Print
Cryptic species of Curvularia in the culture collection of the Queensland Plant Pathology Herbarium
expand article infoYu Pei Tan§, Pedro W. Crous|§, Roger G. Shivas
‡ Biosecurity Queensland, Department of Agriculture and Fisheries, Queensland, Australia
§ Utrecht University, Utrecht, Netherlands
| Westerdijk Fungal Biodiversity Institute, Utrecht, Netherlands
¶ University of Southern Queensland, Queensland, Australia
Open Access

Abstract

Several unidentified specimens of Curvularia deposited in the Queensland Plant Pathology Herbarium were re-examined. Phylogenetic analyses based on sequence data of the internal transcribed spacer region, partial fragments of the glyceraldehyde-3-phosphate dehydrogenase and the translation elongation factor 1-α genes, supported the introduction of 13 novel Curvularia species. Eight of the species described, namely, C. beasleyi sp. nov., C. beerburrumensis sp. nov., C. eragrosticola sp. nov., C. kenpeggii sp. nov., C. mebaldsii sp. nov., C. petersonii sp. nov., C. platzii sp. nov. and C. warraberensis sp. nov., were isolated from grasses (Poaceae) exotic to Australia. Only two species, C. lamingtonensis sp. nov. and C. sporobolicola sp. nov., were described from native Australian grasses. Two species were described from hosts in other families, namely, C. coatesiae sp. nov. from Litchi chinensis (Sapindaceae) and C. colbranii sp. nov. from Crinum zeylanicum (Amaryllidaceae). Curvularia reesii sp. nov. was described from an isolate obtained from an air sample. Furthermore, DNA sequences from ex-type cultures supported the generic placement of C. neoindica and the transfer of Drechslera boeremae to Curvularia.

Keywords

Dothideomycetes, multigene phylogeny, taxonomy, 13 new species

Introduction

Curvularia is a species-rich genus of pathogens and saprobes associated with plant, human and animals worldwide (Sivanesan 1987, Hyde et al. 2014, Madrid et al. 2014, Manamgoda et al. 2015, Marin-Felix et al. 2017a, b). Curvularia species have also been reported from substrates such as air (Almaguer et al. 2012, Hargreaves et al. 2013), aquatic environments (Verma et al. 2013, Su et al. 2015, Sharma et al. 2016) and soil (Manamgoda et al. 2011, Marin-Felix et al. 2017a).

Species delimitation within Curvularia based solely on morphology is difficult as many species share similar characters and have overlapping conidial dimensions. Currently, there are 131 species of Curvularia (excluding varieties) listed in Index Fungorum (accessed on 4 January 2018). Phylogenetic studies based on multilocus sequence analyses of ex-type or reference cultures have recently delimited many cryptic species (Deng et al. 2014, Manamgoda et al. 2014, Tan et al. 2014, Manamgoda et al. 2015, Marin-Felix et al. 2017a, 2017b). Presently, there are 81 accepted species for which taxonomic placement has been established by DNA barcodes to allow accurate identification and comparison (Marin-Felix et al. 2017a, b).

In Australia, 64 species of Curvularia have been reported (DAF Biological Collections 2018, Farr and Rossman 2018). Of these, 17 species were described from Australia, namely C. australiensis, C. australis, C. bothriochloae, C. crustacea, C. dactyloctenii, C. graminicola, C. harveyi, C. heteropogonis, C. micrairae, C. ovariicola, C. perotidis, C. queenslandica, C. ravenelii, C. richardiae, C. ryleyi, C. sorghina and C. tripogonis. Eight of the Australian Curvularia species were originally placed in the closely related genus, Bipolaris, before transfer to Curvularia based on molecular studies (Manamgoda et al. 2012, 2014, Tan et al. 2014).

In this study, 17 unidentified isolates of Curvularia maintained in the culture collection held in the Queensland Plant Pathology Herbarium (BRIP) were compared with ex-type and reference isolates. Thirteen new species of Curvularia were revealed based on multilocus phylogenetic analyses and are formally described here. In addition, phylogenetic analyses of ex-type cultures have confirmed the placement of a Curvularia species, as well as the introduction of a new combination.

Materials and methods

Isolates and morphology

Unidentified isolates of Curvularia were obtained from BRIP (Table 1), which retains cultures in a metabolically inactive state at -80 °C in a sterile solution of 15% v/v glycerol. In order to observe conidia and conidiophores, living cultures were grown on sterilised leaf pieces of Zea mays on modified Sachs agar and on sterilised wheat straws on water agar, incubated at room temperature (approx. 25 °C) for seven days and exposed to near ultraviolet light on a 12 h light/dark diurnal cycle (Sivanesan 1987). Conidia and conidiophores were mounted on glass slides in lactic acid (100% v/v). Images were captured with a Leica DFC 500 camera attached to a Leica DM5500B compound microscope with Nomarski differential interference contrast illumination. Conidial widths were measured at the widest part of each conidium. Means and standard deviations (SD) were calculated from at least 20 measurements. Ranges were expressed as (minimum value–) mean-SD – mean+SD (−maximum value) with values rounded to 0.5 μm.

Curvularia isolates examined.

