Abstract In Euphorbiaceae tribe Hippomaneae is the pantropical genus Microstachys, comprised by 24 species, mostly from Brazil. Palynological studies with several representatives of the genus are scarce. The purpose of this study was to describe the pollen morphology of Microstachys and find possible differentiating characteristics between its species. Ten species of the genus were analysed, represented by 21 herbarium collections. Their pollen grains were acetolysed, measured and photographed under light microscopy (LM) and scanning electron microscopy (SEM). The analysed species possess pollen in monads, of small to medium size, isopolars, amb distincticly trilobed, oblate-spheroidal, prolate-spheroidal or subprolate, tricolporate with narrow and very long colpi, almost fused at the poles sometimes forming an invagination with tapering ends and margo of the colporus wide to very wide and psilate; endoapertures lalongate to very lalongate with tapering ends, presence of a narrow costae distinct in the endoaperture; exine microreticulate homobrochate, walls with simple columella; at the mesocolpus the sexine separates from the nexine forming cavea; and sexine always thicker than the nexine. Microstachys is a stenopalynous genus, despite its species varying in pollen size, shape and width of the cavea, margo of the colporus, and length of the endoapertures, demonstrating taxonomic value, and indicating a contribution towards future systematic analyses.

中文翻译：

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Microstachys（大戟科）的花粉形态，重点是新热带物种

摘要 大戟科Hippomaneae是泛热带的Microstachys属，由24种组成，主要来自巴西。对该属的几个代表的孢粉学研究很少。本研究的目的是描述 Microstachys 的花粉形态，并找到其物种之间可能的区分特征。分析了该属的 10 个物种，代表了 21 个植物标本馆藏品。他们的花粉粒在光学显微镜 (LM) 和扫描电子显微镜 (SEM) 下被乙酰化、测量和拍照。所分析的物种在单子中拥有花粉，小到中等大小，等极，明显的三叶形，扁球状，扁长球状或近扁长的，三孔状的，具有狭窄且非常长的菌核，几乎在两极融合，有时形成内陷，末端逐渐变细，马尾骨从宽到非常宽，呈甲状；内孔细长到非常细长的末端逐渐变细，在内孔中存在明显的窄肋；外壁微网状同型，壁具单小柱；在 mesocolpus，性线与连接线分离，形成小窝；和性总是比nexine 厚。Microstachys 是一种 stenopalynous 属，尽管其物种在花粉大小、腔室的形状和宽度、colporus 的 margo 和内孔的长度方面各不相同，这表明了分类学价值，并表明对未来系统分析的贡献。在内孔中存在明显的狭窄肋骨；外壁微网状同型，壁具单小柱；在 mesocolpus，性线与连接线分离，形成小窝；和性总是比nexine 厚。Microstachys 是一种 stenopalynous 属，尽管它的物种在花粉大小、腔室的形状和宽度、colporus 的 margo 和内孔的长度方面有所不同，这表明了分类学价值，并表明对未来系统分析的贡献。在内孔中存在明显的狭窄肋骨；外壁微网状同型，壁具单小柱；在 mesocolpus，性线与连接线分离，形成小窝；和性总是比nexine 厚。Microstachys 是一种 stenopalynous 属，尽管它的物种在花粉大小、腔室的形状和宽度、colporus 的 margo 和内孔的长度方面有所不同，这表明了分类学价值，并表明对未来系统分析的贡献。