Taxonomic revision of the genus Blastobotrys with description of seven novel species and three new combinations

Abstract

Blastobotrys is a genus of yeasts that primarily reproduce asexually; however, it also encompasses sexual species that were formerly classified within the genus Trichomonascus. Blastobotrys species are known for their diverse origin as they can be found in numerous locations worldwide and on various types of substrates. During a series of independent sampling events in Belgium, Bulgaria, and France, a set of strains were newly isolated from basidiomes, decaying wood, and insects. As a result of this research, seven novel species were identified and described, including previously deposited strains from the CBS collection. This was done by means of a combination of phylogenetic analysis, using the ITS regions and the D1/D2 domain of the large subunit (LSU) rRNA gene, and physiological characteristics. Additionally, based on phylogenetic data generated during this study and phylogenomic analyses available from published data, three new combinations of species previously included in Trichomonascus are also proposed. Furthermore, using the data from metabarcoding studies included in the GlobalFungi database and those known from Blastobotrys strains available from the CBS yeast collection, the currently known distribution and substrate range of Blastobotrys strains are discussed.

Citation: Groenewald M, Hernández-Restrepo M, Zandijk A, Smith M, Gouliamova D, Decock C (2026). Taxonomic revision of the genus Blastobotrys with description of seven novel species and three new combinations. Persoonia 56: 308–327. doi: 10.3114/persoonia.2026.56.04

INTRODUCTION

The yeast genus Blastobotrys (Trichomonascaceae, Dipodascales, Dipodascomycetes, Saccharomycotina) (Groenewald et al. 2023) is widely distributed and reported worldwide, except Australia, where it remains unreported to date (Kurtzman et al. 2011, https://theyeasts.org). Species of Blastobotrys are able to grow on and have been isolated from a wide and uncommon variety of substrates such as mushrooms (Basidiomycetes), insects and other animals including humans, plant debris, wood (including archaeological), moss, soil, dung, compost, nectar, food (honey), paper, air/dust, wall painting/plaster, seawater, and linoleum (Kurtzman et al. 2011, Visagie et al. 2023, https://theyeasts.org). Although isolates mostly originate from environmental substrates (natural or anthropogenic), some species such as B. adeninivorans, B. mokoenaii, B. raffinosifermentans, B. proliferans, B. serpentis and Trichomonascus ciferrii (formerly Stephanoascus ciferrii), have been isolated from humans as the causal agents of ear, eye or skin infections (Cosio et al. 2024), from pulmonary infections in a cystic fibrosis patient (Al-Obaidi et al. 2021), and an invasive fungal infection in an immunocompromised patient (Shiomi et al. 2024). Human infections are a rising concern since there is an increase in antifungal drug resistance in this yeast group (Kumar et al. 2014, Cosio et al. 2024, Shiomi et al. 2024).

On the other hand, Blastobotrys is a potentially valuable source for industrial processes that are conducted in different stress conditions, as it has been found that many species are osmo-, halo- and/or thermotolerant. They can assimilate a variety of substrates and have oleaginous traits (Kurtzman et al. 2011, Sanya et al. 2021). For instance, B. adeninivorans and B. raffinosifermentans can grow on a high glucose concentration (50, 60 or 70 %) (Kurtzman et al. 2015, Sanya et al. 2021). At the same time, Blastobotrys strains have been used for basic biochemical studies, to produce single-cell proteins, and represent a promising source for fatty acid-based fuels and oleo chemicals with application in food, feed and beyond (Sanya et al. 2021). Blastobotrys adeninivorans is an example of a thermotolerant species. It has an optimal growth at 30–40 °C with tolerance up to 48 °C and can survive a few hours at 55 °C (Kunze & Kunze 1996, Malak et al. 2016, Bischoff et al. 2017).

Taxonomically, Blastobotrys includes mostly asexual yeasts once included in other genera such as Candida, Sympodiomyces, or Trichosporon (Kurtzman & Robnett 2007, Visagie et al. 2023). Some species also produce a sexual morph and were included in Stephanoascus or Trichomonascus (Visagie et al. 2023). The type species of Trichomonascus, T. mycophagus, has never been cultivated and still lacks DNA data to confirm its phylogenetic affinity. It will hardly be feasible to identify this species again based on morphological characters and its taxonomical placement will remain unknown. Furthermore, Visagie et al. (2023) proposed that, although Trichomonascus (Jackson 1947) is an older name and therefore has nomenclatural priority (McNeill et al. 2012), Blastobotrys (von Klopotek 1967) should be adopted as many more species have been described in the latter. Currently, 36 species of Blastobotrys are described and listed in the MycoBank database, a depository for fungal names (Crous et al. 2004).

Lachance (2012) proposed that, to distinguish between novel species that were found to reproduce sexually and asexually, the expression forma asexualis (f.a.) should be used for the latter.

During ongoing yeast isolation events in recent years, several Blastobotrys isolates were subjected to phylogenetic (ITS and LSU) and physiological analysis. Only a few isolates were identified as currently known species, including B. arbuscula and B. aristatus, whereas the majority of isolates were shown to represent undescribed species. They are described below as B. bolitophagi sp. nov., B. dehoogii f.a. sp. nov., B. hennebertii f.a. sp. nov., B. jacksonii sp. nov., B. laricis f.a. sp. nov., B. plurivorus f.a. sp. nov., and B. pulvis sp. nov. Additionally, after including several Trichomonascus strains previously deposited in the CBS culture collection they were shown as relatives to the type species B. niveus, and transferred to Blastobotrys. The geographic distribution and substrate preferences of the new species are also assessed.

MATERIALS AND METHODS

Isolates

Sixteen fresh Blastobotrys strains were isolated from basidiomes, deadwood, paper, and insects. During the attempts to isolate pure cultures of Basidiomycetes from their basidiomes or decaying wood, 13 strains from Belgium and France were isolated as culture contaminants on 2 % malt agar supplemented with 50 ppm chloramphenicol (MA2.50) and later purified on the same media. The strain MUCL 56024 = CBS 17993 was isolated using a “swab” methodology from mouldy archival papers stored in a cellar. In this particular case, the “swab” method involved collecting with a swab the moulds (and yeasts) on mouldy archival documents stored in an archive room, and then, in the laboratory, swabbing the same swab onto MA2.50 culture medium and then transferring each individual colony to a second Petri dish, containing 2 % malt agar (MA2), for purification. The strains CBS 12434 and CBS 12455 were isolated from a darkling beetle (Bolitophagus interruptus) collected in Podgorie area, Bulgaria. After identification of the insects at the National Museum of Natural History, Bulgaria, it was stored at −80 °C until dissection, washed sequentially with 70 % ethanol and 0.7 % sterile saline solution, and their guts dissected under a dissecting microscope on sterile Petri dishes. The final saline wash and crushed gut suspensions (in 0.7 % sterile saline) were plated onto acidified yeast extract–malt extract agar (YMA; pH 3.5, adjusted with HCl). Plates were incubated at room temperature for 3 d, after which yeast-like colonies were selected and subcultured until pure cultures were obtained (Dimitrov et al. 2024). Additional strains were obtained from the collection of the Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands (CBS) and from the Mycothèque of the Université catholique de Louvain (BCCM/MUCL) (Table 1). All novel strains were deposited in the CBS, CIRM (INRA Marseille), and BCCM/MUCL. Taxonomic novelties were deposited in MycoBank (Crous et al. 2004).

Table 1.

