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A new hypogeous species, Choiromyces cerebriformis sp. nov. is described and illustrated from Yunnan province, China. Both morphological evidence and sequence analyses of the internal transcribed spacer region (ITS1-5.8S-ITS2) support the species as new to science. C. cerebriformis differs from other Choiromyces species in having ascomata with larger lobes and light orange-brown gleba, and globose ascospores with short stick-like sparse spines ornamentation. Morphological differences and genetic distances with the similar species C. helanshanensis and C. alveolatus are discussed. A phenotypic key including related species is provided.

Choiromyces cerebriformis T. J. Yuan, S. H. Li & Y. Wang, sp. nov. Fig. 2a���f MycoBank: MB837904. Diagnosis: Choiromyces cerebriformis differs from similar species in having ascomata up to 10 cm in diameter, with larger and deeper lobes and light orange-brown gleba. Holotype: CHINA, Yunnan Province, Diqing Autonomous Prefecture, Shangri-La County, Three dam township, Haba village, 27��21���6.3647���N, 100��06��� 34.6895���E, elevation 4005 m, under Abies delavayi Franch. and Rhododendron simsii Planch. in mixed evergreen hill forest, with soil types mainly red and brown soils, 24 Sep. 2020, collected by X. H. Wang (KUN-HKAS 107566, holotype; YAAS 8890, isotype). Etymology: cerebriformis refers to the aspect of ascomata which looks like a brain. Ascomata hypogeous, up to 10 cm in diam, knobby, with deep lobes; surface glabrous, whitish when young, then pale yellow to reddish-brown with dark spots at maturity (Fig. 2b, c). Peridium 210���280 ��m thick, plectenchymatous, with two layers, the outer layer 60���80 ��m thick, reddish-brown, the inner layer 150���200 ��m thick, hyaline with larger cells (25���40 ��m diam, wall 0.5���2.0 ��m thick; Fig. 2d). Gleba (Fig. 2d, e) solid, labyrinthoid, light orange-brown, marbled with greyish white veins. Odor strong, pleasant. Asci hyaline, clavate to sac-like, 8-spored, (75���)75���85.5��� 96(���96) �� (42���)43���54���65(���66) ��m (N = 20). Ascospores (N = 60) (17.5���)17.8���21.3���24.8(���25.0) �� (17.5���)17.6��� 21.0���24.4(���24.5) ��m, Q = (1.00���)0.97���1.02���1.06(���1.12), globose to subglobose, pale yellow-brown, ornamented with straight or slightly curved stick-like sparse spines, 2���3 ��m tall, with truncate or rounded tips (Fig. 2e���g). Habitat, phenology, and distribution: Growing under Abies delavayi Franch., Rhododendron simsii Planch. and Pinus yunnanensis in mixed evergreen hill forest, in late autumn. So far found in Diqing and Yongren counties, Yunnan, China. Other material examined: CHINA, Yunnan Province, Chuxiong Autonomous Prefecture, Yongren County, 26.0810��N 101.6632��E, elevation 1,834 m, under Pinus yunnanensis in mixed evergreen hill forest, with soil types mainly red and brown soils, 01 Nov. 2019, collected by H. K. Xiong. (YAAS TJ16-1 and YAAS TJ16-2). Remarks: Choiromyces cerebriformis is characterized by hypogeous, glabrous, pale yellow or white, irregularly knobby, much lobed ascomata, and globose spores ornamented with conspicuous, straight or slightly curved spines with truncate or rounded tips when observed with SEM. This species resembles white Tuber truffles with white ascomata and sinuous veins in gleba. However, it is different from those Tuber species and from other Choiromyces species by its globose spores ornamented with conspicuous spines and small pits. C. cerebriformis can be further distinguished from C. meandriformis, which has paler gleba, and spores with much taller spines (Csorbain�� et al. 2009; Moreno et al. 2012). C. echinulatus Trappe & Marasas (Ferdman et al. 2005), differs from C. cerebriformis by spores with straight, obtuse spines �� 2 ��m high (spines are 2���3 ��m high in C. cerebriformis). Moreover, C. echinulatus has tissues with greatly inflated cells, which is characteristic of all desert truffles. C. cerebriformis differs from C. alveolatus (Liu et al. 1990) in having larger asci (75���96 �� 42���66) ��m, mostly with 8 spores, compared to 40���85 �� 30���55 ��m asci, with (2���) 4���6 spores in the latter species. C. magnusii (Moreno et al. 2012) spores ornamentation is verrucose-reticulated with a minutely-meshed reticulum, which is clearly different from C. cerebriformis. C. helanshanensis (Chen et al. 2016) differs from C. cerebriformis by its coarsely knobby ascomata 2���8 cm diam (ascomata up to 10 cm and with larger, deeper lobes in C. cerebriformis) and ascosporal ornamentation as conspicuous dense spines (as short stick-like sparse spines in C. cerebriformis)., Published as part of Yuan, Tian-Jun, Rasp��, Olivier, Li, Yong-Jun, Wang, Li, Su, Kai-Mei, Wang, Yun, Su, Hong-Yan, Xiong, Hai-Kuang & Li, Shu-Hong, 2021, Choiromyces cerebriformis (Tuberaceae), a new hypogeous species from Yunnan, China, pp. 251-260 in Phytotaxa 482 (3) on page 256, DOI: 10.11646/phytotaxa.482.3.3, http://zenodo.org/record/5419405, {"references":["Csorbaine, A. G., Illyes, Z., Dimeny, J., Merenyi, Z. & Bratek, Z. (2009) Choiromyces meandriformis and Mattirolomyces terfezioides: peculiar truffles with new perspectives. Micologia Italiana 38 (1): 21 - 28.","Moreno, G., Alvarado, P. & Manjon, J. L. (2012) Phylogenetic affiliation of (Choiromyces magnusii and C. venosus Tuberaceae ascomycota) from Spain. Mycological Progress 11 (2): 463 - 471. https: // doi. org / 10.1007 / s 11557 - 011 - 0762 - 1","Ferdman, Y., Aviram, S., Rothbejerano, N., Trappe, J. M. & Kaganzur, V. (2005) Phylogenetic studies of Terfezia pfeilii and Choiromyces echinulatus (Pezizales) support new genera for southern African truffles: Kalaharituber and Eremiomyces. Mycological Research 109 (2): 237 - 245. https: // doi. org / 10.1017 / S 0953756204001789","Liu, B., Tao, K. & Chang, M. C. (1990) New species and new records of hypogeous fungi from china III. Mycosystema 9 (1): 25 - 30.","Chen, J., Sun, L. H., Su, Y., Zhao, W. Q. & Liu, P. G. (2016) Choiromyces helanshanensis sp. nov., a new species of subterranean truffle from China. Mycoscience 57: 279 - 286. https: // doi. org / 10.1016 / j. myc. 2016.04.001"]}

