Applying early divergent characters in higher rank taxonomy of Melampsorineae (Basidiomycota, Pucciniales)

ABSTRACT

Rust fungi in the order Pucciniales represent one of the largest groups of phytopathogens, which occur on mosses, ferns to advanced monocots and dicots. Seven suborders and 18 families have been reported so far, however recent phylogenetic studies have revealed para- or polyphyly of several morphologically defined suborders and families, particularly in Melampsorineae. In this study, a comprehensive phylogenetic framework was constructed based on a molecular phylogeny inferred from rDNA sequences of 160 species belonging to 16 genera in Melampsorineae (i.e. Chrysomyxa, Cerospora, Coleopuccinia, Coleosporium, Cronartium, Hylospora, Melampsora, Melampsorella, Melampsoridium, Milesina, Naohidemyces, Pucciniastrum, Quasipucciniastrum, Rossmanomyces, Thekopsora, Uredinopsis). Our phylogenetic inference indicated that 13 genera are monophyletic with strong supports, while Pucciniastrum is apparently polyphyletic. A new genus, Nothopucciniastrum was therefore established and segregated from Pucciniastrum, with ten new combinations proposed. At the family level, this study further demonstrates the importance of applying morphologies of spore-producing structures (basidia, spermogonia, aecia, uredinia and telia) in higher rank taxonomy, while those traditionally applied spore morphologies (basidiospores, spermatia, aeciospores, urediniospores and teliospores) represent later diverged characters that are more suitable for the taxonomy at generic and species levels. Three new families, Hyalopsoraceae, Nothopucciniastraceae and Thekopsoraceae were proposed based on phylogenetic and morphological distinctions, towards a further revision of Pucciniales in line with the phylogenetic relationships.

Introduction

Plant parasitic rusts, taxonomically as members of the order Pucciniales, are one of the most diverse groups of fungal pathogens, with over 7 800 species recognised worldwide (Arthur 1934; Hiratsuka et al. 1992; Zhao et al. 2021; Aime et al. 2006; Webster and Weber 2007). Rusts are obligate parasites with up to five different spore types, including basidiospores, spermatia, aeciospores, urediniospores, teliospores, as well as different lifestyles (micro-, hemi-, demi-, or macrocyclic) that occur on a single (autoecious), or alternate between two unrelated host plants (heteroecious) (Cummins and Hiratsuka 1983). Many species are wreaking havoc on agricultural and forest crop plants, resulting in significant economic losses (Cummins and Hiratsuka 2003). Due to the serious threats posed to these crops, Puccinia spp. on wheat and Melampsora lini on flax were listed in the “top 10 most important fungal pathogens” in a recent global survey of important plant pathogens (Dean et al. 2012). Furthermore, many rust species, such as Austropuccinia psidii (myrtle rust), Cronartium ribicola (white pine blister rust), Hemileia vastatrix (coffee rust), Phakopsora pachyrhizi (Asian soybean rust) etc., are known to be among the most important and threatening species to agriculture and forestry (Ono et al. 1992; Beenken 2014, 2017). Despite the importance of rust fungi, their taxonomy is still debated due to the lack of information on host alternation, and morphological characteristics of their various spore stages (Kuprevich and Tranzschel 1957; Savile 1976; Aime 2006).

The taxonomic ranks of plant-parasitic rusts vary at the generic and suprageneric levels. Rust fungi have been classified into different classes (Basidiomycetes, Pucciniomycetes or Urediniomycetes) or orders (Pucciniales or Uredinales) at various time periods (Plowright 1889; Dietel 1928; Cummins 1971; Hiratsuka et al. 1992). Rust fungi were recently found to be monophyletic, and the order Pucciniales was proposed to accommodate these plant parasitic rusts (Aime et al. 2006; Hibbett et al. 2007; Zhao et al. 2016). At the family level, the traditional taxonomy of rust fungi changed dramatically over time, and they were divided into 2–14 families based on criteria applied at the time. At early 20^th century, all rusts were initially divided into 2–4 families on the basis of the presence of teliospore pedicels and basidial formation (Dietel 1928; Arthur 1934; Hiratsuka 1955). Such a taxonomic treatment has been widely debated, as many apparently unrelated genera have been placed in the same family simply because of morphological similarities in their teliospores (Wilson and Henderson 1966; Leppik 1972; Hiratsuka and Sato 1982). Later, spermogonial morphology was introduced as criterion and the taxonomic importance of this criterion at the family level was further evaluated (Hiratsuka and Cummins 1963; Savile 1976). Hiratsuka and Cummins summarised 12 morphological types of spermogonia in rust fungi and categorised them into six major groups based on the structure of spermogonia (Cummins and Hiratsuka 1983). Thus, a taxonomic scheme with 14 families was proposed and uredinologists universally accepted this taxonomic classification (Hiratsuka and Cummins 1983; Hiratsuka et al. 1992; Cummins and Hirastuka 2003). However, several defined families, such as Chaconiaceae, Pucciniaceae, Pucciniastraceae, Pucciniosiraceae and Uropyxidaceae, have been revealed to be poly- or paraphyletic in molecular phylogenetic studies (Maier et al. 2003; Wingfield et al. 2004; Aime 2006). Aime (2006) has roughly divided the order Pucciniales into three suborders based on molecular phylogeny: Melampsorineae, Mikronegeriineae and Uredinineae, but the polyphyly of several morphologically defined families remains unresolved (Maier et al. 2003; Wingfield et al. 2004; Beenken et al. 2012; Beenken and Wood 2015; Qi et al. 2019). Thereafter, Aime and McTaggart (2021) presented a high-rank classification of the Pucciniales, in which the order was divided into seven suborders and 18 families. Among these families, all rusts with sessile teliospores were classified in the suborder Melampsorineae, with 16 genera included in four families, Coleosporiaceae, Melampsoraceae, Milesinaceae and Pucciniastraceae based on their aecial similarities. However, these families showed significant morphological differences in the structures of spermogonia and telia, which have long been employed as the main criteria for family classification (Cummins and Hiratsuka 1983, 2003). As a result, the taxonomic placement of these 16 genera remains a point of contention, and it is necessary to reassign those genera in the proper family in the suborder Melampsorineae.

In this study, we conducted molecular phylogenetic analyses and morphological reappraisal of Melampsorineae. The objectives of this study were: (1) to evaluate the monophyly of traditional morphologically defined genera and determine their familial placements and generic boundaries in Melampsorineae; (2) to propose a taxonomic amendment towards establishing monophyletic families in Melampsorineae.

Materials and methods

Molecular phylogeny and supergeneric-level delimitation

We have included sequence data from our previous taxonomic studies on genera in Melampsorineae (Zhao et al. 2014, 2015, 2016, 2017, 2020, 2021; Qi et al. 2019) as well as some newly generated sequence data from our one unpublished paper (under review), and detailed information of specimens, host species and GenBank accession numbers has been listed in Table 1. In addition, rDNA sequence data from previous taxonomic studies on Pucciniales, particularly those in Melampsorineae, were included in the final alignment (Table 1). Those sequences were acquired from taxonomic references and retrieved from NCBI (https://www.ncbi.nlm.nih.gov/) based on the accession number. To determine the phylogenetic relationships of genera in the suborder Melampsorineae, rDNA ITS and LSU sequences of representative taxa from the genera Chrysomyxa, Coleopuccinia, Coleosporium, Cronartium, Hylospora, Melampsora, Melampsorella, Melampsoridium, Milesina, Naohidemyces, Pucciniastrum, Quasipucciniastrum, Rossmanomyces, Thekopsora, and Uredinopsis were chosen for phylogenetic studies (Table 1). Two Gymnosporangium species were selected as outgroups. The majority of the sequence data came from samples that had detailed morphological information.

Table 1.

rDNA sequence data from selected genera in the Melampsorineae suborder of Pucciniales order used for phylogenetic studies.