Species Isolate no.1 Host Location GenBank accession numbers2
ITS gapdh tef1a
Bipolaris maydis CBS 136.29 T Zea mays USA AF071325 KM034846 KM093794
Curvularia aeria CBS 294.61 T air Brazil HF934910 HG779148
C. affinis CBS 154.34 T unknown Indonesia KJ909780 KM230401 KM196566
C. akaii CBS 317.86 unknown Japan KJ909782 KM230402 KM196569
C. akaiiensis BRIP 16080 T unknown India KJ415539 KJ415407 KJ415453
C. alcornii MFLUCC 10-0703 T Zea mays Thailand JX256420 JX276433 JX266589
C. americana UTHSC 08-3414 T Homo sapiens USA HE861833 HF565488
C. asiatica MFLUCC 10-0711 T Panicum sp. Thailand JX256424 JX276436 JX266593
C. australiensis BRIP 12044 T Oryza sativa Australia KJ415540 KJ415406 KJ415452
C. australis BRIP 12521 T Sporobolus caroli Australia KJ415541 KJ415405 KJ415451
C. bannonii BRIP 16732 T Jacquemontia tamnifolia USA KJ415542 KJ415404 KJ415450
C. beasleyi sp. nov. BRIP 10972 T Chloris gayana Australia MH414892 MH433638 MH433654
BRIP 15854 Leersia hexandra Australia MH414893 MH433639 MH433655
C. beerburrumensis sp. nov. BRIP 12942 T Eragrostis bahiensis Australia MH414894 MH433634 MH433657
BRIP 12555 Eragrostis sororia Australia MH414895 MH433640 MH433656
C. boeremae comb. nov. IMI 164633 T Portulaca oleracea India MH414911 MH433641
C. borreriae MFLUCC 11-0422 unknown Poaceae Thailand KP400638 KP419987 KM196571
C. bothriochloae BRIP 12522 T Bothriochloa bladhii Australia KJ415543 KJ415403 KJ415449
C. brachyspora CBS 186.50 Soil India KJ922372 KM061784 KM230405
C. buchloës CBS 246.49 T Buchloë dactyloides USA KJ909765 KM061789 KM196588
C. carica-papayae CBS 135941 T Carica papaya India HG778984 HG779146
C. chiangmaiensis CPC 28829 T Zea mays Thailand MF490814 MF490836 MF490857
C. chlamydospora UTHSC 07-2764 T Homo sapiens USA HG779021 HG779151
C. coatesiae sp. nov. BRIP 24170 air Australia MH414896 MH433635 MH433658
BRIP 24261 T Litchi chinensis Australia MH414897 MH433636 MH433659
C. clavata BRIP 61680b Oryza rufipogon Australia KU552205 KU552167 KU552159
C. coicis CBS 192.29 T Coix lacryma-jobi Japan AF081447 AF081410 JN601006
C. colbranii sp. nov. BRIP 13066 T Crinum zeylanicum Australia MH414898 MH433642 MH433660
C. crustacea BRIP 13524 T Sporobolus sp. Indonesia KJ415544 KJ415402 KJ415448
C. cymbopogonis CBS 419.78 Yucca sp. Netherlands HG778985 HG779129
C. dactyloctenicola CPC 28810 T Dactyloctenium aegyptium Thailand MF490815 MF490837 MF490858
C. dactyloctenii BRIP 12846 T Dactyloctenium radulans Australia KJ415545 KJ415401 KJ415447
C. ellisii CBS 193.62T air Pakistan JN192375 JN600963 JN601007
C. eragrostidis CBS 189.48 Sorghum sp. Indonesia HG778986 HG779154
C. eragrosticola sp. nov. BRIP 12538 T Eragrostis pilosa Australia MH414899 MH433643 MH433661
C. geniculata CBS 187.50 Andropogon sorghum Indonesia KJ909781 KM083609 KM230410
C. gladioli CBS 210.79 Gladiolus sp. Romania HG778987 HG779123
C. graminicola BRIP 23186 T Aristida ingrata Australia JN192376 JN600964 JN601008
C. harveyi BRIP 57412 T Triticum aestivum Australia KJ415546 KJ415400 KJ415446
C. hawaiiensis BRIP 11987 T Oryza sativa USA KJ415547 KJ415399 KJ415445
C. heteropogonicola BRIP 14579 T Heteropogon contortus India KJ415548 KJ415398 KJ415444
C. heteropogonis CBS 284.91 T Heteropogon contortus Australia KJ415549 JN600969 JN601013
C. hominis CBS 136985 T Homo sapiens USA HG779011 HG779106
C. homomorpha CBS 156.60 T air USA JN192380 JN600970 JN601014
C. inaequalis CBS 102.42 T soil France KJ922375 KM061787 KM196574
C. intermedia CBS 334.64 Avena versicolor USA HG778991 HG779155
C. ischaemi CBS 630.82 T Ischaemum indicum Solomon Islands JX256428 JX276440
C. kenpeggii sp. nov. BRIP 14530 T Triticum aestivum Australia MH414900 MH433644 MH433662
C. kusanoi CBS 137.29 Eragrostis major Japan JN192381 JN601016
C. lamingtonensis sp. nov. BRIP 12259 T Microlaena stipoides Australia MH414901 MH433645 MH433663
C. lunata CBS 730.96 T Homo sapiens USA JX256429 JX276441 JX266596
C. malina CBS 131274 T Zoysia matrella USA JF812154 KP153179 KR493095
C. mebaldsii sp. nov. BRIP 12900 T Cynodon transvaalensis Australia MH414902 MH433647 MH433664
BRIP 13983 Cynodon dactylon x transvaalensis Australia MH414903 MH433646 MH433665
C. miyakei CBS 197.29 T Eragrostis pilosa Japan KJ909770 KM083611 KM196568
C. muehlenbeckiae CBS 144.63 T Sorghum sp. USA KP400647 KP419996 KM196578
C. neergaardii BRIP 12919 T Oryza sativa Ghana KJ415550 KJ415397 KJ415443
C. neoindica IMI 129790 T Brassica nigra India MH414910 MH433649 MH433667
C. nicotiae BRIP 11983 T soil Algeria KJ415551 KJ415396 KJ415442
C. nodosa CPC 28800 T Digitaria ciliaris Thailand MF490816 MF490838 MF490859
C. nodulosa CBS 160.58 Eleusine indica USA JN601033 JN600975 JN601019
C. oryzae CBS 169.53 T Oryza sativa Vietnam KP400650 KP645344 KM196590
C. ovariicola CBS 470.90 T Eragrostis interrupta Australia JN192384 JN600976 JN601020
C. pallescens CBS 156.35 T air Indonesia KJ922380 KM083606 KM196570
C. papendorfii CBS 308.67 T Acacia karroo South Africa KJ415552 KJ415395 KJ415441
C. petersonii sp. nov. BRIP 14642 T Dactyloctenium aegyptium Australia MH414905 MH433667 MH433668
C. perotidis CBS 350.90 T Perotis rara Australia JN192385 KJ415394 JN601021
C. pisi CBS 190.48 T Pisum sativum Canada KY905678 KY905690 KY905697
C. platzii sp. nov. BRIP 27703b T Cenchrus clandestinus Australia MH414906 MH433651 MH433669
C. portulacae BRIP 14541 T Portulaca oleracea USA KJ415553 KJ415393 KJ415440
C. prasadii CBS 143.64 T Jasminum sambac India KJ922373 KM061785 KM230408
C. protuberata CBS 376.65 T Deschampsia flexuosa UK KJ922376 KM083605 KM196576
C. pseudobrachyspora CPC 28808 T Eleusine indica Thailand MF490819 MF490841 MF490862
C. pseudolunata UTHSC 09-2092 T Homo sapiens USA HE861842 HE861842
C. pseudorobusta UTHSC 08-3458 Homo sapiens USA HE861838 HF565476
C. ravenelii BRIP 13165 T Sporobolus fertilis Australia JN192386 JN600978 JN601024
C. reesii sp. nov. BRIP 4358 T air Australia MH414907 MH433637 MH433670
C. richardiae BRIP 4371 T Richardia brasiliensis Australia KJ415555 KJ415391 KJ415438
C. robusta CBS 624.68 T Dichanthium annulatum USA KJ909783 KM083613 KM196577
C. ryleyi BRIP 12554 T Sporobolus creber Australia KJ415556 KJ415390 KJ415437
C. senegalensis CBS 149.71 unknown Nigeria HG779001 HG779128
C. soli CBS 222.96T soil Papua New Guinea KY905679 KY905691 KY905698
C. sorghina BRIP 15900 T Sorghum bicolor Australia KJ415558 KJ415388 KJ415435
C. spicifera CBS 274.52 soil Spain JN192387 JN600979 JN601023
C. sporobolicola sp. nov. BRIP 23040b T Sporobolus australasicus Australia MH414908 MH433652 MH433671
C. subpapendorfii CBS 656.74 T soil Egypt KJ909777 KM061791 KM196585
C. trifolii CBS 173.55 Trifolium repens USA HG779023 HG779124
C. tripogonis BRIP 12375 T Tripogon loliiformis Australia JN192388 JN600980 JN601025
C. tropicalis BRIP 14834 T Coffea arabica India KJ415559 KJ415387 KJ415434
C. tsudae ATCC 44764 T Chloris gayana Japan KC424596 KC747745 KC503940
C. tuberculata CBS 146.63 T Zea mays India JX256433 JX276445 JX266599
C. uncinata CBS 221.52 T Oryza sativa Vietnam HG779024 HG779134
C. variabilis CPC 28815 T Chloris barbata Thailand MF490822 MF490844 MF490865
C. verruciformis CBS 537.75 Vanellus miles New Zealand HG779026 HG779133
C. verruculosa CBS 150.63 Punica granatum India KP400652 KP645346 KP735695
C. warraberensis sp. nov. BRIP 14817 T Dactyloctenium aegyptium Australia MH414909 MH433653 MH433672
Curvularia sp. BRIP 17068b Micraira subulifolia Australia MH414904 MH433648 MH433666
BRIP 17439 Trianthema portulacastrum Australia AF081449 AF081406 MH445455

Colonies were described from 7-d-old cultures grown on potato dextrose agar (PDA) (Becton Dickinson), incubated at room temperature (approx. 25 °C) and exposed to near-ultraviolet light on a diurnal cycle. Images of the colonies and herbarium specimens were captured by an Epson Perfection V700 scanner at a 300 dpi resolution. Colour of the colonies was rated according to Rayner (1970). Taxonomic novelties were deposited in MycoBank (http://www.MycoBank.org; Crous et al. 2004).

