Research Article |
Corresponding author: Tom W. May ( tom.may@rbg.vic.gov.au ) Corresponding author: Li-Wei Zhou ( liwei_zhou1982@im.ac.cn ) Academic editor: R. Henrik Nilsson
© 2022 Qian-Zhu Li, Shi-Liang Liu, Xue-Wei Wang, Tom W. May, Li-Wei Zhou.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Li Q-Z, Liu S-L, Wang X-W, May TW, Zhou L-W (2022) Redelimitation of Heteroradulum (Auriculariales, Basidiomycota) with H. australiense sp. nov. MycoKeys 86: 87-101. https://doi.org/10.3897/mycokeys.86.76425
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Auriculariales accommodates species with diverse basidiomes and hymenophores. From morphological and phylogenetic perspectives, we perform a taxonomic study on Heteroradulum, a recently validated genus within the Auriculariales. The genus Grammatus is merged into Heteroradulum, and thus its generic type G. labyrinthinus is combined with Heteroradulum and G. semis is reaccepted as a member of Heteroradulum. Heteroradulum australiense is newly described on the basis of three Australian specimens. Heteroradulum yunnanense is excluded from this genus and its taxonomic position at the generic level is considered uncertain. Accordingly, the circumscription of Heteroradulum is re-delimited and the concept of this genus is adjusted by including irpicoid to poroid hymenophores and a hyphal system with clamp connections or simple septa. A key to all nine accepted species of Heteroradulum is presented.
Agaricomycetes, Australia, Grammatus, heterobasidiomycetes, two new taxa, wood-inhabiting fungi
Auriculariales (Agaricomycetes, Basidiomycota) is characterized by a wood-inhabiting habit and longitudinally or transversely septate basidia (
On the basis of morphology, the non-gelatinous species of Auriculariales that are resupinate with or without a narrow reflexed pileus (i.e., corticioid or stereoid) have been placed in the genera Eichleriella Bres., Exidiopsis (Bref.) Möller and Heterochaete Pat. (
Heteroradulum, typified by H. kmetii (Bres.) Spirin & Malysheva, was validated by
During field trips in Australia, three specimens bearing corticioid basidiomes and longitudinally septate basidia were collected. Based on these specimens, a new species of Heteroradulum was identified and is presented below along with a revised phylogeny of the genus and its relatives based on molecular data. This phylogenetic analysis leads to a revised circumscription of Heteroradulum.
The studied specimens are preserved at the Fungarium, Institute of Microbiology, Chinese Academy of Sciences (
Crude DNA was extracted from basidiomes of dry specimens using FH Plant DNA Kit (Beijing Demeter Biotech Co., Ltd., Beijing, China), and then directly used as template for subsequent PCR amplifications. The primer pairs ITS5/ITS4 (
Information on species and specimens used in the phylogenetic analysis. The newly generated sequences are in boldface. Type specimens are indicated with an asterisk (*).
Species | Voucher number | GenBank accession number | |
---|---|---|---|
ITS | nLSU | ||
Amphistereum leveilleanum | FP-106715 | KX262119 | KX262168 |
A. schrenkii | HHB8476 | KX262130 | KX262178 |
Aporpium hexagonoides | ML297 | AB871754 | AB871735 |
Auricularia mesenterica | FO25132 | AF291271 | AF291292 |
A. mesenterica | TUFC12805 | AB915192 | AB915191 |
A. polytricha | TUFC12920 | AB871752 | AB871733 |
Basidiodendron eyrei | TUFC14484 | AB871753 | AB871734 |
Eichleriella bactriana | TAAM55071* | KX262121 | KX262170 |
E. leucophaea | LE303261 | KX262111 | KX262161 |
Elmerina caryae | WD2207 | AB871751 | AB871730 |
E. foliacea | Yuan 5691 | JQ764666 | JQ764644 |
E. hispida | WD548 | AB871768 | AB871749 |
E701 | AB871767 | AB871748 | |
Exidia glandulosa | TUFC34008 | AB871761 | AB871742 |
E. glandulosa | MW355 | AF291273 | AF291319 |
E. pithya | MW313 | AF291275 | AF291321 |
Exidiopsis calcea | MW331 | AF291280 | AF291326 |
E. effusa | OM19136 | KX262145 | KX262193 |
E. grisea E. grisea | RoKi162 | AF291281 | AF291328 |
TUFC100049 | AB871765 | AB871746 | |
Exidia sp. | TUFC34333 | AB871764 | AB871745 |
FO46291 | AF291282 | AF291329 | |
Heteroradulum adnatum | LR23453* | KX262116 | KX262165 |
H. australiense | LWZ 20180512–20* | MZ325254 | MZ310424 |