Family	Genus	Species	Specimen No.a	Spore stage	Host	Country	GenBank Accession No.a		Reference
							ITS	LSU
Cronartiaceae	Cronartium	Cronartium appalachianum	Ca-1	0, I	Pinus virginiana	USA	L76484	—	Vogler & Bruns (1998)
		Cronartium arizonicum	MICH253346	II, III	Castilleja linariaefolia	USA	MK208284	MK193824	Qi et al. (2019)
			MICH301493	0, I	Pinus ponderosa	USA	OM746343	OM746511	Present study
			FSprP- 1	0, I	Pinus ponderosa	USA	L76504	—	Vogler & Bruns (1998)
		Cronartium armandii	ZP-R901	II, III	Ribes sp.	China	OM746349	OM746517	Present study
			HMAS45350	0, I	Pinus armandii	China	MZ520620	MZ520623	Present study
		Cronartium bethelii	MICH253453	II, III	Quercus emoryi	USA	OM746353	OM746521	Present study
			FLAS-F-16608	0, I	Pinus palustris	USA	OM746355	OM746523	Present study
			CrKor-1	0, I	Pinus strobus	USA	L76497	—	Vogler & Bruns (1998)
		Cronartium coleosporioides	CsSr-1	0, I	Pinus contorta	USA	L76500	—	Vogler & Bruns (1998)
			SHmC-9	0, I	Pinus contorta	USA	L76511	—	Vogler & Bruns (1998)
			SPC-21	0, I	Pinus contorta var. latifolia	USA	L76513	—	Vogler & Bruns (1998)
		Cronartium comandrae	HMAS24619	II, III	Comandra richardsiana	Canada	OM746358	OM746526	Present study
			ISC392261	II, III	Comandra pallida	USA	OM746362	OM746530	Present study
			MICH253330	II, III	Comandra pallida	USA	OM746365	OM746533	Present study
			MICH253516	II, III	Comandra pallida	USA	OM746367	OM746535	Present study
			MICH253517	II, III	Comandra pallida	USA	OM746368	OM746536	Present study
			UBC-F5867	II, III	Comandra pallida	USA	OM746370	OM746538	Present study
			BCpC-15	0, I	Pinus contorta	USA	L76477	—	Vogler & Bruns (1998)
			CPeEl-1	0, I	Pinus eldarica	USA	L76481	—	Vogler & Bruns (1998)
			NYBG36363	0, I	Pinus sp.	USA	OM746374	OM746542	Present study
			NYBG36381	0, I	Pinus sp.	USA	OM746375	OM746543	Present study
		Cronartium comptoniae	UBC-F5871	II, III	Comptonia peregrina	USA	OM746377	OM746545	Present study
			UBC-F5870	II, III	Comptonia asplenitolia	USA	OM746378	OM746546	Present study
			MICH253506	0, I	Pinus banksiana	Canada	OM746382	OM746550	Present study
		Cronartium flaccidum	FLAS-F-55559	II, III	Paeonia officinalis	Finland	OM746383	OM746551	Present study
			HMAS37551	II, III	Paeonia lactiflora	China	OM746389	OM746557	Present study
			HMAS89231	II, III	Paeonia lactiflora	China	MK208289	MK193822	Present study
			HMAS44164	0, I	Pinus taiwanensis	China	MK208288	MK193816	Present study
		Cronartium floridanum	MICH299992	0, I	Pinus palustris	USA	OM746408	OM746576	Present study
			MICH300092	0, I	Pinus palustris	USA	OM746409	OM746577	Present study
		Cronartium fusiforme	HMAS56356	II, III	Quercus variabilis	China	OM746415	OM746583	Present study
			HMAS71281	II, III	Quercus variabilis	China	OM746416	OM746584	Present study
			HMAS9043	II, III	Quercus emoryii	USA	OM746418	OM746586	Present study
			HMAS35526	II, III	Quercus sp.	China	OM746419	OM746587	Present study
			HMAS52087	0, I	Pinus silvestris	China	OM746420	OM746588	Present study
		Cronartium keteleeriae	HMAS638	0, I	Keteleeria davidiana	China	OM746422	—	Present study
			HMAS11129	0, I	Keteleeria davidiana	China	OM746421	OM746588	Present study
			HMAS638	0, I	Keteleeria davidiana	China	OM746422	—	Present study
		Cronartium occidentale	MICH253479	II, III	Ribes gandfalii	USA	OM746429	OM746594	Present study
			MICH253477	II, III	Ribes odoratum	USA	OM746430	OM746595	Present study
			MICH253481	II, III	Ribes aureum	USA	OM746431	OM746596	Present study
		Cronartium orientale	HMAS242642	II, III	Quercus aquifolioides	China	OM746433	OM746599	Present study
			HMAS77666	II, III	Quercus liaotungensis	China	OM746435	OM746601	Present study
			HMAS77667	II, III	Quercus liaotungensis	China	OM746436	OM746602	Present study
			HMAS82717	II, III	Quercus glandulifera	China	MK208292	MK193817	Qi et al. (2019)
		Cronartium pini	Cclone 3	II, III	Melampyrum sp.	Finland	JF713709	—	Kaitera et al. (2011)
			Crust 1	0, I	Pinus sylvestris	Finland	KJ959593	—	Kaitera et al. (2015)
			Crust 2	0, I	Pinus sylvestris	Finland	KJ959594	—	Kaitera et al. (2015)
		Cronartium pyriforme	MICH253420	0, I	Pinus contorta	USA	OM746451	OM746617	Present study
			MICH253360	II, III	Comandra pallida	USA	OM746452	OM746618	Present study
		Cronartium quercuum	MICH253529	II, III	Quercus rubra	Canada	OM746455	OM746621	Present study
			ISC395258	II, III	Quercus imbricaria	USA	OM746461	OM746627	Present study
			CqE9WM-FP	0, I	Pinus banksiana	USA	JN943197	—	Schoch et al. (2012)
			40CR-PNB-LP1	0, I	Pinus sp.	Canada	JN943249	—	Schoch et al. (2012)
		Cronartium ribicola	UBC-F5886	II, III	Ribes bracteosum	USA	OM746479	OM746645	Present study
			TSH-17009	II, III	Ribes sativum	Japan	OM746480	OM746646	Present study
			NYBG267056	II, III	Ribes sp.	Canada	OM746483	OM746649	Present study
			MICH253525	II, III	Ribes nigrum	Romania	OM746484	OM746650	Present study
			TSH-1094	II, III	Pinus coronata	Japan	OM746491	OM746657	Present study
			UBC-F5879	0, I	Pinus monticola	Canada	OM746492	OM746658	Present study
		Cronartium strobilinum	807-ISFSL-FP	0, I	Pinus sp.	USA	JN943191	—	Schoch et al. (2012)
			G-317-HGS1-FP	0, I	Pinus sp.	USA	JN943192	—	Schoch et al. (2012)
		Cronartium sp.1	HMAS41544	II, III	Saussurea bullockii	China	OM746501	OM746667	Present study
		Cronartium sp.2	HMAS40888	II, III	Ribes aureum	Germany	—	OM746665	Present study
			HMAS49226	II, III	Ribes aureum	USA	OM746500	OM746666	Present study
		Cronartium sp.3	CFB22250	0, I	Pinus banksiana	USA	DQ206982	AY700193	Matheny et al. (2006)
			PUR N11655	II, III	Quercus muehlenbergii	USA	KY587788	—	Abbasi et al. (2017)
			CqL-1	II, III	Lithocarpus densiflorus	USA	L76489	—	Vogler & Bruns (1998)
			CqQ-1	II, III	Quercus agrifolia	USA	L76490	—	Vogler & Bruns (1998)
		Cronartium sp.4	MICH253424	II, III	Quercus rubra	Canada	OM746457	OM746623	Present study
		Cronartium sp.5	HMAS244165	0, I	Pinus taiwanensis	China	OM746503	—	Present study
		Cronartium sp.6	HMAS18841	II, III	Castanea sp.	China	OM746356	OM746524	Present study
			HMAS8970	0, I	Pinus ponderosa	USA	OM746357	OM746525	Present study
		Cronartium sp.7	HMAS242639	II, III	Quercus mongolica	China	OM746423	—	Present study
			ZP-R7	II, III	Quercus mongolica	China	OM746424	OM746589	Present study
		Cronartium sp.8	MICH301494	II, III	Pinus murrayana	USA	OM746425	OM746590	Present study
		Cronartium sp.9	MICH253485	II, III	Myrica asplenifolia	Canada	OM746427	OM746592	Present study
			MICH253505	II, III	Myrica gale	Canada	OM746428	OM746593	Present study
		Cronartium sp.10	NYBG267052	II, III	Pinus sp.	USA	OM746443	OM746609	Present study
			NYBG267053	II, III	Pinus strobus	Canada	MK208298	MK193829	Qi et al. (2019)
			NYBG267051	II, III	Ribes nigrum	USA	MK208296	MK193828	Qi et al. (2019)
		Cronartium sp.11	HMAS56423	II, III	Quercus aliena	China	OM746453	OM746619	Present study
			HMAS74356	II, III	Quercus aliena	China	OM746454	OM746620	Present study
		Cronartium sp.12	HMAS52871	II, III	Ribes nigrum	China	OM746496	OM746662	Present study
			HMAS172046	II, III	Ribes nigrum	China	OM746497	OM746663	Present study
			FLAS-F-16581	0, I	Pinus taeda	USA	OM746498	OM746664	Present study
Family incertae sedis	Quasipucciniastrum	Quasipucciniastrum agrimoniae	HMAS67301	II, III	Agrimonia pilosa	China	MK208261	MK193832	Qi et al. (2019)
			HMAS63888	II, III	Agrimonia pilosa	China	MK208266	MK193837	Qi et al. (2019)
			HMAS13479	II, III	Agrimonia pilosa	China	MK208268	MK193839	Qi et al. (2019)
			HMAS67309	II, III	Agrimonia pilosa	China	MK208263	MK193834	Qi et al. (2019)
			HMAS67306	II, III	Agrimonia pilosa	China	MK208262	MK193833	Qi et al. (2019)
			HMAS24481	II, III	Agrimonia pilosa	China	MK208267	MK193838	Qi et al. (2019)
			HMAS172173	II, III	Agrimonia pilosa	China	MK208265	MK193836	Qi et al. (2019)
			HMAS248095	II, III	Agrimonia pilosa	China	MK208281	MK193852	Qi et al. (2019)
			HMAS172175	II, III	Agrimonia pilosa	China	MK208272	MK193843	Qi et al. (2019)
			HMAS77430	II, III	Agrimonia pilosa	China	MK208271	MK193842	Qi et al. (2019)
			HMAS67302	II, III	Agrimonia pilosa	China	MK208273	MK193844	Qi et al. (2019)
			HMAS82312	II, III	Agrimonia pilosa	China	MK208264	MK193835	Qi et al. (2019)
Chrysomyxaceae	Chrysomyxa	Chrysomyxa arctostaphyli	CFB22246	II, III	―	―	DQ200930	AY700192	AFTOL-ID 442
		Chrysomyxa cassandrae	QFB 25019	II, III	Chamaedaphne calyculata	Canada	GU049446	GU049529	Feau et al. (2011)
			813CHC-PC-LP4	0, I	Picea mariana	Canada	GU049450	GU049531	Feau et al. (2011)
		Chrysomyxa chiogenis	QFB 25026	II, III	Gaultheria hispidula	Canada	GU049452	GU049532	Feau et al. (2011)
			631CHS-GAH-ZM28	II, III	Gaultheria hispidula	Canada	GU049453	GU049533	Feau et al. (2011)
		Chrysomyxa empetri	QFB 25015	II, III	Empetrum nigrum	Canada	GU049434	GU049526	Feau et al. (2011)
		Chrysomyxa ledi	4D10	0, I	Picea abies	Finland	HM037711	HM037707	Kaitera et al. (2010)
			240709	0, I	Picea abies	Finland	HM037708	HM037703	Kaitera et al. (2010)
		Chrysomyxa ledicola	195CHO_PCM_X1c	0, I	Picea mariana	Canada	GU049417	GU049520	Feau et al. (2011)
			24CHO_LEG_RW1	0, I	Picea mariana	Canada	GU049418	FJ666446	Feau et al. (2011)
		Chrysomyxa nagodhii	QFB 25006	II, III	Rhododendron groenlandicum	Canada	GU049431	GU049524	Feau et al. (2011)
			201CH_LE_LE2	II, III	Ledum glandulosumc	Canada	GU049427	J666450	Feau et al. (2011)