DNA isolation, amplification, and phylogenetic analyses

Isolates were grown on PDA for 7 d at room temperature (approx. 25 °C). Mycelium was scraped off the PDA cultures and macerated with 0.5 mm glass beads (Daintree Scientific) in a Tissue Lyser (Qiagen). Genomic DNA was extracted with the Gentra Puregene DNA Extraction Kit (Qiagen) according to the manufacturer’s instructions. Amplification and sequencing of the internal transcribed spacer (ITS) region, glyceraldehyde-3-phosphate dehydrogenase (gapdh) and the translation elongation factor 1-alpha (tef1α) loci followed the methods by Tan et al. (2014). All sequences generated were assembled using Geneious v. 9.1.8 (Biomatters Ltd) and deposited in GenBank (Table 1, in bold). Sequences were aligned with selected sequences of Curvularia species obtained from GenBank (Table 1) using the MAFFT alignment algorithm (Katoh et al. 2009) in Geneious. Bipolaris maydis (CBS 136.29) was included as the outgroup. The sequences of each locus were aligned separately and manually adjusted where necessary. The alignment included sequences from ex-type cultures of 63 species of Curvularia and from the reference cultures of 16 species. The Maximum-Likelihood (ML) and Bayesian Inference (BI) methods were used in phylogenetic analyses as described by Tan et al. (2016). Briefly, the ML analysis was run using RAxML v.7.2.8 (Stamatakis and Alachiotis 2010) in Geneious and started from a random tree topology. The nucleotide substitution model used was GTR with a gamma-distributed rate variation. The Markov chain Monte Carlo (MCMC) algorithm was used to create a phylogenetic tree based on Bayesian probabilities using MrBayes v.3.2.1 (Huelsenbeck and Ronquist 2001, Ronquist and Huelsenbeck 2003) in Geneious. To remove the need for a priori model testing, the MCMC analysis was set to sample across the entire general time-reversible (GTR) model space with a gamma-distributed rate variation across the sites. Ten million random trees were generated using the MCMC procedure with four chains. The sample frequency was set at 100 and the temperature of the heated chain was 0.1. Burn-in was set at 25%, after which the likelihood values were stationary. The concatenated alignment was deposited in TreeBASE (S22563).

Unique fixed nucleotide positions were used to characterise and describe two cryptic species (see applicable species notes). For each of the cryptic species that was described, the closest phylogenetic neighbour was selected (Fig. 1) and this focused dataset was subjected to single nucleotide polymorphism (SNP) analysis. These SNPs were determined for each aligned locus using the Find Variation/SNPs feature in Geneious. The SNPs were determined based on a minimum variant frequency of 0.2.

Figure 1. 

Phylogenetic tree based on maximum likelihood analysis of the combined multilocus alignment. RAxML bootstrap values (bs) greater than 70% and Bayesian posterior probabilities (pp) greater than 0.7 are given at the nodes (bs/pp). Novel species names are highlighted in blue. Ex-type isolates are marked with a T. The outgroup is Bipolaris maydis ex-type strain CBS 136.29.

Results

Molecular phylogeny

Approximately 800 bp of the ITS region, 598 bp of the partial region of the gapdh gene and 969 bp of the partial region of the tef1α gene were sequenced from the BRIP isolates. After removing ambiguously aligned regions, the ITS, gapdh and tef1α alignments were trimmed to 474 bp, 544 bp and 867 bp, respectively. The ITS phylogeny was able to resolve 53 of 79 Curvularia species, including 10 of the new species (data not shown). The gapdh phylogeny inferred 12 new species and the tef1α phylogeny resolved all 13 of the new species (data not shown). As the topologies of the single locus phylogenies for the tree datasets did not show any conflicts, they were analysed in a concatenated alignment. The phylogenetic tree based on the concatenated alignment resolved the 17 BRIP isolates into 13 well-supported and unique clades (Fig. 1), which are described in this study as novel species.

Taxonomy

Curvularia beasleyi Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825449
Fig. 2A–D

Type

Australia, Queensland, Beaudesert, from leaf spot on Chloris gayana, 9 Jan. 1974, J.L. Alcorn (holotype BRIP 10972, includes ex-type culture).

Description

Colonies on PDA approx. 4 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous black. Hyphae subhyaline, smooth to branched, septate, up to 3 µm in width. Conidiophores branched, erect, straight to flexuous, geniculate towards apex, brown, paler towards apex, smooth, septate, up to 110 µm long, 4 µm wide; basal cell swollen and darker than the other cells, up to 6 µm diam. Conidiogenous cells integrated, terminal or intercalary, sympodial, pale brown, smooth, with darkened scars. Conidia fusiform, straight to slightly curved, rounded at the apex, (14–) 26–29 (–34) × (5–) 6.5–7.5 (–9) µm, brown to dark brown, 3–7 (mostly 5)-distoseptate; hila conspicuous, slightly protuberant, thickened and darkened, 1−1.5 µm wide.

Figure 2. 

Curvularia beasleyi (BRIP 10972): A colony on PDA B–C conidiophores and conidia D conidia. Curvularia beerburrumensis (BRIP 12942) E colony on PDA F chlamydospores G conidiophore H–I conidia. Curvularia boeremae (IMI 164633) J colony on PDA K conidiophores L conidia. Curvularia coatesiae (BRIP 24261) M colony on PDA N conidiophores O conidia. Scale bars: 1 cm (A, E, J, M); all others – 10 µm.

Etymology

In recognition of Dr Dean R. Beasley, an Australian plant pathologist, for his dedication and numerous innovative contributions to the curation and promotion of the Queensland Plant Pathology Herbarium (BRIP).

Additional material examined

Australia, Queensland, Atherton, from leaf spot on Leersia hexandra, 1 May 1987, J.L. Alcorn, BRIP 15854 (includes culture).

Notes

Curvularia beasleyi is placed in the same clade as C. dactyloctenii, C. hawaiiensis and C. nodosa (Fig. 1). Curvularia dactyloctenii and C. hawaiiensis have been recorded in Australia (Sivanesan 1987, Tan et al. 2014), but the recently described C. nodosa has only been reported from Thailand (Marin-Felix et al. 2017b). Curvularia beasleyi is distinguished in two loci from the ex-type cultures of C. dactyloctenii (99% in gapdh and 99% in tef1α), C. hawaiiensis (98% in gapdh and 99% in tef1α) and C. nodosa (99% in gapdh and 99% in tef1α). The conidia of C. beasleyi are longer than those of C. nodosa (12–25 µm, Marin-Felix et al. 2017b) and shorter than those of C. dactyloctenii (32–55 µm, Sivanesan 1987). Curvularia beasleyi is morphologically similar to C. hawaiiensis, however the later species has never been recorded on Leersia (Farr and Rossman 2018).

Curvularia beasleyi is only known from Queensland on two unrelated grasses, the introduced host Chloris gayana and the native Leersia hexandra. There are many Curvularia species reported as associated with Chloris spp. (C. australiensis, C. australis, C. hawaiiensis, C. lunata, C. nodosa, C. pallescens, C. tsudae, C. variabilis, C. verruculosa) (Sivanesan 1987, Deng et al. 2014, Manamgoda et al. 2014, Marin-Felix et al. 2017b) and Leersia spp. (C. australiensis, C. geniculata, and C. heteropogonicola) (DAF Biological Collections 2018, Farr and Rossman 2018, Herbarium Catalogue 2018), although not all of the reports have been verified by molecular phylogenetic analyses.

