Research Article
Research Article
Two new species of Scolecobasidium (Venturiales, Sympoventuriaceae) associated with true mangrove plants and S. terrestre comb. nov.
expand article infoShuang Song§, Meng Li, Jun-En Huang§, Fang Liu§
‡ Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
§ University of Chinese Academy of Sciences, Beijing, China
Open Access


Scolecobasidium is cosmopolitan and includes species that inhabit a wide range of ecosystems including soil, water, air, plant and cold-blooded vertebrates. During a fungal survey from mangrove, strains of Scolecobasidium occurring on leaf spots of true mangrove plants, Aegiceras corniculatum and Acanthus ebracteatus, were isolated from Futian Mangrove in Shenzhen and the Qi’ao-Dangan Island Mangrove in Zhuhai, China. Unlike most species in Scolecobasidium that produce dark conidia, our strains are characterized by hyaline to pale brown conidia and inconspicuous thread-like sterigmata. Further detailed morphological comparison and multi-locus (LSU, ITS, tub2, tef1-α) phylogenetic analyses revealed these collections as two new taxa, namely S. acanthi sp. nov. and S. aegiceratis sp. nov. We further emend the generic description of Scolecobasidium, propose one new combination, S. terrestre comb. nov., and clarify the taxonomic status of S. constrictum.


Mangrove, phylogeny, plant pathogen, taxonomy


Scolecobasidium was described based on two species, S. terreum and S. constrictum, with the former as the generic type (Abbott 1927). This genus is slow-growing, and characterized by brownish to black colonies, reduced, hyaline or pigmented conidiophores and septate, smooth- or rough-walled, brown, single, dry and rhexolytic conidia (Abbott 1927; Barron and Busch 1962; Seifert and Gams 2011). A distinguishing feature of Scolecobasidium from other genera is the conidiophores, which are born on aerial hyphae as short non-septate structures producing conidia from the ends of thread-like sterigmata (Abbott 1927). Subsequently, more species with unbranched conidia were described in Scolecobasidium and the conidia of this genus are found to be variable in shape, especially its type species S. terreum producing Y-shaped or T-shaped conidia distinct from other species in the genus. Therefore, Hoog and von Arx (1973) introduced a separate genus Ochroconis, typified by O. constricta (syn. S. constrictum), and transferred many Scolecobasidium species into this genus (De Hoog 1973). At that time, Ochroconis was comprised of species with sympodial conidiogenesis and ellipsoidal, clavate or fusiform conidia, whereas the genus Scolecobasidium was restricted to species with T- or Y-shaped or bilobed, 1- or multiple septate conidia born on ampulliform conidiogenous cells possessing 1–3 conidial-containing denticles at the tip of the conidiophores (De Hoog 1973). Subsequently, Ellis (1976) classified Ochroconis as a synonym of Scolecobasidium, and Gams (2015) and Seifert and Gams (2011) agreed with this interpretation. In addition to the similar morphological characteristics of Scolecobasidium and Ochroconis, recent molecular analyses have clearly shown that the two genera constituted a polyphyletic complex and Ochroconis should not be treated as a separate genus (Hao et al. 2012; Samerpitak et al. 2014). Although the ex-type strains of both S. terreum (CBS 203.27) and O. constricta (CBS 202.27) are sterile after a long period of preservation, they were phylogenetically placed within the Scolecobasidium clade (Shen et al. 2020). Therefore, based on the principle of priority, the older generic name Scolecobasidium was chosen over Ochroconis, and 25 new combinations have been proposed (Shen et al. 2020; Crous et al. 2021; Wei et al. 2022).

Scolecobasidium is the largest genus within Sympoventuriaceae, Venturiales, Dothideomycetes (Shen et al. 2020) and about 98 epithets are currently listed in Index Fungorum (Index Fungorum accession date: 10.01.2023). Scolecobasidium is a cosmopolitan genus of saprotrophic soil hyphomycetes, some of which are also parasitic on plants (De Hoog 1985; Crous et al. 2016), human (Giraldo et al. 2014), fish (Ross and Yasutake 1973) or other animals (VanSteenhouse et al. 1988; Singh et al. 2006). In our study, during the fungal investigations of mangrove plants in China, several strains of Scolecobasidium were isolated from leaf spots on Aegiceras corniculatum and Acanthus ebracteatus, and they were revealed as two novel species through polyphasic analyses. In addition, on the basis of Shen et al. (2020) and Wei et al. (2022), we correct the taxonomic status of ambiguous species in this group.

