ABSTRACT We documented male and female gametogenesis, auxospore structure and development of the biddulphioid diatom species Biddulphia tridens (Ehrenberg) Ehrenberg, a close relative of the generitype. Our mating experiments showed that the B. tridens clones were homothallic, self-fertile and produced two eggs per oogonium. During spermatogenesis, spermatogonia developed by depauperating mitosis from spermatogonangium cells and four hologenous uniflagellate male gametes were produced per spermatocyte. In the early stage of auxospore development, cells were globular to sub-globular in shape and covered with a siliceous envelope. The incunabular scales on these auxospores showed a great diversity in size and shape. In the later stages of development, auxospores grew anisodiametrically, facilitated by transverse perizonial bands. Initial epivalve formation was preceded by the retraction of the protoplast from the auxospore wall. The structural features of sex cells such as incunabular scales found in B. tridens are distinct from other broadly defined biddulphioid diatoms thus far examined. This is consistent with the distant relationship between true Biddulphia species and the Biddulphia-like diatoms indicated by molecular phylogenies. Morphological and molecular examination of B. tridens clones were performed here only to confirm species identity. This complete reproductive dataset from a true Biddulphia species will provide valuable insights for future studies of the relationships between Biddulphia-like diatoms and true Biddulphia species.

中文翻译：

---

Biddulphia tridens (Ehrenberg) 中的辅助孢子形成 Ehrenberg (Mediophyceae, Bacillariophyta)

摘要 我们记录了双生硅藻物种 Biddulphia tridens (Ehrenberg) Ehrenberg（该属型的近亲）的雄性和雌性配子发生、辅助孢子结构和发育。我们的交配实验表明 B. tridens 克隆是同种的，可以自我繁殖，每个卵原体产生两个卵。在精子发生过程中，通过使精原细胞的有丝分裂脱贫而发展出的精原细胞和每个精母细胞产生四个完整的单鞭毛雄性配子。在辅助孢子发育的早期，细胞呈球状至近球状，并被硅质包膜覆盖。这些副孢子上的原状鳞片在大小和形状上表现出很大的多样性。在发育的后期阶段，副孢子在横向地缘带的促进下呈等径生长。在原生质体从辅助孢子壁回缩之前，初始表壳形成。在 B. tridens 中发现的性细胞的结构特征，例如在 B. tridens 中发现的 incunabular 鳞片与迄今为止研究的其他广泛定义的双生硅藻不同。这与分子系统发育表明的真正的 Biddulphia 物种和类 Biddulphia 硅藻之间的远亲是一致的。在这里对 B. tridens 克隆进行形态学和分子检查只是为了确认物种身份。这个来自真正 Biddulphia 物种的完整繁殖数据集将为未来研究类 Biddulphia 硅藻与真正 Biddulphia 物种之间的关系提供有价值的见解。在 B. tridens 中发现的性细胞的结构特征，例如在 B. tridens 中发现的 incunabular 鳞片与迄今为止研究过的其他广泛定义的双生硅藻不同。这与分子系统发育表明的真正的 Biddulphia 物种和类 Biddulphia 硅藻之间的远亲是一致的。在这里对 B. tridens 克隆进行形态学和分子检查只是为了确认物种身份。这个来自真正 Biddulphia 物种的完整繁殖数据集将为未来研究类 Biddulphia 硅藻与真正 Biddulphia 物种之间的关系提供有价值的见解。在 B. tridens 中发现的性细胞的结构特征，例如在 B. tridens 中发现的 incunabular 鳞片与迄今为止研究过的其他广泛定义的双生硅藻不同。这与分子系统发育表明的真正的 Biddulphia 物种和类 Biddulphia 硅藻之间的远亲是一致的。在这里对 B. tridens 克隆进行形态学和分子检查只是为了确认物种身份。这个来自真正 Biddulphia 物种的完整繁殖数据集将为未来研究类 Biddulphia 硅藻与真正 Biddulphia 物种之间的关系提供有价值的见解。这与分子系统发育表明的真正 Biddulphia 物种和类 Biddulphia 硅藻之间的远亲相一致。在这里对 B. tridens 克隆进行形态学和分子检查只是为了确认物种身份。这个来自真正 Biddulphia 物种的完整繁殖数据集将为未来研究类 Biddulphia 硅藻与真正 Biddulphia 物种之间的关系提供有价值的见解。这与分子系统发育表明的真正的 Biddulphia 物种和类 Biddulphia 硅藻之间的远亲是一致的。在这里对 B. tridens 克隆进行形态学和分子检查只是为了确认物种身份。这个来自真正 Biddulphia 物种的完整繁殖数据集将为未来研究类 Biddulphia 硅藻与真正 Biddulphia 物种之间的关系提供有价值的见解。