Research Article |
Corresponding author: Yan-Feng Han ( swallow1128@126.com ) Academic editor: Nalin Wijayawardene
© 2019 Wan-Hao Chen, Chang Liu, Yan-Feng Han, Jian-Dong Liang, Wei-Yi Tian, Zong-Qi Liang.
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:
Chen W-H, Liu C, Han Y-F, Liang J-D, Tian W-Y, Liang Z-Q (2019) Three novel insect-associated species of Simplicillium (Cordycipitaceae, Hypocreales) from Southwest China. MycoKeys 58: 83-102. https://doi.org/10.3897/mycokeys.58.37176
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In this paper, we introduce three new species of Simplicillium, viz. S. cicadellidae, S. formicidae and S. lepidopterorum, which were isolated from an infected leafhopper, ant and carpenterworm, respectively. Morphological comparisons and phylogenetic analyses based on multigene datasets (LSU+RPB1+RPB2+TEF and ITS+LSU) support the establishment of the three new species. Simplicillium cicadellidae was distinguished from other species in morphological characteristics by having smaller phialides and ellipsoidal conidia, and lacking octahedral crystals. The reverse of colonies were yellowish (#FFBF00), especially in the middle, and radially sulcate. Simplicillium formicidae was morphologically distinguished from other by having longer phialides and filiform to fusoid conidia, and by lacking octahedral crystals. Simplicillium lepidopterorum was morphologically distinguished from other species by having smaller, ellipsoidal to fusiform conidia, and by lacking octahedral crystals. The reverse of the colony was pale white. The three new species are likely to be nourished by plant to animal (especially insect) nutrients based on the evolutionary pattern of the Hypocreales, and they are described herein as being clearly distinct from other species in Simplicillium.
Commensal fungi, morphology, nutritional preference, phylogeny
The genus Simplicillium W. Gams & Zare was introduced by
Kepler et al. (2017) re-evaluated the Cordycipitaceae based on the multigene dataset (SSU, LSU, TEF, RPB1 and RPB2), and indicated that Simplicillium species group in a clade and are the earliest diverging lineage in Cordycipitaceae. The nuclear ribosomal ITS and LSU were first used to identify cryptic diversification among Simplicillium species by
Three infected insect specimens were found during a survey of araneogenous fungi and allies from southwestern China. Some fungal strains were isolated and purified from the three specimens. Based on polyphasic approach (morphological, ecological characteristics along with a phylogenetic analysis), they were identified as three new species, Simplicillium cicadellidae sp. nov., S. formicidae sp. nov. and S. lepidopterorum sp. nov.
Three infected insect specimens (DL1004, GY1101 and GY2913) were collected from Dali, Rongjiang Country (26°01'58.70"N, 108°24'48.06"E) and Tongmuling (26°23'25.92"N, 106°41'3.35"E), Huaxi District, Guizhou Province, on 1 October, 9 November and 31 July, 2018, respectively. The surface of the specimens were rinsed with sterile water, followed by surface sterilization with 75% ethanol for 3–5 s. A part of the insect body was cut off and used to inoculate a piece of tissue in haemocoel on potato dextrose agar (PDA) and improved potato dextrose agar (PDA, 1% w/v peptone) (
The strains were incubated in PDA at 25 °C for 14 d. Macroscopic and microscopic morphological characteristics of the fungi were examined using classical mycological techniques, and the growth rates were determined. The fresh hyphae were observed with an optical microscope (OM, BX35, Olympus, Japan) following pretreatment with lactophenol cotton blue solution or normal saline. The ex-type cultures and dried culture as holotype specimens were deposited in GZAC, Guizhou University, Guiyang, China.
DNA extraction was carried out in accordance with
The new species Simplicillium cicadellidae, S. formicidae and S. lepidopterorum were registered in MycoBank with the numbers MB 831336, MB 831337 and MB 831335, respectively.
DNA sequences generated in this study were assembled and edited using DNASTAR Lasergene software (version 6.0). Sequences of ITS, LSU, RPB1, RPB2 and TEF were selected based on previously published data by
Two different analyses have been carried out using Bayesian inference (BI) and maximum likelihood (ML) methods. Analysis 1: To check the relationship between Simplicillium species and its allies in Cordycipitaceae based on the combined dataset of (LSU+RPB1+RPB2+TEF). Analysis 2: To check the relationship among Simplicillium spp. based on the combined dataset of (ITS+LSU). For the BI analysis, two runs were executed simultaneously for 10,000,000 generations, saving trees every 500 generations, with the GTR+G nucleotide substitution model across all the partitions, in MrBayes 3.2 (
A phylogenetic tree of Simplicillium in Cordycipitaceae was generated from the maximum-likelihood (ML) and Bayesian inference (BI) based on a combined data set of LSU, RPB1, RPB2 and TEF sequence data. Statistical support (≥ 50%/0.5) is shown at the nodes for ML bootstrap support/BI posterior probabilities (Fig.