Materials and methods

Sample collection and fungal isolation

During our fungal investigations on mangrove plants in China, 90 strains of 48 species have been isolated from true mangrove plants, Acanthus ebracteatus and Aegiceras corniculatum (Table 1). Among them, Scolecobasidium-like strains piqued our interest because their unique characters differed from known species and were further studied herein. Type specimens made from ex-type strains of the novel species were preserved in the Fungarium (HMAS), Institute of Microbiology, CAS, and the living cultures were preserved in the China General Microbiological Culture Collection Center (CGMCC) and LC culture collection (personal culture collection of Lei Cai housed in the Institute of Microbiology, Chinese Academy of Sciences).

Table 1.

Pathogens and endophytes associated with true mangrove plant Acanthus ebracteatus and Aegiceras corniculatum.

Strains No. Fungus species Host plant Remark
SS1 Acrocalymma medicaginis Ac. ebracteatus Pathogen
ds0003, SS2012, SS2094, SS2108, SS2009, SS2017, SS2096, SS2103 Alternaria angustiovoidea Ac. ebracteatus Endophyte
SS2047 Arthrinium xenocordella Ae. corniculatum Endophyte
ds0016 Cercospora beticola Ae. corniculatum Endophyte
SS2097, SS27 Cladosporium austrohemisphaericum Ae. corniculatum Endophyte
ds1001, ds1030, SS10 Cladosporium cladosporioides Ae. corniculatum Pathogen
SS2010 Cladosporium colombiae Ae. corniculatum Endophyte
ds0017, ds1043, ds1032, ds1042 Cladosporium dominicanum Ae. corniculatum Endophyte
SS8, SS42 Cladosporium oryzae Ac. ebracteatus Pathogen
SS2110 Cladosporium rugulovarians Ae. corniculatum Endophyte
ds1038-2 Cladosporium sphaerospermum Ae. corniculatum Pathogen
SS28 Cladosporium tenuissimum Ac. ebracteatus Pathogen
ds0011 Colletotrichum gigasporum complex Ac. ebracteatus Endophyte
SS2109, SS2046 Cytospora sp. nov. Ae. corniculatum Endophyte
SS2107 Diaporthe hongkongensis Ae. corniculatum Endophyte
SS2041 Diaporthe perseae Ae. corniculatum Endophyte
ds1038, SS2106 Fusarium incarnatum Ae. corniculatum Pathogen
ds1018 Fusarium luffae Ae. corniculatum Pathogen
SS14 Fusarium solani Ae. corniculatum Pathogen
ds1045 Halorosellinia sp. nov. Ae. corniculatum Pathogen
ds0021, ds0022 Halorosellinia xylocarpi Ac. ebracteatus Endophyte
ds1093, ds1094, ds1095 Hortaea werneckii Ae. corniculatum Pathogen
ds1044 Hypocreales sp. nov. Ae. corniculatum Pathogen
SS29 Nemania sp. nov. Ae. corniculatum Endophyte
ds1087 Neodevriesia tabebuiae Ae. corniculatum Pathogen
SS2015, SS2045, SS2100, ds1062, ds1075 Neofusicoccum kwambonambiense Ae. corniculatum Endophyte
ds1060 Neopestalotiopsis eucalypticola Ae. corniculatum Pathogen
ds1020 Neopestalotiopsis phangngaensis Ae. corniculatum Pathogen
ds1061 Neopestalotiopsis sp. nov. Ae. corniculatum Pathogen
SS2092 Nigrospora oryzae Ae. corniculatum Endophyte
ds1025 Occultifur sp. nov. Ac. ebracteatus Pathogen
SS2069, SS2038, SS2067, SS2068 Penicillium brevicompactum Ac. ebracteatus Endophyte
SS2051, SS2048, SS2052, SS2056, SS2058, SS2066, SS2077, SS2081, SS2083 Penicillium chrysogenum Ae. corniculatum Endophyte
SS2087 Penicillium coffeae Ae. corniculatum Endophyte
ds1019 Pestalotiopsis kandelicola Ae. corniculatum Pathogen
SS2011 Phyllosticta capitalensis Ac. ebracteatus Endophyte
ds1081 Phyllosticta sp. nov. Ae. corniculatum Pathogen
SS20 Pseudopestalotiopsis chinensis Ae. corniculatum Pathogen
ds1028 Rhodotorula sphaerocarpa Ac. ebracteatus Pathogen
ds1031 Roussoella mediterranea Ae. corniculatum Pathogen
LC19368 Scolecobasidium acanthi sp. nov. Ac. ebracteatus Pathogen
LC19369, LC19370 Scolecobasidium aegiceratis sp. nov. Ae. corniculatum Pathogen
SS2089 Stemphylium solani Ae. corniculatum Endophyte
ds1100 Symmetrospora marina Ae. corniculatum Pathogen
ds1084 Thyridium pluriloculosum Ae. corniculatum Pathogen
SS2044 Tricharina ochroleuca Ac. ebracteatus Endophyte
SS2040, SS2043 Trichoderma harzianum Ae. corniculatum Endophyte
ds1086, ds1026, ds1027, ds1079, ds1082, ds1026-2, ds1037 Zasmidium anthuriicola Ae. corniculatum Pathogen