Taxa and strain information used for phylogenetic analyses. New species, combinations and strains studied are marked in bold.

Taxon name	Strain	*Status	Country/Location	Source	GenBank accession #		References
					ITS	LSU
Blastobotrys adeninivorans	CBS 8244 = NRRL Y-17692 = IFO 10858	T	The Netherlands, Wageningen	Soil	KY101746	DQ442697	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys allociferrii	CBS 5166 = NBRC 10194 = IFO 10194	T	Germany	Unknown, probably human	LC158134	LC158143	Tsang (2017)
Blastobotrys americanus	CBS 10337 = NRRL Y-6844	T	USA, Kansas	Unknown	KY101748	DQ442699	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys apis comb. nov.	CBS 10922 = NRRL Y-48475 = NCAIM Y.01848	T	Hungary	Mouldy honeycomb	KY105699	EU790643	Vu et al. (2016); Péter et al. (2009)
Blastobotrys arbuscula	CBS 227.83 = NRRL Y-17585	T	Finland	Indoor air	OL772655	DQ442689	Visagie et al. (2023); Kurtzman & Robnett (2007)
	CBS 17995 = MUCL 38854		Belgium	On basidiome of Amyloporia xantha, private house	PV744843	PV744862	This study
Blastobotrys aristatus	CBS 521.75 = NRRL Y-17579 = ATCC 34215	T	Czech Republic	Moldy plaster	OL772656	DQ442686	Visagie et al. (2023); Kurtzman & Robnett (2007)
	CBS 18003 = MUCL 58098		France	Bore dust of Xestobium rufovillosum, house	PV744844	PV744863	This study
	CBS 18004 = MUCL 58241		France	Decaying wood, private house	PV744845	PV744864	This study
Blastobotrys attinorum	CBS 9734 = NRRL Y-27639	T	Brazil, Sao Paulo	Fungal garden of nests of the leaf-cutting ant (Atta sexdens)	KY101749	AY442294	Vu et al. (2016)
Blastobotrys baotianmanensis	CBS 16024 = CICC 33083	T	China, Henan Province, Baotianman Nature Reserve	Gut of Pterostichus gebleri	KU128710	KU128725	Chai et al. (2020)
Blastobotrys bolitophagi sp. nov.	CBS 12455	T	Bulgaria	From an imago, Tenebrioidae	PV744846	PV744865	This study
	CBS 12434		Bulgaria	From an imago of Bolitophagus interruptus	PV744847	PV744866	This study
Blastobotrys bombycis	CBS 15274	T	India, Dharwad	On Bombyx mori	OL772657	OL772653	Visagie et al. (2023)
Blastobotrys buckinghamii+A18:A21	CBS 13900 = NRRL Y-63727	T	USA, Michigan, Tahquamenon Falls State Park	On mushroom associated with Fagus grandfolia	OL772658	OL772654	Visagie et al. (2023)
Blastobotrys capitulatus	CBS 287.82 = NRRL Y-17573	T	South Africa	On decaying flowers of Euphorbia ingens	OL772659	DQ442688	Visagie et al. (2023); Kurtzman & Robnett (2007)
Blastobotrys chiropterorum	CBS 6064 = NRRL Y-17071	T	Colombia, Santander, San Gil	Liver of bat (Mormoops megalophylla)	KY101750	DQ442682	Visagie et al. (2023); Kurtzman & Robnett (2007)
Blastobotrys ciferrii comb. nov.	CBS 5295 = NRRL Y-10943 = ATCC 58443 = IFO 1854 = IMI 344641		The Netherlands	Human throat	AY493435	DQ442681	Pryce et al. (2003); Kurtzman & Robnett (2007)
Blastobotrys davincii	CBS 16861 = DAOMC 251467 = CMW 56638	T	Canada, Ontario, Stittsville	House dust	MW367648	MW367634	Visagie et al. (2023)
Blastobotrys dehoogii sp. nov.	CBS 181.75	T	Germany, Berlin	Unknown	PV744850	PV744869	This study
	CBS 17996 = MUCL 58093 = CIRM-BRFM 3299		France, Normandie	Decaying wood of Quercus sp.	PV744851	PV744870	This study
	CBS 17997 = MUCL 58091 = CIRM-BRFM 3298		France, Normandie	Decaying wood, h-cellar, private house	PV744852	PV744871	This study
Blastobotrys elegans	CBS 530.83A = NRRL Y-17572	T	Finland	Indoor air	OL772660	DQ442687	Visagie et al. (2023); Kurtzman & Robnett (2007)
Blastobotrys farinosus	CBS 140.71 = NRRL Y-17593	T	The Netherlands	Auricularia auricula-judae	OL772661	DQ442685	Visagie et al. (2023); Kurtzman & Robnett (2007)
Blastobotrys fungorum	CBS 259.70	T	Germany	On old basidiome of Fomes fomentarius	KX590837	KX590883	de Beer et al. (2016)
Blastobotrys guizhouensis	CGMCC 2.7784 = JCM 36892	T	China	Gray jiuqu	PP192707	PZ373576	Hu et al. (2025)
Blastobotrys hennebertii sp. nov.	CBS 17993 = MUCL 56024	T	Belgium	Moldy paper, archives, cellar, private house	PV744848	PV744867	This study
	CBS 17994 = MUCL 31788		Belgium	Wet coniferous timber, stairs, house	PV744849	PV744868	This study
Blastobotrys illinoisensis	CBS 10339 = NRRL YB-1343	T	USA, Illinois, Marion, Wohlwend farm	From forest debris	KY101751	DQ442696	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys indianensis	CBS 9600 = NRRL YB-1950	T	USA, Indiana, Spencer, McCormick’s Creek State Park	On white fungus associated with pine	KY101752	DQ442692	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys jacksonii sp. nov.	CBS 18002 = MUCL 56485 = CIRM-BRFM 2517	T	France	Old basidiome of Leucogyrophana sp., cellar, house	PV744854	PV744873	This study
	CBS 17991 = MUCL 58086 = CIRM-BRFM 3297		France	Decaying wood, gymnosperm, private house	PV744855	PV744874	This study
Blastobotrys laricis sp. nov.	CBS 17998 = MUCL 7707	T	Belgium	Rotten wood of Larix sp.	PV744853	PV744872	This study
Blastobotrys malaysiensis	CBS 10336 = NRRL Y-6417	T	Malaysia	Cave soil	KY101753	DQ442695	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys meliponae	CBS 14100 = URM 7224	T	Brazil, Pernambuco, Recife	Honey	KT448719	KR779217	Barbosa et al. (2024)
Blastobotrys mokoenaii	CBS 8435 = NRRL Y-27120	T	South Africa	Soil	KY101754	DQ442694	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys mucifer	CBS 7409 = IFO 10918	T	Brazil, Manaus	Liver of toad (Rhinella granulosa)	KY102217	KY106587	Vu et al. (2016)
Blastobotrys muscicola	CBS 10338 = NRRL Y-7993	T	USA, Louisiana, near New Orleans	Moss on fallen log	KY101755	DQ442680	Vu et al. (2016)
Blastobotrys navarrensis	CBS 139.77 = ATCC 36955	T	Spain, Navarra, Pamplona	Black pepper (Piper nigrum)	OK623478	OK623486	Palma et al. (2022)
Blastobotrys nigripullensis	CBS 17879	T	The Netherlands, Zwammerdam	Oak wood from ancient Roman ship	OQ876814	OQ876819	Visagie et al. (2024)
Blastobotrys niveus	CBS 163.67 = NRRL Y-17581 = ATCC 18420 = MUCL 6078	T	Germany, Heidelberg	Municipal compost	OL772662	DQ442690	Visagie et al. (2023); Kurtzman & Robnett (2007)
Blastobotrys parvus	CBS 6147 = NRRL Y-10004	T	Antarctic Ocean	Seawater	KY101757	DQ442693	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys peoriensis	CBS 10340 = NRRL YB-2290	T	USA, Illinois, Peoria	On unidentified fungus	KY101758	DQ442700	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys persicus	CBS 14259 = IBRC-M30238	T	Iran, Ilam	Soil	OL772663	KU659141	Visagie et al. (2023); Nouri et al. (2018)
Blastobotrys petasosporus comb. nov.	CBS 9602 = NRRL Y-B2092	T	USA, Missouri, Salem	White Oak (Quercus sp.)	KY105704	DQ442691.2	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys plurivorus sp. nov.	CBS 137.78	T	The Netherlands	Dung of mouse	PV744859	PV744878	This study
	CBS 17992 = MUCL 55272		France	On basidiome of Donkioporia expansa	PV744860	PV744879	This study
	CBS 18001 = MUCL 46524		France	On basidiome of Fomitiporia pseudopunctata	PV744861	PV744880	This study
Blastobotrys proliferans	CBS 522.75 = NRRL Y-17577 = ATCC 34216	T	Brazil	Mite-infested nut (Bertholletia excelsa)	EU343812	DQ442684	Tsui et al. (2007); Kurtzman & Robnett (2007)
Blastobotrys pulvis sp. nov.	CBS 232.85	T	Sweden	House dust	PV744856	PV744875	This study
	CBS 17999 = MUCL 31040		Belgium	On unidentified basidiome	PV744857	PV744876	This study
	CBS 18000 = MUCL 56215		France	On basidiomata of Serpula puverulenta, cellar	PV744858	PV744877	This study
Blastobotrys raffinosifermentans	CBS 6800 = NRRL Y-27150	T	Unknown	Unknown	KY101759	DQ442698	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys robertii	CBS 10106 = NRRL Y-27775	T	The Netherlands, Wageningen	Rotten wood of Pinus sylvestris	KY101760	DQ839395	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys serpentis	CBS 10541 = NRRL Y-48249	T	India, Hyderabad City	From snake gut	KY101761	AM410667	Vu et al. (2016); Bhadra et al. (2008)
Blastobotrys terrestris	CBS 7376 = NRRL Y-17704 = IFO 10859	T	South Africa, Barberton	Soil	KY101762	DQ442683	Vu et al. (2016); Kurtzman & Robnett (2007)
Blastobotrys vanleenenianus	CBS 14902	T	The Netherlands	Soil	MG986487	MG986492	Groenewald et al. (2018)
Blastobotrys xishuangbannaensis	CBS 16044 = CICC 33360	T	China, Yunnan Province, Jinghong	Rotting wood	MK682811	MK682809	Chai et al. (2020)
Trigonopsis californica	CBS 10351 = NRRL Y-27307	T	USA	Unknown	KY105760	KY109968	Vu et al. (2016)
Trigonopsis vinaria	CBS 4077 = NRRL Y-5715	T	Japan	Grape must	KY105765	KY109976	Vu et al. (2016)

^*T = ex-type strains.

Morphological and physiological examination

Colony characteristics and cell morphology were examined on glucose-peptone-yeast extract agar (GPYA) for 1–2 wk of incubation at 24 °C.

Physiological characteristics were tested using an API 32C system (bioMérieux) according to the manufacturer’s instructions. The tests were performed for 14 d with an interval of 3–4 d. Fermentation tests and growth on nitrogen sources, tested by the auxanography method, were done for 14 d described by Kurtzman et al. (2015). All tests were done in duplicate and incubated at 24 °C. Growth at 6 °C to 33 °C at 3 °C intervals, and at 37 °C and 40 °C was tested on GPYA for 2 wk.

Sexual reproduction of all newly isolated strains was tested on V8-juice (V8) agar, yeast extract-malt extract (YM) agar, 5 % Difco Malt and yeast carbon base supplemented with 0.01 % ammonium sulphate (YCBAS) agar (Kurtzman et al. 2015) and regularly examined up to 3 mo.

DNA extraction and sequencing

The protocols for DNA extraction, PCR, and sequencing followed Stielow et al. (2015). The primers used for PCR amplification were V9G (de Hoog & Gerrits van den Ende 1998) and LR5 (Vilgalys & Hester 1990) to amplify the ITS regions (ITS 1, ITS 2 and the intervening 5.8S rRNA gene), and the D1/D2 domain of the large subunit (LSU) rRNA gene. The amplicons were sequenced in both directions using the primers LR0R (Vilgalys & Hester 1990) and LR5 for the D1/D2 domain, whereas the primers V9G and ITS4 (White et al. 1990) were used for the ITS regions. The BigDye Terminator v. 3.1 Cycle Sequencing kit (Applied Biosystems) was used according to the manufacturer’s recommendations, and the products were analysed on an ABI Prism 3730xl DNA Sequencer (PerkinElmer).

Phylogenetic analysis

The ITS and LSU sequences generated during the study as well as Blastobotrys and Trichomonascus sequences retrieved from GenBank and that of the outgroups and used in the phylogenetic analysis are listed in Table 1. Sequences generated in this study were deposited in GenBank (Table 1), and the alignments in Zenodo (doi: 10.5281/zenodo.18338587).

Sequence alignments were performed in MAFFT online v. 7 (Katoh et al. 2017) with the default settings and visualized and edited in MEGA v. 7 (Kumar et al. 2016) and Geneious Prime v. 2023.2.1 (Biomatters Inc., New Zealand). SequenceMatrix v. 1.7.8 was used to concatenate the ITS and LSU datasets after individual loci alignments. Phylogenetic analyses of individual and combined loci were performed with Maximum Likelihood estimation (ML) and conducted with IQ-TREE v. 2.1.2 (Nguyen et al. 2015, Minh et al. 2020), incorporating ultrafast bootstrapping (UFBoot2; Hoang et al. 2018). The phylogenetic trees were visualized in FigTree v. 1.4.2 (http://tree.bio.ed.ac.uk/software/figtree) and edited with Adobe Illustrator CC 2024 (USA).

Species descriptions

The novel species descriptions were done in concordance with the guidelines published by Aime et al. (2021).

Distribution and range of substrate

The geographic distribution and substrate preferences of the new taxa and of Blastobotrys species worldwide were analysed using data retrieved from the GlobalFungi Database (Větrovský et al. 2020) v. 5 (released on 16 November 2023; https://globalfungi.com/). GlobalFungi Database stored mostly data obtained through high-throughput environmental fungal DNA sequencing. This version of the database comprises 84 972 samples from 846 studies, totalling 593 399 355 ITS sequence variants worldwide. It uses the taxonomy based on UNITE v. 10.0 (4 April 2024) including only SH numbers for undescribed species. Each of the ITS sequences of our new taxa was subjected to ITSx extractor using the sequence editor SEED2 v. 2.1.34 (Větrovský et al. 2018), and ITS1 and ITS2 haplotypes were analysed separately following Réblová et al. (2022). This information is provided in the notes associated with each new species described. Furthermore, an additional query was executed on the taxon search functionality within the same database, employing the generic name Blastobotrys, with the objective of assessing the global distribution and substrate preferences of other described species.

The general discussion is also enhanced by the incorporation of information pertaining to supplementary publicly accessible Blastobotrys strains, which was obtained from the CBS strain database (https://wi.knaw.nl).

RESULTS AND DISCUSSION

Molecular species characterization

The combined dataset (ITS+LSU) consisted of 1705 characters (ITS: 734 and LSU: 971). Of these, 592 characters were informative (ITS: 344, LSU: 248), and 984 were invariable (ITS: 317, LSU: 667). The best-fit models of evolution selected according to the BIC criterion were TVM+F+I+G4 for ITS and GTR+F+I+G4 for LSU.

The resulting phylogenetic tree (Fig. 1) showed that our new strains were dispersed in seven different clades, which were interpreted as seven undescribed species. They are formally described in the taxonomic section as B. bolitophagi (CBS 12434, CBS 12455), closely related to B. peoriensis and B. americana; B. dehoogii (CBS 181.75, CBS 17996, CBS 17997), related to B. xishuangbannaensis; B. jacksonii (CBS 17991, CBS 18002), related to B. baotianmanensis; B. hennebertii (CBS 17993, CBS 17994) related to B. aristatus, B. bombycis and B. elegans; B. pulvis (CBS 232.85, CBS 17999, CBS 18000), related to B. navarrensis and B. proliferans; and B. plurivorus (CBS 137.78, CBS 17992, CBS 18001), related to B. farinosus and B. fungorum. Blastobotrys laricis (CBS 17998) forms a single branch that does not cluster with any of the known Blastobotrys species (Fig. 1).

Fig. 1.

Maximum Likelihood phylogenetic tree showing the phylogenetic position of the novel Blastobotrys species based on the combined analysis of the D1/D2 domain (971 bp) and the ITS region sequences (734 bp). Two Trigonopsis species were used as outgroup. Type strains are denoted with a T after the collection number. Scale bar represents 0.09 substitutions per nucleotide position.

Three of our new strains were found to also belong to known Blastobotrys species: CBS 18003 = MUCL 58098 and CBS 18004 = MUCL 58241 are identified as B. aristatus, whereas CBS 17995 = MUCL 38854 is identified as B. arbuscula (Fig. 1).

From the analyses of the combined dataset (ITS+LSU) (Fig. 1), as well as the phylogenomic approach used by Opulente et al. (2024) it is evident that the Trichomonascus ex-type strains of T. apis, T. ciferrii, and T. petasosporus cluster within the clade comprising currently described Blastobotrys species and are affiliated to the Blastobotrys type species, B. niveus. Considering the phylogenetic (Fig. 1) and phylogenomic (Opulente et al. 2024) results and the lack of a specimen representing the type species of Trichomonascus, T. mycophagus, and DNA thereof, we propose to transfer T. apis, T. ciferrii, and T. petasosporus to Blastobotrys.

TAXONOMY

Blastobotrys apis (G. Péter et al.) M. Groenew., M.T. Sm & Hern.-Restr., comb. nov. MB 860903.

Basionym: Trichomonascus apis G. Péter et al., Int. J. Syst. Evol. Microbiol. 59(6): 1551. 2009. MB 514356.

Typus: Hungary, isolated from mouldy honeycomb, unknown date and collector, isolated by G. Peter, (holotype NCAIM Y.01848; ex–type strain CBS 10922).

Blastobotrys bolitophagi M. Groenew., M.T. Sm, Hern.-Restr. & Gouliam., sp. nov. MB 857494. Fig. 2.

Fig. 2.

Blastobotrys bolitophagi CBS 12455 growth after 2 wk at 24 °C on GPYA. A. Budding cells with pseudo and septate hyphae. B. Pseudo and septate hyphae. C. Sexual morph; CBS 12455 × CBS 12434 after 2 wk at 24 °C on YMA. Asci crowned with a cylindrical cell containing one hat-shaped ascospore each indicated with arrows. Scale bars = 10 μm.

Etymology: bolitophagi (Lat., noun); named after the insect from which the ex-type strain was isolated from, Bolitophagus interruptus.

Typus: Bulgaria, Podgorie area, isolated from an imago of Bolitophagus interruptus (Tenebrionidae, Insecta), Oct. 2009, D. Gouliamova (holotype designated here preserved in a metabolically inactive state, CBS 12455; ex-type strain CBS 12455 mating type h⁺).

Description: After 2 wk at 24 °C on GPYA, the culture is off-white or ivory coloured, soft and slightly wrinkled. Budding cells globose, 2–3 µm diam. or ovoid and elongate, 2–4 × 2.5–6 µm. Hyphae hyaline, septate, 1.5–2.5 µm wide. Pseudo hyphae hyaline. Secondary conidia not observed.

Asci with ascospores were observed after 2 wk at 24 °C by mixing strain CBS 12455 with CBS 12434 on YMA and MEA. Asci are persistent and crowned with a cylindrical cell. Asci contain one hat-shaped ascospore.

Physiological characteristics: Fermentation of D-glucose is positive and is absent for D-galactose, sucrose, maltose, lactose, raffinose and trehalose. Carbon compounds assimilated are D-glucose, sucrose, melibiose, D-galactose, lactose, trehalose, maltose, cellobiose, methyl-α-D-glucoside, L-sorbose, D-xylose, L-arabinose, D-ribose, erythritol, D-mannitol, D-sorbitol, inositol, D-gluconate, glucosamine, N-acetyl-D-glucosamine, potassium-2-keto-D-gluconate and D-glucuronate, while growth is absent on raffinose, melezitose, L-rhamnose, glycerol and lactic acid.

Growth occurs on L-lysine, cadaverine, nitrate and D-glucosamine HCl as sole nitrogen compounds and is negative on ethylamine. Growth occurred at 6 °C up to 30 °C and is absent at 37 °C. Growth in the presence of 0.01 % cycloheximide is positive.

Additional material examined: Bulgaria, Podgorie area, isolated from an imago of Bolitophagus interruptus (Tenebrionidae, Insecta), Oct. 2009, D. Gouliamova, strain CBS 12434, mating type h⁻.

Distribution and substrates: This species is only known from the type locality Bulgaria, growing on imago of Bolitophagus interruptus. No identical ITS sequences were recovered in the GlobalFungi database.

Notes: The two B. bolitophagi strains CBS 12455 and CBS 12434 have 1 nt difference in their ITS and are identical in their LSU. The ex-type strain (CBS 12455) differs from the ex-type strain (CBS 10340) of its closest relative, B. peoriensis, with 36 nt (12 gaps) and 5 nt (no gaps) in the ITS (500 nt) and LSU (847 nt) regions, respectively. Blastobotrys peoriensis can assimilate raffinose, glycerol, and melizitose whereas B. bolitophagi not. However, B. bolitophagi can assimilate trehalose and B. peoriensis not (Table 3).

Table 3.

Differential physiological characteristics among Blastobotrys species and their closest relatives (this study, * from Kurtzman et al. 2011, ** from Chai et al. 2020, *** from Palma et al. 2022).

