Staurastrum gracile

is a highly polymorphic species that overlaps morphologically with other species of the genus. The observation of some reproductive features, such as zygospore development, is necessary for correct identification of some Staurastrum species. This study describes the sexual and asexual reproduction of S. gracile in culture and emphasises the importance of characters observed in the fully developed stage of vegetative individuals and zygospores. The description of the life cycle is based on isolated populations from Mexico studied in light and scanning electron microscopy. We describe morphology in the asexual reproductive stages, resulting from an early division before complete cell development, but also results from the number (3, 4, or 7), the length, and the plane of projection of the arms (divergent, moderately divergent to straight, and slightly convergent). We describe gamete fusion type in S. gracile and establish that meiosis occurs in early stages of zygospore formation, characterising the morphology of all stages until germination. The phylogenetic position of the Mexican populations was confirmed by sequence analysis of the ATPase beta-subunit gene (atpB), and the resulting phylogeny was compared with zygospore characters of species. The result suggests that zygospore morphology can be a significant phylogenetic signal in desmid taxonomy.

中文翻译：

---

新近发现的金缕梅有性生殖和无性生殖的新发现（Desmidiaceae，Zygnematophyceae）

十字花

是高度多态的物种，在形态上与该属的其他物种重叠。对某些生殖特征的观察，例如合子孢子的发育，对于正确鉴定某些Staastastrum物种是必要的。这项研究描述了S. gracile的有性和无性繁殖在文化上，并强调了在营养个体和合子孢子充分发育阶段观察到的性格的重要性。生命周期的描述基于在光学和扫描电子显微镜下研究的来自墨西哥的孤立种群。我们描述了无性生殖阶段的形态，这是由完整细胞发育之前的早期分裂所致，也是由臂的数量（3、4或7），臂长和投影平面（发散，中度发散）引起的到直线，并且稍微会聚）。我们在S. gracile中描述配子融合类型并确定减数分裂发生在合子孢子形成的早期阶段，表征了直到发芽之前所有阶段的形态。通过对ATPaseβ-亚基基因（atp B）的序列分析，确认了墨西哥种群的系统发育位置，并将所形成的系统发育与物种的子孢子特征进行了比较。结果表明，合子孢子形态可能是desmid分类学中的重要系统发育信号。