Morphological observations

Colony features including color and growth rate were recorded for the strains grown on oatmeal agar (OA) and malt extract agar (MEA) after 14 days at 25 °C. To enhance sporulation, strains were incubated at 25 °C under near UV light with a 12 h photoperiod for 14 d or longer period. Morphological observations of reproductive structures were made in lactic acid and observed using a Nikon Eclipse 80i microscope using differential interference contrast (DIC) illumination. At least 30 measurements per structure were taken, and the mean value, standard deviation, and minimum–maximum values were given.

DNA extraction, PCR amplification and sequencing

Fresh fungal mycelia grown on potato dextrose agar (PDA) for 14 d at 25 °C were scraped from the colony margin and used for genomic DNA extraction using a modified CTAB protocol as described previously (Guo et al. 2000). Genomic DNA was diluted to 1 ng/μL using sterile water as the template for PCR. The amplification of internal transcribed spacer (ITS) region including the flanking 5.8S rRNA gene, was carried using the primer pairs ITS1 and ITS4 (White, Bruns, Lee, Taylor, 1990), the 28S nuclear large subunit (nuLSU) with LR0R/LR5 (White, Bruns, Lee, Taylor, 1990), with EF1-728F/EF-2 (Qiao et al. 2016) for the partial translation elongation factor 1-alpha gene (tef1-α) and Bt2a/Bt2b to amplify the partial beta-tubulin gene (tub2) (Glass and Donaldson 1995), respectively. The reaction volume of 25 μL consisted of 10× PCR buffer 2.5 μL, MgCl2 2 mM, dNTPs 50 μm/L, forward and reverse primers 0.1 μm/L, DNA polymerase 0.5 U, and DNA template 10 ng. PCR amplification reactions for LSU and ITS were performed as follows: pre-denaturation at 95 °C for 10 min, followed by 35 cycles of denaturation at 95 °C for 45 s, annealing at 52 °C for 45 s, extension at 72 °C for 1 min, and a final extension step at 72 °C for 10 min, but the annealing temperature was adjusted to 56 °C for tef1-α and tub2. PCR products were detected by 1% agarose gel electrophoresis and then sequenced by SinoGenoMax. MEGA v. 7 was used to obtain consensus sequences from DNA data generated from forward and reverse primers.

Phylogenetic analyses

Phylogenetic analysis was performed using sequences of LSU, ITS, tub2, and tef1-α from 64 type and reference strains of Ochroconis, Scolecobasidium and one outgroup Verruconis calidifluminalis CBS 125818 (Table 2). Single locus alignment was performed using an online version of MAFFT v. 7 (Katoh and Standley 2013) and then concatenated for Maximum Likelihood (ML) and Bayesian analysis (BA). ML and BA were implemented using RAxML-HPC BlackBox v. 8.2.12 and MrBayes v. 3.2.7a, respectively, in the CIPRES Science Gateway portal (; Miller et al. 2010). For ML analysis, GTR+GAMMA substitution model with 1,000 bootstrap iterations was set. For BA, MrModeltest v. 2.4 (Guindon and Gascuel 2003; Matic et al. 2012) was firstly used to determine the best evolutionary model for each locus. Bayesian analysis was computed with four simultaneous Markov Chain Monte Carlo chains, 10,000,000 generations, and a sampling frequency of 1,000 generations, ending the run automatically when standard deviation of split frequencies fell below 0.01. The burn-in fraction was set to 0.25, after which the 50% majority rule consensus trees and posterior probability (PP) values were calculated. The resulting trees were plotted using FigTree v. 1.4.4 ( and the layout was edited in Adobe Illustrator 2020. Newly obtained sequences in this study are submitted to GenBank. New descriptions and nomenclature were deposited in MycoBank ( (Crous et al. 2014).

Table 2.

Strains used in the phylogenetic analysis of Scolecobasidium and GenBank accession numbers.

