Research Article |
Corresponding author: XiaoYong Liu ( liuxiaoyong@im.ac.cn ) Corresponding author: Bo Huang ( bhuang@ahau.edu.cn ) Academic editor: Kerstin Voigt
© 2021 Yue Cai, Yong Nie, Heng Zhao, ZiMin Wang, ZhengYu Zhou, XiaoYong Liu, Bo Huang.
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:
Cai Y, Nie Y, Zhao H, Wang Z, Zhou Z, Liu X, Huang B (2021) Azygosporus gen. nov., a synapmorphic clade in the family Ancylistaceae. MycoKeys 85: 161-172. https://doi.org/10.3897/mycokeys.85.73405
|
The fungal genus Conidiobolus sensu lato was delimited into four genera based on morphology and phylogeny. However, the taxonomic placement of C. parvus has not been determined until now. Here, we show that C. parvus belongs to a distinct lineage based on mitochondrial (mtSSU) and nuclear (TEF1 and nrLSU) phylogenetic analyses. Phylogenetic analyses further revealed a new species as sister to C. parvus. We identified a synapomorphy uniting these lineages (azygospore production) that was not observed in other allied genera of the family Ancylistaceae, and erected a new genus Azygosporus gen. nov. for this monophyletic group, with a new combination, A. parvus comb. nov. as the type species. Within Azygosporus, the novel species A. macropapillatus sp. nov. was introduced from China based on morphological characteristics and molecular evidence, which is characterized by its prominent basal papilla, in comparison to other closely related species, measuring 7.5–10.0×5.0–10.0 µm. Our study resolved the phylogenetic placement of C. parvus and improved the taxonomic system of the Ancylistaceae family.
Entomophthorales, resting spores, saprophytic fungi, taxonomy
Conidiobolus is the largest genus within the family Ancylistaceae, and includes mainly saprotrophs occurring in soil and plant debris, but also parasites of insects and animals (
In addition to the size of primary conidia and the type of secondary conidia, resting spores are another character with taxonomic importance for recognizing Conidiobolus species (
Previous phylogenetic analyses have shown that is it not only Conidiobolus parvus that has questionable taxonomic placement. Our recent research has indicated that C. lampragues and C. nanodes should be assigned into the genus Neoconidiobolus (
Plant debris was collected from Tiantangzhai National Forest Parks (31°17'48" N, 115°78'18") and Fangtang (30°30'57" N, 118°42'17" E), Anhui Province, China. Isolations were carried out using the canopy-plating approach (
Fungal mycelia were incubated on PDA for 7 d at 21 °C. Total genomic DNA was extracted from fresh fungal mycelia by using a CTAB method followed
Species | Strains* | GenBank accession numbers | ||
---|---|---|---|---|
nucLSU | TEF1 | mtSSU | ||
Azygosporus macropapillatus |
|
MZ542004 | MZ555648 | MZ542277 |
A. macropapillatus |
|
MZ542005 | MZ555649 | MZ542278 |
A. macropapillatus |
|
MZ542006 | MZ555650 | MZ542279 |
A. parvus | ATCC 14634 (T) | KX752051 | KY402207 | MK301192 |
Capillidium adiaeretum |
|
MN061284 | MN061481 | MN061287 |
Ca. bangalorense | ARSEF 449 (T) | DQ364204 | – | DQ364225 |
Ca. heterosporum |
|
JF816225 | JF816239 | MK301183 |
Ca. lobatum | ATCC 18153 (T) | JF816218 | JF816233 | MK301187 |
Ca. rhysosporum | ATCC 12588 (T) | JN131540 | JN131546 | MK301195 |
Conidiobolus bifurcatus |
|
MN061285 | MN061482 | MN061288 |
C. brefeldianus | ARSEF 452 (T) | EF392382 | – | EF392495 |
C. chlamydosporus | ATCC 12242 (T) | JF816212 | JF816234 | MK301178 |
C. coronatus | NRRL 28638 | AY546691 | DQ275337 | – |
C. dabieshanensis |
|
KY398125 | KY402206 | MK301180 |
C. firmipilleus | ARSEF 6384 | JX242592 | – | JX242632 |
C. gonimodes | ATCC 14445 (T) | JF816221 | JF816226 | MK301182 |
C. humicolus | ATCC 28849 (T) | JF816220 | JF816231 | MK301184 |
C. iuxtagenitus | ARSEF 6378 (T) | KC788410 | – | – |
C. khandalensis | ATCC 15162 (T) | KX686994 | KY402204 | MK301185 |
C. lichenicolus | ATCC 16200 (T) | JF816216 | JF816232 | MK301186 |