		Chrysomyxa neoglandulosi	DAOM 229530	II, III	Ledum glandulosumc	Canada	GU049498	GU049550	Feau et al. (2011)
		Chrysomyxa piperiana	DAFVP 14997	II, III	Ledum macrophyllumc	Canada	GU049497	GU049565	Feau et al. (2011)
		Chrysomyxa purpurea	BJFC-R02299	0, I	Picea purpurea	Sichuan, China	NR_158401	MW063518	Cao et al. (2017)
			BJFC-R02300	II, III	Rhododendron oreodoxa	China	KX225402	MW898418	Cao et al. (2017)
			BJFC-R01698	II, III	Rhododendron oreodoxa	China	KX225401	—	Cao et al. (2017)
			BJFC-R02448	II, III	Rhododendron oreodoxa	China	MK770362	MK874622	Cao et al. (2017)
			BJFC-R01699	II, III	Rhododendron oreodoxa	China	KX225405	—	Cao et al. (2017)
			HMAS55188	0, I	Picea purpurea	China	KX225403	MW898421	Yang (2015)
			BJFC-R02623	II, III	Rhododendron sp.	China	MK770364	—	Yang (2015)
			BJFC-R02302	0, I	Picea purpurea	China	MK770363	MK874623	Yang (2015)
		Chrysomyxa rhododendri	DAFVP14606	II, III	Ledum lapponicumc	Canada	GU049467	GU049560	Feau et al. (2011)
		Chrysomyxa vaccinii	DAOM 45774	II, III	Vaccinium parvifolium	Canada	GU049463	GU049561	Feau et al. (2011)
			DAVFP 10115	II, III	Vaccinium parvifolium	Canada	GU049465	GU049562	Feau et al. (2011)
		Chrysomyxa woroninii	QFB 25025	II, III	Ledum groenlandicum	Canada	GU049462	GU049540	Feau et al. (2011)
		Chrysomyxa zhuoniensis	BJFC-R02733	II, III	Rhododendron sp.	China	MK770374	MK874636	Yang (2015)
	Rossmanomyces	Rossmanomyces monesis	DAOM 221982	II, III	Pyrola uniflora	Canada	GU049476	GU049547	Feau et al. (2011)
			DAVFP 14528	0, I	Picea sitchensis	Canada	GU049479	GU049566	Feau et al. (2011)
		Rossmanomyces pyrolae	Only DNA extraction	II, III	Pyrola asarifolia	Canada	GU049481	GU049558	Feau et al. (2011)
			DAOM 214476	II, III	Pyrola minor	Canada	GU049483	GU049553	Feau et al. (2011)
			QFB 16517	0, I	Picea sp.	Canada	GU049484	GU049554	Feau et al. (2011)
			Herbarium 12886	0, I	Picea glauca	Canada	GU049485	GU049555	Feau et al. (2011)
			Herbarium CPP	0, I	Picea glauca	Canada	GU049486	GU049556	Feau et al. (2011)
			QFB 25055	0, I	Picea glauca	Canada	GU049487	—	Feau et al. (2011)
			QFB 25057	II, III	Pyrola sp.	Canada	GU049489	—	Feau et al. (2011)
			390CHP-PCG-VF1	II, III	Pyrola sp.	Canada	—	FJ666456	Vialle et al. (2013)
Coleosporiaceae	Coleosporium	Coleosporium asterum	BPI 879270	II, III	Solidago sp.	USA	GU058009	—	Dixon (unpublished)
			RS1325	II, III	Solidago sp.	Canada	HQ317530	—	Beenken et al. (2017)
			N43	II, III	Kalimeris sp.	Japan	KX386012	KX386044	Zhao (unpublished)
		Coleosporium cacaliae	LB09281 / ZT-Myc-58004	II, III	Adenostyles aliariae	Switzerland	KY810462	—	Beenken et al. (2017)
			LB09265 / ZT-Myc-58002	II, III	Campanula latifolia	Switzerland	KY810467	—	Beenken et al. (2017)
		Coleosporium clematidis	N81	II, III	Clematis sp.	Japan	KX386007	KX386039	Zhao (unpublished)
			N99	II, III	Clematis sp.	Japan	KX386008	KX386040	Zhao (unpublished)
			N79	II, III	Clematis sp.	Japan	KX386010	KX386042	Zhao (unpublished)
		Coleosporium delicatulum	BPI 877848	II, III	Solidago sp.	USA	MF769637	—	McTaggart et al. (2018)
			BPI 871731	II, III	Symphyotrichum novae-angliae	USA	MF769638	—	McTaggart et al. (2018)
		Coleosporium inulae	GBOL / KR-M-0024937	0, I	Pinus sylvestris	Germany	KY783673	—	Beenken et al. (2017)
			LB09168 / ZT-Myc-57996	II, III	Inula salicina	Switzerland	KY810470	—	Beenken et al. (2017)
		Coleosporium montanum	BPI 877858	II, III	Solidago sp.	USA	MF769635	—	McTaggart et al. (2018)
			BPI 877849	II, III	Solidago sp.	USA	MF769636	—	McTaggart et al. (2018)
			WU:43601	II, III	Symphyotrichum novae-angliae	Austria	MW284589	—	Voglmayr (2020)
		Coleosporium petasitidis	LB09254 / ZT-Myc-58000	II, III	Petasites hybridus	Switzerland	KY810471	—	Beenken et al. (2017)
		Coleosporium phellodendri	N7	II, III	Phellodendron amurense	Japan	KX386015	KX386047	Zhao (unpublished)
			TSH-R8823	II, III	Solidago sp.	Russia	KX386016	KX386048	Zhao et al. (2017)
		Coleosporium plectranthi	N16	II, III	Phellodendron amurense	Japan	KX386009	KX386041	Zhao (unpublished)
			N85	II, III	Phellodendron amurense	Japan	KX386011	KX386043	Zhao (unpublished)
		Coleosporium plumeriae	GDPR 2-4	II, III	Plumeria sp.	Caribbean	KF879087	—	Beenken et al. (2017)
			BPI 880744	II, III	Plumeria sp.	—	KY764063	—	Demers et al. (unpublished)
			BPI 844177	II, III	Plumeria sp.	Guyana	MF769645	—	McTaggart (2018)
			U50	II, III	Plumeria rubra	Guyana	MG907225	—	Vialle (2013)
		Coleosporium senecionis	PDD-98309	II, III	Senecio sp.	New Zealand	KJ716348	—	Beenken et al. (2017)
		Coleosporium solidaginis	BPI 863448	II, III	Solidago sp.	USA	DQ354559	—	Aime (2006)
			BPI 877855	II, III	Solidago sp.	USA	MF769649	—	McTaggart et al. (2018)
			BPI 877852	II, III	Solidago sp.	USA	MF769652	—	McTaggart et al. (2018)
		Coleosporium tussilaginis	PDD 93250	II, III	Brachyglottis huntii	New Zealand	KX985766	—	McTaggart et al. (2018)
			BPI 843412	II, III	Senecio triangularis	USA	MF769653	—	McTaggart et al. (2018)
			MCA2389	II, III	Sonchus sp.	USA	MG907228	—	Vialle et al. (2018)
		Coleosporium vernoniae	BPI 877867	II, III	Elephantopus tomentosus	USA	MF769654	—	McTaggart et al.(2017)
			BPI 877869	II, III	Vernonia sp.	USA	MF769655	—	McTaggart et al. (2017)
		Coleosporium zanthoxyli	KUS-F29608	II, III	Zanthoxylum planispinum	South Korea	MH465095	MH460677	Kim (unpublished)
			KUS-F25423	II, III	Zanthoxylum planispinum	South Korea	MH465096	MH460678	Kim (unpublished)
Thekopsoraceae	Thekopsora	Thekopsora areolata	LR 4B	0, I	Picea abies	Norway	DQ445892	—	Hietala et al. (2008)
			SPL3 5	0, I	Picea abies	Norway	DQ445893	—	Fossdal et al. (unpublished)
			Spl 3 5	0, I	Picea abies	Norway	DQ087229	—	Hietala et al. (2008)
			Thek 2	0, I	Picea abies	Norway	DQ087230	—	Hietala et al. (2008)
			Ru 4	0, I	Prunus padus	Norway	DQ087231	—	Hietala et al. (2008)
			2_0910	0, I	Picea engelmannii	Finland	KJ546897	KJ546894	Kaitera et al. (2010)
Melampsoraceae	Ceropsora	Ceropsora weirii	574CHW_X_MA7	0, I	Picea sp.	Canada	GU049473	GU49544	Feau et al. (2011)
			912CHW_PCG_BU3	0, I	Picea sp.	Canada	GU049474	GU49545	Feau et al. (2011)
	Melampsora	Melampsora abietis-canadensis	666X-TSC-SH11	II, III	—	Canada	EU808020	FJ666512	Feau et al. (2009)
			1399MEA-POG-USA	II, III	Populus grandidentata	USA	JN881733	JN934918	Vialle et al. (2013)
		Melampsora aecidioides	—	II, III	Populus alba	Canada	EU808021	FJ666510	Feau et al. (2009)
		Melampsora albertensis	BPI 0021209	II, III	—	USA	JX416848	JX416843	Vialle et al. (2013)
		Melampsora allii-populina	1260MEAP-POC-HU	II, III	Populus canadensis	—	JN881728	JN934902	Vialle et al. (2013)
		Melampsora apocyni	LYR3	II, III	Apocynum venetum	China	KR296802	KR296803	Gao et al. (unpublished)
		Melampsora arctica	HMAS 8629	II, III	Salix iliensis	China	KX386083	KX386112	Zhao et al. (2017)
		Melampsora capraearum	NYS-F-003819	II, III	Salix caprea	Germany	KU550034	KU550033	Zhao et al. (2016)
		Melampsora coleosporioides	HNMAP3114	II, III	Salix reinii	Japan	KF780755	KF780638	Zhao et al. (2015)
		Melampsora epiphylla	TSH-R12280	II, III	Salix sachalinensis	Japan	KF780787	KF780670	Zhao et al. (2017)
		Melampsora epitea	TNS-F-121034	II, III	Salix viminalis	Germany	KX386070	KX386097	Zhao et al. (2017)
		Melampsora euphorbiae	BPI 871135	II, III	Euphorbia heterophylla	—	DQ911599	AF426195	Deadman et al. (unpublished)
		Melampsora euphorbiae-gerardianae	BRIP 39560	II, III	Euphorbia peplus	—	EF192199	—	Aime et al. (unpublished)
		Melampsora ferrinii	PUR N6742	II, III	Salix babylonica	USA	KJ136570	KJ136563	Toome (2015)
			SAG-21943/2016	II, III	Salix sp.	Chile	KY053852	KY053853	Zapata (2016)
		Melampsora humilis	TSH-R7650	II, III	Salix koriyanagi	Japan	KF780812	KF780695	Zhao et al. (2017)
		Melampsora iranica	HMAAC4055	II, III	Salix sp.	China	MK372158	MK372191	Wang et al. (2020)
		Melampsora kamikotica	HNMAP3186	II, III	Chosenia arbutifolia	China	KF780760	KF780643	Zhao et al. (2015)
		Melampsora laricis-miyabeana	TSH-R18314	II, III	Salix reinii	Japan	KX386071	—	Zhao et al. (2017)
		Melampsora laricis-pentandrae	HNMAP3201	II, III	Salix pentandra	China	KF780801	KF780684	Zhao et al. (2015c)
		Melampsora larici-tremulae	PFH-99-1	II, III	Populus tremula	—	JN881744	JN934956	Vialle et al. (2013)
		Melampsora magnusiana	1426MEG-CJ-DSD	II, III	Chelidonium majus	Sachsen	GQ479845	JN934927	Vialle et al. (2013)
		Melampsora medusae f. sp. deltoidis	98D10	II, III	Populus euramericana	South Africa	GQ479307	JN934962	Vialle et al. (2013)
		Melampsora medusae f. sp. tremuloides	1028ME-LAL-LJ	II, III	Larix laricina	Canada	GQ479883	—	Vialle et al. (2013)
		Melampsora microsora	HH-53150	II, III	Salix subfragilis	Japan	KF780834	KF780717	Zhao et al. (2015c)
		Melampsora microspora	97MP10a	II, III	Populus nigra	Iraq	JN881737	JN934931	Vialle et al. (2013)
		Melampsora nujiangensis	AAH00-1	II, III	Pinus alba	England	AY444772	AY444786	Pei et al. (2005)
		Melampsora occidentalis	1366MEPR-POPRURT	II, III	Populus diversifolia	China	GQ479899	JN934938	Vialle et al. (2013)
		Melampsora rostrupii	O8ZK4	II, III	Mercurialis annua	Italy	GQ479320	JN934941	Vialle et al. (2013)
		Melampsora pakistanica	BA13c	II, III	Euphorbia helioscopia	Pakistan	KX237555	KX237556	Ali et al. (2016)
		Melampsora pinitorqua	1367MPI-PNI-FI	0, I	Pinus sylvestris	Finland	GQ479897	JN934973	Vialle et al. (2013)
		Melampsora populnea	PDD 98363	II, III	Ricinus communis	New Zealand	KJ716352		Padamsee and McKenzie (2014)