Species Straina Genbank accession numbersb
ITS LSU tub2 tef1
acanthi CGMCC 3.24352 = LC19368T OQ448957 OQ448949 OQ442218 OQ442215
S. aegiceratis CGMCC 3.24353 = LC19369T OQ448958 OQ448950 OQ442219 OQ442216
S. aegiceratis CGMCC 3.24354 = LC19370 OQ448959 OQ448951 OQ442220 OQ442217
S. ailanthi MFLU 18-2110 MK347731 MK412881
S. ailanthi MFLUCC 17-0923T MK347730 MK347947 MK412883
S. anellii CBS 284.64T FR832477 KF156138 KF156184 KF155995
S. anomalum CBS 131816T HE575201 KF156137 KF156194 KF155986
S. aquaticum CBS 140316T KX668258 KX668259
S. bacilliforme CBS 100442T KP798632 KP798635 KT272059 KT272070
S. blechni CBS 146055T MN562134 MN567641 MN556843 MN556826
S. camellicola GUCC 18242T MZ503728 MZ503761 MZ546907 MZ546874
S. capsici CBS 142096T KY173427 KY173518
S. constrictum CBS 202.27T MH854929 MH866423 KF156161 KF156003
S. cordanae CBS 412.51 HQ667540 KF156123 KF156200 KF155980
S. cordanae CBS 475.80T KF156022 KF156122 KF156197 KF155981
S. crassihumicola CBS 120700 KJ867429 KJ867430 KJ867433 KJ867428
S. dracaenae CBS 141323T KX228283 KX228334 KX228377
S. echinulatum GUCC 18247T MZ503733 MZ503766 MZ546912 MZ546879
S. echinulatum GUCC 18248 MZ503734 MZ503767 MZ546913 MZ546880
S. ellipsoideum CBS 131796T MN077367
S. ellipsoideum GUCC 18264 MZ503750 MZ503783 MZ546929 MZ546896
S. ferulica IRAN3232CT MF186874 MH400207
S. gamsii CBS 239.78T KF156019 KF156150 KF156190 KF155982
S. globale CBS 119644T KF961086 KF961097 KF961065 KF961075
S. globale CBS 135924 KF961092 KF961104 KF961070 KF961079
S. guangxiensis SS23T MK934570 MK956169
S. guangxiensis X22 MK961215 MK961247
S. helicteris NFCCI 4310T MK014833 MK321318
S. humicola CBS 116655T HQ667521 KF156124 KF156195 KF155984
S. icarus CBS 116645 HQ667525 LM644604
S. icarus CBS 536.69T HQ667524 KF156132 KF156174 KF156009
S. lascauxense CBS 131815T FR832474 KF156136 KF156183 KF155994
S. lascauxense CBS 423.64 HQ667523 KF156131 KF156173 KF156008
S. leishanicola GUCC 18259 MZ503745 MZ503778 MZ546924 MZ546891
S. leishanicola HGUP1808T MK377301 MK377073
S. longiphorum CBS 435.76T KF156038 KF156135 KF156182 KF155978
S. macrozamiae CBS 137971T KJ869123 KJ869180
S. minimum CBS 510.71T HQ667522 KF156134 KF156172 KF156007
S. mirabilis CBS 413.51T HQ667536 KF156140 KF156164 KF156001
S. musae CBS 729.95T KF156029 KF156144 KF156171 KF155999
S. musicola CBS 144441T MH327824 MH327860 MH327898 MH327887
S. musicola CPC 37308 MW063428 MW071116 MW071096
S. musicola CPC 37309 MW063429 MW071117 MW071097
S. obovoideum GUCC 18246T MZ503732 MZ503765 MZ546911 MZ546878
S. olivaceum CBS 137170T LM644521 LM644564 LM644605 KT272067
S. pandanicola CBS 140660T KT950850 KT950864
S. phaeophorum CBS 206.96T KP798631 KP798634 KT272062 KT272098
S. podocarpi CBS 143174T MG386032 MG386085
S. podocarpicola CBS 146057T MN562138 MN567645
S. ramosum CBS 137171 LM644522 LM644565 LM644606 KT272068
S. ramosum CBS 137173T LM644524 LM644567 MZ546928 KT272069
S. robustum CBS 112.97T KP798633 KP798636 KT272060 KT272071
S. sexuale CBS 131965 KF156017 KF156119 KF156188 KF155977
S. sexuale CBS 135765T KF156018 KF156118 KF156189 KF155976
S. spiralihyphum GUCC 18245T MZ503731 MZ503764 MZ546910 MZ546877
S. terrestre CBS 211.53T NR_145365 NG_058014 KF156187 KF156005
S. terreum CBS 203.27T HQ667544 HQ877665
S. tshawytschae CBS 100438T HQ667562 KF156126 KF156180 KF155990
S. tshawytschae CBS 228.66 KF156016 KF156128 KF156179 KF155992
S. variabile NBRC 32268 DQ307334 EU107310 DQ307356
S. verrucaria GUCC 18240T MZ503726 MZ503759 MZ546905 MZ546872
S. verrucosum CBS 383.81T KF156015 KF156129 KF156185 KT272099
S. zunyiense GUCC 18241T MZ503727 MZ503760 MZ546906 MZ546873
V. calidifluminalis CBS 125818T AB385698 KF156108 KF156202 KF155959



