Insemination by a kiss? Interactive 3D-microanatomy, biology and systematics of the mesopsammic cephalaspidean sea slug Pluscula cuica Marcus, 1953 from Brazil (Gastropoda: Euopisthobranchia: Philinoglossidae)
Insemination by a kiss? Interactive 3D-microanatomy, biology and systematics of the mesopsammic cephalaspidean sea slug Pluscula cuica Marcus, 1953 from Brazil (Gastropoda: Euopisthobranchia: Philinoglossidae)
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DOI：
10.1007/s13127-012-0093-3
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发表时间：
2013-03-01
影响因子：
1.6
通讯作者：
Schroedl, Michael
中科院分区：
文献类型：
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作者：
Brenzinger, Bastian;Padula, Vinicius;Schroedl, Michael
越来越多的分子证据表明，euthyneuran腹足类的进化与百年教科书的概念有很大不同。因此，需要重新研究主要亚群中性状的存在、同源性和进化。传统的基底后鳃类Cephalaspidea（“头盾蜗牛和蛞蝓”）被修剪到一个新的分类群概念，底栖euopisthobranch和触角轴承cephalaspidean谱系基底穴居，头盾轴承philinoidean物种。在后者中，mesopsammic“microslug”谱系至少进化了两次。在此，我们探讨了在3D显微解剖细节的pupelium基底philinoglossan Pluscula cuica（马库斯，Boletim da Faculdade de Filosofia，Cincias e Letras。Universidade de So Paulo 164：165-203，1953 a）来自巴西的模式产地。该物种拥有几个“附属”神经节和一个减少的后地幔腔，保留了一些假定的壳建造组织和一个卵巢。雌雄同体，单尾生殖系统开放于后方位置，保留交配囊，但缺乏明显的生殖器接受器。自体精子通过外部的精子沟转移到头部的交配器官，而不是像原始描述中所建议的那样通过血腔。阴茎通过口腔管打开，精子通过“吻”转移。一个明显的黄色腺体被认为是改良的布洛克曼腺。Pluscula是小型底栖动物Philinoglossidae中最基本的分支，与Philinoids保持了几个假定的合模。然而，融合而不是分离的胸膜神经节和三叉神经节而不是五节内脏神经索的假设“连续性”是基于错误的观察。更高的分类，如Philinoglosacea的Philinoglossidae，和一个单独的家庭Plusculidae的P. cuica不再是必要的。内部cephalinoglossid的关系和方案或多或少连续philinoglossid适应小型底栖动物环境的分子研究进行了调查，更全面的分类单元采样。
Increasing molecular evidence suggests that the phylogeny of euthyneuran gastropods differs greatly from centenary textbook concepts. The presence, homology and evolution of characters in major subgroups thus need to be reinvestigated. Traditionally basal opisthobranch Cephalaspidea ("head-shield snails and slugs") were pruned to a new taxon concept, with benthic euopisthobranch and tentacle-bearing cephalaspidean lineages basal to burrowing, head-shield bearing philinoidean species. Among the latter, mesopsammic "microslug" lineages evolved at least twice. Herein we explore in 3D microanatomical detail the putatively basal philinoglossan Pluscula cuica (Marcus, Boletim da Faculdade de Filosofia, Cincias e Letras. Universidade de So Paulo 164:165-203, 1953a) from its type locality in Brazil. The species possesses several "accessory" ganglia and a reduced posterior mantle cavity that retains some putative shell-building tissue and an osphradium. The hermaphroditic, monaulic genital system opens in a posterior position; it retains a bursa copulatrix but lacks a distinct receptaculum seminis. Autosperm is transferred to the cephalic copulatory organ via an external sperm groove, not through the hemocoel, as suggested in the original description. The penis opens through the oral tube, sperm is transferred by a "kiss". A conspicuous yellow gland is discussed as a modified Blochmann's gland. Retaining several putative symplesiomorphies with philinoids, Pluscula is discussed as the most basal offshoot in meiofaunal Philinoglossidae. However, the supposed "primitiveness" of the fused rather than separate cerebropleural ganglia and the triganglionate rather than pentaganglionate visceral nerve cord was based on misobservations. Higher categories such as Philinoglossacea for Philinoglossidae, and a separate family Plusculidae for P. cuica are no longer warranted. Inner cephalaspidean relationships and a scenario of more or less successive philinoglossid adaptation to meiofaunal environments should be investigated by molecular studies with more comprehensive taxon sampling.