LWZ 20180512–25* | MZ325255 | MZ310425 | |
LWZ 20180515–26* | MZ325256 | MZ310426 | |
H. deglubens | FO12006 | AF291272 | AF291318 |
LE38182 | KX262112 | KX262162 | |
LE225523 | KX262113 | KX262163 | |
TAAM064782 | KX262101 | KX262148 | |
Solheim1864 | KX262133 | KX262181 | |
H. kmetii | Kmet* | KX262124 | KX262173 |
VS8858 | KX262105 | KX262154 | |
VS8864 | KX262106 | KX262155 | |
VS8981 | KX262132 | KX262180 | |
VS8988 | KX262107 | KX262156 | |
LE38181 | KX262109 | KX262159 | |
DAOM145605 | KX262135 | KX262183 | |
DAOM31292 | KX262134 | KX262182 | |
OF-295640 | KX262122 | KX262171 | |
OF-295641 | KX262117 | KX262166 | |
H. kmetii | OF-295639 | KX262128 | KX262177 |
VS7967 | KX262108 | KX262157 | |
TAAM9847 | KX262125 | KX262174 | |
VS6466 | KX262104 | KX262152 | |
LE303456 | KX262103 | KX262151 | |
TAAM149179 | KX262102 | KX262149 | |
CWU4563 | KX262127 | KX262176 | |
CWU6152 | KX262126 | KX262175 | |
LR14389 | KX262131 | KX262179 | |
H. labyrinthinum | Yuan 1759* | KM379137 | KM379138 |
Yuan 1600* | KM379139 | KM379140 | |
H. semis | OM10618* | KX262146 | KX262194 |
H. yunnanense | CLZhao 4023* | MT215568 | MT215564 |
CLZhao 8106* | MT215569 | MT215565 | |
CLZhao 9132* | MT215570 | MT215566 | |
CLZhao 9200* | MT215571 | MT215567 | |
Heteroradulum sp. | USJ55639 | AF291285 | AF291336 |
Hirneolina hirneoloides | USJ55480 | AF291283 | AF291334 |
Sclerotrema griseobrunneum | VS7674 | KX262140 | KX262188 |
Sistotrema brinkmannii | 236 | JX535169 | JX535170 |
Tremellochaete japonica | LE303446 | KX262110 | KX262160 |
Besides the newly sequenced specimens, additional taxa representing all main lineages within the Auriculariales were also included in the current phylogenetic analysis, and Sistotrema brinkmannii (Bres.) J. Erikss. within the Cantharellales was selected as an outgroup taxon following
Three ITS and three nLSU sequences were newly generated from three Australian specimens of Heteroradulum for this study. The alignment used for phylogenetic analysis has 62 collections and 1583 characters. The ML analysis ended after 300 BS replicates. The BI analysis converged after 10 million generations as indicated by an average standard deviation of split frequencies = 0.004375, the effective sample sizes of all parameters above 4960 and the potential scale reduction factors equal to 1.000. The ML and BI analyses generated similar topologies in main lineages, and thus the topology generated from ML analysis is presented along with BS values above 50% and BPPs above 0.8 at the nodes (Figure
Phylogenetic delimitation of Heteroradulum within the Auriculariales inferred from the combined dataset of ITS and nLSU regions. The topology generated by the maximum likelihood analysis is presented along with bootstrap values and Bayesian posterior probabilities above 50% and 0.8, respectively, at the nodes. The specimens of the newly described species are in boldface.
The current phylogeny groups Grammatus and Heteroradulum, with the exception of H. yunnanense, as a strongly supported clade (BS = 94%, BPP = 1; Figure
= Grammatus H.S. Yuan & Decock, in Yuan, Lu & Decock, MycoKeys 35: 32 (2018)
Following the phylogenetic analysis, we treat Grammatus and Heteroradulum as a single genus, for which Heteroradulum has priority. The newly revealed Australian lineage is described as the new species Heteroradulum australiense below. In addition, G. labyrinthinus is combined to Heteroradulum and G. semis (Spirin & Malysheva) H.S. Yuan & Decock is reaccepted as a member of Heteroradulum.
australiense (Lat.), refers to Australia.
Australia, Tasmania, Tahune Adventures, Arve River Picnic Area, on fallen angiosperm branch, 15 May 2018, L.W. Zhou, LWZ 20180515–26 (holotype in MEL, isotype in
Heteroradulum australiense differs from other species in this genus by the generative hyphae having a mixture of simple septa and clamp connections.
Basidiomes annual, resupinate, adnate, without odor or taste when fresh, leathery, covering 24.5 cm in widest dimension and up to 0.4 mm thick. Hymenophore odontioid, covered by irregularly arranged spines, up to 0.2 mm long, 3–5 per mm, pale red to reddish lilac when fresh, pale orange to brownish gray upon drying. Margin smooth, adnate, yellowish white, 0.5 mm wide.