The BLAST searches in the NCBI’s GenBank nucleotide database using ITS sequences of LC19368, LC19369 and LC19370 showed their closest similarities to Scolecobasidium spp. In the following multi-locus phylogenetic analysis of Scolecobasidium, the dataset comprised 2,932 characters including alignment gaps (LSU: 855 bp, ITS: 818 bp, tub2: 542 bp, tef1-α: 717 bp). The ML search revealed a best tree with an InL of -34731.383727. For the Bayesian inference, a GTR+I+G model was selected for ITS, LSU, tef1-α and tub2. The BA was run for 1,535,000 generations, and a 50% consensus tree and posterior probabilities were calculated from 2,304 trees from two runs. The topologies of phylogenetic trees generated by ML and BA were congruent. Our strains were separated into two distinct clades from all known species of Scolecobasidium (Fig. 1).

Figure 1. 

Phylogenetic tree of Scolecobasidium calculated with a maximum likelihood analysis of the combined ITS, LSU, tef1-α, and tub2 sequences alignment. The tree was rooted with Verruconis calidifluminalis (CBS 125818). Bootstrap values (ML > 50%) and Bayesian posterior probabilities (PP > 0.90) are shown at the nodes in the order of ML/PP. T indicates ex-type strains. The novel taxa and new combination are showed in bold. The scale bar represents the expected changes per site.


Scolecobasidium E.V. Abbott, Mycologia 19: 30. 1927. emend. F. Liu

Ochroconis de Hoog & Arx, Kavaka 1: 57. 1974 [1973]. Synonym.


Colonies restricted, slow-growing, brown or olivaceous. Aerial hyphae smooth- or somewhat rough-walled, pigmented. Cleistothecia up to 40 μm in diam, dark brown; peridium wall composed of textura angularis. Ascomata bearing antler-shaped appendages, with serrate edges. Asci bitunicate, clavate, 8-spored; ascospores pale brown, verruculose, 1–3-septate. Conidiophores reduced, unbranched or sparingly branched, arising from the aerial hyphae or hyphal ropes, continuous or septate, hyaline or pigmented, ovoid, clavate, wedge-shaped, cylindrical, or irregular. Conidiogenous cells scattered, monoblastic or sympodial, elongate to cylindrical. Conidia produced in clusters or acropetal series from the ends of tubular extensions of the conidiophores; conidia 1–4-celled, pigmented or hyaline, smooth or verrucose, ellipsoidal, ovoid, cylindrical, or T- or Y-shaped. (emended from Abbott 1927; Barron and Busch 1962; Seifert and Gams 2011; Samerpitak et al. 2014).


Abbott (1927) summarized the asexual features of Scolecobasidium as its generic character based on only two species S. terreum and S. constrictum. Over time multiple species of Scolecobasidium have been described, and the boundaries between this genus and closely related genera have also been clarified (Barron and Busch 1962; Seifert and Gams 2011; Samerpitak et al. 2014; Shen et al. 2020; Wei et al. 2022). However, no one has updated the generic character of Scolecobasidium. In this study, we update the generic character of Scolecobasidium based on previous descriptions, especially the morphological features of the sexual stage of the fungus.

Type species

Scolecobasidium terreum E.V. Abbott.

Scolecobasidium acanthi S. Song, L. Cai & F. Liu, sp. nov.

MycoBank No: 847639
Fig. 2


Named after the host plant Acanthus from which this fungus was isolated.


China. Guangdong Province: Qi’ao-Dangan Island Provincial Nature Reserve, from leaf of Acanthus ebracteatus, Nov 2019, M. Li, Z.F. Zhang and J.E. Huang (Holotype HMAS 352373, culture ex-type CGMCC 3.24352 = LC19368).


Sexual morph : unknown. Asexual morph: Mycelium consisting of branched, septate, hyaline to pale brown, smooth, and thick-walled hyphae. Conidiophores solitary, erect, brown, smooth, arising from superficial hyphae, subcylindrical, straight to geniculous, brown, thick-walled, 0(–2)-septate, 14.5–20.5 × 1.5–2 µm, often reduced to conidiogenous cells, bearing a few conidia near the apex. Conidiogenous cells brown, smooth, 4.5–9.5 × 1.5–2 µm, terminal and lateral on conidiophores, containing several apical, cylindrical denticles. Conidia 1-septate, smooth-walled, subhyaline to pale brown, cylindrical, rarely pyriform, constricted at the septum, 5.5–8.5 × 2.5–4 µm (av. ± SD = 6.9 ± 0.7 × 3.05 ± 0.2 µm, n = 42).