Curvularia beerburrumensis Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825450
Fig. 2E–I

Type

Australia, Queensland, Beerburrum, from blackened inflorescence of Eragrostis bahiensis, 24 May 1979, J.L. Alcorn (holotype BRIP 12942, includes ex-type culture).

Description

Colonies on PDA approx. 2 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbrillate, olivaceous black. Hyphae subhyaline, smooth to asperulate, branched, septate, 3−4 µm in width; chlamydospores intercalary in chains, 4–9 µm, smooth, thick-walled. Conidiophores erect, straight to flexuous, geniculate towards apex, subhyaline to pale brown, smooth, septate, up to 500 µm long, 5−6 µm wide. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia fusiform to subcylindrical or clavate, straight to slightly curved, rounded at the apex, (40–) 51–56 (–71) × (10–) 12–13 (–14) µm, subhyaline to pale yellowish-brown, 2–4 (mostly 3)-distoseptate; hila mostly inconspicuous or minutely thickened and darkened.

Etymology

Named after the town Beerburrum, where the holotype was collected.

Additional material examined

Australia, Queensland, Beerburrum, New South Wales, Yetman, blackened inflorescence of Eragrostis sororia, 12 May 1977, J.L. Alcorn, BRIP 12555 (includes culture).

Notes

Curvularia beerburrumensis is phylogenetically sister to C. australis and C. ovariicola (Fig. 1), which have both been recorded in Australia on Eragrostis (Sivanesan 1987, Tan et al. 2014). Curvularia beerburrumensis is distinguished from the ex-type culture of C. australis in three loci (98% in ITS, 96% in gapdh and 98% in tef1α). Furthermore, C. beerburrumensis has larger conidia than C. australis (25−48 × 9.0−12.5 µm, Sivanesan 1987). Curvularia beerburrumensis differs from the ex-type culture of C. ovariicola in three loci (99% in ITS, 99% in gapdh and 99% in tef1α). Curvularia beerburrumensis has longer conidiophores than C. ovariicola (up to 325 µm, Sivanesan 1987). Curvularia beerburrumensis also produced chlamydospores in culture, which are not known for C. australis and C. ovariicola.

Curvularia beerburrumensis is only known from inflorescences of the invasive South American grass Eragrostis bahiensis, as well as the Australian native E. sororia (Simon and Alfonso 2011). Other Curvularia associated with Eragrostis include C. australis, C. clavata, C. crustacea, C. ellisii, C. eragrostidis, C. geniculata, C. kusanoi, C. lunata, C. miyakei, C. nodulosa, C. ovariicola, C. perotidis, C. protuberata, C. ravenelii and C. verrucosa, (Sivanesan 1987, Farr and Rossman 2018, Herbarium Catalogue 2018), although many of these reports are yet to be verified by molecular phylogenetic analyses.

Curvularia boeremae (A.S. Patil & V.G. Rao) Y.P. Tan & R.G. Shivas, comb. nov.

MycoBank No: 825451
Fig. 2J–L

Basionym

Drechslera boeremae A.S. Patil & V.G. Rao, Antonie van Leeuwenhoek 42: 129 (1976).

Description

Colonies on PDA approx. 3 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous green to citrine, velutinous with aerial mycelium. Hyphae subhyaline, smooth to asperulate, branched, septate, 2–3 µm in width. Conidiophores straight to flexuous, slightly geniculate towards apex, uniformly subhyaline to pale brown, smooth, septate, up to 110 µm long, 4 µm wide. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia broadly ellipsoidal to oval, brown to dark brown, smooth, (42–) 46–52 (–55) × (17–) 20–23 (–25) µm, brown to dark brown, 4–6-distoseptate, hila protuberant, thickened and darkened, 2–3 µm wide.

Type

India, Poona, from leaves of Portulaca oleracea, 28 Apr. 1970, A.S. Patil (holotype IMI 164633, includes ex-type culture), (isotype BRIP 13934, includes ex-type culture).

Notes

Multilocus phylogenetic analyses placed the ex-type culture of D. boeremae within the clade that includes C. lunata, the type species of the genus (Fig. 1). Curvularia boeremae differs from C. neoindica in one locus (98% identities in gapdh). Furthermore, C. boeremae has shorter conidia than C. neoindica (27–65 µm, Manamgoda et al. 2014). Sivanesan’s (1987) synonymy of Drechslera boeremae with Bipolaris indica was based on similar conidial morphology and is not supported by the phylogenetic analyses in this study.

Curvularia boeremae is only known from the type specimen on P. oleraceae and has not been recorded in Australia. Curvularia portulacae is the only other species recorded on P. oleraceae (Farr and Rossman 2018). Curvularia boeremae is morphologically distinct from C. portulacae, which has comparatively long, cylindrical conidia (average 110 × 13 µm, Rader 1948).

Curvularia coatesiae Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825452
Fig. 2M–O

Type

Australia, Queensland, Eudlo, from rotted fruit of Litchi chinensis, 28 Jan. 1992, L.M. Coates (holotype BRIP 24261, includes ex-type culture).

Description

Colonies on PDA 6–7 cm diam. after 7 d at 25 °C, surface funiculose, floccose, olivaceous black at the centre, olivaceous to grey olivaceous towards the edge, margin fimbriate. Hyphae subhyaline, smooth to asperulate, septate, up to 3 µm in width. Conidiophores erect, flexuous, geniculate in the top half, uniformly brown, sometimes pale towards apex, septate, up to 190 µm long, 4 µm wide; basal cell sometimes swollen, up to 8 µm diam. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown, mono- or polytretic, with darkened nodes. Conidia ellipsoidal to obovoid, asymmetrical, sometimes the third cell from base is unequally enlarged, intermediate cells dark brown and usually verruculose, end cells paler and less ornamented than central cells, (20–) 23–26 (–30) × (7–) 8–9 (–10) µm, 3-distoseptate; hila protuberant, thickened and darkened, 1–2 µm wide.

Etymology

Named after Dr Lindel (Lindy) M. Coates, an Australian plant pathologist in recognition of her contributions to the study of post-harvest fruit pathology.

Additional material examined

Australia, New South Wales, Alstonville, isolated from the air in a mango orchard, 11 Mar. 1991, G.I. Johnson, BRIP 24170 (includes culture).

Notes

Curvularia coatesiae is morphologically similar and phylogenetically related to a reference culture of C. borreriae and the ex-type culture of C. pallescens (Fig. 1). Curvularia coatesiae differs from the ex-type culture of C. pallescens in three loci: ITS position 439 (T); gapdh positions 219 (C), 287 (C); tef1α positions 43 (C), 257 (C), 259 (C). Although C. borreriae and C. pallescens have been recorded in Australia, these have not been verified by molecular phylogenetic analyses and there have been no additional records beyond the 1980s (Sivanesan 1987, Shivas 1989). Other species recorded from L. chinensis are C. geniculata, C. hawaiiensis, C. lunata and C. pallescens (DAF Biological Collections 2018, Herbarium Catalogue 2018), although not all the reports have been verified by molecular phylogenetic analyses.

Curvularia colbranii Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825453
Fig. 3A–D

Type

Australia, Queensland, Brisbane, from leaf spot on Crinum zeylanicum, 11 Oct. 1976, R.C. Colbran (holotype BRIP 13066, includes ex-type culture).