		Melampsora pruinosae	1366MEPR-POPR-UR	II, III	Populus pruinosa	Canada	GQ479898	JN934939	Feau et al. (2011)
		Melampsora pulcherrima	O8ZK2	II, III	Mercurialis annua	Canada	JN934940	GQ479321	Feau et al. (2011)
		Melampsora ribesii-purpureae	HMAS62584	II, III	Salix purpurea	China	KF780766	KF780649	Zhao et al. (2017)
		Melampsora ribesii-viminalis	HNMAP1968	II, III	Salix viminalis	China	KX386069	KX386096	Zhao et al. (2017)
		Melampsora ricini	PDD 98363	II, III	Ricinus communis	—	KJ716352	—	Padamsee (2014)
		Melampsora rostrupii	PFH08-3	II, III	Populus alba	France	JN881752	JN934981	Vialle et al. (2013)
		Melampsora salicis-albae	NWC-06210	II, III	Salix alba	England	KF780757	KF780640	Zhao et al. (2015c)
		Melampsora salicis-argyraceae	HMAS52984	II, III	Salix argyracea	China	KF780733	KF780616	Zhao et al. (2015c)
		Melampsora salicis-bakko	HNMAP1710	II, III	Salix sinica	China	KC631839	KC685596	Zhao et al. (2015c)
		Melampsora salicis-cavaleriei	HMAAC4043	II, III	Salix serrulatifolia	China	MK277296	MK277301	Wang et al. (2020)
		Melampsora salicis-futurae	TSH-R9620	II, III	Salix futura	Japan	KC631860	KC685617	Zhao et al. (2017)
		Melampsora salicis-purpureae	HMAS62584	II, III	Salix purpurea	China	KF780766	KF780649	Zhao et al. (2017)
		Melampsora salicis-sinicae	HNMAP1710	II, III	Salix sinica	China	KC631839	KC685596	Zhao et al. (2014)
			HNMAP1716	II, III	Salix sinica	China	KC631844	KC685601	Zhao et al. (2015c)
		Melampsora salicis-triandrae	HNMAP3181	II, III	Salix triandra	China	KF780829	KF780712	Zhao et al. (2017)
		Melampsora salicis-viminalis	HMAS38658	II, III	Salix viminalis	China	KF780732	KF780615	Zhao et al. (2015c)
		Melampsora x columbiana	sn-35	II, III	Populus angustifolia	USA	JQ042235		Busby et al. (2012)
		Melampsora yezoensis	TSH-R1504	II, III	Salix jessoensis	Nagano	KF780806	KF780731	Zhao et al. (2015)
			TSH-R1507	II, III	Salix jessoensis	Nagano	KF780832	KF780715	Zhao et al. (2015)
Pucciniastraceae	Melampsorella	Melampsorella caryophyllacearum	PUR 82	II, III	Cerastium sp.	USA	—	MG907233	Aime et al. (2018)
			WM 1092	0, I	Abies alba	—	—	AF426232	Maier et al. (2003)
	Pucciniastrum	Pucciniastrum circaeae	TSH-R10187	II, III	Circaea erubescens	Japan	AB221456	AB221387	Liang et al. (2006)
			B 2098	II, III	Circaea lutetiana	Canada	—	AY74569	Vialle (unpublished)
		Pucciniastrum epilobii	MK697276	II, III	Oenothera acaulis	—	MK697276	—	Hietala et al. (2008)
			Ru11	II, III	Epilobium watsonii	Norway	DQ445907	—	Vialle et al. (2013)
			Ru6	II, III	Epilobium angustifolium	USA	DQ445906	—	Vialle et al. (2013)
			PUR N11088	II, III	Chamaenerion angustifolium	—	—	MW049277	Aime & McTaggart (2021)
		Pucciniastrum guttatum	PDD 91889	II, III	Galium odoratum	New Zealand	KJ716345		Padamsee (2014)
		Pucciniastrum lanpingensis	BJFC-R00355	0, I	Pinus sylvestris	France	KF551225	KF551208	Yang et al. (2015)
		Pucciniastrum minimum	LD 1081	II, III	Vaccinium corymbosum	Mexico	—	HM439777	Rebollar-Alviter et al. (2011)
			PREM 60245	II, III	Vaccinium corymbosum	South Africa	—	GU355675	Yang et al. (2015)
		Pucciniastrum myosotidii	PDD 93251	II, III	Myosotidium hortensia	New Zealand	—	KJ716347	Padamsee (2014)
		Pucciniastrum nipponicum	HMBF-GS-53.1	II, III	Galium davuricum	China	KC415792	KC416001	Yang et al. (2015)
			HMBF-GS-54.1	II, III	Galium aparine	China	KC415793	KC416003	Yang et al. (2015)
		Pucciniastrum pustulatum	PDD 101572	II, III	Epilobium chlorifolium	New Zealand	KJ698631	—	Padamsee (2014)
		Pucciniastrum rubiae	HMBF-XZ-1.1	II, III	Rubia cordifolia	China	KC415802	KC416009	Yang (2015)
		Pucciniastrum verruculosum	KUS-F29482	II, III	Aster tataricus	Korea	MZ725013	MZ724685	Lee et al. (2021)
Nothopucciniastraceae	Nothopucciniastrum	Nothopucciniastrum actinidiae	TSH-R23801	II, III	Actinidia arguta	Japan	AB221446	AB221403	Liang et al. (2006)
		Nothopucciniastrum boehmeriae	TSH-R21289	II, III	Boehmeria tricuspis	Japan	AB221450	AB221393	Liang et al. (2006)
		Nothopucciniastrum corni	TSH-R4273 (IBA7671)	II, III	Clethra kuosa	Japan	AB221436	AB221408	Liang et al. (2006)
		Nothopucciniastrum fagi	TSH-R21254	II, III	Fagus crenata	Japan	AB221424	AB221375	Liang et al. (2006)
			TSH-R10724	II, III	Fagus crenata	Japan	AB221425	AB221378	Liang et al. (2006)
		Nothopucciniastrum hikosanense	TSH-R4287 (IBA2565)	II, III	Acer rufinerva	Japan	AB221441	AB221388	Liang et al. (2006)
			TSH-R4289 (IBA8441)	II, III	Actinidia rufinerva	Japan	AB221440	AB221389	Liang et al. (2006)
		Nothopucciniastrum kusanoi	HH98635	II, III	Clethra barbinervis	Japan	AB221429	AB221400	Liang et al. (2006)
			TSH-R21252	II, III	Clethra barbinervis	Japan	AB221430	AB221401	Liang et al. (2006)
		Nothopucciniastrum miyabeanum	TSH-R4281 (IBA8721)	II, III	Viburnum furcatum	Japan	AB221442	AB221394	Liang et al. (2006)
			TSH-R10202	II, III	Viburnum furcatum	Japan	AB221443	AB221397	Liang et al. (2006)
		Nothopucciniastrum styracinum	TSH-R t015	II, III	Styrax japonica	Japan	AB221431	AB221416	Liang et al. (2006)
		Nothopucciniastrum tiliae	TSH-R4294 (IBA7670)	II, III	Tilia japonica	Japan	AB221453	AB221414	Liang et al. (2006)
			TSH-R4295 (IBA7878)	II, III	Tilia japonica	Japan	AB221454	AB221415	Liang et al. (2006)
		Nothopucciniastrum yoshinagai	TSH-R4272 (IBA8430)	II, III	Stewartia monadelpha	Japan	AB221434	AB221411	Liang et al. (2006)
			TSH-R4270 (IBA8404)	II, III	Stewartia monadelpha	Japan	AB221435	AB221410	Liang et al. (2006)
Hyalopsoraceae	Coleopuccinia	Coleopuccinia sinensis	BJFC-R02506	II, III	Cotoneaster microphyllus	China	MF802288	MF802285	Cao et al. (2018)
			BJFC-R02364	II, III	Cotoneaster rubens	China	MF802287	MF802284	Cao et al. (2018)
			BJFC-R02506	II, III	Cotoneaster rubens	China	MF802286	MF802283	Cao et al. (2018)
	Hyalopsora	Hyalopsora nodispora	PR # 40	II, III	Adiantum capillus-veneris	Pakistan	—	MW899330	Riaz et al. (unpublished)
			BPI 893262	II, III	Adiantum capillus-veneris	USA	—	KY798373	Demers (unpublished)
			BPI 893261	II, III	Adiantum capillus-veneris	USA	KY798372		Demers (unpublished)
		Hyalopsora polypodii	BPI 893256	II, III	Athyrium attenuatum	USA	—	KY798367	Demers (unpublished)
			K187058	II, III	—	United Kingdom	MZ159483		Gaya et al. (unpublished)
			PDD 71999	II, III	Deparia petersenii	New Zealand	—	KJ698627	Padamsee & McKenzie (2014)
		Hyalopsora neocheilanthis	BJFC-R00590	II, III	—	China	MK795975	MK795969	Liang et al. (unpublished)
		Hyalopsora japonica	BJFC-R00401	II, III	—	China	MK795974	MK795968	Liang et al. (unpublished)
		Hyalopsora aspidiotus	PUR N4641	II, III	—	China	—	MW049264	Liang et al. (unpublished)
		Hyalopsora sp. 1	BJFC-R02435	II, III	—	China	MK795976	MK795970	Liang et al. (unpublished)
	Melampsoridium	Melampsoridium alni	H7019539	II, III	Alnus mandshurica	Finland	KF031557	KF031534	McKenzie et al. (2013)
		Melampsoridium betulinum	ZP-R490	II, III	Betula sp.	China	MK518946	MK518638	Zhao et al. (2021)
			H 6035417	II, III	Betula pubescens	Finland	KF031556	KF031539	McKenzie et al. (2013)
			PDD 102645	II, III	Alnus cordata	New Zealand	KF031559	KF031544	McKenzie et al. (2013)
		Melampsoridium hiratsukanum	PDD 77191	II, III	Alnus pubescens	Austria	KF031564	KF031546	McKenzie et al. (2013)
			PDD 78493	II, III	Alnus incana	Austria	KF031565	KF031547	McKenzie et al. (2013)
Milesinaceae	Uredinopsis	Uredinopsis osmundae	U856	II, III	Osmunda sp.	USA	—	MG907245	Aime et al. (2018)
			U1188	II, III	Athyrium sp.	USA	—	MG907244	Aime et al. (2018)
		Uredinopsis pteridis	U856	II, III	Osmunda sp.	USA	—	KM249869	Aime et al. (2018)
		Uredinopsis filicina	U1188	II, III	Athyrium sp.	USA	—	MG907244	Aime et al. (2018)
			BRIP 60091	II, III	Pteridium esculentum	Australia	—	KM249869	McTaggart et al. (2014)
	Milesina	Milesina blechni	KR-M-0038519	II, III	Struthiopteris spicant	Germany	MH908412	MK302189	Bubner et al. (2019)
		Milesina carpatica	KR-M-0043192	II, III	Dryopteris filix-mas	Germany	MH908454	—	Bubner et al. (2019)
		Milesina exigua	KR-M-0050247	II, III	Polystichum braunii	Austria	MH908478	MK302211	Bubner et al. (2019)
		Milesina feurichii	KR-M-0043159	II, III	Asplenium septentrionale	Germany	MH908476	—	Bubner et al. (2019)
		Milesina kriegeriana	KR-M-0048480	II, III	Dryopteris dilatata	Germany	MH908452	MK302207	Bubner et al. (2019)
		Milesina leviuscula	BRIP 58421	II, III	Nephrolepis sp.	Viet Nam	MW049269	KM249868	McTaggart et al. (2014)
		Milesina murariae	KR-M-0048133	II, III	Asplenium ruta-muraria	Germany	MH908422	MK302194	Bubner et al. (2019)
		Milesina philippinensis	BRIP 58421	II, III	Nephrolepis sp.	Viet Nam	MW049269	KM249868	McTaggart et al. (2014)
		Milesina polypodii	KR-M-0043190	II, III	Polypodium vulgare	Germany	MH908415	MK302190	Bubner et al. (2019)
		Milesina scolopendrii	KR-M-0049051	II, III	Asplenium scolopendrium	Germany	MH908467	MK302209	Bubner et al. (2019)
		Milesina vogesiaca	KR-M-0043187	II, III	Polystichum aculeatum	Germany	MH908440	MK302202	Bubner et al. (2019)
		Milesina whitei	KR-M-0050248	II, III	Polystichum aculeatum	Germany	MH908479	MK302212	Bubner et al. (2019)
		Milesina woodwardiana	KR-M-0049033	II, III	Woodwardia radicans	Spain	MH908474	—	Bubner et al. (2019)
	Naohidemyces	Naohidemyces vaccinii	WM 1098	II, III	Vaccinium uliginosum	—	—	AF426238	Maier et al. (2003)
			MIN 928279	II, III	Vaccinum sp.	USA	—	KJ698628	Padamsee (2014)
			BPI 871754	II, III	Vaccinium ovatum	Washington, USA	—	DQ354563	Padamsee (2014)

