A new species of Diacheopsis (Myxomycetes) and a new habitat for myxomycetes

We describe a new species, Diacheopsis resinae (Myxomycetes), collected from a microhabitat new for myxomycetes: stem wounds of coniferous trees (Norway spruce) where the resin is overgrown with a community of resinicolous fungi. The 80 known collections come from the Vosges (France), the Black Forest (Germany), Swabian Alp (Germany), and several localities in Denmark and Norway. Observations, but as well as metabarcoding of substrate samples with fungal (ITS [internal transcribed spacer]), bacterial (16S rDNA), and myxomycete (18S nuc rDNA) primers from eight trunks, revealed the new myxomycete to co-occur with resin-degrading ascomycetes (Infundichalara microchona, Lophium arboricola, Zythia resinae). The gram-negative bacterial genera Endobacter and Sphingomonas were found to be abundant in the substrate and may be a food source for the myxomycete. Fruit bodies were found mostly during the more humid winter season, with a peak in January/February. Partial sequences of two independent molecular markers (18S nuc rDNA, EF1α [elongation factor 1-alpha] gene) were obtained for 41 accessions, which form a monophyletic cluster in a two-gene phylogeny of Stemonititidales but do not group with other species of Diacheopsis, thus rendering this genus paraphyletic. The new species, although exclusively developing sessile sporocarps and morphologically undoubtedly falling into the genus Diacheopsis, is most closely related to species of Lamproderma, especially L. album, L. zonatum, and L. zonatopulchellum. Within D. resinae, three groups can be differentiated, which show nearly complete reproductive isolation, as judged from a recombination analysis of the two unlinked markers and the allelic combinations of the EF1α gene.本研究描述了一个黏菌（Myxomycetes）新种——树脂黏囊菌（Diacheopsis resinae），其采集自黏菌研究中全新的微生境：针叶树（挪威云杉）的树干伤口处，该生境的树脂表面被一类树脂生真菌群落覆盖。目前已记录的80份标本采自法国孚日山脉、德国黑森林、德国施瓦本阿尔卑斯山脉，以及丹麦和挪威的多处分布点。通过对8株树干的基质样本采用真菌ITS（内转录间隔区）、细菌16S rDNA及黏菌18S核rDNA引物开展元条形码测序，并结合野外观察，发现该新黏菌与降解树脂的子囊菌类群——Infundichalara microchona、Lophium arboricola及Zythia resinae——伴生共存。研究发现基质中富含革兰氏阴性菌属Endobacter与Sphingomonas，二者或为该黏菌的食物来源。该新种的子实体多在湿度较高的冬季被发现，峰值出现在1月至2月期间。本研究对41份标本的两个独立分子标记——18S核rDNA与EF1α（延伸因子1-α）基因——的部分序列进行了扩增与测序。基于双基因位点构建的团毛菌目（Stemonititidales）系统发育树显示，该新种形成一个单系分支，但并未与Diacheopsis属的其他物种聚类，这表明Diacheopsis属为并系群。尽管该新种仅产生无柄孢囊，且形态上无疑隶属于Diacheopsis属，但其系统发育关系与亮皮黏菌属（Lamproderma）的物种最为接近，尤其是L. album、L. zonatum及L. zonatopulchellum。在树脂黏囊菌（D. resinae）内部，可区分出三个类群；基于两个非连锁标记的重组分析以及EF1α基因的等位基因组合判断，这三个类群间几乎完全生殖隔离。