Culture characteristics

Colonies reaching up to 16–20 mm diam after 14 days at 25 °C, producing dense aerial mycelium on MEA and OA. On MEA, surface wheat to greyish brown, reverse saddlebrown, felty, dry, margins smooth. On OA, surface burlywood to peru, reverse brown black, margins smooth.

Figure 2. 

Scolecobasidium acanthi (ex-type CGMCC 3.24352) A the habitat of Acanthus ebracteatus B leaf spot on Acanthus ebracteatus C, D forward and reverse colony on OA after 14 days E, F forward and reverse colony on MEA after 14 days G–J conidiophores, conidiogenous cells and conidia K–P conidia. Scale bars: 10 μm (G–P).


Although represented by single strain, S. acanthi sp. nov. formed a distinct clade (Fig. 1) that was phylogenetically related to S. aegiceratis sp. nov. The two species differ from each other in 820/825 bp (99.39%) in LSU, 474/514 bp (92.22%) in ITS, 525/538 bp (97.58%) in tef1-α, and 433/464 bp (93.32%) in tub2. Morphologically, S. acanthi sp. nov. differs from S. aegiceratis sp. nov. in the septa number of conidiophores (0–2 vs. 0–1) and the size of conidiogenous cells (4.5–9.5 × 1.5–2 µm vs. 7.5–24 × 1.5–2.5 µm) and conidia (5.5–8.5 × 2.5–4 µm vs. 8–15(–26.5) × 2.5–3.5(–6.5) µm).

Scolecobasidium aegiceratis S. Song, L. Cai & F. Liu, sp. nov.

MycoBank No: 847640
Fig. 3


Named after the host plant Aegiceras from which this fungus was isolated.


China. Guangdong Province: Futian Mangrove National Nature Reserve, from leaf of Aegiceras corniculatum, July 2020, Z.F. Zhang (Holotype HMAS 352374, culture ex-type CGMCC 3.24353 = LC19369).

Other material examined

China. Guangdong Province: Futian Mangrove National Nature Reserve, from leaf of Aegiceras corniculatum, July 2020, Z.F. Zhang (Holotype HMAS 352375, culture ex-type CGMCC 3.24354 = LC19370).


Sexual morph : unknown. Asexual morph: Mycelium consisting of branched, septate, hyaline to pale brown, smooth, and thick-walled hyphae. Conidiophores arising from the aerial hyphae or hyphal ropes, continuous or septate, usually reduced to conidiogenous cells, 0(–1)-septate. Conidiogenous cells solitary, hyaline to pale brown, smooth, subcylindrical, straight to geniculous-sinuous, thick-walled, 7.5–24 × 1.5–2.5 µm, bearing a few conidia near the apex. Conidia smooth-walled, subhyaline to pale brown, ellipsoidal or cylindrical, tapering torwards the base, mostly 1-septate, rarely 2–3-septate, sometimes constricted at the septum, 8–15(–26.5) × 2.5–3.5(–6.5) µm (av. ± SD = 9.3 ± 1.16 × 2.83 ± 0.26 µm, n = 40).

Figure 3. 

Scolecobasidium aegiceratis (ex-type CGMCC 3.24353) A, B leaf spots of Aegiceras corniculatum C, D forward and reverse colony on OA after 14 days E, F forward and reverse colony on MEA after 14 days G–I conidiophores, conidiogenous cells and conidia J–M conidia. Scale bars: 10 μm (G–M).

Culture characteristics

Colonies reaching up to 20–22 mm diam after 14 days at 25 °C, dense aerial mycelium on MEA and OA. On MEA, smooth to felty, dry, surface greyish brown to dark brown, reverse saddle brown. On OA, surface ivory to peru, reverse brown black.


Scolecobasidium aegiceratis is phylogenetically related to S. dracaenae (Fig. 1) and can be differentiated from the later by DNA sequences of LSU (99.52% similarity), ITS (93.55%) and tef1-α (96.60%) regions. Morphological characters of the two species are overlapping but their conidiophores and conidia show differences. Scolecobasidium aegiceratis can be distinguished from S. dracaenae as it produces hyaline to pale brown (vs. brown in S. dracaenae) conidiogenous cells. In addition, the dimensions of their conidia (8–15(–26.5) × 2.5–3.5(–6.5) µm vs. 6.5–10 × 3–4 μm) and conidiogenous cells (7.5–24 × 1.5–2.5 µm vs. 5–15 × 2.5–3 μm) are different (Crous et al. 2016).