C. marcosporus | ATCC 16578 (T) | KY398124 | KY402209 | MK301188 |
C. megalotocus | ATCC 28854 (T) | MF616383 | MF616385 | MK301189 |
C. mycophagus | ATCC 16201 (T) | JX946694 | JX946698 | MK301190 |
C. mycophilus | ATCC 16199 (T) | KX686995 | KY402205 | MK301191 |
C. polyspermus | ATCC 14444 (T) | MF616382 | MF616384 | MK301193 |
C. polytocus | ATCC 12244 (T) | JF816213 | JF816227 | MK301194 |
C. taihushanensis |
|
MT250088 | MT274290 | MT250086 |
C. variabilis |
|
MT250087 | MT274289 | MT250085 |
Erynia conica | ARSEF 1439 | EF392396 | – | EF392506 |
Entomophthora muscae | ARSEF 3074 | DQ273772 | DQ275343 | – |
Microconidiobolus nodosus | ATCC 16577 (T) | JF816217 | JF816235 | MK333391 |
M. paulus | ARSEF 450 (T) | KC788409 | – | – |
M. terrestris | ATCC 16198 (T) | KX752050 | KY402208 | MK301199 |
M. undulatus | ATCC 12943 (T) | JX946693 | JX946699 | MK301201 |
Neoconidiobolus couchii | ATCC 18152 (T) | JN131538 | JN131544 | MK301179 |
N. kunyushanensis |
|
MN061286 | MN061483 | MN061289 |
N. lamprauges | CBS 461.97 | MH874268 | – | – |
N. lachnodes | ARSEF 700 | KC788408 | – | – |
N. mirabilis |
|
MH282852 | MH282853 | MK333392 |
N. nanodes | CBS 154.56 (T) | MH869096 | – | – |
N. osmodes | ARSEF 79 | EF392371 | – | DQ364219 |
N. pachyzygosporus |
|
KP218521 | KP218524 | MK333393 |
N. sinensis |
|
JF816224 | JF816238 | MK301196 |
N. stilbeus |
|
KP218522 | KP218525 | MK301197 |
N. stromoideus | ATCC 15430 (T) | JF816219 | JF816229 | MK301198 |
N. thromboides | ATCC 12587 (T) | JF816214 | JF816230 | MK301200 |
We downloaded nrLSU, mtSSU, and TEF1 sequences of 5 Capillidium species, 19 Conidiobolus s.s. strains, four Microconidiobolus strains, 12 Neoconidiobolus species, C. parvus, and two outgroup taxa (Entomophthora muscae and Erynia conica) from GenBank. Individual sequences of each locus were aligned using MUSCLE 3.8.31 (Edgar 2004) and concatenated matrices were assembled by SequenceMatrix 1.7.8 (
The total alignment length of the 46 taxa was 2,002: nrLSU, 1–1,095; TEF1, 1,096–1,597; and mtSSU, 1,598–2,002. The concatenated matrix contained 957 parsimony-informative and 225 parsimony-uninformative sites. The MP tree had a length of 5,463 with CI = 0.3815, RC = 0.2467, RI = 0.6404, and HI = 0.6471. We found that the optimal model of sequence evolution for nrLSU and TEF1 were GTR+I+G4, while TVM+I+G4 was selected for mtSSU, and the resulting BI, ML, and MP trees had similar topologies; the ML tree was selected to represent the phylogeny with MP/ML/BI support values (Fig.
ML tree of Coniobolus s.l. using nrLSU + TEF1 + mtSSU sequences. Entomophthora muscae and Erynia conica are selected as outgroups. Support for each node is shown as MP bootstrap support/ML bootstrap support/Bayesian posterior probability (MPBS/MLBS/BPP) for nodes with MPBS≧70%, MLBS≧70%) and BPP≧0.95. The new genus, Azyosporus, and new species, A. macropapillatus, are shown in red, and the new combination is shown in blue.
Referring to produce azygospores.
Azygosporus parvus (Drechsler) B. Huang & Y. Nie.
Mycelia colorless. Primary conidiophores simple, bearing single primary conidia. Primary conidia forcibly discharged multinucleate, colourless, globose to subglobose, small, less than 22.5 μm. Producing only globose or subglobose replicative conidia, similar to and smaller than primary conidia. Azygospores formed in the middle region of the old hyphal segments. Mature azygospores colourless or yellowish, smooth, without thickening or less thickening (0.5–1.2 μm).
Azygosporus is strongly supported as monophyletic and is distinguished from other Ancylistaceae lineages by the synapomorphy of azygospore production. Therefore, we classify this lineage as a new genus, named Azygosporus gen. nov. Azygosporus currently contains only two members: C. parvus (= A. parvus) and A. macropapillatus sp. nov. (Fig.
Morphological measurements of A. macropapillatus and other related species.