Hyphal system dimitic; generative hyphae with simple septa or clamp connections; skeletal hyphae IKI–, CB+; tissue unchanged in KOH. Subicular generative hyphae hyaline, thin to thick-walled, rarely branched, 2–4 μm in diam; skeletal hyphae hyaline to brownish, thick-walled, interwoven, occasionally branched, 2.5–4 μm in diam, sometimes irregularly inflated up to 6 μm. Subhymenial generative hyphae hyaline to brownish, thin-to slightly thick-walled, 2–3.5 μm in diam; skeletal hyphae brownish, thick-walled, encrusted by grainy crystals, subparallel and vertical along substrate, compact, 2–4.5 μm in diam. Clavate to subcylindrical cystidia abundant, septate with or without clamp connections, thin-walled, 24–56 × 3–8 μm. Skeletocystidia present as endings of subicular skeletal hyphae, distinctly thick-walled, heavily encrusted by grainy crystals, 4–7 μm in diam. Dendrohyphidia abundant, scattered among hymenial cells, covering the hymenial surface, branched, up to 54 μm long, 2–3 μm in diam. Basidia narrowly ovoid to obconical, longitudinally septate, four-celled, 29–34.5 × 10–13.5 μm, with enucleate stalk up to 14 × 4 μm. Basidiospores cylindrical, slightly or distinctly curved, hyaline, thin-walled, smooth, occasionally with oily inclusions, IKI–, CB–, (14.5–)15–20(–20.5) × 5–7(–7.5) μm, L = 17.0 μm, W = 6.2 μm, Q = 2.66–2.88 (n = 90/3).
Australia, Victoria, Yarra Ranges National Park, Dandenong Ranges Botanic Garden, on a fallen branch of Eucalyptus, 12 May 2018, L.W. Zhou, LWZ 20180512–20 (
Heteroradulum australiense is characterized by pale red to reddish lilac basidiomes, a dimitic hyphal system, generative hyphae with simple septa or clamp connections, abundant skeletocystidia in the hymenium, and basidia with an enucleate stalk. Heteroradulum kmetii and H. spinulosum resemble H. australiense by odontoid hymenophores, a dimitic hyphal system and the presence of skeletocystidia (
In regard to previously described Australian species against which H. australiense should be compared, the coriaceous, resupinate species of the Auriculariales are poorly sampled from Australia.
Heterochaete cheesmanii was described by
Irpex depauperatus was introduced by
Irpex depauperatus potentially belongs in Heteroradulum but due to slight morphological differences between species such as H. australiense and H. spinulosum, and the potential for further species to occur in the region, DNA sequences would be ideal to assist in interpretation of the old name. However, it is unlikely to be able to readily obtain DNA from the more than 100-year old type of Irpex depauperatus, which is borne out by unsuccessful attempts to amplify ITS and LSU sequences from several Australian collections in MEL filed under Heterochaete, collected in the 1950s and 1960s. Collections for which DNA amplification was unsuccessful included MEL 2313650 (which is a duplicate of the K collection Miller s.n., Herb. F.P.S.M. No. 4996). The morphology of Miller s.n. as recorded by
Grammatus labyrinthinus H.S. Yuan & Decock, in Yuan, Lu & Decock, MycoKeys 35: 32 (2018)
Heteroradulum labyrinthinum was placed in the new genus Grammatus as the generic type (
Heteroradulum yunnanense has a white to gray hymenophore and colorless hyphae (
1 | Hymenophore irpicoid to poroid | H. labyrinthinum |
– | Hymenophore grandinioid to odontioid | 2 |
2 | Hyphal system monomitic | 3 |
– | Hyphal system dimitic | 4 |
3 | Basidiospores up to 14.2 μm long | H. adnatum |
– | Basidiospores up to 20.4 μm long | H. deglubens |
4 | Basidiomes perennial | H. kmetii |
– | Basidiomes annual | 5 |
5 | Skeletocystidia present | 6 |
– | Skeletocystidia absent | 7 |
6 | Generative hyphae septa with or without clamp connections | H. australiense |
– | Generative hyphae septa with clamp connections | H. spinulosum |
7 | Cystidia absent | H. brasiliense |
– | Cystidia present | 8 |
8 | Basidiospores more than 15 μm long | H. lividofuscum |
– | Basidiospores less than 15 μm long | H. semis |
In this study, the circumscription of Heteroradulum is emended by merging the genus Grammatus, adding the newly described species H. australiense and excluding the species H. yunnanense.
Recently, the concept of Protomerulius, another genus of the Auriculariales, was redefined to accommodate species bearing smooth, poroid and spiny hymenophores (
Heteroradulum yunnanense was placed in Heteroradulum based on a quite simple phylogeny with limited samples (
The research was financed by the National Natural Science Foundation of China (Project Nos. 31970012 & 31770008).