Description

Colonies on PDA approx. 5 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous black, aerial mycelium white. Hyphae subhyaline, smooth, septate, up to 3 µm in width. Conidiophores erect, flexuous, geniculate, uniformly pale brown to brown, smooth, septate, up to 145 µm long, 4–6 µm wide, basal cell sometimes swollen, up to 8 µm diam. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia fusiform to subcylindrical with rounded apex and obconical at the base, brown, end cells pale, (54–) 83–92 (–110) × (13–) 14–16 (–17) µm, brown to dark brown, 6–9-distoseptate; hila slightly protuberant, thickened and darkened, 1–2 µm wide.

Figure 3. 

Curvularia colbranii (BRIP 13066): A colony on PDA B conidiophore C–D conidia. Curvularia eragrosticola (BRIP 12538) E colony on PDA F conidiophore G chlamydosphores H conidia. Curvularia kenpeggii (BRIP 14530) I colony on PDA J conidiophores and conidium K conidia. Curvularia lamingtonensis (BRIP 12259) L colony on PDA M conidiophore O conidia. Scale bars: 1 cm (A, E, I, L); all others – 10 µm.

Etymology

Named after Dr Robert (Bob) Chester Colbran (1926–2010), an Australian nematologist and Director of the Plant Pathology Branch, Queensland Department of Primary Industries, in recognition of his significant contributions to Australian plant pathology.

Notes

Curvularia colbranii is sister to C. boeremae, C. lamingtonensis (see this paper), C. neoindica and C. portulacae, although separated by a considerable genetic distance (Fig. 1). Curvularia colbranii has fusiform to subcylindrical conidia that are distinct from the ellipsoidal to oval conidia of C. boeremae (42–55 × 17–25 µm, this study) and C. neoindica (27–65 × 17–27 µm, Manamgoda et al. 2014) and longer than those of C. lamingtonensis (45–76 × 11–14 µm, this study). Curvularia colbranii has conidia that are 6–9-distoseptate, while C. portulacae has conidia reported as 3–15 celled (Rader 1948).

Only one other species, C. trifolii, has been reported on Crinum sp. (Shaw 1984), but this record has not been verified by phylogenetic analyses. Curvularia colbranii is morphologically distinct from C. trifolii, which has curved conidia.

Curvularia eragrosticola Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825454
Fig. 3E–H

Type

Australia, New South Wales, Yetman, from inflorescence on Eragrostis pilosa, 12 May 1977, J.L. Alcorn (holotype BRIP 12538, includes ex-type culture).

Description

Colonies on PDA approx. 2 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, dark olive with white patches, velutinous with some aerial mycelium. Hyphae subhyaline, smooth, branched, septate, 4−5 µm wide; chlamydospores abundant, subglobose to ellipsoidal or irregular, terminal and intercalary, 5−20 µm diam. Conidiophores erect, straight to flexuous, slightly geniculate, pale brown to brown, paler towards apex smooth, septate, up to 145 µm long, 4−5 µm wide. Conidiogenous cells integrated, terminal or intercalary, sympodial, pale brown to brown, smooth, with darkened scars. Conidia hemi-ellipsoidal, curved, asymmetrical, brown to dark brown, end cells slightly paler, (25–) 26–30 (–34) × (9–) 13–15 (–19) µm, 3-distoseptate with a faint narrow median septum; hila non-protuberant, minutely thickened and darkened.

Etymology

Named after Eragrostis, the grass genus from which this fungus was isolated.

Notes

Curvularia eragrosticola is phylogenetically close to C. papendorfii and C. sporobolicola (see this paper) (Fig. 1). Curvularia eragrosticola is distinguished in three loci from the ex-type culture of C. papendorfii (97% in ITS, 92% in gapdh and 98% in tef1α) and C. sporobolicola (98% in ITS, 92% in gapdh and 98% in tef1α). Curvularia eragrosticola has conidia that are smaller than C. papendorfii (30–50 × 17–30 µm, Sivanesan 1987) and C. sporobolicola (34–45 × 14–23 µm, this study).

Curvularia eragrosticola is only known from the type specimen on Eragrostis pilosa, which is native to Eurasia and Africa and is considered a troublesome weed in Australia (Simon and Alfonso 2011). Neither C. papendorfii nor C. sporobolicola have been reported on Eragrostis. Other Curvularia spp. associated with Eragrostis are listed in the notes for C. beerburrumensis.

Curvularia kenpeggii Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825455
Fig. 3H–J

Type

Australia, Queensland, from mouldy grain of Triticum aestivum, 26 Oct. 1984, J.L. Alcorn (holotype BRIP 14530, includes ex-type culture), (isotype IMI 290719).

Description

Colonies on PDA 3–4 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, floccose and olivaceous black at the centre with white patches, velutinous with some aerial mycelium. Hyphae hyaline, asperulate, branched, septate, 4−5 µm in width. Conidiophores erect, straight to flexuous, slightly geniculate in the upper part, pale brown to brown, sometimes paler towards the apex, verrucose, septate, up to 360 µm long, 4−5 µm wide, basal cell sometimes swollen, up to 8 µm. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia ellipsoidal to clavate to obovoid, asymmetrical, third cell from the base is unequally enlarged, brown, end cells paler, verruculose, (31–) 35–39 (–42) × (10–) 13–14 (–15) µm, 3-distoseptate, hila protuberant, thickened and darkened, 1–2 µm wide.

Etymology

Named after Dr Kenneth G. Pegg AM (member of the Order of Australia), in celebration of his 60 years of dedication to plant pathology in Australia and to thank him for his generous mentorship.

Notes

Curvularia kenpeggii is only known from the holotype specimen and is genetically distinct from all other Curvularia species (Fig. 1). Curvularia kenpeggii is basal to a clade comprised of C. australis, C. beerburrumensis, C. crustacea, C. miyakei, C. ovariicola, C. ravenelii and C. ryleyi. These species are mostly reported as pathogens of Eragrostis and Sporobolus spp. and not known to be associated with wheat (Triticum aestivum). Curvularia species associated with T. aestivum in Australia are C. brachyspora, C. harveyi, C. hawaiiensis, C. lunata, C. perotidis, C. ramosa and C. spicifera, (Shivas 1989, Farr and Rossman 2018), although not all the reports have been verified by molecular phylogenetic analyses.

Curvularia lamingtonensis Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825456
Fig. 3L–N

Type

Australia, Queensland, Lamington National Park, from Microlaena stipoides, 09 May 1977, J.L. Alcorn (holotype BRIP 12259, includes ex-type culture).

Description

Colonies on PDA cover the whole plate after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous green, velutinous with some aerial mycelium. Hyphae hyaline, branched, septate, 4 µm in width. Conidiophores erect, straight to flexuous, geniculate towards apex, pale brown to dark brown on wheat straw agar, septate, up to 160 µm long, 3−4 µm wide. Conidiogenous cells integrated, terminal or intercalary, sympodial, pale brown to brown, smooth, with darkened scars. Conidia ellipsoidal to fusiform, straight, pale brown, (45–) 59–66 (–76) × (11–) 11.5–13 (–14) µm, 4–11-distoseptate with inconspicuous transverse septa, hila protuberant, thickened and darkened, 1–2 µm wide.

Etymology

Named after the locality, Lamington National Park, where the holotype was collected.

Notes

Curvularia lamingtonensis is phylogenetically closely related to C. boeremae and C. neoindica. Curvularia lamingtonensis is distinguished from the ex-type culture of C. boeremae in two loci (96% in ITS and 98% in gapdh) and from the ex-type culture of C. neoindica in three loci (95% in ITS, 98% in gapdh and 99% in tef1α). Curvularia lamingtonensis has longer and straighter conidia than C. boeremae and C. neoindica, both of which have broad, ellipsoidal conidia (42–55 × 20–23 µm, and 27–65 × 17–27 µm, respectively). Curvularia lamingtonensis is only known from the type specimen on Microlaena stipoides. This is the first record of a Curvularia species associated with Microlaena.