Scolecobasidium constrictum E.V. Abbott, Mycologia 19(1): 30. 1927.

Ochroconis constricta (E.V. Abbott) de Hoog & Arx, Kavaka 1: 57. 1974.

Dactylaria constricta (E.V. Abbott) D.M. Dixon & Salkin, J. Clin. Microbiol. 24: 13. 1986.


USA Louisiana, from soil, 1927, E.V. Abbott ex-type culture CBS 202.27 = MUCL 9471 (metabolically inactive).


Scolecobasidium constrictum was introduced at the same time as the generic type of Scolecobasidium, S. terreum, by Abbott (1927). Later, Heterosporium terrestre was treated as a synonym of S. constrictum due to their similar morphological characteristics (Barron and Busch 1962). Their original descriptions differ, however, in that H. terrestre produces rough conidia and variable conidiophores both in shape and size, and has occasional phragmospores. Therefore, Barron (1962) thought that Abbott described only a facet of S. constrictum and emended the species description. Subsequently, Ochroconis was introduced to accommodate species with sympodial conidiogenesis and unbranched, subspherical to cylindrical or clavate, melanised conidia, and S. constrictum was transferred to this genus as O. constricta and designated as the generic type (De Hoog 1973).

With the help of molecular analyses, Shen et al. (2020) synonymized Ochroconis under Scolecobasidium, and S. constrictum should be resurrected as a result. We observed that the ex-type cultures of H. terrestre (CBS 211.53) and S. constrictum (CBS 202.27) were separated into two distinct clades with relatively long branches in the current study (Fig. 1) and sequences similarities between the two species were very low (LSU: 98.7%; ITS: 88%, tef1-α: 85%, tub2: 79%). Since S. constrictum (CBS 202.27) is now sterile (Shen et al. 2020), we could only make a detailed morphological comparison among multiple descriptions of ex-type cultures of H. terrestre (CBS 211.53) and S. constrictum (CBS 202.27) (Abbott 1927; Atkinson 1952; Barron and Busch 1962; Samerpitak et al. 2014), and found that the two fungi were morphologically different in the shape (oval to ovate, short-cylindrical and long cylindrical to sole-shaped in H. terrestre vs. echinulate to verrucose in S. constrictum) and number of septa (0–3 vs. 0–1) in the conidia, as well as the size of conidiophores (2–31.5 × 1.5–2.5 μm vs. 5–8 × 2–2.5 μm). Based on morphology combined with the phylogeny, we consider that H. terrestre R.G. Atk. should not be treated as a synonym of S. constrictum, and a new combination Scolecobasidium terrestre comb. nov. is proposed in this study.

In addition, the type strain of S. constrictum should be CBS 202.27, rather than CBS 211.53, which was incorrectly listed in tables 2, 3 and figs 1, 2 in Wei et al. (2022).

Scolecobasidium terrestre (R.G. Atk.) F. Liu, S. Song & L. Cai, comb. nov.

MycoBank No: 847635

Heterosporium terrestre R.G. Atk., Mycologia 44: 813. 1952.


Canada. Ontario: Ancaster, obtained from soil obtained, isolated by R.G. Atkinson, 31 Oct. 1947, holotype DAOM 28282, ex-type culture CBS 211.53 (= ATCC 11419; DAOM 28282; IMI 051380; MUCL 9896).


See the notes under S. constrictum.


Zhifeng Zhang is thanked for his help in sample collection. This work was supported by Science & Technology Fundamental Resources Investigation Program (Grant No. 2019FY100700), and the Youth Innovation Promotion Association of Chinese Academy of Sciences (2021085).