Phylogenetic relationships among the genus Simplicillium and its allies in Cordycipitaceae based on multigene dataset (LSU, RPB1, RPB2 and TEF). Statistical support values (≥ 0.5/50%) are shown at the nodes for ML bootstrap support/BI posterior probabilities. The tree is rooted with Purpureocillium lilacinum (CBS 284.36 and CBS 431.87). The new species are in bold face. T in the upper right corner indicates the type strains.
A phylogenetic tree of Simplicillium species level was generated from the maximum-likelihood (ML) and Bayesian inference (BI) analysis based on a combined data set of ITS and LSU sequence data set. Statistical support (≥ 50%/0.5) are shown at the nodes for ML bootstrap support/BI posterior probabilities. The strain numbers are noted after each species’ name. The tree is rooted with Pochonia chlamydosporia (Goddard) Zare & W. Gams (CBS 103.65). The dataset includes 16 taxa and consists of 1,000 characters with gaps (ITS: 489 and LSU: 511).
Analysis 1: family Cordycipitaceae. The RAxML analysis of the combined dataset (LSU+RPB1+RPB2+TEF) yielded a best scoring tree (Fig.
Analysis 2: Simplicillium species. The RAxML analysis of the combined dataset (ITS+LSU) yielded a best scoring tree (Fig.
Phylogenetic relationships among the new taxa S. cicadellidae, S. formicidae, S. lepidopterorum and other Simplicillium species by ITS+LSU sequences. Statistical support values (≥ 0.5/50%) are shown at the nodes for ML bootstrap support/BI posterior probabilities. The tree is rooted with Pochonia chlamydosporia (CBS 103.65). The new species are in bold face. T in the upper right corner indicates the type strains.
The epithet cicadellidae refers to an insect host in family Cicadellidea.
Characterized by phialides always solitary and rather long and narrow, 12.9–18.3 × 0.8–1.1 μm. Conidia adhering in globose slimy heads, mostly ellipsoidal, 1.8–2.8 × 1.4–1.8 μm. Octahedral crystals absent. Reverse of colony yellowish, especially in the middle, and radially sulcate.
CHINA, Guizhou Province, Huaxi District (26°23'25.92"N, 106°41'3.35"E), 9 November 2018, Wanhao Chen, holotype GZAC GY1101, ex-type culture GZAC GY11011. Sequences from isolated strain GY11011 has been deposited in GenBank with accession numbers: ITS = MN006243, LSU = MN006249, RPB1 = MN022271 and TEF = MN022263.
Simplicillium cicadellidae A infected leafhopper (Hemiptera) B–C culture plate, showing the front (B) and the reverse (C) of the colony, cultured on PDA medium D–F phialides solitary, conidia adhering ellipsoidal slimy head and conidia G conidia. Scale bars: 10 mm (B, C), 10μm (D, E, F, G).
Colonies reaching 45–47 mm in diameter in 14 d on PDA; white; reverse yellowish, especially in the middle, and radially sulcate. Hyphae septate, hyaline, smooth-walled, 0.9–1.9 μm wide. Phialides arising from aerial hyphae, gradually tapering towards apex, without basal septa, always solitary and rather long and narrow, 12.9–18.3 × 0.8–1.1 μm. Conidia adhering in ellipsoidal slimy heads, mostly ellipsoidal, hyaline, smooth-walled, 1.8–2.8 × 1.4–1.8 μm. Octahedral crystals absent.
