Data from: Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand

The genus Empodisma comprises two species that are ecologically important in wetland habitats. Empodisma gracillimum is restricted to south-western Australia, whereas Empodisma minus is found in Tasmania, eastern Australia and New Zealand. We sequenced three cpDNA genes for 15 individuals of Empodisma sampled from throughout the range of the species. The results support an Australian origin for Empodisma sometime during the late Oligocene to early Miocene with more recent dispersal, colonization and diversification in New Zealand. We recovered six genetically distinct maternal lineages: three Empodisma gracillimum haplotypes corresponding to the three accessions in our analysis, a wide-ranging Empodisma minus haplotype found in eastern Australia and Tasmania, an Empodisma minus haplotype found in New Zealand from Stewart Island to approximately 38° S latitude on the North Island, and a distinct haplotype restricted to the North Island of New Zealand north of 38° S latitude. The Eastern Australian and New Zealand haplotypes of Empodisma minus were supported by only one cpDNA gene, and we felt the relatively minor morphological differences and the small amount of genetic divergence did not warrant taxonomic recognition. However, we recommend that the northern New Zealand haplotype should be recognized as the new species Empodisma robustum and provide descriptions and a key to the species of Empodisma. Monophyly of Empodisma robustum is supported by all three cpDNA genes. Empodisma robustum can be distinguished from Empodisma gracillimum and Empodisma minus by its robust growth stature and distinct ecology. It is typically eliminated by fire and re-establishes by seed (seeder strategy), whereas Empodisma minus and Empodisma gracillimum regrow after fire (sprouter strategy).

Empodisma属（Empodisma）包含两个在湿地生境中具有重要生态价值的物种。细弱帚灯草（Empodisma gracillimum）仅分布于澳大利亚西南部，而减帚灯草（Empodisma minus）则见于塔斯马尼亚、澳大利亚东部及新西兰。我们从该属所有物种的自然分布范围内采集了15份Empodisma属样本，并对其中3个叶绿体DNA（chloroplast DNA, cpDNA）基因进行了测序。研究结果支持Empodisma属起源于澳大利亚，起源时间大致为渐新世晚期至中新世早期，后续发生了向新西兰的近期扩散、定殖与物种多样化过程。本研究共鉴定出6个遗传分化显著的母系谱系：3个对应本研究中3份采样材料的细弱帚灯草单倍型（haplotype）、1种广泛分布于澳大利亚东部与塔斯马尼亚的减帚灯草单倍型、1种分布于新西兰斯图尔特岛至北岛约南纬38°区域的减帚灯草单倍型，以及1种仅局限于新西兰北岛南纬38°以北区域的独特单倍型。仅通过1个cpDNA基因序列的分析即可支持澳大利亚东部与新西兰的减帚灯草单倍型分化，且我们认为二者之间相对细微的形态差异与有限的遗传分化，尚不满足分类学上的物种认定标准。但我们建议将新西兰北岛的该特有单倍型认定为新物种——粗壮帚灯草（Empodisma robustum），并在此提供该属物种的形态描述与分类鉴定检索表。基于全部3个cpDNA基因序列的分析均支持粗壮帚灯草为单系类群。粗壮帚灯草可通过其粗壮的生长株型与独特的生境特征，与细弱帚灯草及减帚灯草相区分。该物种通常会在火灾中完全死亡，并通过种子进行种群重建（火后种子更新策略）；而减帚灯草与细弱帚灯草则可在火灾后重新萌发（火后萌芽策略）。