  • Crous PW, Shivas RG, Quaedvlieg W, van der Bank M, Zhang Y, Summerell BA, Guarro J, Wingfield MJ, Wood AR, Alfenas AC, Braun U, Cano-Lira JF, García D, Marin-Felix Y, Alvarado P, Andrade JP, Armengol J, Assefa A, den Breeÿen A, Camele I, Cheewangkoon R, De Souza JT, Duong TA, Esteve-Raventós F, Fournier J, Frisullo S, García-Jiménez J, Gardiennet A, Gené J, Hernández-Restrepo M, Hirooka Y, Hospenthal DR, King A, Lechat C, Lombard L, Mang SM, Marbach PAS, Marincowitz S, Marin-Felix Y, Montaño-Mata NJ, Moreno G, Perez CA, Pérez Sierra AM, Robertson JL, Roux J, Rubio E, Schumacher RK, Stchigel AM, Sutton DA, Tan YP, Thompson EH, Vanderlinde E, Walker AK, Walker DM, Wickes BL, Wong PTW, Groenewald JZ (2014) Fungal planet description sheets: 214–280. Persoonia 32(1): 184–306.
  • Crous PW, Wingfield MJ, Richardson DM, Leroux JJ, Strasberg D, Edwards J, Roets F, Hubka V, Taylor PWJ, Heykoop M, Martín MP, Moreno G, Sutton DA, Wiederhold NP, Barnes CW, Carlavilla JR, Gené J, Giraldo A, Guarnaccia V, Guarro J, Hernández-Restrepo M, Kolařík M, Manjón JL, Pascoe IG, Popov ES, Sandoval-Denis M, Woudenberg JHC, Acharya K, Alexandrova AV, Alvarado P, Barbosa RN, Baseia IG, Blanchette RA, Boekhout T, Burgess TI, Cano-Lira JF, Čmoková A, Dimitrov RA, Dyakov MY, Dueñas M, Dutta AK, Esteve-Raventós F, Fedosova AG, Fournier J, Gamboa P, Gouliamova DE, Grebenc T, Groenewald M, Hanse B, Hardy GESTJ, Held BW, Jurjević Ž, Kaewgrajang T, Latha KPD, Lombard L, Luangsa-ard JJ, Lysková P, Mallátová N, Manimohan P, Miller AN, Mirabolfathy M, Morozova OV, Obodai M, Oliveira NT, Ordóñez ME, Otto EC, Paloi S, Peterson SW, Phosri C, Roux J, Salazar WA, Sánchez A, Sarria GA, Shin H-D, Silva BDB, Silva GA, Smith MTH, Souza-Motta CM, Stchigel AM, Stoilova-Disheva MM, Sulzbacher MA, Telleria MT, Toapanta C, Traba JM, Valenzuela-Lopez N, Watling R, Groenewald JZ (2016) Fungal Planet description sheets: 400–468. Persoonia 36(1): 316–458.
  • Crous PW, Carlier J, Roussel V, Groenewald JZ (2021) Pseudocercospora and allied genera associated with leaf spots of banana (Musa spp.). Fungal systematics and evolution 7: 1–19.
  • Giraldo A, Sutton DA, Samerpitak K, de Hoog GS, Wiederhold NP, Guarro J, Gené J (2014) Occurrence of Ochroconis and Verruconis species in clinical specimens from the United States. Journal of Clinical Microbiology 52(12): 4189–4201.
  • Glass NL, Donaldson GC (1995) Development of primer sets designed for use with the PCR to amplify conserved genes from filamentous ascomycetes. Applied and Environmental Microbiology 61(4): 1323–1330.
  • Hao L, Chen C, Zhang R, Zhu M, Sun G, Gleason ML (2012) A new species of Scolecobasidium associated with the sooty blotch and flyspeck complex on banana from China. Mycological Progress 12(3): 489–495.
  • Katoh K, Standley DM (2013) MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Molecular Biology and Evolution 30(4): 772–780.
  • Miller MA, Pfeiffer W, Schwartz T (2010) Creating the CIPRES Science Gateway for inference of large phylogenetic trees. 2010 Gateway Computing Environments Workshop (GCE): 1–8.
  • Qiao TM, Zhang J, Li SJ, Han S, Zhu TH (2016) Development of nested PCR, multiplex PCR, and loop-mediated isothermal amplification assays for rapid detection of Cylindrocladium scoparium on Eucalyptus. The Plant Pathology Journal 32(5): 414–422.
  • Ross AJ, Yasutake WT (1973) Scolecobasidium humicola, a fungal pathogen of fish. Journal of the Fisheries Research Board of Canada 30(7): 994–995.
  • Samerpitak K, Van der Linde E, Choi HJ, Gerrits van den Ende AHG, Machouart M, Gueidan C, de Hoog GS (2014) Taxonomy of Ochroconis, genus including opportunistic pathogens on humans and animals. Fungal Diversity 65(1): 89–126.
  • Singh K, Flood J, Welsh RD, Wyckoff JH III, Snider TA, Sutton DA (2006) Fatal systemic phaeohyphomycosis caused by Ochroconis gallopavum in a dog (Canis familaris). Veterinary Pathology 43(6): 988–992.
  • VanSteenhouse JL, Padhye AA, Ajello L (1988) Subcutaneous phaeohyphomycosis caused by Scolecobasidium humicola in a cat. Mycopathologia 102(2): 123–127.
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