For phylogenetic analyses, raw sequence data were aligned by BioEdit v. 7.0.9 (Hall 1999), and multiple alignments were performed with MAFFT v. 7.394 (Katoh et al. 2017). Ambiguous alignment positions were manually adjusted before the final analyses. Topologies were constructed based on maximum likelihood (ML) analyses using RAxML v. 0.95 (Stamatakis 2006). Bayesian Markov Chain Monte Carlo (MCMC) analyses were performed using MrBayes v. 3.1.2 (Huelsenbeck and Ronquist 2001), and Bayesian posterior probabilities (Bpp) were calculated. In ML and Bayesian analyses, the best-fit substitution model was estimated using Modeltest v. 3.7 (Posada and Crandall 1998).

Morphological comparison

The type specimens, original descriptions, and other published descriptions of the species involved were compared with detailed morphological traits of species, genus and family from previous literature (e.g. Sydow and Sydow 1915; Kuprevich and Tranzschel 1957; Arthur 1933; Wilson and Henderson 1966; Hiratsuka et al. 1992; Cummins and Hiratsuka 2003; Liang et al. 2006 Liang 2006; Yang 2015). Different spore stages of rust fungi were designated by following Roman numerals according to Cummins and Hiratsuka (1983, 2003): spermagonia/spermatia (0), aecia/aeciospores (I), uredinia/urediniospores (II), telia/teliospores (III), and basidia/basidiospore (IV). We applied the definitions of spore stage and morphological types in the whole life cycle based on Cummins and Hiratsuka (2003).