Leafhopper (Hemiptera)
Huaxi District, Guizhou Province, China
Morphological comparison of three new species with other Simplicillium species
Species | Morphological characteristics | Notes | |||
Phialide (Conidiogenous cell) (μm) | Conidia (μm) | Conidia mass | Octahedral crystals | ||
S. aogashimaensea | (19–)23–53 × 1.2–2.0 | cylindrical, 4.2–6.5 × 1.2–2.0 | globose heads | present | Chlamydospores present |
S. calcicolab | 14–38 × 1–2 | micro-: globose, oval or ellipsoidal, 2–3.5 × 1–1.5 | absent | ||
macro-: fusiform, 4.5–8 × 1–2 | |||||
S. chinensec | (6.0–)15–30(–68.0) × 1.5 | oval, ellipsoidal or cylindrical 3.5–5.0 × 1.0–1.5 | branched or unbranched chains | present | |
S. coffeanumd | 11–40(–70) × 1.0–2.4 | micro-: spindle-shaped, 5.3–8.8 × 1.0–1.6 | subglobose to ellipsoidal heads | absent | |
macro-: ellipsoidal to fusiform, 2.2–3.8 × 0.8–1.5 | |||||
S. cylindrosporuma | 17–32 × 1.2–2.0(–2.5) | cylindrical, 3.0–4.5(–5.0) × 1.0–2.0 | globose heads | present | |
S. filiformee | 9–18 × 1 | fusoid to filiform, 7.2–12.5 × 1 | zigzag chains | absent | |
S. lamellicolaf | 15–50 × 0.7–1.0 | micro-: spindle-shaped, 4.5–9.0 × 0.8–1.2 | subglobose to ellipsoidal heads | present | |
macro-: oval to ellipsoidal, 2.0–3.0 × 0.7–1.2 | |||||
S. lanosoniveumf | 15–35 × 0.7–1.5 | subglobose, oval, ellipsoidal 1.5–3 × 0.7–1.3 | globose heads | present | |
S. minatensea | 11–31(–47) × 1.0–1.7 | globose to subglobose, sometimes ellipsoidal, 2.0–3.5 × 1.8–2.5(–2.8) | globose heads | present | |
S. obclavatumf | 30–52 × 0.8–1.2 | obclavate to ellipsoidal, 2.5–3.5 × 1–2 | short imbricate chains | present | |
S. subtropicuma | (15–)20–42(–50) × 1.0–2.3 | subglobose to ellipsoidal, 2.3–4.0(–4.5) × 1.5–3.3 | globose heads | present | |
S. sympodiophoruma | 20–34(–47) × 0.5–1.3 denticles present |
oval to ellipsoidal, 2.2–3.5 × 1.0–2.0 | present | ||
S. cicadellidae | 12.9–18.3 × 0.8–1.1 | ellipsoidal, 1.8–2.8 × 1.4–1.8 | ellipsoidal heads | absent | colonies reverse pale white |
S. formicidae | 51–70.1 × 0.7–0.9 | filiform to fusoid, 3.9–7.9 × 0.8–1.3 | globose heads | absent | |
S. lepidopterorum | 15.3–26.2 × 0.7–1.4 | ellipsoidal, 1.6–2.4 × 1.4–1.7 | globose heads | absent | colonies reverse yellowish |
The epithet formicidae refers to an insect host in family Formicidae.
Characterized by phialides always being solitary and rather long and narrow, 51–70.1 × 0.7–0.9 μm. Conidia adhering in globose slimy heads, mostly filiform to fusoid, 3.9–7.9 × 0.8–1.3 μm. Octahedral crystals absent.
CHINA, Guizhou Province, Rongjiang County (26°01'58.70"N, 108°24'48.06"E), 1 October 2018, Wanhao Chen, holotype GZAC DL1004, ex-type culture GZAC DL10041. Sequences from isolated strain DL10041 has been deposited in GenBank with accession numbers: ITS = MN006241, LSU = MN006247, RPB1 = MN022269 and RPB2 = MN022267.
Colonies reaching 26–32 mm in diameter in 14 d on PDA; white; reverse pale brown to brown, and with brown secretions. Hyphae septate, hyaline, smooth-walled, 1.2–1.8 μm wide. Phialides arising from aerial hyphae, gradually tapering towards the apex, without basal septa, always solitary and rather long and narrow, 51–70.1 × 0.7–0.9 μm. Conidia adhering in globose slimy heads, mostly filiform to fusoid, hyaline, smooth-walled, 3.9–7.9 × 0.8–1.3 μm. Octahedral crystals absent.
Ant (Hymenoptera)
Rongjiang County, Guizhou Province, China
Simplicillium formicidae was easily identified as belonging to Simplicillium because of its solitary phialides, conidia adhering in globose slimy heads, and lack of octahedral crystals. Compared with the typical characteristics of 12 species (Table
The epithet lepidopterorum refers to an insect host in order Lepidoptera.
Characterized by phialides always being solitary and rather long and narrow, 15.3–26.2 × 0.7–1.4 μm, Conidia adhering in globose slimy heads, mostly ellipsoidal, 1.6–2.4 × 1.4–1.7 μm. Octahedral crystals absent. The reverse of colony was pale white.
CHINA, Guizhou Province, Huaxi District (26°23'25.92"N, 106°41'3.35"E), 31 July 2018, Wanhao Chen, holotype GZAC GY2913, ex-type culture GZAC GY29131, sequences from isolated strain GY29131 has been deposited in GenBank with accession numbers: ITS = MN006246, LSU = MN006251, RPB1 = MN022273 and TEF = MN022265.
Simplicillium formicidae A isolated substrate an infected ant (Hymenoptera) B–C culture plate, showing the front (B) and the reverse (C) of the colony, cultured on PDA medium D, E phialides solitary, conidia adhering globose slimy head and conidia F conidia. Scale bars: 10 mm (B, C), 10μm (D, E, F).