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A new pig truffle species, Choiromyces helanshanensis sp. nov., was identified and illustrated in China using a morphological approach and sequence analyses of the internal transcribed spacer region (ITS1-5.8S-ITS2) and the D1–D2 domains of the nuclear ribosomal large subunit (LSU) locus. This new species differs from other species of the genus in globose ascospores with conspicuously spiny ornamentation. Phylogenetic analysis also supports its identification as a distinct species. Several species with similar morphological characters are herein discussed, and a phenotypic key to related species is provided. This study confirms the occurrence of members of Choiromyces in China and provides fundamental information about the species diversity of this genus for further studies.

Tuberaceae is one of the most diverse lineages of symbiotic truffle-forming fungi. To understand the molecular underpinning of the ectomycorrhizal truffle lifestyle, we compared the genomes of Piedmont white truffle (Tuber magnatum), Périgord black truffle (Tuber melanosporum), Burgundy truffle (Tuber aestivum), pig truffle (Choiromyces venosus) and desert truffle (Terfezia boudieri) to saprotrophic Pezizomycetes. Reconstructed gene duplication/loss histories along a time-calibrated phylogeny of Ascomycetes revealed that Tuberaceae-specific traits may be related to a higher gene diversification rate. Genomic features in Tuber species appear to be very similar, with high transposon content, few genes coding lignocellulose-degrading enzymes, a substantial set of lineage-specific fruiting-body-upregulated genes and high expression of genes involved in volatile organic compound metabolism. Developmental and metabolic pathways expressed in ectomycorrhizae and fruiting bodies of T. magnatum and T. melanosporum are unexpectedly very similar, owing to the fact that they diverged ~100 Ma. Volatile organic compounds from pungent truffle odours are not the products of Tuber-specific gene innovations, but rely on the differential expression of an existing gene repertoire. These genomic resources will help to address fundamental questions in the evolution of the truffle lifestyle and the ecology of fungi that have been praised as food delicacies for centuries.

The ITS region including the 5.8S rRNA gene as well as the 5′ end of the 28S rRNA gene of hypogeous Pezizaceae and Tuberaceae were studied to clarify the generic placement of two southern African desert truffles, Terfezia pfeilii and Choiromyces echinulatus. The results show that neither species belongs in the genus to which it has been assigned on the basis of morphological characters. As expected, two Choiromyces spp. grouped close to the representative of the Tuberaceae (Tuber melanosporum). However, C. echinulatus diverged from the other Choiromyces species and emerged near members of the genus Terfezia, being even closer to that genus than T. pfeilii. Two new genera and new species combinations, Kalaharituber gen. nov. with K. pfeilii (syn. T. pfeilii) comb. nov. and Eremiomyces gen. nov. with E. echinulatus (syn. C. echinulatus) comb. nov. are therefore introduced to accomodate these taxa. Both genera are closely related to Terfezia, and thus are placed in the Pezizaceae.

A recent collection of Choiromyces gangliiformis is described and illustrated. The asci have multi-layered walls clearly visible with the light microscope. Scanning electron microscopy revealed that the ascospores are ornamented with minute hemispherical pits. Ascospore nuclei were studied with HCl-Giemsa staining and each ascospore was found to contain four nuclei. The systematic position of the genus and the significance of ascospore nuclear numbers in the phylogeny of the Pezizales are discussed in the light of these discoveries.