Curvularia mebaldsii Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825457
Fig. 4A–C

Type

Australia, Victoria, Hopetoun, from Cynodon transvaalensis, Apr. 1979, M. Mebalds (holotype BRIP 12900, includes ex-type culture).

Description

Colonies on PDA approx. 5 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous black with white patches, velutinous with some aerial mycelium. Hyphae hyaline to subhyaline, smooth to asperulate, septate, 3–4 µm wide. Conidiophores erect, straight to flexuous, sometimes slightly geniculate towards apex, branched, uniformly brown, paler at apex, smooth to asperulate, septate, up to 180 µm long, 4–5 µm wide. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, subhyaline to pale brown, smooth, mono- or polytretic, with darkened scars. Conidia ellipsoidal to obovoid, sometimes straight to slightly curved, rounded at the apex, (22–) 25–28 (–30) × (7–) 8–9 (–10) µm, pale brown to brown, 3-distoseptate, hila protuberant, thickened and darkened, 1–2 µm wide.

Figure 4. 

Curvularia mebaldsii (BRIP 12900): A colony on PDA B conidiophores and conidium C conidia. Curvularia petersonii (BRIP 14642) D colony on PDA E–F conidiophores and conidium G conidia. Curvularia platzii (BRIP 27703b) H colony on PDA I conidiophores J–K conidia. Scale bars: 1 cm (A, D, H); all others – 10 µm.

Etymology

Named after the collector, Martin Mebalds, in recognition of his contributions to Australian plant pathology and biosecurity.

Additional material examined

Australia, New South Wales, Tweed Heads, from necrotic leaf on Cynodon dactylon × transvaalensis, 10 Jun. 1983, G. Thomas, BRIP 13983 (includes culture).

Notes

The multilocus phylogenetic analyses showed that C. mebaldsii was sister to C. tsudae, although separated by a considerable genetic distance (Fig. 1). Curvularia mebaldsii is distinguished from the ex-type culture of C. tsudae in three loci (98% in ITS, 97% in gapdh and 99% in tef1α). Morphologically, C. mebaldsii cannot be reliably separated from C. tsudae.

Curvularia mebaldsii is known from two specimens on Cynodon spp. Several Curvularia species have been associated with Cynodon, including C. aeria, C. australiensis, C. brachyspora, C. clavata, C. fallax, C. geniculata, C. hawaiiensis, C. inaequalis, C. lunata, C. pallescens, C. ramosa, C. senegalensis, C. spicata, C. spicifera and C. verruculosa (DAF Biological Collections 2018, Farr and Rossman 2018, Herbarium Catalogue 2018), although these records have not been verified by phylogenetic analyses.

Curvularia petersonii Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825458
Fig. 4D–G

Type

Australia, Northern Territory, Daly Waters, from leaf spot on Dactyloctenium aegyptium, 20 Mar. 1985, R.A. Peterson (holotype BRIP 14642, includes ex-type culture).

Description

Colonies on PDA approx. 5 cm diam. after 7 d at 25 °C, surface funiculose, olivaceous black, velutinous with some aerial mycelium, margin fimbriate. Hyphae subhyaline, smooth to asperulate, septate, up to 3 µm in width. Conidiophores erect, straight to flexuous, rarely branched, slightly geniculate, uniformly brown, sometimes pale brown at apex, smooth, septate, up to 110 µm long, 4 µm wide. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia obovoid to ellipsoidal, straight to slightly curved, (15–) 17–19 (–21) × (5–) 5.5–6 (–7) µm, brown, end cells pale, 3-distoseptate, hila non-protuberant, thickened and darkened.

Etymology

Named after Ron A. Peterson, an Australian plant pathologist, in recognition of his contributions to tropical plant pathology.

Notes

The multilocus phylogenetic analyses placed C. petersonii sister to C. americana and C. verruculosa, although separated by a considerable genetic distance (Fig. 1). Both C. americana and C. verruculosa have been found in Australia (DAF Biological Collections 2018, Herbarium Catalogue 2018). Curvularia petersonii is distinguished from the ex-type culture of C. americana in two loci (94% in ITS and 92% in gapdh) and from a reference culture of C. verruculosa in three loci (92% in ITS, 92% in gapdh and 98% in tef1α). Curvularia petersonii has smaller conidia than C. americana (13–28 × 7–15 µm, Madrid et al. 2014) and C. verruculosa (20–40 × 12–17 µm, Sivanesan 1987).

Curvularia petersonii is only known from a single specimen on Dactyloctenium aegyptium in the Northern Territory. Many Curvularia species have been associated with Dactyloctenium, including C. clavata, C. dactyloctenicola, C. dactyloctenii, C. eragrostidis, C. lunata, C. neergaardii, C. pallescens and C. verruculosa (Sivanesan 1987, Manamgoda et al. 2014, Farr and Rossman 2018, Herbarium Catalogue 2018, Marin-Felix et al. 2017b), although these records have not been verified by phylogenetic analyses.

Curvularia platzii Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825459
Fig. 4H–I

Type

Australia, Queensland, Warwick, from leaf spot on Cenchrus clandestinus, 24 Jan. 2001, G.J. Platz (holotype BRIP 27703b, includes ex-type culture).

Description

Colonies on PDA approx. 2 cm diam. after 7 d at 25 °C, surface dark olivaceous green. Hyphae subhyaline, smooth, septate, up to 3 µm wide. Conidiophores erect, straight to flexuous, geniculate towards apex, uniformly brown, sometimes pale brown towards apex, septate, up to 75 µm long, 5–6 µm wide, swollen at base, 8–10 µm. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia fusiform to narrowly clavate, brown, end cells sometimes paler, (65–) 94–105 (–115) × (11–) 12.5–13.5 (–14) µm, 9–13-distoseptate; hila non-protuberant, thickened and darkened.

Etymology

Named after Gregory (Greg) J. Platz, in recognition of his contributions to Australian cereal plant pathology for the past 30 years, as well as his prowess as an international and Queensland rugby league footballer.

Notes

The multilocus phylogenetic analyses indicated C. platzii was sister to C. hominis, C. meuhlenbeckiae and C. pisi (Fig. 1). Curvularia platzii is distinguished in one locus from the ex-type culture of C. hominis (97% in tef1α) and in two loci from the reference culture of C. meuhlenbeckiae (99% in gapdh and 99% in tef1α) and the ex-type culture of C. pisi (98% in gapdh and 99% in tef1α). Curvularia platzii differs from C. hominis, C. meuhlenbeckiae and C. pisi, which have much shorter asymmetrical conidia with fewer septa (Madrid et al. 2014, Marin-Felix et al. 2017a).

Curvularia platzii is only known from the holotype. The host, Cenchrus clandestinus (syn. Pennisetum clandestinus), is a perennial grass with a worldwide distribution (Simon and Alfonso 2011). Other Curvularia species associated with C. clandestinus are C. lunata, C. nodulosa and C. trifolii (Farr and Rossman 2018, Herbarium Catalogue 2017), although these records have not been verified by phylogenetic analyses.

Curvularia reesii Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825460
Fig. 5A–C

Type

Australia, Queensland, Brisbane, isolated from air, 22 Jun. 1963, R.G. Rees (holotype BRIP 4358, includes ex-type culture).

