The peculiar nemertean larva pilidium recurvatum belongs to Riserius sp., a basal heteronemertean that eats Carcinonemertes errans, a hoplonemertean parasite of Dungeness crab
The peculiar nemertean larva pilidium recurvatum belongs to Riserius sp., a basal heteronemertean that eats Carcinonemertes errans, a hoplonemertean parasite of Dungeness crab
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DOI：
10.1111/ivb.12023
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发表时间：
2013-09-01
影响因子：
1.2
通讯作者：
Maslakova, Svetlana
中科院分区：
文献类型：
--
作者：
Hiebert, Terra C.;von Dassow, George;Maslakova, Svetlana
一种典型的线虫幼虫就像一顶带耳盖的帽子。但有一种类型，称为下垂皮毛，看起来更像一只袜子，先是游泳的高跟鞋。这种独特的幼虫于1883年在罗德岛海岸被发现，随后在世界其他地区的浮游生物样本中被发现。尽管这种幼虫的发现已经很久了，而且它在幼虫进化的讨论中具有重要意义，但这种幼虫即使在家庭层面上也仍然没有被识别出来。我们在美国库斯湾的浮游生物样品中采集了螺旋藻幼虫，根据幼体形态和DNA序列数据，将其鉴定为异形幼虫属Riserius。系统发育分析表明，来自俄勒冈州的两个截然不同的类型代表了这一目前单型属中的两个新种。我们用共聚焦显微镜描述了下垂纤毛的形态，并将其与典型的纤毛进行了比较，讨论了对幼虫摄食的可能意义。我们还报告了我们令人惊讶的发现：Riserius sp.的幼虫。来自俄勒冈州的猎物对另一种线虫，CarcinonEmertes errans，一种商业上重要的物种癌症巨蟹(Dungeness Crab)的卵捕食者。我们推测，Riserius的物种水平多样性和地理分布可能比目前所认识的要大得多。
A typical nemertean pilidium larva resembles a hat with ear flaps. But one type, called pilidium recurvatum, looks more like a sock, swimming heel first. This distinctive larva was discovered in 1883 off the coast of Rhode Island and subsequently found in plankton samples from other parts of the world. Despite the long time since discovery, and its significance in discussions of larval evolution, this larva remained unidentified even to the family level. We collected pilidium recurvatum larvae from plankton samples in Coos Bay, OR, and identified them as belonging to the heteronemertean genus Riserius based on juvenile morphology and DNA sequence data. Phylogenetic analysis suggests that two distinct types of pilidium recurvatum from Oregon represent two new species within this currently monotypic genus. We describe the morphology of pilidium recurvatum using confocal microscopy and compare it to that of the typical pilidium, discussing possible implications for larval feeding. We also report our surprising discovery that juveniles of Riserius sp. from Oregon prey on another nemertean, Carcinonemertes errans, an egg predator of Cancer magister (Dungeness crab), a commercially important species. We speculate that the species-level diversity and geographic distribution of Riserius may be much greater than currently appreciated.