Results

For ML and Bayesian analyses, a dataset containing selected species from 16 genera in Melampsorineae was used. Phylogenetic trees using the combined dataset yielded higher confident values for the generic level than that of the single locus tree, with 570 bp nucleotide positions for ITS and 800 bp for LSU. An overview of the inferred topology is given in Figure 1. Melampsorineae is divided into 16 well-supported clades. The monophylies of several genera in Melampsorineae, i.e. Ceropsora, Chrysomyxa, Coleopuccinia, Cronartium, Coleosporium, Hylospora, Melampsorella, Melampsoridium, Naohidemyces, Quasipucciniastrum, and Thekopsora, were confirmed, in agreement with previous studies (Aime et al. 2018; Qi et al. 2019; Zhao et al. 2020; Aime and McTaggart 2021). Pucciniastrum, the type genus of the Pucciniastraceae, was split into two different clades. The type species of Pucciniastrum, P. epilobii clustered with other nine species (i.e. P. circaeae, P. guttatum, P. lanpingensis, P. minimum, P. myosotidii, P. nipponicum, P. pustulatum, P. rubiae, and P. verruculosum) in one clade, whilst 10 other Pucciniastrum species (i.e. P. actinidiae, P. boehmeriae, P. corni, P. fagi, P. hikosanense, P. kusanoi, P. miyabeanum, P. styracinum, P. tiliae and P. yoshinagai) were in another distinct clade. Species of Milesina and Uredinopsis were found in a same clade, with the later merged into the Milesina species, forming a sister clade to M. vogesiaca.

Figure 1.

(Continued).

Figure 1.

(Continued).

Figure 1..

(Continued).

Figure 1.

Multilocus phylogenetic tree of the Melampsorineae suborder in the Pucciniales order. Support values indicated at nodes. Bayesian posterior probabilities ≤ 50% and Maximum Likelihood bootstrap (ML) ≤ 50% were indicated by dash line (–). Family and generic names are listed after each taxon.

Morphological comparison of each clade is shown in Figure 1. Morphologies in spore-producing structures (i.e. spermogonia, aecia, uredinia, telia and basidia), exhibited the strongest association with the phylogeny. Based on our morphological comparisons and phylogenetic analyses of 16 genera in Melampsorineae, ten families, including three new families, Hyalopsoraceae, Nothopucciniastraceae, Thekopsoraceae, and one new genus, Nothopucciniastrum, were proposed. These families differ from their phylogenetically allied families in their spore-producing structures (basidia, spermogonia, aecia, uredinia and telia), as shown in Figure 2. Previous studies have demonstrated that spore-producing structures were phylogenetically informative at the family level (Zhao et al. 2020, 2021; Aime and McTaggart 2021), and we have further confirmed that these characters throughout the life cycle are of great importance to facilitate natural familial delimitation, especially in the suborder Melampsorineae (Figure 3).

Figure 2.

Correlation of phylogeny and morphological criteria used of family delimitation. Dash line (–) in the phylogenetic tree indicated the family or genera lacks of one certain spore stage.

Figure 3.

Taxonomic importance of morphological characters in different spore stages during the whole life cycle in the rust fungi is illustrated. The spore-producing structures, i.e. basidia, spermogonia, aecia, uredinia and telia are indicated in red colour and bold, while the spore morphologies, i.e. basidiospores, spermatia, aeciospores, urediniospores and teliospores, are indicated in black colour and bold.

Taxonomy

Family: Chrysomyxaceae Gäum. ex Leppik, Ann. Bot. Fenn. 9: 139. 1972

Type genus

Chrysomyxa Unger, Beitr. Vergleich. Pathologie: 24. 1840.

Type species

Chrysomyxa abietis (Wallr.) Unger, Beitr. Vergleich. Pathologie: 24. 1840. Genus included in this family. Chrysomyxa and Rossmanomyces. Spermogonia Group I (type 2), subepidermal, determinate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, subepidermal, with well-developed peridia, aeciospores catenulate, with intercalary cells, mainly verrucose. Uredinia Caeoma-type, subepidermal, erumpent, with or without inconspicuous peridia, wiitalicthout ostiolar cells, urediniospores with intercalary cells, germ pores scattered. Telia subepidermal, erumpent, teliospores aseptate, catenulate, crowded but loosely adherent, wall thin, germination occurs without dormancy. Basidia external or without basidiospores.

Notes – Chrysomyxa was previously placed in Chrysomyxaceae, Coleosporiaceae, or Melampsoraceae by different taxonomists based on various morphological criteria in teliospores (Sydow and Sydow 1915; Dietel 1928; Leppik 1972; Savile 1976). Cummins and Hiratsuka (1983) placed Chrysomyxa in Coleosporiaceae together with Coleosporium by emphasising the importance of spermogonial and teliospore’s morphologies, however, telial differences between the two genera have been clearly demonstrated (Sydow and Sydow 1915; Crane et al. 2005). Chrysomyxa was then placed in Coleosporiaceae by Aime and McTaggart (2021), along with Coleosporium, Cronartium, Quasipucciniastrum, Rossmanomyces and Thekopsora, but these genera in this broadly defined family have high morphological variations in the structures of spermogonia and telia, which had long been used as important criteria at the familial level (Cummins and Hiratsuka 2003).

The polyphyly of the family Coleosporiaceae defined by Aime and McTaggart (2021) has been revealed by our previous molecular phylogenetic analyses (Zhao et al. 2020, 2021). Our current findings further demonstrated the phylogenetic distinction of Chrysomyxa from Coleosporium, and two genera have different spermogonial, uredinial and telial morphologies (Figure 1). Furthermore, the divergence time of two genera and their median ages were in a general range of divergent time of families in Basidiomycota (Aime et al. 2018; He et al. 2019). All these findings supported the taxonomic treatments of Dietel and Neger (1900) and Leppik (1972), who placed the genus Chrysomyxa in the Chrysomyxaceae. The family name Chrysomyxaceae is therefore resurrected here. Aime and McTaggart (2021) established a new genus Rossmanomyces, which is phylogenetic allied to Chrysomyxa but differs in forming a systemic sporothallus in telia. Here we placed genera Chrysomyxa and Rossmanomyces in the family Chrysomyxaceae.

Family: Coleosporiaceae Dietel, in Engler and Prantl, Nat. Pflanzenfam., Teil. I (Leipzig) 1(1): 548. 1900, emend. P. Zhao and L. Cai

Type genus

Coleosporium Lév., Annls Sci. Nat., Bot., Sér. 3 8: 373. 1847.

Type species

Coleosporium campanulae (Pers.) Tul., Annls Sci. Nat., Bot., Sér. 42: 137. 1854.

Genus included in this family. Coleosporium.

Spermogonia Group I (type 2), subepidermal, determinate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, with well-developed peridia, aeciospores catenulate, with intercalary cells, verrucose. Uredinia Caeoma-type, with rudimentary peridia or none, without ostiolar cells, urediniospores echinulate, with intercalary cells, mostly verrucose. Telia erumpent as low or rarely columnar cushions, gelatinous, teliospores aseptate, sessile, catenulate, in 1-layered crusts or pseudocatenulate by intrusion of young spores among older ones. Basidia internal.

Notes – Coleosporiaceae has undergone multiple taxonomic reassignments over the years based on various morphological criteria in teliospores and spermogonia (Wilson and Henderson 1966; Hiratsuka et al. 1992; Cummins and Hiratsuka 2003). Recently, Aime and Taggart (2021) included seven genera in this family, despite the fact that the spore-producing structures (i.e. spermogonia, aecia, uredinia, telia and basidia) from those genera have broad morphological variations (Figure 1). Based on phylogenetic analyses and morphological comparisons with the spore-producing structures (Figure 1), we included two genera (i.e. Chrysomyxa, Rossmanomyces) in the newly resurrected family Chrysomyxaceae. The genus Cronartium was re-classified in the family Cronartiaceae, and genus Thekopsora was classified in the new family Thekopsoraceae. Thus, Coleosporiaceae is emended with a narrower concept based on the type genus Coleosporium, which is distinctive from other families in telia with internal basidia and unicellular teliospores in 1-layered crust, wall thick and gelatinising above (Figure 1).

Family: Cronartiaceae Dietel, in Engler and Prantl, Nat. Pflanzenfam., Teil. I (Leipzig) 1(1): 548. 1900

Type genus

Cronartium Fr., Observ. Mycol. (Havniae) 1: 220. 1815.

Type species

Cronartium asclepiadeum (Willd.) Fr., Observ. Mycol. (Havniae) 1: 220. 1815.

Genera included in this family. Cronartium.

