Xiang-Hua Wang

Three new species of Lactarius subgenus Lactiflui (Russulaceae, Russulales) in southwestern China

Three new species of Lactarius subgen. Lactiflui are described from tropical and its adjacent regions in southwestern China. Lactarius longivelutinus is characterized by the basidiocarps with an eccentric to almost lateral stipe, very long terminal cells in the pileipellis (300-400 mu m long) and a lamprotrichoderm as a stipitipellis structure with terminal cells 6.0-7.0 mu m wide and walls 2.0-4.0 mu m thick. Lactarius pseudoluteopus is similar to the tropical African L. luteopus because of its bright yellow stipe and lamellae margin and the brittle basidiocarps, but can be distinguished from the latter by the long marginal cells and absence of macrocystidia. It differs from the American L. hygrophoroides by its long marginal cells and much longer terminal cells in the pileipellis. Lactarius tenuicystidiatus is characterized by the rather robust basidiocarps with whitish stipe, the presence of thin-walled true macrocystidia, and the lowly ornamented basidiospores (up to 0.2 mu m high). This is the first time that a member of Lactarius sect. Pseudogymnocarpi is recorded outside tropical Africa.

Ectomycorrhizae of Tuber huidongense and T. liyuanum with Castanea mollissima and Pinus armandii.

Tuber huidongense and T. liyuanum are common commercial white truffles in China that belong to the Rufum and Puberulum groups of the genus Tuber, respectively. Their mycorrhizae were successfully synthesized with two native trees—Castanea mollissima and Pinus armandii—under greenhouse conditions. The identities of the mycorrhizae were confirmed through internal transcribed spacer (ITS) sequence analyses, and their morphological characteristics were described. All of the obtained mycorrhizae have an interlocking pseudoparenchymatous mantle, which is a typical feature of truffle mycorrhizae. The mycorrhizae of T. huidongense on the two trees have hyaline branched emanating hyphae, similar to the documented mycorrhizae of the Rufum group. The unramified, spiky, and hyaline cystidia on the mycorrhizae of T. liyuanum with both C. mollissima and P. armandii further confirmed that this characteristic is constant for the mycorrhizae of the Puberulum group. The successful mycorrhizal syntheses on the two nut-producing trees will be of economic importance in the cultivation of the two truffles.

New combinations in Lactifluus. 2. L. subg. Gerardii

In this second of a series of three papers, new combinations in the genus Lactifluus are proposed. This paper treats Lactarius subg. Gerardii (proposed here as new combination in Lactifluus). In this subgenus 17 combinations at species level are proposed.

Lactifluus parvigerardii sp. nov., a new link towards the pleurotoid habit in Lactifluus subgen. Gerardii (Russulaceae, Russulales)

Abstract Lactifluus parvigerardii, a new species from subtropical southwestern China, is described. Worldwide, this is the third representative of Lactifluus subgen. Gerardii with coloured latex, as in the Asian L. ochrogalactus and the American L. petersenii. Microscopically, this new species differs from L. ochrogalactus in having thin-walled hyphae in the pileipellis and robust macrocystidia in the hymenium. Compared with L. petersenii, L. parvigerardii has distant lamellae and heavily ornamented spores. Despite this morphological similarity to the L. ochrogalactus-L. petersenii clade phylogenetic analysis placed L. parvigerardii close to L. uyedae, taking a basal position in a strictly pleurotoid subclade. It is a key species demonstrating additional morphological and molecular diversity within Lactifluus subgen. Gerardii.