Colonies reaching 48–51 mm in diameter in 14 d on PDA; white; reverse pale white. Hyphae septate, hyaline, smooth-walled, 1.1–2.2 μm wide. Phialides arising from aerial hyphae, gradually tapering towards the apex, without basal septa, always solitary and rather long and narrow, 15.3–26.2 × 0.7–1.4 μm. Conidia adhering in globose slimy heads, ellipsoidal to fusiform, hyaline, smooth-walled, 1.6–2.4 × 1.4–1.7 μm. Octahedral crystals absent.
Carpenter worm (Lepidoptera)
Huaxi District, Guizhou Province, China
Simplicillium lepidopterorum was easily identified as belonging to Simplicillium because of its solitary phialides, conidia adhering in globose slimy heads, and lack of octahedral crystals. Comparing with the typical characteristics of 12 species (Table
1 | Conidia in globose or subglobose heads | 2 |
– | Conidia in chains or solitary | 11 |
2 | Macro- and microconidia present | 3 |
– | Only one type of conidia present | 4 |
3 | Octahedral crystals present | S. lamellicola |
– | Octahedral crystals absent | S. coffeanum |
4 | Octahedral crystals present | 5 |
– | Octahedral crystals absent | 9 |
5 | Conidia cylindrical | 6 |
– | Conidia subglobose or ellipsoidal | 7 |
6 | Chlamydospores present, conidia 4.2–6.5 × 1.2–2.0 μm | S. aogashimaense |
– | Chlamydospores absent, conidia 3.0–4.5 (–5.0) × 1.0–2.0 μm | S. cylindrosporum |
7 | Conidia subglobose to ellipsoidal | 8 |
– | Conidia oval or ellipsoidal to subcylindrical, 1.5–3.0 × 0.7–1.3 μm | S. lanosoniveum |
8 | Conidia subglobose to ellipsoidal, 2.3–4.0 (–4.5) × 1.5–3.3 μm | S. subtropicum |
– | Conidia globose to subglobose, sometimes ellipsoidal, 2.5–3.5 × 1.8–2.5 (–2.8) μm | S. minatense |
9 | Conidia ellipsoidal | 10 |
– | Conidia filiform to fusoid | S. formicidae |
10 | The reverse of colony pale white, phialide 12.9–18.3 × 0.8–1.1 μm | S. cicadellidae |
– | The reverse of colony yellowish, phialide 15.3–26.2 × 0.7–1.4 μm | S. lepidopterorum |
11 | Denticles present in conidiogenous cell (phialide) | S. sympodiophorum |
– | Denticles absent in conidiogenous cell (phialide) | 12 |
12 | Macro- and microconidia present | S. calcicola |
– | Only one type of conidia present | 13 |
13 | Conidia ellipsoidal | 14 |
– | Conidia fusoid to filiform, form zigzag chains | S. filiforme |
14 | Conidia in branched or unbranched chains, 3.5–5.0 × 1.0–1.5 μm | S. chinense |
– | Conidia in short imbricate chains, 2.5–3.5 × 1.0–2.0 μm | S. obclavatum |
Two types of the evolutionary correlation patterns between fungi and hosts are known, co-evolutionary patterns and the more frequent host jump events (
Among the 12 reported Simplicillium species, S. aogashimaense (soil), S. calcicola (calcareous rock), S. chinense (decaying wood), S. cylindrosporum (soil), S. minatense (soil), S. obclavatum (air), S. subtropicum (soil) and S. sympodiophorum (soil) were isolated from soil, marine water, rock, decaying wood and air (
The hosts of Simplicillium cicadellidae and S. lepidopterorum were larvae of Cicadidae and Lepidoptera, which feed through piercing-sucking and chewing. Moreover, S. formicidae was isolated from an infected ant. These three strains are likely to receive nutrients from plants (including living plants and plant residues) and animals (especially insects) based on the evolutionary pattern of Hypocreales. Simplicillium cicadellidae, S. formicidae and S. lepidopterorum represent three new species based on their nutritional preferences. To our knowledge, this is the first report of insect-associated Simplicillium species.
ITS and LSU have been widely used in the identification of Simplicillium (
This work was supported by the National Natural Science Foundation of China (Grant No. 31460010, 31860002), the Doctoral Fund of Guiyang University of Chinese Medicine (3043-043170023), the National first-class construction discipline in Guizhou province (Chinese medical science) (GNYL[2017]008), and Engineering Research Center of General Higher Education in Guizhou Province (Qianjiaohe(2015)337). We thank Dr. Lesley Benyon, from Liwen Bianji and Edanz Group China (http://www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript.