Tuber elevatireticulatum sp. nov., a new species of whitish truffle from Taiwan

Chieh-Lung Lin; Ming-Jer Tsai; Chuen-Hsu Fu; Tun-Tschu Chang; Hoi-Tung Li; King-Fai Wong

doi:10.1186/s40529-018-0241-y

Original Article
Open Access

Tuber elevatireticulatum sp. nov., a new species of whitish truffle from Taiwan

Chieh-Lung Lin¹,
Ming-Jer Tsai^{2, 3},
Chuen-Hsu Fu⁴,
Tun-Tschu Chang⁴,
Hoi-Tung Li⁵ and
King-Fai Wong⁶Email author View ORCID ID profile

Botanical StudiesAn International Journal201859:25

https://doi.org/10.1186/s40529-018-0241-y

Received: 20 March 2018
Accepted: 22 October 2018
Published: 29 October 2018

Abstract

Background

There are estimated 180–220 species of Tuber described in the world, but the diversity of the genus in Taiwan is poorly known, with only two species recorded, i.e., Tuber formosanum and T. furfuraceum. During our survey of hypogenous fungi in Taiwan, a whitish truffle belongs to Puberulum clade was collected from roots of Keteleeria fortunei var. cyclolepis in central Taiwan and appeared to differ from the two recorded species.

Results

The whitish truffle is herein described as a new species Tuber elevatireticulatum, which is distinguished from closely resembled Asian whitish truffles species like Tuber thailandicum, T. panzhihuanense, T. latisporum and T. sinopuberulum by the association with Keteleeria host, small light brown ascocarps with a dark brown gleba, dark brownish and elliptical ascospores ornamented with a prominently raised alveolate reticulum. Molecular phylogenetic analyses of both ITS and LSU loci clearly supports T. elevatireticulatum as a new species without any significant incongruence.

Conclusions

The whitish truffle is herein described as a new species T. elevatireticulatum based on the evidence from morphology and DNA sequences. T. elevatireticulatum is the first scientific record of whitish truffle in Taiwan.

Keywords

Keteleeria
Morphology
Phylogeny
Taxonomy
Taiwan
Truffle
Tuber

Background

True truffles, belonging to the genus Tuber (Tuberaceae, Pezizales, Pezizomycetes), produce hypogeous ascocarps, which are formed in soil or sometimes within layers of leaf litter. They have lost the ability to actively discharge ascospores (Bonito and Smith 2016). They are symbiotic fungi that develop association with fine roots of specific host trees (T. oregonense Trappe, Bonito and P. Rawl. with Douglas fir) or broad host ranges (T. aestivum (Wulfen:Fr.) Spreng. with some plant species in Betulaceae, Corylaceae, Fagaceae, Tiliaceae, Pinaceae and Cistaceae) (Hall et al. 2007). The unique aroma makes some species greatly sought after as high-end culinary ingredients throughout the world, especially in Europe (Hall et al. 2007). The scarcity and irreplaceably scent of French Périgord black truffle (T. melanosporum Vittad.) and Italian Alba white truffle (T. magnatum Pico.) render them among the most famous and demanding truffles in the world (Hall et al. 2007; Bonito et al. 2010a).

Index Fungorum (http://www.indexfungorum.org/names/Names.asp) lists out three hundred and five Tuber names, however, many of them required clarification (Suwannarach et al. 2015; Kinoshita et al. 2016). Bonito et al. (2013) reassessed the published names and estimated 180–220 accepted species in the genus, was subdivided into 11 major clades according to their phylogenetic relationships. Puberulum clade, Maculatum clade and closely related lineage Gibbosum clade were phylogenetically grouped with as Puberulum Group and members of this group commonly called “whitish truffle” in order to distinguish them from Italian white truffle (T. magnatum in Aestivum clade) (Bonito et al. 2010a; Lancellotti et al. 2016). Researches in Tuber have a long history and are well-documented in Europe and North America. However, research in Asia are still scarce despite the estimated high diversity (Bonito et al. 2010a; Kinoshita et al. 2011). Hypogeous fungi in Taiwan are poorly documented, with only T. formosanum Hu (invalidly described in 1992 due to the lack of designated holotype and later re-typification in 2013) and T. furfuraceum Hu and Wang reported previously. Both species form symbiotic association with roots of Quercus glauca (Thunb. ex Murray) Oerst. in the family of Fagaceae (Hu 1992; Hu and Wang 2005; Qiao et al. 2013). A whitish truffle was mentioned in Hu (1987) but lacks a formal description.

During our survey of hypogenous fungi in Taiwan, a whitish truffle was found under Keteleeria fortunei var. cyclolepis (Flous) Silba, in Sitou Tract, Nantou County of central Taiwan. It resembles several known Asian whitish truffles in the Puberulum Clade, such as T. thailandicum Suwannarach et al. (2015), T. panzhihuanense Deng et al. (2013), T. latisporum Chen and Liu (2007), T. pseudosphaerosporum Fan and Yue (2013), and T. alboumbilicum Wang and Li (Li et al. 2014), but differs from species in the Puberulum clade by the only species associated with Keteleeria host, small light brown ascocarps with hyphae-like hairs arised, dark brownish and elliptical ascospores ornamented with a prominently raised alveolate reticulum.

Methods

Sample collection

Ascocarps were collected with three-pronged garden cultivators, wrapped with tissue paper and kept in separate plastic zipper bags until further morphological and molecular analyses in laboratory. Ascocarps were weighted freshly within 24 h, and the pH value of adjacent soil were measured by JENCO 6010M pH meter following protocol of the manufacturer.

Morphological analysis

Ascocarps were cleaned with dry toothbrush, and then cut into halves for observing gleba color or color change under air exposure. Sections of fresh tissue were made with a razor blade by hand, then mounted in 0.1% (w/v) cotton blue in lacto-phenol for describing morphological characteristics by a Leica DMLB light microscope. Ascospore dimensions, with the ornamentation excluded, were based on at least 100 randomly selected ascospores. The range of ascospore length to width ratio (Q), average Q with ± standard deviation (Q) was calculated, and number of meshes across the ascospore width was measured.

For scanning electron microscopy (SEM), ascospores from dried gleba were mounted onto SEM stubs with carbon double-sided tape (Nisshin EM CO., Ltd, Tokyo), coated with gold–palladium, then examined and photographed with a tabletop HITACHI TM3000 SEM. Holotype was deposited at Herbarium of Taiwan Forestry Research Institute, Taipei, Taiwan (Index Herbarium: TAIF).

Molecular analysis

DNA extraction

Approximately 9–14 mg of gleba tissue of fresh ascocarps were ground by plastic pestle with 800 µl of Lysis Buffer (Taiwan Advanced Nanotech Inc.; containing Guanidine salt, Tris buffer and surfactants) in 1.5 ml centrifuge tube for DNA extraction. DNA was then extracted using the TANBead^Ⓡ fungal Nucleic Acid Extraction Kit and TANBead^Ⓡ Nucleic Acid Extractor (Taiwan Advanced Nanotech Inc.) following protocol of the manufacturer.

Polymerase chain reaction (PCR) amplification and sequencing

Two nuclear ribosomal DNA loci were used for amplifying and sequencing, including the internal transcribed spacer (ITS) with forward primer ITS5 (5′-GGAAGTAAAAGTCGTAACAAGG-3′) was paired with reverse primer ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (White et al. 1990); and ribosomal large subunit (LSU) with forward primer LR0R (5′-ACCCGCTGAACTTAAGC-3′) (Rehner and Samuels 1994) was paired with reverse primer LR5 (5′-TCCTGAGGGAAACTTCG-3′) (Vilgalys and Hester 1990). PCR was performed in 25 µl reactions containing 2.5 µl DNA template, 1 µl primer each, 8 µl ddH₂0 and 12.5 µl 2× Taq Master Mix (including 20 mM KCl, 4 mM MgSO₄·7H₂O, 40 mM Tris–HCl with pH 8.8, 0.2% Triton X-100, 20 mM (NH₄)₂SO₄, 0.2 mg/ml BSA, 0.4 mM dNTP mix, 100 U/ml Taq DNA Polymerase and stabilizers) (Genomics Bioscience and Technology CO., Ltd.). PCR for ITS/LSU were run as an initial denaturation at 94/95 °C for 3/2 min, then at 94/95 °C for 30 s, annealing at 56/50 °C for 30 s, extension at 72 °C for 30 s/1 min by 30 cycles and a final extension at 72 °C for 5/10 min on a multigene thermal cycler (Labnet International, Inc.). PCR products were checked on agarose gel containing 1.4% agarose and 0.5× Tris–acetate-EDTA (TAE) and stained with 5 µl/100 ml Healthview™ nucleic acid stain under UV light by multilmage™ light cabinet (Alphalmager 2200). The PCR products were sent to Seeing Bioscience Co., Ltd. for purification and sequencing by Sanger Sequencing Method (ABI 3730).

Phylogenetic analyses

Six ITS and eight LSU sequences were obtained from ascocarps of T. elevatireticulatum and were submitted to GenBank with Accession Numbers MF540616–MF540621 (ITS) and LSU sequences: LC425119–LC425126 (LSU). Other whitish Tuber sequences were obtained from GenBank database for phylogenetic analyses (Table 1), with Choiromyces alveolatus as the outgroup. Sequences were aligned using MAFFT 7 (Katoh and Standley 2013) with default settings, and poorly aligned sites were identified using Gblocks 0.91b (Castresana 2000) with gaps allowed in conserved blocks and with all other parameters left as default values. Ambiguous sites were excluded from phylogenetic analyses. Maximum likelihood (ML) analyses were conducted with MEGA 6.0 (Tamura et al. 2013) using K2P model. Bootstrap analyses were conducted with 1000 replications (Felsenstein 1985). Bayesian phylogenetic analyses were conducted with MrBayes 3.2.6 (Ronquist et al. 2012), for evaluating the effect of different phylogenetic approach. K2P model was used and MCMC chains were run for 1,000,000 generations, sampling every 100th tree. Among these, the first 20% trees were discarded as burn-in phase and the remaining trees were used to calculate Bayesian posterior probabilities. The consensus tree was viewed with FigTree 1.4.3 (Rambaut 2014).

Table 1

Details of the whitish Tuber ITS sequences used in phylogenetic study

Taxa	Voucher no.	Origin	GenBank Accession no.		References
Taxa	Voucher no.	Origin	ITS	LSU	References
Choiromyces alveolatus	MES97	USA	HM485332		Bonito et al. (2010a)
Choiromyces alveolatus	HS2886	USA	HM485333		Bonito et al. (2010a)
Choiromyces alveolatus	p688L	USA		EU669426	Unpublished
Choiromyces alveolatus	MES97	USA		JQ925660	Bonito et al. (2013)
T. alboumbilicum	YAAS L2324^a	China	KJ742702		Li et al. (2014)
T. bellisporum	JT7270	USA	FJ809856	FJ809827	Bonito et al. (2010b)
T. bellisporum	JT6060	USA	FJ809857	FJ809828	Bonito et al. (2010b)
T. borchii	GB45	Italy	HM485344		Bonito et al. (2010a)
T. borchii	CMI-UNIBO 3405	Italy	FJ554521		Bonuso et al. (2010)
T. borchii	Tar042	Italy	KT165326		Belfiori et al. (2016)
T. borchii	AH39139	Spain		JN392291	Alvarado et al. (2012)
T. borchii	GB32	Italy		FJ809852	Bonito et al. (2010b)
T. californicum	JT22590	USA	HM485351		Bonito et al. (2010a)
T. californicum	src880	USA	HM485350		Bonito et al. (2010a)
T. californicum	RPC-9	USA		AF156927	Taylor and Bruns (1999)
T. castellanoi	JT19924	USA	FJ809859	FJ809830	Bonito et al. (2010b)
T. castellanoi	JT28069	USA	FJ809860	FJ809831	Bonito et al. (2010b)
T. dryophilum		Italy	AF003917		Unpublished
T. dryophilum	GB37	Italy	HM485354	JQ925688	Bonito et al. (2013)
T. dryophilum	GB35	Italy		JQ925687	Bonito et al. (2013)
T. elevatireticulatum ^b	XTAM1	Taiwan	MF540616	LC425119	This study
T. elevatireticulatum	XTAM2	Taiwan	MF540617	LC425120	This study
T. elevatireticulatum	XTAM3 ^a	Taiwan	MF540618	LC425121	This study
T. elevatireticulatum	XTAM4	Taiwan	MF540619	LC425122	This study
T. elevatireticulatum	XTAM5	Taiwan	MF540620		This study
T. elevatireticulatum	XTAM7	Taiwan	MF540621	LC425123	This study
T. elevatireticulatum	XTBX1	Taiwan		LC425124	This study
T. elevatireticulatum	XTBX4	Taiwan		LC425125	This study
T. elevatireticulatum	XTBX5	Taiwan		LC425126	This study
T. flavidosporum	K213^a	Japan	AB553446	AB553520	Kinoshita et al. (2016)
T. gibbosum	SPCP_B2a	Canada	KP972062		Berch and Bonito (2016)
T. gibbosum	JT6555	USA		FJ809833	Bonito et al. (2010a)
T. gibbosum	JT19424	USA	HM485362	FJ809834	Bonito et al. (2010a)
T. huizeanum	BJTC FAN186^a	China	JQ910651	NG_059991	Fan et al. (2013a)
T. japonicum	N88^a	Japan	AB553444		Kinoshita et al. (2016)
T. japonicum	K228	Japan		AB553519	Kinoshita et al. (2016)
T. latisporum	HKAS 44315^a	China	DQ898183		Chen and Liu (2007)
T. latisporum	BJTC FAN126	China		KP276204	Fan et al. (2016a)
T. lijiangense	BJTC FAN307	China	KP276188	KP276203	Fan et al. (2016a)
T. liui	HKAS 48269	China	DQ898182		Chen and Liu (2007)
T. liyuanum	BJTC FAN162^a	China	JQ771191		Fan and Cao (2013)
T. liyuanum	BJTC FAN162^a	China		KT067698	Fan et al. (2016b)
T. maculatum	M4TM	Poland	KJ524530		Unpublished
T. maculatum	Mac1	Italy	AF106889		Unpublished
T. maculatum	ZB2656	Hungary		JF261366	Unpublished
T. microsphaerosporum	BJTCFan152^a	China	KF805726		Fan and Yue (2013)
T. microverrucosum	BJTC FAN142^a	China	JN870099		Fan et al. (2011)
T. microverrucosum	BJTC FAN142^a	China		KT067696	Fan et al. (2016b)
T. oligospermum	AH39338	France	JN392266	JN392319	Alvarado et al. (2012)
T. oligospermum	AH37867	Italy	JN392259	JN392322	Alvarado et al. (2012)
T. oregonense	SPCP_B26	Canada	KP972064		Berch and Bonito (2016)
T. oregonense	DUKE GB284^a	USA	FJ809874		Bonito et al. (2010b)
T. oregonense	JT27945	USA		FJ809836	Bonito et al. (2010b)
T. oregonense	JT8767	USA		FJ809837	Bonito et al. (2010b)
T. panzhihuanense	DXJ267^a	China	JQ978648		Deng et al. (2013)
T. panzhihuanense	HKAS:95329			KY174963	Unpublished
T. panzhihuanense	HKAS:95328			KY174962	Unpublished
T. pseudomagnatum	BJTC FAN163^a	China	JQ771192		Fan and Cao (2013)
T. pseudomagnatum	BJTC FAN163^a	China		KP276192	Fan et al. (2016b)
T. pseudosphaerosporum	BJTCFan250^a	China	KF744063		Fan and Yue (2013)
T. pseudosphaerosporum	BJTCFan250^a	China		KP276194	Fan et al. (2016a)
T. puberulum		Serbia	FM205642		Marjanovic et al. (2010)
T. puberulum	ZB436	Hungary		JF261369	Unpublished
T. shearii	OSC51052	USA	HM485389		Bonito et al. (2010a)
T. shearii	OSC51052	USA		JF419280	Guevara et al. (2013)
T. shearii	JT12498	USA	GQ221450		Unpublished
T. sinopuberulum	BJTC FAN157^a	China	JQ690073	JQ690070	Fan et al. (2013b)
T. sinosphaerosporum	BJTC FAN135^a	China	JX092086		Fan et al. (2013c)
T. sinosphaerosporum	BJTC FAN135^a	China		KP276195	Fan et al. (2016a)
T. sphaerospermum	AH37798	Morocco	JN392245	JN392304	Alvarado et al. (2012)
T. sphaerospermum	AH39197	Spain	JN392242	JN392307	Alvarado et al. (2012)
T. thailandicum	CMU-MTUF1^a	Thailand	KP196328	KP196333	Suwannarach et al. (2015)
T. thailandicum	CMU-MTUF2	Thailand	KP196329	KP196334	Suwannarach et al. (2015)
T. turmericum	BJTC FAN473^a	China	KT758837		Fan et al. (2015)
T. vesicoperidium	BJTC FAN155^a	China	JQ690071	JQ690068	Fan et al. (2013b)
T. xanthomonosporum	YAAS L3185^a	China	KJ162154		Qing et al. (2015)
T. zhongdianense	wang0299^a	China	DQ898187		Chen and Liu (2007)
T. zhongdianense	BJTC FAN176	China		KP276201	Fan et al. (2016a)

^aHolotype

^bNew species described in this study are bold as indication

Results

Taxonomy

Tuber elevatireticulatum K.F. Wong and H.T. Li, sp. nov. Fig. 1

MycoBank no.: MB824068.

Etymology: Referring to the prominently elevated reticulum on the ascospores.

Ascocarp hypogeous, scattered, solitary, subglobose or irregular, 12–19 mm long × 10–15 mm wide, 0.32–1.7 g in fresh weight, solid, smooth on the surface, whitish to pale yellowish when fresh, becoming light brown at maturity. Peridium two-layered; inner layer 85–425 μm thick, hyaline, composed of intricately interwoven hyphae; outer layer 75–110 μm thick, light brownish, pseudoparenchymatous, composed of globose, subglobose, rod-shaped or angular cells, 5–25 μm diam. Hyphae-like hairs arise from outermost cells, hyaline, septate, tapering towards the ends, acute or round at the apex, 50–275 × 1.25–3.75 μm. Gleba translucent or light-brown, marbled with narrow, white veins when young, becoming dark brown, marbled with narrow, light brown veins at maturity. Asci 1-3(-4)-ascospored, globose, subglobose, ovoid to ellipsoid, 47.5–88 × 37.5–75 µm, hyaline, with a wall 2.5 µm thick. Ascospores broadly ellipsoid to ellipsoid, rarely subglobose and globose, with mature ascospore ratio ranging 0.2–53% (n = 1000), yellowish brown to dark brown, with a wall 2.5–5 µm thick, 32.5–50 × 20–32.5 µm from 1-ascospored asci, 20–48 × 20–32.5 µm from 2-ascospored asci, 20–40 × 20–27.5 µm from 3-ascospored asci, 22.5–35 × 17.5–25 µm from 4-ascospored asci (Q = 1.0–1.75, Q = 1.30 ± 0.19), ornamented with irregular reticulations 2.5–7.5 µm high, with meshes varying in size, mostly 3-4(-5) across the ascospore width.

Specimens examined: TAIWAN, Nantou County, Sitou Tract, associated with roots of K. fortunei var. cyclolepis, 1 Jun 2017, collected by C.-L. Lin, K.-F. Wong, H.-T. Li and F.-Y. Lin, XTAM3 (holotype), ITS sequences: MF540616–MF540621; LSU sequences: LC425119–LC425126.

Notes: Tuber elevatireticulatum grows in montane area of central Taiwan with elevation of 1150 m. It is associated with a cluster of K. fortunei var. cyclolepis in a mixed coniferous plantation, at least 4 m apart from the nearest Cryptomeria japonica (L. f.) D. Don, Chamaecyparis formosensis Matsum. and a few Pinus species which all have no record of association with Tuber species. Ascocarps are mostly scattered and distributed in solitary in loamy soil with pH ranging from 5 to 6. Ascocarps are usually found within 0–2 m from tree trunks, starting to develop in March and maturing in June. Odor is pleasant, mild, peculiar but superb, rarely becoming unpleasant with ageing. The temperature during the ascocarp formation is 20–25 °C.

Phylogenetic analyses

The ITS matrix consisted of 52 sequences and 1661 aligned bases, of which 1198 bp were identified as poorly aligned and were excluded by Gblocks. The resultant ITS alignment was 463 bp. The LSU matrix consisted of 47 sequences and 1519 aligned bases, of which poorly aligned and were excluded by Gblocks and the resultant LSU alignment was 580 bp. As Maximum likelihood and Bayesian analyses yielded similar tree topologies of ITS region, thus the only tree generated form ML analysis is shown in Fig. 2. The ML and Bayesian analyses of LSU region is similar in general, due to the limited availability of sequences in database, the tree inferred form ML analysis is presented in Fig. 3, separate trees are presented as Additional files 1, 2.

Fig. 2
Phylogenetic tree of *Tuber elevatireticulatum* and related whitish truffles based on the ITS-rDNA sequences. *Choiromyces alveolatus* was used as the outgroup taxa. Numbers identify the bootstrap values and Bayesian posterior probabilities are indicated near branches as BS/PP. Values of BS and PP below 50% are not indicated. The sequences of new species described in this study are bold as indication

Fig. 3
Phylogenetic tree of *Tuber elevatireticulatum* and related whitish truffles based on the LSU-rDNA sequences. *Choiromyces alveolatus* was used as the outgroup taxa. Numbers identify the bootstrap values and Bayesian posterior probabilities are indicated near branches as BS/PP. Values of BS and PP below 50% are not indicated. The sequences of new species described in this study are bold as indication

There has no significant incongruence among ITS and LSU region of ribosomal DNA. Tuber elevatireticulatum is clearly different from other whitish truffles and formed a monophyletic clade with strong bootstrap (BS) and posterior probability (PP) values (1.00/1.00). Based on the ITS analysis, T. elevatireticulatum was placed clearly in the Puberulum clade, within which it formed a subclade with five Asian species, including T. thailandicum, T. pseudosphaerosporum, T. alboumbilicum, T. latisporum, and T. panzhihuanense, with strong branching supports by BS (0.89) and PP (0.99) value. Also included in the Puberulum clade were T. borchii, T. dryophilum, T. oligospermum and T. sphaerospermum from Europe; T. microsphaerosporum, T. sinopuberulum, T. vesicoperidium, T. lijiangense, T. sinosphaerosporum, T. zhongdianense, T. huizeanum, T. liui and T. liyuanum from China; and T. californicum from the USA. These whitish truffle species formed a subclade within the Puberulum clade with strong PP value of 1.00 and was sister to the one where T. elevatireticulatum was placed. The groupings of whitish truffles were similar from those in Kinoshita et al. (2011), Suwannarach et al. (2015) and Bonito and Smith (2016).

Discussion

Tuber elevatireticulatum is distinguished from other whitish truffle species by the only species associated with Keteleeria host, its small light brown ascocarps with a dark brown gleba and brown, ellipsoid ascospores with a prominent raised alveolate reticulum. Phylogenetic analyses clearly placed T. elevatireticulatum among other whitish truffle species in the Puberulum clade as a distinct taxon. Morphologically, truffles belonging to the Puberulum clade tend to have small and light-colored ascocarps, globose to subglobose ascospores with an alveolate-reticulate ornamentation (Bonito and Smith 2016). However, ascospores of T. elevatireticulatum are mostly ellipsoid, resembling those of the species in the Maculatum clade.

Tuber elevatireticulatum clustered in a subclade of the Puberulum group with several Asian whitish truffle species, including T. thailandicum, T. pseudosphaerosporum, T. alboumbilicum, T. panzhihuanense, and T. latisporum (Fig. 2). Tuber elevatireticulatum is similar to T. thailandicum in having a dark brown gleba at maturity, hyphae-like hairs, and the size of alveolae of the reticulum. However, T. thailandicum differs by having a larger ascocarp size (> 2 cm in diam.), a thinner peridium (150–225 µm), shorter hyphae-like hairs (20–63.5 µm), subglobose ascospores with a smaller Q value (1.09 ± 0.08), and larger ascospores in one-ascospored asci (40–65 × 40–62 µm) (Suwannarach et al. 2015). In addition, T. thailandicum is associated with roots of Betula, whereas T. elevatireticulatum is with Keteleeria roots, a host previously unknown to Tuber species. Tuber elevatireticulatum resembles T. pseudosphaerosporum in having light-colored ascocarps with a smooth surface and the same numbers of ascospores in asci but differs from the latter by a smaller ascocarp size, well-developed hyphae-like hairs, larger ellipsoid ascospores, a lower reticulum, and occurrence in a different season (Fan and Yue 2013). Tuber alboumbilicum is different from T. elevatireticulatum by a smaller ascocarp size (< 1 cm), a thinner peridium, and globose ascospores. Tuber panzhihuanense is distinct from T. elevatireticulatum by a dark grey to blackish gleba (Deng et al. 2013). Tuber latisporum is different from T. elevatireticulatum by reddish brown ascocarps, a blackish gleba and larger ascospores (62–93 × 41–74 µm) (Chen and Liu 2007). Beyond this subclade, Tuber sinopuberulum resembles T. elevatireticulatum in having light brown ascocarps with a smooth surface but differs from it in lacking hyphae-like hairs arising from the peridium, a light brown to brown gleba color, and globose ascospores (Fan et al. 2012).

Truffles in general favor dry, alkaline and calcareous soil (Hall et al. 2007), but T. elevatireticulatum was found in an area with a subtropical humid climate, slightly acidic soil of pH 5–6, and relatively high annual rainfall. This phenomenon has also been observed in Asia like Japan (Kinoshita et al. 2011) and Thailand (Suwannarach et al. 2015).

Declarations

Authors’ contributions

CLL, HTL and KFW collected, recorded and photographed the Tuber ascomatas, and all the authors prepared the manuscript. All authors read and approved the final manuscript.

Acknowledgements

We are thankful to the Experimental Forest, College of Bio-resources and Agriculture, National Taiwan University for assisting specimen collecting. We appreciate Dr. Yu-Ming Ju, Institute of Plant and Microbial Biology, Academia Sinica, Taiwan, for suggesting the epithet of Tuber elevatireticulatum; and Dr. Huei-Mei Hsieh for assistance in multi-gene analyses.

Competing interests

The authors declare that they have no competing interests. All the experiments undertaken in this study comply with the current laws of Taiwan.

Availability of data and materials

Not applicable.

Consent for publication

Not applicable.

Ethics approval and consent to participate

Not applicable.

Funding

This study is supported by the Council of Agriculture, Taiwan, under Grant No. 106AS-11.1.5-Fl-G2 to C-H Fu.

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Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Additional files

40529_2018_241_MOESM1_ESM.pdf Additional file 1. Phylogenetic tree of Tuber elevatireticulatum and related whitish truffles based on the ITS-rDNA sequences by Bayesian phylogenetic analyses

40529_2018_241_MOESM2_ESM.pdf Additional file 2. Phylogenetic tree of Tuber elevatireticulatum and related whitish truffles based on the LSU-rDNA sequences by Bayesian phylogenetic analyses.

Authors’ Affiliations

(1)

Division of Watershed Management, Taiwan Forestry Research Institute, COA, Taipei, Taiwan

(2)

Department of Forestry and Resource Conservation, National Taiwan University, Taipei, Taiwan

(3)

The Experimental Forest, National Taiwan University, Nantou County, Taiwan

(4)

Division of Forest Protection, Taiwan Forestry Research Institute, COA, Taipei, Taiwan

(5)

Tianroei Limited Company, Taipei, Taiwan

(6)

Advance Plant Protection Limited Company, Hsinchu, Taiwan

References

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