Description

Colonies on PDA approx. 6−7 cm diam. after 7 d at 25 °C, surface funiculose, greenish-grey, velutinous with some aerial mycelium, margin fimbriate. Hyphae hyaline, branched, septate, 3−4 µm in width. Conidiophores erect, straight to flexuous, slightly geniculate towards apex, pale brown to brown, sometimes paler towards the apex, septate, up to 200 µm long, 4−5 µm wide. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia ellipsoidal to obclavate, straight, third cell from pore swollen, brown, end cells paler, smooth, (28–) 31–35 (–39) × (10–) 12–13 (–14) µm, mostly 3 septate; hila inconspicuous, sometimes darkened.

Figure 5. 

Curvularia reesii (BRIP 4358): A colony on PDA B conidiophore C conidia. Curvularia sporobolicola (BRIP 23040b) D colony on PDA E conidiophores F conidia. Curvularia warraberensis (BRIP 14817) G colony on PDA H conidiophore I conidia. Scale bars: 1 cm (A, D, G); all others – 10 µm.

Etymology

Named after Dr Robert (Bob) G. Rees, an Australian plant pathologist, in recognition of his extensive contributions to cereal pathology.

Notes

The multilocus phylogenetic analyses indicated C. reesii was sister to C. oryzae and C. tuberculata. Curvularia reesii is distinguished in two loci from the ex-type cultures of C. oryzae (98% in gapdh and 99% in tef1α) and C. tuberculata (96% in gapdh and 99% in tef1α). Morphologically, C. reesii has conidia similar in size to C. oryzae (24–40 × 12–22 µm, Sivanesan 1987) and C. tuberculata (23–52 × 13–20 µm, Sivanesan 1987). The isolate of C. reesii examined in this study had become sterile.

Curvularia sporobolicola Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825461
Fig. 5C–E

Type

Australia, Queensland, Musselbrook Reserve, leaf of Sporobolus australasicus, 2 May 1995, J.L. Alcorn (holotype BRIP 23040b, includes ex-type culture).

Description

Colonies on PDA approx. 6 cm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous black, velutinous. Hyphae subhyaline, smooth, branched, septate, 3 µm wide. Conidiophores erect, straight to flexuous, geniculate, pale yellowish-brown, septate, up to 55 µm long, 4−5 µm wide, basal cell swollen, 6−10 µm diam. Conidiogenous cells cylindrical, slightly flared at the apex, integrated, sympodial, pale brown, smooth, with darkened and thickened scars. Conidia hemi-ellipsoidal, curved, 4-distoseptate with a faint narrow median septum, (34–) 37–41 (–45) × (14–) 17–20 (–23) µm, brown to dark brown, end cells rounded and paler, hila non-protuberant, sometimes darkened.

Etymology

Named after Sporobolus, the grass genus from which it was isolated.

Notes

Based on multilocus phylogenetic analyses, C. sporobolicola clustered sister to C. papendorfii, which are both sister to C. eragrosticola (Fig. 1). Curvularia sporobolicola is distinguished in three loci from the ex-type cultures of C. papendorfii (99% in ITS, 96% in gapdh and 98% in tef1α) and C. eragrosticola (98% in ITS, 92% in gapdh and 98% in tef1α). These three species are similar in having dark brown, hemi-ellipsoidal, curved, conidia, which makes identification by morphology difficult. The conidia of C. sporobolicola tend to be wider than those of C. eragrosticola (25–35 × 9–19 µm, this study) and C. papendorfii (30–50 × 9–19 µm, Sivanesan 1987).

Curvularia sporobolicola is only known from the type specimen on S. australasicus, which is a native Australian grass with a broad distribution in the tropics and subtropics (Simon and Alfonso 2011). Other Curvularia species associated with Sporobolus include C. australis, C. crustacea, C. eragrostidis, C. geniculata, C. lunata, C. ovariicola, C. pallescens, C. ravenelii and C. ryleyi (Sivanesan 1987, Farr and Rossman 2018), although this is the first Curvularia species associated with S. australasicus.

Curvularia warraberensis Y.P. Tan & R.G. Shivas, sp. nov.

MycoBank No: 825462
Fig. 5F–H

Type

Australia, Queensland, Torres Strait, Warraber Island, from leaf spot on Dactyloctenium aegyptium, 2 Jun. 1985, R.A. Peterson (holotype BRIP 14817, includes ex-type culture).

Description

Colonies on PDA 6–7 mm diam. after 7 d at 25 °C, surface funiculose, margin fimbriate, olivaceous green, velutinous with some aerial mycelium. Hyphae subhyaline, smooth, septate, up to 3 µm wide. Conidiophores erect, flexuous, geniculate towards apex, uniformly pale brown to brown, septate, up to 360 µm long, 4–5 µm wide, basal cell sometimes swollen, 6–8 µm diam. Conidiogenous cells integrated, terminal or intercalary, with sympodial proliferation, pale brown to brown, smooth, mono- or polytretic, with darkened scars. Conidia ellipsoidal, curved, the third cell from base swollen, end cells paler, smooth, (20–) 23–26 (–28) × (8–) 9.5–11 µm, pale brown to brown, 3-distoseptate, hila conspicuous, sometimes slightly protuberant, thickened and darkened.

Etymology

Named after the locality, Warraber Island in the Torres Straits, where the specimen was collected.

Notes

Multilocus phylogenetic analyses placed C. warraberensis sister to C. caricae-papayae and C. prasadii (Fig. 1). Curvularia warraberensis differs from the ex-type culture of C. caricae-papayae in gapdh positions 40 (C), 102 (C), 230 (A), 233 (C) and 321 (A) and from the ex-type culture of C. prasadii in two loci, gapdh positions 102 (C), 131 (C), 230 (A), 233 (C), 321 (A) and tef1α positions 214 (C), 337 (C), 542 (A), 543 (C), 685 (C). These three species belong to the lunata-clade sensu Madrid et al. (2014), which also includes C. aeria, C. brachyspora, C. chlamydospora, C. lunata and C. pseudolunata. All the species in the lunata-clade sensu Madrid et al. (2014) have 4-celled conidia in which the third cell from the base is often swollen (unequally sided and larger) and darker than the other cells. Curvularia warraberensis has longer conidiophores than C. caricae-papayae (up to 100 µm long, Srivastava and Bilgrami 1963) and longer conidia than C. caricae-papayae (12.8–18.0 × 6–8 µm) and C. prasadii (12.8–18.0 × 6–8 µm, Mathur and Mathur 1959).

Curvularia warraberensis is only known from the holotype. Curvularia species associated with Dactyloctenium are listed in the notes for C. petersonii.

Discussion

Although the ITS locus is the universal barcode marker for fungi (Schoch et al. 2012), secondary loci are often essential for the accurate identification of many helminthosporioid species (Manamgoda et al. 2012, 2015, Madrid et al. 2014, Tan et al. 2014, 2016, Stielow et al. 2015. Hernández-Restrepo et al. 2018). The protein-coding loci of gapdh, tef1α and RNA polymerase II second largest subunit (rpb2) have been reported as phylogenetically informative in the phylogenetic analyses of sequence data from species of Curvularia (Hernández-Restrepo et al. 2018, Manamgoda et al. 2014, Marin-Felix et al. 2017a, 2017b). In this study, sequences of three loci (ITS, gapdh and tef1α) from 17 cultures in BRIP were compared with those from ex-type cultures as well as published reference cultures for species of Bipolaris and Curvularia. The phylogenetic analyses of the concatenated three-locus dataset resolved the 17 BRIP isolates into 13 novel Curvularia species.

Eight Curvularia species are described here from grasses (Poaceae) exotic to Australia, namely, C. beasleyi on Chloris gayana, C. beerburrumensis on Eragrostis bahiensis, C. eragrosticola on E. pilosa, C. kenpeggii on Triticum aestivum, C. mebaldsii on Cynodon dactylon × transvaalensis, C. petersonii and C. warraberensis on Dactyloctenium aegyptium and C. platzii on Cenchrus clandestinus. Only two species were described from native Australian grasses, C. lamingtonensis on Microlaena stipoides and C. sporobolicola on Sporobolus australasicus. Two species were described from other hosts, C. coatesiae from Litchi chinensis (Sapindaceae) and C. colbranii from Crinum zeylanicum (Amaryllidaceae). One species, C. reesii, was described from an isolate obtained from an air sample. Furthermore, DNA sequences derived from ex-type cultures have supported the generic placement of C. neoindica and the transfer of Drechslera boeremae to Curvularia.

It is not known whether the species described here are pathogens, endophytes or saprobes. It is also unclear as to whether these species are native or introduced. Curvularia beasleyi and C. beerburrumensis were both isolated from a native Australian grass species, as well as an exotic host. Some grass species have been reported to be associated with multiple Curvularia species, such as Chloris and Cynodon, with nine and 15 species, respectively. Many of the published records on Chloris and Cynodon have not been verified by molecular analyses. The number of new species described from non-Australian grasses indicates a need for a molecular-based reassessment of previous host-species records. The description of these species provides a foundation upon which additional sampling and accumulation of molecular data will improve knowledge of the host ranges and ecological roles of helminthosporioid fungi in Australia and overseas.

Acknowledgements

The authors wish to thank Dr John L. Alcorn (former curator of the BRIP) for his support, as well as acknowledge his foresight in preserving the cultures examined in this study.

References

  • Almaguer M, Rojas TI, Dobal V, Batista A, Aira MJ (2013) Effect of temperature on growth and germination of conidia in Curvularia and Bipolaris species isolated from the air. Aerobiologia 29: 13–20. https://doi.org/10.1007/s10453-012-9257-z
  • Atlas of Living Australia (2018) Atlas of Living Australia. http://www.ala.org.au [Accessed 11 January 2018]
  • Crous PW, Gams W, Stalpers JA, Robert V, Stegehuis G (2004) MycoBank: An online initiative to launch mycology into the 21st century. Studies in Mycology 50: 19–22
  • Deng H, Tan YP, Shivas RG, Niu YC (2014) Curvularia tsudae comb. nov. et nom. nov., formerly Pseudocochliobolus australiensis, and a revised synonymy for Curvularia australiensis. Mycoscience 56: 24–28. https://doi.org/10.1016/j.myc.2014.02.002
  • Hargreaves M, Parappukkaran S, Morawska L, Hitchins J, He C, Gilbert D (2003) A pilot investigation into associations between indoor airborne fungal and non-biological particle concentrations in residential houses in Brisbane, Australia. Science of The Total Environment 312: 89–101. https://doi.org/10.1016/S0048-9697(03)00169-4
  • Madrid H, da Cunda KC, Gené J, Dijksterhuis J, Cano J, Sutton DA, Guarro J, Crous PW (2014) Novel Curvularia species from clinical specimens. Persoonia 33: 48–60. https://doi.org/10.3767/003158514X683538
  • Manamgoda DS, Cai L, McKenzie EHC, Crous PW, Madrid H, Chukeatirote E, Shivas RG, Tan YP, Hyde KD (2012) A phylogenetic and taxonomic re-evaluation of the Bipolaris-Cochliobolus-Curvularia complex. Fungal Diversity 56: 131–144. https://doi.org/10.1007/s13225-012-0189-2
  • Manamgoda DS, Rossman AY, Castlebury LA, Chukeatirote E, Hyde KD (2015) A taxonomic and phylogenetic re-appraisal of the genus Curvularia (Pleosporaceae): human and plant pathogens. Phytotaxa 212(3): 175–198. https://doi.org/10.11646/phytotaxa.212.3.1
  • Mathur RL, Mathur BL (1959) A new species of Curvularia from the leaves of Jasminum sambac. Current Science 28(11): 448–449.
  • Morgan-Jones G (1988) Notes on hyphomycetes. LIX. Curvularia bannonii sp. nov., an undescribed leaf pathogen of Jacquemontia tamnifolia. Mycotaxon 33(1–2): 407–412.
  • Rayner RW (1970) A Mycological Colour Chart. Commonwealth Mycological Institute, Kew.
  • Schoch CL, Seifert KA, Huhndorf S, Robert V, Spouge JL, Levesque CA, Chen W, Bolchacova E, Voigt K, Crous PW, Miller AN (2012) Nuclear ribosomal internal transcribed spacer (ITS) region as a universal DNA barcode marker for fungi. Proceedings of the National Academy of Sciences USA 109(16): 6241–6246. https://doi.org/10.1073/pnas.1117018109
  • Sharma R, Prakash O, Sonawane MS, Nimonkar Y, Golellu PB et al. (2016) Diversity and distribution of phenol oxidase producing fungi from soda lake and description of Curvularia lonarensis sp. nov. Frontiers in Microbiology 7: 1847. https://doi.org/10.3389/fmicb.2016.01847
  • Shaw DE (1984) Microorganisms in Papua New Guinea. Department of Primary Industry Research Bulletin 33: 1–344.
  • Shivas RG (1989) Fungal and bacterial diseases of plants in Western Australia. Journal of the Royal Society of Western Australia 72: 1–62.
  • Sivanesan A (1987) Graminicolous species of Bipolaris, Curvularia, Drechslera, Exserohilum and their teleomorphs. Mycological Papers 158: 1–261
  • Sivanesan A, Alcorn JL, Shivas RG (2003) Three new graminicolous species of Curvularia (anamorphic fungi) from Queensland, Australia. Australian Systematic Botany 16(2): 275–278. https://doi.org/10.1071/SB02007
  • Srivastava HP, Bilgrami KS (1963) A new species of Curvularia on the leaves of Carica papaya L. Current Science 32(12): 558–559.
  • Stielow JB, Lévesque CA, Seifert KA, Meyer W, Iriny L, Smits D, Renfurm R, Verkley GJM, Groenewald M, Chaduli D, Lomascolo A, Welti S, Lesage-Meessen L, Favel A, Al-Hatmi AMS, Damm U, Yilmaz N, Houbraken J, Lombard L, Quaedvlieg W, Binder M, Vaas LAI, Vu D, Yurkov A, Begerow D, Roehl O, Guerreiro M, Fonseca A, Samerpitak K, van Diepeningen AD, Dolatabadi S, Moreno LF, Casaregola S, Mallet S, Jacques N, Roscini L, Egidi E, Bizet C, Garcia-Hermoso D, Martín MP, Deng S, Groenewald JZ, Boekhout T, de Beer ZW, Barnes I, Duong TA, Wingfield MJ, de Hoog GS, Crous PW, Lewis CT, Hambleton S, Moussa TAA, Al-Zahrani HS, Almaghrabi OA, Louis-Seize G, Assabgui R, McCormick W, Omer G, Dukik K, Cardinali G, Eberhardt U, de Vries M, Robert V (2015) One fungus, which genes? Development and assessment of universal primers for potential secondary fungal DNA barcodes. Persoonia 35: 242–263. https://doi.org/10.3767/003158515X689135
  • Tan YP, Madrid H, Crous PW, Shivas RG (2014) Johnalcornia gen. et. comb. nov., and nine new combinations in Curvularia based on molecular phylogenetic analysis. Australasian Plant Pathology 43(6): 589–603. https://doi.org/10.1007/s13313-014-0315-6
  • Verma P, Singh S, Singh R (2013) Seven species of Curvularia isolated from three lakes of Bhopal. Advances in Life Science and Technology 8: 13–15.