Spermogonia Group II (type 9), intracortical, indeterminate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, the peridia large and blister-like, strongly developed, rupturing widely, aeciospores catenulate, with intercalary cells, verrucose with rod-like columns. Uredinia Milesia-type, subepidermal, opening by a pore, with ostiolar cells, urediniospores borne singly, echinulate, germ pore scattered. Telia with high variations, subepidermal, erumpent, vteliospores aseptate, crowded but loosely adherent, some catenulate, thin-walled, germination occurs without dormancy. Basidia external.

Notes – Cronartium was originally placed in the family Pucciniaceae (Dietel 1897), but then classified as a member of Cronartiaceae, Coleosporiaceae, Melampsoraceae or Pucciniastraceae in different time periods based on various morphological criteria in teliospores or spermogonia (Dietel 1928; Cummins and Hiratsuka 1983, 2003; Aime and Taggart 2021). Recent molecular phylogenetic studies confirmed the placement of Cronartium in the suborder Melampsorineae (Aime 2006; Aime et al. 2018), but its relationship with several other genera, including Chrysomyxa, Coleosporium, Diaphanopellis, Quasipucciniastrum, Rossmanomyces and Thekopsora, was still uncertain (Aime and Taggart 2021). Our current results and previous phylogenetic studies of the order Pucciniales (Zhao et al. 2020, 2021) clearly revealed the phylogenetic distinction between Cronartium and the above-mentioned genera (Figure 1), and Cronartium clade differs from other families in the spore-producing structures, especially in Group II spermonogia, Milesia-type uredinia with ostiolar cells, and telia with sessile, catenulate teliospores (Figure 1). Thus, here we resurrected the family Cronartiaceae to accommodate the genus Cronartium.

Family: Hyalopsoraceae P. Zhao and L. Cai, fam. nov. – MycoBank MB842413

Etymology

Name derived from the type genus, Hyalopsora.

Type genus

Hyalopsora Magnus, Ber. Dt. Bot. Ges. 19: 582. 1902.

Type species

Hyalopsora aspidiotus (Peck) Magnus, Ber. Dt. Bot. Ges. 19: 582. 1901.

Genus included in this family. Coleopuccinia, Hyalopsora, Melampsoridium.

Spermogonia Group I (type 2 or type 3), subepidermal or subcuticular, determinate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, with peridium, subepidermal, aeciospore catenulate. Uredinia Milesia-type, subepidermal, with peridium opening by a discrete pore, with ostiolar cells, urediniospores borne singly, wall colourless, echinulate, germ pores scattered or bizonate. Telia intraepidermal, not erumpent, 2 to many-celled by septa, wall colourless, teliospores aseptate, sessile, pigmented. Basidia external.

Notes – The traditionally defined Pucciniastraceae has been revealed to be polyphyletic, with members dispersed across several distant and well-supported clades (Figure 1; Aime et al. 2018; Zhao et al. 2020). Three closely related clades, representing genera Coleopuccinia, Hyalopsora and Melampsoridium, show a high morphological consistency in the spore-producing structures with each other, and they can be distinguished from phylogenetically allied families in intraepidermal telia with sessile and unicellular teliospores with intercalary cell (Figure 1). Thus, a new family Hyalopsoraceae is proposed to accommodate Coleopuccinia, Hyalopsora and Melampsoridium. Previously, Cummins and Hiratsuka (2003) considered the genus Coleopuccinia as a synonym of Gymnosporangium (Gymnosporangiaceae) based on teliospores similarities, and Cao et al. (2018) recognised the phylogenetic distinctiveness of two genera. Here we confirm its familial position in Hyalopsoraceae for the first time, and our findings further highlight the importance of the spore-producing structures for familial delimitation.

Family: Melampsoraceae Dietel, in Engler and Prantl, Nat. Pflanzenfam., Teil. I (Leipzig) 1(1): 38. 1897

Type genus

Melampsora Castagne (1843).

Type species

Melampsora euphorbiae (Ficinus and C. Schub.) Castagne, Observ. Uréd. 2: 18.1843.

Genus included in this family. Ceropsora and Melampsora.

Spermogonia Group I (type 2 or type 3), subepidermal or subcuticular, determinate, with flat hymenia, bounding structures lacking. Aecia Caeoma-type, subepidermal, with rudimentary or no peridia, aeciospore catenulate, with intercalary cells. Uredinia Uredo-type, subepidermal, erumpent, without ostiolar cells, with abundant capitate paraphyses, urediniospores borne singly, echinulate, germ pores scattered or bizonate. Telia subepidermal or subcuticular, not erumpent, consisting of laterally adherent teliospores in crusts one spore deep or some species with subjacent spore-like cells, teliospores aseptate, sessile, pigmented. Basidia external.

Notes – Both Ceropsora and Melampsora are distinctive from the rest families in Caeoma-type aecia, Uredo-type uredinia, and telia with sessile and unicellular teliospores (Figure 1; Sydow and Sydow 1915; Cummins and Hiratsuka 2003; Aime and Taggart 2021). Two genera constitute the family Melampsoraceae, which is confirmed to be monophyly by Tian et al. (2004), Feau et al. (2009), and Zhao et al. (2017, 2020). This family was estimated to be diverged around 12 ~ 42 MYA (median ages 31.94 MYA), within the generally acknowledged divergent time range for families of Basidiomycota (Aime et al. 2018; He et al. 2019).

Family: Milesinaceae Aime and McTaggart, Fungal Systematics and Evolution 7: 32. 2020

Genera included in this family. Milesina, Naohidemyces and Uredinopsis.

Spermogonia Group I (type 1), subepidermal, with concave hymenia, bounding structures lacking. Aecia Peridermium-type, subepidermal, erumpent, with peridia, aeciospores catenulate, verrucose. Uredinia Milesia-type, subepidermal, urediniospores mostly echinulate, borne singly. Telia intraepidermal, consisting of spores in the epidermal cells, teliospores aseptate or multiseptate, with oblique septa. Basidia external.

Notes – Milesina, Naohidemyces and Uredinopsis were classified in Pucciniastraceae based on their teliospores that are embedded in the host tissue and the Peridermium-type aecia (Cummins and Hiratsuka 1984; Cummins and Hiratsuka 2003). Phylogenetically, Milesia, Naohidemyces and Uredinopsis clustered in one phylogenetic group, and separated from Hyalopsora, Melampsorella, Melampsoridium, Pucciniastrum and Thekopsora (Figure 1). In morphology, Milesia, Naohidemyces and Uredinopsis have similar morphological features in all spore-producing structures, but clearly differentiate themselves from other families in Milesia-type uredinia without ostiolar cells and wall colourless (Figure 1). Thus, Aime and McTaggart (2021) proposed Milesinaceae to accommodate these three genera. Our results is in agreement of Aime and McTaggart (2021).

Family: Nothopucciniastraceae P. Zhao and L. Cai, fam. nov. – MycoBank MB842414

Etymology

Notho = nothus in Greek, fake, close but different; pucciniastraceae = Pucciniastraceae-like morphology.

Type genus

Nothopucciniastrum P. Zhao and L. Cai, gen. nov.

Type species

Nothopucciniastrum tiliae (Miyabe) P. Zhao and L. Cai, comb. nov.

Genera included in this family. Nothopucciniastrum.

Spermogonia Group I (type 2 and 3), subepidermal or subcuticular, determinate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, or Milesia-type, with well-developed peridia, aeciospores borne singly on pedicels, verrucose. Uredinia Milesia-type, with well-developed ostiolar cells, urediniospores borne singly, verrucose. Telia subepidermal, not erumpent, consisting of laterally adherent teliospores one spore deep, teliospores sessile, aseptate or multiseptate, with vertical septa. Basidia external.

New combinations:

Nothopucciniastrum actinidiae (Hirats. f.) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum actinidiae Hirats. f., Mem. Tottori Agric. Coll. 4: 279. 1936.

Nothopucciniastrum boehmeriae ((Dietel) Syd. and P. Syd.) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum boehmeriae (Dietel) Syd. and P. Syd., Ann. Mycol. 1(1): 19. 1903.

Nothopucciniastrum corni (Dietel) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum corni Dietel, Bot. Jb. 34: 587. 1905.

Nothopucciniastrum fagi (Dietel) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum fagi G. Yamada, Bot. Mag., Tokyo 44: 280. 1930.

Nothopucciniastrum kusanoi (Dietel) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum kusanoi Dietel, Bot. Jb. 32: 629. 1903.

Nothopucciniastrum hikosanense (Hirats. f.) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum hikosanense Hirats. f., Ann. Phytopath. Soc. Japan 10: 154. 1940.

Nothopucciniastrum miyabeanum (Hirats.) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum miyabeanum Hirats., Bot. Mag., Tokyo 12: 3 (extr.). 1898.

Nothopucciniastrum styracinum (Hirats.) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum styracinum Hirats., Bot. Mag., Tokyo 12: 2 (extr.). 1898.

Nothopucciniastrum tiliae (Miyabe) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum tiliae Miyabe, in Hiratsuka, Bot. Mag., Tokyo 11: 47. 1897.

Nothopucciniastrum yoshinagae (Hirats.) P. Zhao and L. Cai, comb. nov.

Basionym. Pucciniastrum yoshinagae Hirats. f. [as “yoshinagai”], Trans. Tottori Soc. Agric. Sci. 2: 247. 1931.

