Undersized and underestimated: 3D visualization of the Mediterranean interstitial acochlidian gastropod Pontohedyle milaschewitchii (Kowalevsky, 1901)
Undersized and underestimated: 3D visualization of the Mediterranean interstitial acochlidian gastropod Pontohedyle milaschewitchii (Kowalevsky, 1901)
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DOI：
10.1016/j.ode.2007.09.002
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发表时间：
2008-01-01
影响因子：
1.6
通讯作者：
Schroedl, Michael
中科院分区：
文献类型：
--
作者：
Joerger, Katharina M.;Neusser, Timea P.;Schroedl, Michael
Pontohedyle milaschewitchii(科瓦列夫斯基，1901)是地中海和黑海最常见的中层亚种之一，被认为是一种描述相对较好的足目动物。然而，由于可用的方法不充分，而且不同来源之间的矛盾，关于其复杂的内部解剖的数据是支离破碎的，很少详细。本研究利用Amira软件，通过连续半薄切片的三维重建，对米氏并殖吸虫的所有主要器官系统进行了详细的描述。米氏对虾的咽前中枢神经系统高度集中，呈真神经和表皮状态。与早期的报道相反，大脑和胸膜神经节没有融合。大脑前副神经节的聚集体可分为三个复合体，由不同的脑神经供应。鼻咽神经节具有细小的双脑-鼻-鼻神经节，这在棘目动物中是第一次被描述。汉考克的风琴以一种显眼的..口腔触须后面的表皮上的弧形褶皱。对脑神经特征和感觉结构进行了对比讨论。我们的研究证实了P.milaschewitchii的男性生殖器开口位于嘴上方的一个不寻常的位置。文中还讨论了雌雄同体的具纤毛的输精管与雌雄同源的雌雄同源的附着体。与以前的描述相反，米氏松齿根公式为41-54×1-1-1，即单侧齿宽且不分。扫描电子显微镜检查了整个标本的体壁，发现了一种特殊而恒定的纤毛图案。外部扫描电子显微镜检查为分类和系统发育提供了一组新的附加特征，被建议作为未来描述无尾类物种的标准方法。(C)2008年Gesellschaft毛皮生物系统。由Elsevier GmbH出版。版权所有。
Pontohedyle milaschewitchii (Kowalevsky, 1901) is one of the most common mesopsammic opisthobranchs in the Mediterranean and Black Seas and has been considered as a comparably well-described acochlidian species. However, data on its complex internal anatomy were fragmentary and little detailed due to inadequate methodology available, and contradictory between different sources. The present study redescribes all major organ systems of P. milaschewitchii in full detail by three-dimensional reconstruction from serial semithin sections using AMIRA software. The prepharyngeal central nervous system (cns) of P. milascheiiitchii is highly concentrated and shows a euthyneurous and epiathroid condition. Contrary to earlier reports, the cerebral and pleural ganglia are not fused. Aggregations of precerebral accessory ganglia can be grouped into three complexes supplied by distinct cerebral nerves. Rhinophoral ganglia with thin, double cerebro-rhinophoral connectives are described for the first time in acochlidians. A Hancock's organ is present in the form of a Conspicuous.. curved fold in the epidermis posterior to the oral tentacles. Cerebral nervous features and sensory structures are discussed comparatively. Our study confirms P. milaschewitchii as having the male genital opening in an unusual position above the mouth. Homology of the ciliated vas deferens of the gonochoristic and aphallic P. milaschewitchii with that of hermaphroditic acochlidian species with cephalic male genitals is discussed. The radula formula of P. milaschewitchii is 41-54 x 1-1-1, i.e. the single lateral teeth are broad and, contrary to previous descriptions, undivided. SEM examination of the body wall of entire specimens revealed a special and constant ciliary pattern. Providing a novel additional set of characters for taxonomic and phylogenetic purposes, external SEM examination is suggested as the standard method for describing acochlidian species in the future. (C) 2008 Gesellschaft fur Biologische Systematik. Published by Elsevier GmbH. All rights reserved.