Physiological attributes	Related species and physiological differences1
	B. hennebertii	B. elegans
All	No differences found
	B. plurivorus	B. farinosus
All	No differences found
	B. jacksonii	B. baotianmensis**
Sucrose	−	+
L-sorbose	+	−
D-xylose	+	−
L-arabinose	+	−
Maltose	+	−
D-Mannitol	+	−
Sorbitol	+	−
Inositol	+	−
Potassium-2-keto-D-gluconate	+	−
Ethylamine	+	−
D-glucosamine HCl	+	−
	B. dehoogii	B. xishuangbanniensis**
L-sorbose	−	+
Sucrose	−	+
Raffinose	−	+(w)
Melibiose	−	+(w)
Lactose	−	+(w)
Melezitose	−	+(w)
Methyl-α-D-glucoside	−	+
Lactic acid	−	+
Ethylamine	+	−
37 °C	−	+
	B. pulvis	B. proliferans* / B. navarrensis***
37 °C	−	+
	B. bolitophagi	B. peoriensis*
Trehalose	+	−
Raffinose	−	+
Glycerol	−	+
Melezitose	−	+

¹B. laricis did not have a close relative and therefore no comparison was made.

Blastobotrys ciferrii (Kreger-van Rij) M. Groenew., M.T. Sm & Hern.-Restr., comb. nov. MB 860911.

Basionym: Candida ciferrii Kreger-van Rij, Mycopathol. Mycol. Appl. 26: 50. 1965. MB 327426.

Synonyms: Stephanoascus ciferrii M.T. Sm. et al., Antonie van Leeuwenhoek 42(1–2): 125. 1976. MB 324077.

Trichomonascus ciferrii (M.T. Sm. et al.) Kurtzman & Robnett, FEMS Yeast Res. 7(1): 149. 2007. MB 530083.

Sporothrix catenata de Hoog & Constant., Antonie van Leeuwenhoek 47(4): 367. 1981. MB 111942.

Typus: The Netherlands, isolated from the neck of a cow, 1962, isol. A.H. Klokke (holotype preserved in a metabolically inactive state CBS 4856).

Additional material examined: The Netherlands, isolated from a human throat, collection date and collector unknown, CBS 5295.

Blastobotrys dehoogii M. Groenew., M.T. Sm, Hern.-Restr. & Decock, sp. nov. MB 860905. Fig. 3.

Fig. 3.

Blastobotrys dehoogii CBS 181.75 growth after 2 wk at 24 °C on GPYA. A. Budding cells and pseudo and septate hyphae. B. Septate hyphae with primary globose conidia produce secondary conidia. C. Primary conidium with seta, and secondary conidia. Scale bars = 10 μm.

Etymology: dehoogii (Lat., noun); named after Sybren de Hoog for his contribution to the taxonomy of Blastobotrys and related genera.

Typus: Germany, Berlin, unknown source, date and collector (holotype designated here and preserved in a metabolically inactive state, CBS 181.75, ex-type strain CBS 181.75).

Description: After 2 wk at 24 °C on GPYA the culture is white, dry, dull, corrugated. Budding cells globose 2–3 µm diam. and elongate, 2–3.5 × 2.5–6 µm. Hyphae hyaline, septate without denticles, 1.5–2.5 µm wide. Pseudohyphae hyaline without denticles. Secondary conidia produced by primary conidia at the apex, may contain refractive body, or by loose primary conidia with setae, globose 1.5–2.5 µm diam.

Sexual reproduction was not observed in the single strains nor in the pairwise co-cultures.

Physiological characteristics: Fermentation of D-glucose is positive and is absent for D-galactose, sucrose, maltose, lactose, raffinose and trehalose. Carbon compounds assimilated are D-glucose, D-galactose, trehalose, maltose, cellobiose, L-rhamnose (weak), D-xylose, L-arabinose, D-ribose, glycerol, erythritol, D-mannitol, D-sorbitol, inositol, glucosamine, N-acetyl-D-glucosamine, potassium-2-keto-D-gluconate and D-glucuronate, while growth is absent on sucrose, raffinose, melibiose, lactose, melezitose, methyl-α-D-glucoside, lactic acid and D-gluconate.

Growth occurred on ethylamine, L-lysine, cadaverine and D-glucosamine HCl as sole nitrogen compounds and was negative on nitrate. Growth occurred at 6 °C up to 30 °C and was absent at 37 °C. Growth in the presence of 0.01 % cycloheximide is positive.

Additional materials examined: France, Normandie, Orne, from decaying wood, Quercus sp., Jan. 2021, C. Decock, strain CBS 17996 = MUCL 58093 = CIRM-BRFM 3299; ibid., decaying wood in a damp cellar, Quercus sp., Jan. 2021, C. Decock, strain CBS 17997 = MUCL 58091 = CIRM-BRFM 3298.

Distribution and substrates: This species is known from France and Germany growing on decaying wood. According to the GlobalFungi database, samples with identical ITS sequences originate from the Czech Republic on deadwood from forest.

Notes: The three B. dehoogii strains, CBS 181.75, CBS 17997 and CBS 17996 are 100 % similar in both the ITS and LSU regions. The ex-type strain (CBS 181.75) differs from the ex-type strain (NYNU 181030) of B. xishuangbannaensis with 74 nt (27 gaps) and 26 nt (five gaps) in the ITS (515 nt) and LSU (568 nt) regions respectively. Blastobotrys xishuangbannaensis can assimilate much more carbon sources than B. dehoogii, such as sucrose, raffinose, melibiose, lactose, L-sorbose, methyl-α-D-glucoside and lactic-acid. Blastobotrys xishuangbannaensis can also growth at 36 °C where B. dehoogii cannot (Table 3).

Blastobotrys hennebertii M. Groenew., M.T. Sm, Hern.-Restr. & Decock, sp. nov. MB 860906. Fig. 4.

Fig. 4.

Blastobotrys hennebertii CBS 17993 growth after 2 wk at 24 °C on GPYA. A. Budding cells and septate hyphae. B. Pseudo and septate hyphae. Scale bars = 10 μm.

Etymology: hennebertii (Lat., noun); named after G.L. Hennebert, former director of MUCL, who isolated one of the strains.

Typus: Belgium, Prov. Liège, Limbourg, private building, damp cellar, isolated from mouldy archive paper, Mar. 2016, C. Decock (holotype preserved in a metabolically inactive state, CBS 17993, ex-type strain CBS 17993 = MUCL 56024).

Description: After 2 wk at 24 °C on GPYA the culture is off-white to cream coloured, dry, dull, tough, corrugated. Budding cells subglobose, 2.5–4 µm. Hyphae septate, 2–2.5 µm wide without denticles. Pseudohyphae hyaline without denticles. Secondary conidia not observed.

Sexual reproduction has not been observed in the single strains neither in the pairwise mixture.

Physiological characteristics: Fermentation of D-glucose and D-galactose is positive (delayed) and is absent for sucrose, maltose, lactose, raffinose and trehalose. Carbon compounds assimilated are D-glucose, D-galactose, lactose (weak), trehalose, maltose, cellobiose, D-xylose, L-arabinose, D-ribose, glycerol, erythritol, D-mannitol, D-sorbitol, glucosamine, N-acetyl-D-glucosamine, and D-glucuronate, while growth is absent on sucrose, raffinose, melibiose, melezitose, methyl-α-D-glucoside, L-sorbose, L-rhamnose, inositol, lactic acid, D-gluconate and potassium-2-keto-D-gluconate. Growth is positive on L-lysine and cadaverine as sole nitrogen compounds, negative on nitrate, ethylamine, and D-glucosamine HCl. Growth occurred at 6 °C up to 30 °C and is absent at 37 °C. Growth is positive in the presence of 0.01 % cycloheximide.

Additional material examined: Belgium, Prov. Hainaut, Fleurus, private housing, wet timber from stairs, unidentified gymnosperm, Nov. 1991, G.L. Hennebert, strain CBS 17994 = MUCL 31788.

Distribution and substrates: This species is known from Belgium, growing on paper and timber. According to the GlobalFungi database, identical ITS sequences were obtained from a soil sample of an abandoned building in Brazil and from marine sediment at the Pacific Ocean, soil samples in cropland and forest in China.

Notes: The two B. hennebertii strains CBS 17993 and CBS 17994 have 3 nt differences in the LSU and are 100 % similar in their ITS sequences. The ex-type strain (CBS 17993) differs from the ex-type strain (CBS 530.83) of its closest relative, B. elegans, with 69 nt (35 gaps) and 24 nt (seven gaps) in the ITS (550 nt) and LSU (855 nt) regions respectively. Blastobotrys hennebertii and B. elegans showed no significant physiological differences (Table 3).

Blastobotrys jacksonii M. Groenew., M.T. Sm, Hern.-Restr. & Decock, sp. nov. MB 860907. Fig. 5.

Fig. 5.

Blastobotrys jacksonii CBS 18002 growth after 2 wk at 24 °C on GPYA. A. Budding cells and pseudo hyphae. B. Primary globose conidia produce secondary conidia. C. Septate hyphae with conidia. Scale bars = 10 μm.

Etymology: jacksonii (Lat., noun); named after H.S. Jackson, who first described Trichomonascus, the sexual stage of Blastobotrys.

Typus: France, Maine et Loire, Essonne, Sermaise, from a decaying basidiome of Leucogyrophana sp., private house, Jul. 2017, C. Decock (holotype designated here and preserved in a metabolically inactive state, CBS 18002, ex-type strain CBS 18002 = MUCL 56485 = CIRM-BRFM 2517).

Description: After 2 wk at 24 °C on GPYA the culture is snow-white, dry, dull, tough and corrugated. Budding cells globose, 4–6 µm diam. and elongate, 2.5–3.5 × 2.5–8 µm. Hyphae hyaline, septate without denticles, 2–2.5 µm wide. Pseudohyphae hyaline without denticles. Secondary conidia produced by primary conidia at the apex, may contain refractive body, globose 2–3 µm diam.

Sexual reproduction has not been observed in the single strains neither in the mixture.

Physiological characteristics: Fermentation of D-glucose is positive and weak for D-galactose and is absent for sucrose, maltose, lactose, raffinose and trehalose. Carbon compounds assimilated are D-glucose, D-galactose, lactose (weak), trehalose, maltose, cellobiose, L-sorbose, D-xylose, L-arabinose, D-erythritol, D-mannitol, D-sorbitol, inositol, lactic acid (weak), glucosamine, N-acetyl-D-glucosamine, potassium-2-keto-D-gluconate, D-glucuronate, while growth is absent on sucrose, raffinose, melibiose, melezitose, methyl-α-D-glucoside, L-rhamnose, D-ribose, glycerol and D-gluconate.

Growth is positive on ethylamine, L-lysine, cadaverine and D-glucosamine HCl as sole nitrogen compounds, negative on nitrate. Growth occurs at 6 °C up to 30 °C and is absent at 37 °C. Growth in the presence of 0.01 % cycloheximide is positive.

Additional material examined: France, Normandie, Orne, private housing, from decaying wood, unidentified gymnosperm, Jan. 2021, C. Decock, strain CBS 17991 = MUCL 58086 = CIRM-BRFM 3297.

Distribution and substrates: This species in known from France, growing on basidiome and decaying wood (timber). No identical ITS sequences were recovered in the GlobalFungi database.

Notes: The two B. jacksonii strains, CBS 18002 and CBS 17991 have 1 nt difference in the LSU and are 100 % similar in the ITS sequences. The ex-type strain (CBS 18002) differs from the ex-type strain (NYNU 1581) of its closest relative, B. baotianmanensis, with 42 nt (23 gaps) and 19 nt (no gaps) in the ITS (516 nt) and LSU (571 nt) regions respectively. Blastobotrys baotianmanensis is unable to assimilate many carbon sources such as L-sorbose, D-xylose, L-arabinose, maltose, D-mannitol, D-sorbitol, inositol, potassium-2-keto-D-gluconate and is negative for ethylamine hydrochloride and D-glucosamine, whereas B. jacksonii shows growth (Table 3).

Blastobotrys laricis M. Groenew., M.T. Sm, Hern.-Restr. & Decock, sp. nov. MB 860913. Fig. 6.

Fig. 6.

Blastobotrys laricis CBS 17998 growth after 2 wk at 24 °C on GPYA. A. Budding cells, pseudo and septate hyphae. B. Hyphae with primary and secondary conidia. Scale bars = 10 μm.

Etymology: Larix (Lat., noun) wood; named after the substrate, wood, the ex-type strain was isolated from.

Typus: Belgium, Brabant Wallon, Braine-le-Comte, from rotten larch wood (Larix sp.), Sep. 1965, G.L. Hennebert (holotype preserved in a metabolically inactive state, CBS 17998, ex-type strain CBS 17998 = MUCL 7707).

Description: After 2 wk at 24 °C on GPYA the culture is corrugated, cream coloured, dull, tough. Budding cells globose, 1.5–2.5 µm diam, or ovoid, 1.5–5 × 2.5–4 µm. Hyphae septate, hyaline, without denticles, 1.5–2.5 µm wide. Pseudohyphae hyaline without denticles. Secondary conidia produced by primary conidia, globose 1–1.5 µm diam.

Sexual reproduction has not been observed.

Physiological characteristics: Fermentation of D-glucose and D-galactose is positive and is absent for sucrose, maltose, lactose, raffinose, and trehalose. Carbon compounds assimilated are D-glucose, sucrose, raffinose, melibiose, D-galactose, trehalose, maltose, methyl-α-D-glucoside, cellobiose, L-sorbose, L-rhamnose, D-xylose, L-arabinose, D-ribose, glycerol, erythritol, D-mannitol, D-sorbitol, inositol, D-gluconate, glucosamine, N-acetyl-D-glucosamine, potassium-2-keto-D-gluconate (weak) and D-glucuronate, while growth is absent on lactose, melezitose, and lactic acid.

Growth is positive on ethylamine, L-lysine, cadaverine and D-glucosamine HCl as sole nitrogen compounds and negative on nitrate. Growth occurs at 6 °C up to 30 °C and is absent at 37 °C. Growth is positive in the presence of 0.01 % cycloheximide.

Distribution and substrates: This species is known only from the type locality in Belgium, growing on wood. No identical ITS sequences were recovered in the GlobalFungi database.

Notes: Blastobotrys laricis have no close relatives to date for comparison (Fig. 1).

Blastobotrys petasosporus (Kurtzman) M. Groenew., M.T. Sm & Hern.-Restr., comb. nov. MB 860914.

Basionym: Trichomonascus petasosporus Kurtzman, Antonie van Leeuwenhoek 85(4): 300. 2004. MB 530085.

Typus: USA, Missouri, Salem, isolated from White Oak (Quercus sp.), C. Kurtzman, NRRL YB-2093; ex-type strain CBS 9603.

Blastobotrys plurivorus M. Groenew., M.T. Sm, Hern.-Restr. & Decock, sp. nov. MB 860915. Fig. 7.

Fig. 7.

