The dorsal plate is a critical feature in the reassessment of the rotiferan genus Ptygura (Monogononta; Gnesiotrocha; Flosculariidae)
The dorsal plate is a critical feature in the reassessment of the rotiferan genus Ptygura (Monogononta; Gnesiotrocha; Flosculariidae)
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DOI：
10.11646/zootaxa.5428.1.5
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发表时间：
2024-03-20
期刊：
影响因子：
0.9
通讯作者：
Wallace，Robert L.
中科院分区：
文献类型：
--
作者：
Franch，Vicente;Meksuwan，Phuripong;Wallace，Robert L.
所有种类的Flosculariidae（轮虫;单角体; Gnesiotrocha; Flosculariaceae）都具有柔软的珠被;它们被称为illoricate。但是四个属（Beauchampia，Floscularia，Limnias和Ptygura）的物种在其前端的背侧具有独特的硬化区域，不幸的是，这在物种水平之外很少受到关注。在我们的工作中，我们研究这些硬化区域的超微结构。在Beauchampia，Limnias和一些Ptygura物种中，硬化区采取背板（以下简称DP）的形式，有或没有额外的突起。DP为直径约50 μm的圆盘状，包裹动物的前背部区域，具有外周向内褶皱、光滑表面和孔。角叶石首鱼的DP在超微结构上与其他鱼体有三个主要区别：（1）糖萼类型，（2）表面无小土丘，（3）孔底部有宽池。在Floscularia和一些Ptygura中，硬化的结构被简化为一对保护背侧触角的背侧突起：即，缺少完整的DP。这些结构值得关注，因为它们的适应性重要性尚未得到研究。在这里，我们用其他字符来增强这些观察结果：即，在后期胚胎中双折射体的存在/不存在以及它们的trophi和冠的形态。我们的目标是提供信息，以帮助制定更好的分类，以及推进我们的理解，无柄类群的一般和潜在的多系Ptygura属特别是进化。
All species of Flosculariidae (Rotifera; Monogononta; Gnesiotrocha; Flosculariaceae) possess a flexible integument; they are termed illoricate. But species of four genera (Beauchampia, Floscularia, Limnias, and Ptygura) possess a distinctive hardened region on the dorsal side of their anterior end, which unfortunately has received little attention beyond the species level. In our work we study the ultrastructure of these hardened regions. In Beauchampia, Limnias, and some species of Ptygura the hardened zone takes the form of a dorsal plate (hereafter DP) with or without additional protruding processes. The DP has the shape of a ~50 μm diameter disc enfolding the anterior dorsal region of the animal, with a perimetral inward fold, smooth surface, and pores. The DP of Limnias ceratophylli shows three main ultrastructural differences from the rest of the body: (1) type of glycocalyx, (2) absence of small mounds on its surface, and (3) presence of broad cisternae at the base of the pores. In Floscularia and some Ptygura the hardened structures are reduced to a pair of dorsal projections protecting the dorsal antenna: i.e., lacking a full DP. These structures deserve attention because their adaptive importance has not been studied. Here we augment those observations with other characters: i.e., presence/absence of a birefringent body in late-stage embryos and morphology of their trophi and corona. Our goal was to provide information to help develop better taxonomy, as well as advance our understanding of the evolution of sessile taxa in general and of the potentially polyphyletic Ptygura genus in particular.