Notes – The traditionally defined Pucciniastraceae with 9 genera (Cummins and Hiratsuka 1984; Cummins and Hiratsuka 2003) has been demonstrated to be highly polyphyletic (Figure 1; Aime et al. 2018; Zhao et al. 2021). Recent treatments of Pucciniastraceae have placed Milesia, Naohidemyces and Uredinopsis in Milesinaceae (Aime and McTaggart 2021), Coleopuccinia, Hyalopsora, and Melampsoridium in Hyalopsoraceae, and Thekopsora in Thekopsoraceae (this study). Furthermore, Pucciniastrum species were found to cluster in two distant clades (Figure 1). Ten species formerly classified into genus Pucciniastrum, (i.e. P. actinidiae, P. boehmeriae, P. corni, P. fagi, P. hikosanense, P. kusanoi, P. miyabeanum, P. styracinum, P. tiliae and P. yoshinagai) constituted one well-supported clade distinct from the clade of Pucciniastrum comprising the type species P. epilobii (Figure 1). This result is consistent with Qi et al. (2019), and Zhao et al. (2020). The morphological difference between these Pucciniastrum species in above two clades were discussed in Liang (2006) and Yang (2015), and those ten species different from Pucciniastrum and Melampsorella in their Milesia-type with ostiolar cells. Based on morphological and molecular evidences, we propose a new family Nothopucciniastraceae and a new genus Nothopucciniastrum to accommodate these ten species which are herein treated as new combinations. Results further emphasised the importance of uredinial morphologies for familial delimitation.

Family: Pucciniastraceae Gäum. Ex Leppik, Ann. Bot. Fenn. 9: 139. 1972, emend. P. Zhao and L. Cai

Type genus

Pucciniastrum G.H. Otth (1861).

Type species

Pucciniastrum epilobii (Pers.) G.H. Otth, Mitt. Naturf. Ges. Bern 469–496: 72. 1861.

Genera included in this family. Melampsorella and Pucciniastrum.

Spermogonia Group I (type 2 and 3), subepidermal or subcuticular, determinate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, or Milesia-type, with well-developed peridia, aeciospores borne singly on pedicels, verrucose. Uredinia Milesia-type, without ostiolar cells, urediniospores borne singly, verrucose. Telia subepidermal or intraepidermal, not erumpent, consisting of laterally adherent teliospores one spore deep, teliospores sessile, aseptate or ultiseptated, with vertical septa. Basidia external.

Notes – With the segregation of Coleopuccinia, Hyalopsora, Melampsoridium silesia, Naohidemyces, Quasipucciniastrum, Thekopsora, Uredinopsis from Pucciniastraceae, we herein redefine the Pucciniastraceae with a narrower concept which include genera Melampsorella and Pucciniastrum. Pucciniastraceae is distinctive from the rest families by the absence of ostiolar cells in Milesia-type uredinia (Figure 1).

Family: Thekopsoraceae P. Zhao and L. Cai, fam. nov. – MycoBank MB842415

Etymology

Name derived from the type genus, Thekopsora.

Type genus

Thekopsora Magnus, Hedwigia 14: 123. 1875.

Type species

Thekopsora areolata (Fr.) Magnus, Sber. Gesellschaft Naturf. Freunde Berlin: 58. 1875.

Genera included in this family. Thekopsora.

Spermogonia Group I (type 2 and 3), subepidermal or subcuticular, determinate, with flat hymenia, bounding structures lacking. Aecia Peridermium-type, or Milesia-type, with well-developed peridia, aeciospores borne singly on pedicels, verrucose. Uredinia Milesia-type, with well-developed ostiolar cells with apparent spines, urediniospores borne singly, verrucose. Telia intraepidermal, not erumpent, consisting of laterally adherent teliospores one spore deep, teliospores sessile, aseptate or multiseptated, with vertical septa. Basidia external.

Notes – The Thekopsora clade, including the type of the genus, Thekopsora areolata, was phylogenetically close to Cronartium but distinct from Pucciniastrum species (Figure 1), in agreement with Aime et al. (2018). In morphology, it resembles Coleopuccinia, Hylospora, Melampsoridium, and Pucciniastrum, but differs from these genera in the aecia, uredinia and telia (Figure 1; Yang 2015). It also differs from the phylogenetically allied family Cronartiaceae in the structures of spermogonia, uredinia and telia. Thus, a new family Thekopsoraceae is proposed to accommodate the genus Thekopsora.

Discussion

Phylogenetic reappraisal of rust families and genera

To date, more than 7 800 rust species have been described in 289 genera in Pucciniales (Laundon 1965; Kirk et al. 2008). Cummins and Hiratsuka (2003) in their monograph “Illustrated Genera of Rust Fungi” included 120 holomorphic genera and 13 asexual typified genera, in which most genera are traditionally morphologically defined. At the family level, since the first system proposed by Dietel (1897), different mycologists have classified 289 recognised genera into 2–14 families mainly based on morphological characters in spermogonia and teliospores (Arthur 1907, 1934; Kuprevich and Tranzschel 1957; Wilson and Henderson 1966; Azbukina 1972; Cummins and Hiratsuka 1984; Buriticá 1991; Hiratsuka et al. 1992; Cummins and Hiratsuka 2003). Although urediniologists have generally accepted Cummins and Hiratsuka (2003)’s taxonomy system, subsequent studies have found numerous inconsistencies between this system and the molecular phylogeny (Wingfield et al. 2004; Aime 2006; Aime et al. 2018; Zhao et al. 2020). A definite family level resolution has not been obtained due to the lack of a comprehensive molecular phylogenetic study within the order Pucciniales. In our previous studies on the whole order, we proposed four new families based on extensive phylogenetic and morphological comparisons, and also recognised inconsistencies between morphologically-defined families in Melampsorineae suborder and their molecular phylogenetic relationships (Zhao et al. 2020, 2021). Thus, we conducted phylogenetic studies of 16 genera in the Melampsorineae suborder, and confirmed boundaries at the familial and generic level. Traditional morphology-defined families such as Coleosporiaceae, Chrysomyxaceae, and Melampsoraceae have been shown to be monophyletic with the core of species around the type (Figure 1). Pucciniastraceae has been found to be polyphyletic and its traditional members scattered in numerous discrete lineages. This family has been redefined by emphasising the importance of traditional taxonomic criteria used by Cummins and Hiratsuka (2003) and Aime and McTaggart (2021). In this study, we further emphasised several newly recognised criteria for familial delineation, i.e. the structures of uredinia and telia, including the colour of urediniospores, the existence of peridia in uredinia and telia, the existence of ostiolar cells in uredinia and their ornamentations. Our phylogenetic studies further emphasised that morphologies throughout their life cycles, especially the uredinial and aecial morphologies, are of great diagnostic value in delineating at the familial and generic level.

Importance of applying early diverged characters in higher rank taxonomy

Hitherto, classification of the rust fungi at species, generic and family levels relies on morphological features of different spores and spore-producing structures in different stages throughout the life cycles. Spore morphologies, such as basidiospores, spermatia, aeciospores, urediniospores and teliospores, as well as spore-producing structures like basidia, spermogonia, aecia, uredinia and telia, were hitherto not seriously investigated to see if they are phylogenetically significant at particular taxonomic levels.

Our previous and current studies on the phylogeny of Pucciniales, particularly those in the Melampsorineae, have revealed that morphological characters, especially spore-producing structures throughout the whole life cycle, such as basidia spermogonia, aecia, uredinia and telia, were phylogenetically more informative at higher taxonomic ranks (family level). By contrast, spore morphologies such as basidiospores, spermatia, aeciospores, urediniospores and teliospores, were phylogenetically more informative at lower taxonomic rank (species level) (Tian et al. 2004; Crane et al. 2005; Feau et al. 2009, Beenken 2014, 2017; Zhao et al. 2015, 2017). These spore-producing structures represent early diverged morphological characters, while spore morphologies have already been proved to be recently diverged characters by our continuous investigations (Figure 1; Zhao et al. 2020, 2021). Our findings were further supported by the successive evolutionary process of rust fungi, because the structures of basidia, spermogonia, aecia, uredinia and telia might be directly influenced at early adaptation stages of rust fungi when they shifted from ferns to conifers and angiosperms (Leppik 1965). Based on these findings, taxonomic significance of morphological features in different spore stages throughout the whole life cycle in the rust fungi is proposed as shown in Figure 4. It is quite obvious that the polyphylies of many traditionally defined genera and families were resulted from the inappropriate use of recently diverged characters (particularly morphology of teliospores) at higher level taxonomy, and the use of the early diverged characters at lower-level taxonomy. Apparently these recently diverged characters have evolved more than once in different lineages during the evolutionary process.

Among the early diverged characters, the structures of spermogonia and telia have long been employed for classification at the family level, but the structures of aecia and uredinia have long been overlooked at higher taxonomic ranks (Hiratsuka and Cummins 1963; Hiratsuka and Hiratsuka 1980; Cummins and Hiratsuka 1983, 2003). Our studies indicated the importance of aecia and uredinia morphology for higher level classification, especially differences in spore ontogeny, hymenium shape, position in host tissues, presence of intercalary cells and paraphyses. Until now, fourteen different morphological types in aecial and uredinial structure have been recognised (Kenny 1970; Sato and Sato 1985). These morphological variations appear to be very useful criteria at family and generic level taxonomy in rust fungi.

Funding Statement

This work was financially supported by the National Nature Science Foundation of China [31725001 and 31670017], and Biological Resources Programme, Chinese Academy of Sciences [KFJ-BRP-009].

Disclosure statement

No potential conflict of interest was reported by the author(s).