et al. (2018)
P. curvata Aseptate Smooth, thin-walled, hyaline, clavate to obovoid and pointed at base, curved, occasionally sickle-shaped Rotten leaves of Parinari capensis South West Africa de Hoog and Papendorf (1976)
P. dalbergiae Aseptate Solitary, hyaline, smooth, thin-walled, guttulate, subcylindrical to obovoid, tapering towards both ends, apex subobtuse, base with truncate hilum

On bark of Dalbergia armata

South africa, Northern Province Crous et al. (2021)
P. fasciculata Aseptate Ellipsoidal to obovoid, straight, rounded at the apex, obtuse and tapering towards base, hyaline, smooth-walled

Decorticated wood of Sambucus nigra

Canada, Ontario, Goulbourn Twp Réblová et al. (2016)
P. filiformis - -

Decaying wood submerged in freshwater stream

Thailand, Sai khu Waterfall Luo et al. (2019)
P. glauca Aseptate Smooth, thin-walled, hyaline, guttuliform to ellipsoidal,with pointed base, occasionally sickle-shaped

On rotten wood of Quercus sp.

America, Newfield de Hoog and Papendorf (1976)
P. guttulata Aseptate Globose to obovoid, hyaline, smooth-walled, guttulate

Decaying wood submerged in Suoluo River

China, Guizhou Province Hyde et al. (2018)
P. infrafertilis Aseptate, rarely 1-sepate Conidia falcate,hyaline

On dead leaves of Eucalyptus

Brazil de Hoog and Papendorf (1976), Sutton and Hodges (1976)
P. loranthacearum - Solitary, hyaline, smooth, fusoidal-ellipsoidal with obtuse ends, straight to falcate, guttulate

On twigs of Loranthus europaeus

Germany Crous et al. (2015)
P. magnifica Aseptate Straight, ellipsoidal to obovo1d, clavate, very pale olivaceous, smooth

On Bambusa

New Caledonia de Hoog and Papendorf (1976), Deighton (1974)
P. microspora Aseptate Solitary, fusiform, straight, smooth-walled, guttulate, hyaline On decaying wood Thailand, Krabi, Wat ThumSua Hyde et al. (2017)
P. muscariformis 3-sepate Cylindrical-fusiform, subhyaline, smooth

On leaves of Tiliacora kenyensis

Kenya Castañeda Ruiz et al. (2002), Siboe et al. (1999)
P. pseudoclematidis Aseptate Cylindrical-ovate, straight, hyaline, smooth-walled, guttulate

On dead culm of bamboo (Bambusae)

Thailand, Chiang Rai Liu et al. (2015)
P. sedimenticola Aseptate, 1-septate Smooth-walled, hyaline, with a pointed base, usually aseptate when attached to the conidiogenous cells, 0–1-septate after release; aseptate conidia, obovoid to ellipsoidal; 1-septate conidia, obovoid, slightly constricted at septum

Isolated from surface of marine sediment in intertidal zone

China, Shandong Province Cheng et al. (2014)
P. siamensis Aseptate Globose to subglobose, hyaline

Saprobic on decaying fruits

Thailand, Chiang Mai Province Hyde et al. (2019)
P. sparsa 0-3-septate Fusiform to clavate, conidia straight, ellipsoidal to fusiform, hyaline, not attenuated at the apex

On bark of Acer spicatum

Saskatchewan de Hoog and Papendorf (1976), Sutton (1973)
P. sparsa var. cubensis 0–1(–4)-septate Fusiform, cylindrical or clavate, hyaline, sometimes slightly curved

On dead branch

Cuba Mercado-Sierra et al. (1997), Mel’nik (2012)
P. synnematica 0–1-septate Dimorphic, clavate to ellipsoidal, cylindrical to falcate, base narrowly truncate, tip obtuse, variable in size, sometimes constricted near septa, 1–2-guttulate, hyaline, smooth-walled

Dead bark of Azadirachta indica (Meliaceae)

India, Maharashtra Boonmee et al. (2021)
P. tuberculata Asepate, rarely 1-sepate Conidia fusiform, straight, the apex attenuated, hyaline, smooth, guttulate On Labiatae Malawi Castañeda Ruiz et al. (2002), de Hoog and Papendorf (1976), Sutton (1993)
P. uniseptata Mostly with a median septum Two-celled, fusiform, ellipsoid, hyaline, cylindrical or clavate On dead branch Cuba de Hoog and Papendorf (1976), Mercado-Sierra (1984), Mel’nik (2012)
P. vietnamensis A single median septum Fusiform-subcylindrical to short obovoid-subclavate, somewhat attenuated towards the base, apex obtuse, straight to slightly curved, not constricted, hyaline, smooth, often guttulate On bark of a living unidentified liane South Vietnam, Dong Nai Province Mel’nik (2012)

Phaeoisaria predominantly occurs on leaves, barks, decaying wood and twigs of plants from the freshwater or terrestrial habitats (Table 3), while some are isolated from surface marine sediments (e.g. P. sedimenticola, Cheng et al. 2014), some from soil (e.g. P. annesophieae, Crous et al. 2017) and some from saprobic decaying fruits (e.g. P. siameneis, Hyde et al. 2019). Consequently, the habitats of Phaeoisaria are various. In this research, we introduce another lignicolous freshwater fungus, P. laianensis, discovered in China and it is noteworthy that the freshwater in which this species exists has been somewhat polluted. Phaeoisaria is thought to play an important role in nutrient and carbon cycling, biological diversity and ecosystem functioning of freshwater ecosystems, for their ability to decompose lignocellulose in woody litter, softening the wood and releasing nutrients (Bucher et al. 2004, Vijaykrishna et al. 2005, Hyde et al. 2016, Luo et al. 2018). Nonetheless, some Phaeoisaria species are pathogenic to humans, for example, it has been reported that P. clematidis and Phaeoisaria sp. can cause corneal inflammation of the eye (keratitis) (Guarro et al. 2000, Chew et al. 2010) and the former species is saprotrophic, which is similar to P. laianensis. What is the role of P. laianensis in ecosystem functioning? Is this species also pathogenic to humans? Such questions are waiting to be investigated by researchers.

Acknowledgements

We are grateful to Deng-Mei Fan (Agricultural college, Jiangxi Agricultural University) for very helpful comments on earlier drafts of this manuscript. This study was supported by the National Natural Science Foundation of China (NSFC 32070023 and NSFC 32060014), the Natural Science Foundation of Jiangxi Province (20151BAB214002) and Science and Technology Plan Project of Jiangxi Province (GJJ160417).

References

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