Blastobotrys plurivorus CBS 137.78 growth after 2 wk at 24 °C on GPYA. A. Pseudo and septate hyphae and budding cells, primary conidia form secondary conidia. Scale bar = 10 μm.

Etymology: plurivorus (Lat., noun); named as strains from this species were isolated from various substrates.

Typus: The Netherlands, isolated from mouse-dung, 1977, unknown collector (holotype designated here and preserved in a metabolically inactive state, CBS 137.78; ex-type strain CBS 137.78).

Description: Budding cells globose, 1.5–2.5 µm diam, or ovoid, 2–4 × 2.5–5 µm. Hyphae hyaline, septate, without denticles, 1.5–2.5 µm wide. Pseudohyphae hyaline without denticles. Secondary conidia produced by primary conidia at the apex, globose 1–1.5 µm diam.

Sexual reproduction has not been observed in the single strains nor in the pairwise mixtures.

Culture characteristics: After 2 wk at 24 °C on GPYA the culture is snow-white, dry, dull, tough and corrugated.

Physiological characteristics: Fermentation of D-glucose and D-galactose is weak (delayed) and is absent for sucrose, maltose, lactose, raffinose and trehalose. Carbon compounds assimilated are D-glucose, D-galactose, lactose (weak), trehalose, maltose, cellobiose, L-sorbose, D-xylose, L-arabinose, D-ribose, glycerol, erythritol, D-mannitol, D-sorbitol, glucosamine, N-acetyl-D-glucosamine, potassium-2-keto-D-gluconate and D-glucuronate, while growth is absent on sucrose, raffinose, melibiose, melezitose, methyl-α-D-glucoside, L-rhamnose, inositol, lactic acid and D-gluconate.

Growth is positive on ethylamine, L-lysine, cadaverine and D-glucosamine HCl and negative on nitrate as sole nitrogen compounds. Growth occurred at 6 °C and 30 °C and is absent at 37 °C. Growth in the presence of 0.01 % cycloheximide is positive.

Additional materials examined: France, Occitanie, from a basidiome of Donkioporia expansa (Polyporales) growing on Quercus wood, Jan. 2014, C. Decock, strain CBS 17992 = MUCL 55272; Mediterranean area, from a basidiome of Fomitiporia pseudopunctata (Hymenochaetaceae), Apr. 2015, C. Decock, strain CBS 18001 = MUCL 46524.

Distribution and substrates: This species is known from France (basidiome), and The Netherlands (mouse dung). According to the GlobalFungi database, samples with identical ITS sequences were obtained from samples originating from St. Helena (Peak Dale), Iran, Europe (Austria, Belgium, Czech Republic, Estonia, France, Germany, Hungary, Netherlands, Sweden, and UK), and North America (Canada), growing on soil, deadwood, shoot, and air samples from forest, woodland, cropland and anthropogenic biomes.

Notes: The three B. plurivorus strains, CBS 137.78, CBS 18001 and CBS 17992 are identical in both the ITS and LSU regions. The ex-type strain (CBS 137.78) differs from the ex-type strain (CBS 140.71) of B. farinosus with 75 nt (29 gaps) and 28 nt (five gaps) in the ITS (533 nt) and LSU (842 nt) regions respectively. Blastobotrys plurivorus and B. farinosus showed no significant physiological differences (Table 3).

Blastobotrys pulvis M. Groenew., M.T. Sm, Hern.-Restr. & Decock, sp. nov. MB 860916. Fig. 8.

Fig. 8.

Blastobotrys pulvis CBS 232.85 growth after 2 wk at 24 °C on GPYA. A. Septate hyphae with primary globose conidia produce secondary conidia. B. Budding cells and pseudo hyphae. C. Sexual reproduction CBS 232.85 × CBS 17999 after 1 wk at 24 °C on YCBAS. Asci crowned with an apical cell containing 1–3 hat-shaped ascospores indicated with arrows. Scale bars = 10 μm.

Etymology: pulvis (Lat., noun); named after the substrate, dust, the ex-type strain was isolated from.

Typus: Sweden, Stockholm, house dust, date and collector unknown (holotype preserved in a metabolically inactive state, CBS 232.85; ex-type strain CBS 232.85 mating type h⁺).

Description: After 2 wk at 24 °C on GPYA the culture is off-white to cream coloured, dry, dull and delicately corrugated. Budding cells globose, 1.5–2.5 µm diam, or ovoid and elongate, 2–4 × 3–7 µm. Hyphae hyaline, septate without denticles, 1.5–2 µm wide. Pseudohyphae hyaline without denticles. Conidiophores with primary conidia. Secondary conidia produced by primary conidia, globose, 1–1.5 µm diam.

After 1 wk at 24 °C, sexual reproduction is obtained by mixing strain CBS 232.85 either with CBS 17999 or CBS 18000 on YCBAS sporulation medium. Asci are crowned with an apical cell, persistent and containing 1–3 hat-shaped ascospores. Apical cells may contain a refractive body.

Physiological characteristics: Fermentation of D-glucose is positive and is absent for D-galactose, sucrose, maltose, lactose, raffinose and trehalose. Carbon compounds assimilated are D-glucose, sucrose, raffinose, melibiose, D-galactose, trehalose, maltose, methyl-α-D-glucoside, cellobiose, L-sorbose, L-rhamnose, D-xylose, L-arabinose, D-ribose, glycerol, erythritol, D-mannitol, D-sorbitol, inositol, lactic acid, glucosamine, N-acetyl-D-glucosamine, potassium-2-keto-D-gluconate and D-glucuronate, while growth is absent on lactose, melezitose and D-gluconate.

Growth occurs on ethylamine, L-lysine, cadaverine and D-glucosamine HCl as sole nitrogen compounds, negative on nitrate. Growth occurred at 6 °C and 30 °C and is absent at 37 °C. Growth in the presence of 0.01 % cycloheximide in positive.

Additional materials examined: Belgium, Prov. Brabant Wallon, Louvain-la-Neuve, from basidiome of an unidentified species, Oct. 1990, C. Decock, strain CBS 17999 = MUCL 31040, mating type h⁻. France, Ile de France, Seine-Saint-Denis, Noisy le Grand, private housing, damp cellar, from basidiome of Serpula pulverulenta, Sep. 2016, C. Decock, strain CBS 18000 = MUCL 56215, mating type h⁻.

Distribution and substrates: This species is known from Sweden from house dust and from Belgium and France growing on a basidiome. No identical ITS sequences were recovered in the GlobalFungi database.

Notes: The three B. pulvis strains, CBS 232.85, CBS 17999 and CBS 18000 differed with up to 8 nt in the ITS and 1 nt in the LSU sequences. The ex-type strain (CBS 232.85) differs from the ex-type strain (CBS 522.75) of B. proliferans with 73 nt (38 gaps) and 31 nt (two gaps) in the ITS (543 nt) and LSU (849 nt) regions, respectively, and from the ex-type strain (CBS 139.77) of B. navarrensis, with 42 nt (12 gaps) and 28 nt (four gaps) in the ITS (418 nt) and LSU (568 nt) regions, respectively. Blastobotrys proliferans and B. navarrensis can grow at 37 °C where B. pulvis is not able to (Table 3).

PHYSIOLOGICAL CHARACTERISTICS

Strains of all seven novel species were positive for the assimilation of D-glucose, galactose, trehalose, maltose, cellobiose, D-xylose, L-arabinose, erythritol, D-mannitol, D-sorbitol, glucosamine, D-glucoronate, N-acetyl-D-glucosamine, Lysine, and cadaverine and can growth from 6 °C up to 30 °C and at a concentration of cycloheximide of 0.01 %.