Species | Growth rate (mm/d) at 21oC on PDA | Diameter of mycelia (μm) | Primary conidiophores (μm) | Primary conidia (μm) | Basal papilla (μm) | Resting spores (μm) | References |
---|---|---|---|---|---|---|---|
A. macropapillatus | 5.7–7.7 | 3.0–7.5 | 37.0–150.0×5.0–8.5 | 16.5–22.5×12.0–19.0 | 7.5–10.0×5.0–10.0 | azygosporus, 25.0–30.0×27.0–34.0 | This article |
A. parvus | 1.5 | 1.4–8.0 (3.5–5) | 15.0–30.0×3.0–8.0 | 6.0–20.0×4.5–17.0 | 1.5–6.0×1.5–4.5 | azygosporus, 20.0–25.0×8.0–20.0 |
|
M. nodosus | 7.1 | 3.5–6.5 | 30.0–50.0 | 17.0–22.0×13.0–16.0 | 2.5–5.0×1.5–2.5 | chlamydosporus |
|
M. paulus | 1.3–3.3 | 1.5–7.0 (4.0–5.0) | 15.0–30.0×3.5–7.0 | 5.0–19.0×4.0–14.0 | 2.0–7.0×1.0–5.0 | zygosporus, 10.0–15.0 |
|
M. terrestris | 2.6 | 2.8–4.5 | 15.0–80.0 ×3.0–5.0 | 8.0–12.0 | 2.0–4.0×1.5–2.0 | chlamydosporus |
|
N. lamprauges | less than 5.0 | 3.0–8.0 (4.0–7.0) | 25.0–100.0 (25.0–50.0)×4.0–8.0 (5.0–15.0) | 15.0–22.0×12.5–20.0 | 2.5–7.0×1.5–4.0 | zygosporus, 12.0–18.0 |
|
N. kunyushanensis | 8.3–10.0 | 3.5–9.0 | 62.0–121.0×7.0–12.0 | 15.0–21.0×13.0–17.0 | 4.0–8.0×1.0–4.0 | zygosporus, 12.0–25.0 |
|
N. pachyzygosporus | 12.0 | 3.0–14.0 | 34.0–156.0×6.0–12.0 | 15.5–23.0×11.0–18.0 | 3.0–5.0×1.0–4.0 | zygosporus, 15.0–25.0 |
|
Conidiobolus parvus Drechsler, Bull. Torrey bot. Club 89: 233 (1962) Basionym.
Refer to
Isolated from decaying leaves in Maryland, United States.
The ex-type living culture is ATCC 14634 (United States, Maryland, Cumberland, 4 November 1962, Drechsler). It was reported to produce azygospores in Conidiobolus (
macropapillatus (Lat.), named by its prominent basal papilla.
Isolated from plant debris and mosses in Anhui Province, China.
China, Anhui Province, Ningguo City, Fangtang Town, 30°30'57" N, 118°42'17" E, from plant debris, 12 Nov 2020, Y. Nie, HMAS 350621, holotype, culture ex-holotype
Morphological characters of Azygosporus macropapillatus: a) colony on PDA after 3 d at 21 °C, b) mycelia rarely branched at the colony edge, c-f) primary conidiophores bearing primary conidia, g-h) Primary conidia with prominent basal papillum, j-k) secondary conidia arising from primary conidia, i-m) azygospores formed in the middle region of the old hyphal segment, n) immature azygospore, and o-q) mature azygospores. Scale bars: a) 10 mm, b) 100 μm, and c-q) 20 μm.
China, Anhui Province, Jinzhai County, Tiantangzhai National Forest Park, 31°20'68" N, 115°81'25" E, from mosses, 6 Nov 2008, C.F. Wang, culture
Colonies white, reaching ca 17.0–23.0 mm diameter on PDA after 3 d at 21°C. Mycelia colorless, 3.0–7.5 µm wide, usually unbranched at the colony edge. Primary conidiophores colorless, without widening upward near the tip, unbranched and producing a single conidium, 37.0–150.0 × 5.0–8.5 µm. Primary conidia forcibly discharged, colorless, subglobose, 12.0–19.0 µm wide and 16.5–22.5 µm long, most primary conidia possessed a prominent basal papilla 5.0–10.0 µm wide and 7.5–10.0 µm long. Secondary conidia arising from the primary ones with a similar shape and a smaller size. Resting spores (azygospores) observed after 10 d, and the young spores formed in the middle region of the old hyphal segments. The young spores enlarge gradually to form mature azygpspores with less thickening. Mature azygospores colorless, subglobose 25.0–30.0 × 27.0–34.0 μm with a wall 0.5–1.0 μm thick.
Morphologically, Azygosporus macropapillatus sp. nov. has conidial dimensions similar to six Conidiobolus s.l. species without capilliconidia and microconidia: C. parvus, M. nodosus, M. paulus, N. kunyushanensis, N. lamprauges, and N. pachyzygosporus (
The genus Microconidiobolus, typified by M. paulus, was recently established as a monotypic genus based on its small discharged primary conidia (less than 20 μm) (
The phylogeny presented here (Fig.
For decades, most published Conidiobolus species had been described by only one strain, with the exception of some pandemic species (e.g., C. coronatus, N. osmodes, and N. thromboides) (
The authors are grateful to Dr. Ian Gilman (Yale University) for improving the manuscript. Mrs. C.F. Wang and Mrs. X.X. Tang (Anhui Agricultural University) are acknowledged for helping with specimen collection and molecular work.
This work was supported by the National Natural Science Foundation of China (Nos. 31900008, 30770008 and 31970009) and the Natural Science Foundation of Anhui Province (No. 2108085MH318).