Data from: Seed morphology of Ruellieae Species (Acanthaceae) in Brazil and its taxonomic implications

Ruellieae is a highly diverse tribe of Acanthaceae in Brazil, and
morphological studies of its seeds have revealed important information
about the systematics of the tribe. We analyzed the seed morphology of
Brazilian species of Ruellieae, using stereoscopic, light, and scanning
electron microscopy. The best-sampled genus was Ruellia (53 species),
followed by Dyschoriste (seven), and Hygrophila (three); including
external groups, a total of 65 species of Ruellieae (68 of Acanthaceae)
were sampled. We observed capsular fruits with explosive dehiscence,
important for autochory, and discoid seeds covered by hygroscopic and
mucilaginous trichomes. The characters most relevant to the taxonomy of
the groups were fruit shape, number of ovules, and the distribution,
shape, and number of rings on the seed trichomes, the latter two addressed
here for the first time. Those characters proved useful for discriminating
and characterizing the sampled genera within Ruellieae, and especially the
infrageneric clades of Ruellia. Based on the morphological patterns
observed, we provide a key for those taxa, and suggest the infrageneric
placement of unclassified Ruellia species: R. hypericoides and Ruellia sp.
4 for the clade “Ebracteolati” s. l., Ruellia spp. 2 and 3 for “R.
inflata”, Ruellia sp. 1 for “Euruellia” s. s., and R. anamariae for the
clade “Blechum”. In a broader context, we corroborate the finding that
partial loss of seed trichomes is exclusive to one of the two large
lineages of Neotropical Ruellia (lineage II). The hygroscopic and
mucilaginous trichomes of Ruellieae seeds play important roles in water
retention, germination, protection, and secondary dispersal, and we
discuss some aspects of secondary hydrochory and epizoochory on medium-
and long-range dispersal of Ruellieae, including transatlantic distances.

芦莉族（Ruellieae）是巴西爵床科（Acanthaceae）中多样性极高的类群，其种子形态学研究已为该族的系统分类学提供了关键信息。本研究借助体视显微镜、光学显微镜与扫描电子显微镜，对巴西境内芦莉族物种的种子形态展开分析。本次采样量最大的属为芦莉属（Ruellia，共53种），其次为双翅爵床属（Dyschoriste，7种）与水蓑衣属（Hygrophila，3种）；连同外类群，本次共采样芦莉族65个物种（爵床科总计68个物种）。研究观察到两类关键结构：其一为具爆裂开裂特性的蒴果，该性状对自体传播（autochory）至关重要；其二为被吸湿粘质毛状体覆盖的盘状种子。与该类群分类学关联最为紧密的性状包括果实形状、胚珠数量，以及种子毛状体的分布、形态与环纹数量，其中后两项性状为本研究首次报道。上述性状可有效区分并表征芦莉族的各采样属，尤其是芦莉属的属下分支。基于观测到的形态模式，我们为本次研究涉及的类群编制了分类检索表，并提出未分类芦莉属物种的属下归属建议：金丝桃叶芦莉（R. hypericoides）与芦莉属未定种4归入"无苞片群（Ebracteolati，s. l.）"，芦莉属未定种2、3归入"膨胀芦莉（R. inflata）类群"，芦莉属未定种1归入"狭义真芦莉亚属（Euruellia s.s.）"，而安娜玛丽亚芦莉（R. anamariae）归入"Blechum分支"。在更宏观的研究框架下，我们证实了"种子毛状体部分缺失仅存在于新热带界芦莉属的两大谱系之一（谱系II）"这一既有发现。芦莉族种子的吸湿粘质毛状体在保水、种子萌发、物理保护及次级传播中发挥重要功能，本研究还探讨了次级水力传播与表皮动物传播（epizoochory）在芦莉族中远程传播（包括跨大西洋传播）中的相关作用机制。