Larval and post-larval development of the branchiopod clam shrimp Cyclestheria hislopi (Baird, 1859) (Crustacea, Branchiopoda, Conchostraca, Spinicaudata)
Larval and post-larval development of the branchiopod clam shrimp Cyclestheria hislopi (Baird, 1859) (Crustacea, Branchiopoda, Conchostraca, Spinicaudata)
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DOI：
10.1046/j.1463-6395.1999.80220015.x
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发表时间：
1999-04-01
期刊：
影响因子：
1.2
通讯作者：
Olesen, J
中科院分区：
文献类型：
--
作者：
Olesen, J
用扫描电子显微镜观察了环纹夜蛾的幼虫和幼虫后的发育。至少有九个阶段(不包括成虫)--六个幼虫阶段和三个幼虫后阶段。前四个阶段在卵膜内通过。幼虫和后幼虫的形态在第VI期和第VII期之间发生了深刻的变化。幼虫从背腹扁平的‘幼虫’出现到第VI期，从第VII期转向横向扁平的更‘成虫’的外观。本研究揭示了新的形态数据，包括：(1)幼虫背部器官大而球状；(2)甲壳从第一和第二上颌节开始发育；(3)成虫第二触角的前支为内足，后支为外足。与枝角类幼虫的直接发育进行了比较，这在甲壳类中是独一无二的。如果环角虫是枝角类的姐妹群，就像这项工作所支持的那样，那么必须重新考虑支角类的经典新生理论，因为枝角类的任何成虫和环角虫的任何幼虫阶段之间都没有特别的相似之处。这表明，单角类显示了在支角类祖先中存在的发育类型。将Cyclestheria与上寒武统‘Orsten’化石中的Rehbchiella kinnekullensis进行比较，发现其躯干四肢的尾部形态有显著的相似性。
The larval and post-larval development of Cyclestheria hislopi is examined by SEM. There are at least nine stages (excluding the adult) - six larval and three post-larval stages. The first four stages are passed within the egg-membrane. The larval and the post-larval phase are separated by a profound change in morphology that takes place between stages VI and VII. The larva shifts from a dorso-ventrally flattened 'larval' appearance up to stage VI to a laterally flattened, more 'adult' appearance from stage VII. New morphological data have been revealed by this study, including (1) a large and globular larval dorsal organ; (2) the carapace starts its development from the segments of the first and second maxillae; (3) the anterior ramus of the second antenna in adult Cyclestheria hislopi is the endopod, and the posterior ramus the exopod. Direct development of the brood in Cyclestheria hislopi unique among conchostracans - is compared with that of the Cladocera. If Cyclestheria is the sister group to the Cladocera, as favoured in this work, the classical neoteny theory of the Cladocera must be reconsidered, as there is no particular similarity between any adults of the Cladocera and any of the larval stages of Cyclestheria. It is suggested that Cyclestheria displays the type of development present in a cladoceran ancestor. A comparison between Cyclestheria and the Upper Cambrian 'Orsten' fossil Rehbachiella kinnekullensis reveals a remarkable similarity in the endite morphology of the trunk limbs.