Strains of all seven novel species fermented D-glucose but were negative for lactose, maltose, raffinose, sucrose, trehalose, and xylose.

All strains were negative for the assimilation of melezitose and for growth at 37 °C. Compounds that had dissimilar assimilation profiles among the species are listed in Table 2.

Table 2.

Differential physiological characteristics among (1) Blastobotrys hennebertii sp. nov. (CBS 17993^T, CBS 17994); (2) Blastobotrys plurivorus sp. nov. (CBS 137.78^T, CBS 17992, CBS 18001); (3) Blastobotrys jacksonii sp. nov. (CBS 17991, CBS 18002^T); (4) Blastobotrys dehoogii sp. nov. (CBS 181.75^T, CBS 17996, CBS 17997); (5) Blastobotrys pulvis sp. nov. (CBS 232.85^T, CBS 17999, CBS 18000); (6) Blastobotrys laricis sp. nov. (CBS 17998^T); and (7) Blastobotrys bolitophagi sp. nov. (CBS 12434, CBS 12455T), (+, positive; −, negative; w, weak results; v, variable; d, delayed; T, ex-type strain).

Physiological attributes	1	2	3	4	5	6	7
Fermentation
D-Galactose	+/d	w/d	w	−	−	+	+
Assimilation of carbon compounds
Sucrose	−	−	−	−	+	+	+
Raffinose	−	−	−	−	+	+	−
Melibiose	−	−	−	−	+	+	+
Lactose	w	w	w	−	−	−	+
Methyl-α-D-glucoside	−	−	−	−	+	+	+
L-sorbose	−	+	+	−	+	+	+
L-rhamnose	−	−	−	w	+	+	−
D-ribose	+	+	−	+/w	w/+	w/+	w/+
Glycerol	+	+	−	+/w	+	+	−
Inositol	−	−	+	+/w	+	+	+
Lactic acid	−	−	w	−	+	−	−
D-gluconate	−	−	−	−	−	+	+
Potassium-2-keto-D-gluconate	−	+	+	+	+	w	+
Assimilation of nitrogen compounds
Nitrate	−	−	−	−	−	−	+
Ethylamine	−	+	+	+	+	+	−
D-glucosamine HCl	−	+	+	+	+	+	+

Differences observed in the physiological profiles of the novel species obtained from the commercial test (Biomerieux) and published data from their closest relatives (Kurtzman et al. 2011, Chai et al. 2020, Palma et al. 2022) are listed in Table 3.

MATING CAPABILITIES

Strains with complementary mating types for a specific species are indicated with or h⁺ or h⁻. This designation was used to specify complementary mating types in heterothallic species in the genera Metschnikowia, Clavispora, or Kodamea (Kurtzman et al. 2011).

Sexual reproduction was only observed in B. pulvis and B. bolitophagi. Ascospores were observed after 1 wk at 24 °C on YCBAS sporulation medium in B. pulvis, by mixing strain CBS 232.85 (mating type h⁺) either with CBS 17999 or CBS 18000, both belonging to the complementary mating type h⁻. In B. bolitophagi, ascospores were observed after 2 wk at 24 °C on YMA and MEA by mixing strain CBS 12455 (mating type h⁺) with CBS 12434 (mating type h⁻). These two species are heterothallic and need strains of complementary mating types to go into the sexual live cycle.

DISTRIBUTION AND SUBSTRATE RANGE

The known distribution range and substrates of the newly described taxa revealed distinct patterns. Certain species, including B. bolitophagi, B. jacksonii, B. laricis, and B. pulvis, appear to be restricted to their type localities and substrates. They have no matches in datasets of environmental sequences. This suggests that they are either rare or have been sampled insufficiently.

Blastobotrys dehoogii is to date restricted to Europe. In addition to our records from Germany and France, this species is represented by two environmental records, made on deadwood in the Czech Republic. Blastobotrys hennebertii, inversely, shows a disjunct distribution. In addition to our isolates from Belgium, it is known from environmental records made in Brazil and China. This species is reported from diverse substrates including soil, sediments, water, paper, and timber. By contrast, B. plurivorus is widely distributed across Europe (Austria, Belgium, Czech Republic, Estonia, France, Germany, Hungary, Netherlands, Sweden, and UK) and it is also known from North America (Canada), West Asia (Iran), and St. Helena (Peak Dale). Its range of substrate includes soil, deadwood, shoot, air, dung, and other fungi.

According to the GlobalFungi database, members of Blastobotrys are present in 1356 “environmental” samples. Asia accounts for 51.84 % and Europe 26.36 %. This may reflect the intensity of samplings (Fig. 9A). Regarding to the substrate type, most of the samples come from soil (70.5 %, including topsoil) but, interestingly, several records originate from deadwood (10.32 %), air (4.72 %), and water (3.61 %) (Fig. 9B). The most common biome is forest (59.44 %) followed by cropland (11.5 %), and woodland (7.15 %).

Fig. 9.

Global distribution (A) and substrate range (B) of Blastobotrys metabarcoding sequences obtained from the GlobalFungi database as well as the data from the CBS yeast collection (www.wi.knaw.nl) on global distribution (C) and substrate range (D) of Blastobotrys strains.

On the other hand, amongst 182 strains deposited in the CBS collection, 47.25 % were isolated from North and South America with the most from Panama (42/86) and the USA (36/86). Europe accounted for 36.26 % with the Netherlands (22/66) and France (11/66) as the countries where the genus was the most abundantly found (perhaps the most abundantly sampled) (Fig. 9C). Asia and Africa are represented only by 11 and 9 strains, or 6 and 5 %, respectively. Three strains (1.65 %) were isolated from the Arctic, and five strains (2.7 %) are from unknown origin (Fig. 9C).

Blastobotrys strains have a wide range of substrates, as indicated in Fig. 9D. More than 50 % originated from natural environments, with approximately 40 % from insects, 11 % from soil, 7.5 % from deadwood, and 7 % were associated with other (mostly) basidiomycetous fungi. Approximately 4 % were associated with foodstuffs.

This contrasts with the data from environmental samples, for which soil is the most frequent substrate. This also likely reflects both the intensity and the selection of sampled substrates between environmental sampling and culture dependant sampling. As an illustration of this, approximately 40 % of the Blastobotrys isolates from the CBS collection, from which data were used, were isolated during a five-year survey of yeast diversity associated with insects in the USA and Panama. Nonetheless, it is still clear that natural environments are the most important niche for this genus that include plants, soil, air, water, insects, and other fungi. Anthropogenic habitats and substrates such as food, walls/paintings, paper, or decaying timber, is also a non-negligible reservoir of rare or undescribed species.

Blastobotrys species are not commonly known as human disease-causing agents. Nonetheless, 3 % of the strains available worldwide were associated with humans, and belong to B. ciferrii (Gunsilius et al. 2001, Cheng et al. 2004), B. chiropterorum (Furman & Ahearn 1983), B. proliferans (Quirin et al. 2007), B. mokoenaii, B. raffinosifermentans, and B. serpentis (Kumar et al. 2014, Al-Obaidi et al. 2021, Cosio et al. 2024, Shiomi et al. 2024). Our strains of the novel species could not grow at 37 °C and are most likely not able to induce or be associated with human disease.

Supplementary material

Table S1

Blastobotrys strains available from the CBS collection used for the substrate and origin data analyse.