Tantulum elegans reloaded:: a computer-based 3D-visualization of the anatomy of a Caribbean freshwater acochlidian gastropod
Tantulum elegans reloaded:: a computer-based 3D-visualization of the anatomy of a Caribbean freshwater acochlidian gastropod
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DOI：
10.1111/j.1744-7410.2007.00073.x
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发表时间：
2007-01-01
影响因子：
1.2
通讯作者：
Schroedl, Michael
中科院分区：
文献类型：
--
作者：
Neusser, Timea P.;Schroedl, Michael
Acochlidian腹足类结合了几种异常的生物学和形态特征。鲜为人知的加勒比海Tantulum elegans是为数不多的栖息在淡水系统中的异地物种之一，也是唯一一种在加勒比海山泉沼泽的泥泞空隙中发现的物种。这种微小物种的形态细节要么未知，要么不完全可靠，特别是关于复杂的中枢神经和生殖系统。我们严格地重新检查了原始的副类型切片系列，并准备了另外两个副类型的半薄序列切片。使用Amira软件对所有器官系统进行三维重建。我们的结果显示了与原始描述的几个不同之处：咽是一个由不同肌肉组成的复杂系统，但与其他棘目动物的肌肉相似；循环系统显示出一个双腔心脏；神经系统中有独立的视神经节和鼻咽神经节，后者支配着一对我们认为是汉考克器官的小感官凹陷，并发现了大量大脑前副神经节的聚集。肾小管、肛门和雌性生殖孔向右开。令我们惊讶的是，线虫的成虫是顺序两性的，具有不同寻常的雄蕊生殖系统和发育良好的头复合体。在线虫中，在不同的属中发现了一种混合的特征条件，例如假单胞菌和曲霉属。线虫的系统发育位置仍然不清楚。
Acochlidian gastropods combine several aberrant biological and morphological features. The poorly known Caribbean Tantulum elegans is one of the few opisthobranch species inhabiting a freshwater system, and the only one found in muddy interstices of a Caribbean mountain spring swamp. Morphological details of this tiny species were either unknown or not fully reliable, especially with regard to the complex central nervous and reproductive systems. We critically re-examined original paratype section series and prepared semi-thin serial sections of two additional paratypes. All organ systems were three-dimensionally reconstructed using AMIRA software. Our results show several discrepancies from the original description: the pharynx is a complex system of different muscles, but similar to that of other acochlidian species; the circulatory system shows a two-chambered heart; in the nervous system there are separate optic and rhinophoral ganglia, the latter innervating a pair of small sensory pits we assume to be Hancock's organs, and large aggregations of precerebral accessory ganglia were found. Nephropore, anus, and female gonopore open dextroventrally. To our surprise, adults of T. elegans are sequential hermaphrodites with an unusual androdiaulic reproductive system and a well-developed cephalic penial complex. In T. elegans, there is a mix of character conditions found in different genera, e. g., Pseudunela and Asperspina. The phylogenetic position of T. elegans still remains unclear.