Taxonomy and life history of the Acropora-eating flatworm Amakusaplana acroporae nov. sp. (Polycladida: Prosthiostomidae)
Taxonomy and life history of the Acropora-eating flatworm Amakusaplana acroporae nov. sp. (Polycladida: Prosthiostomidae)
复制标题
吃鹿角珊瑚的扁虫 Amakusaplana acroporae 的分类学和生活史。
作者：
K. A. Rawlinson;K. A. Rawlinson;J. Gillis;R. Billings;Eric H. Borneman
在水族馆中培养和保护顶孔珊瑚的努力导致了一种食珊瑚的多包层扁形虫（称为AEFW -吃顶孔珊瑚的扁形虫）的发现，如果不被移除，它可以吃掉整个殖民地。对AEFW的活体观察、整体标本、连续组织切片以及28 S rDNA序列与其他多枝类的比较表明，这是一个新种，属于前口科Lang，1884和以前的单种属Amakusaplana（Kato 1938）。顶孔天蛾与大岛天蛾的区别在于眼的排列和数量不同，一个大的储精囊和背腹压缩的壳腺囊。A.顶孔，缺乏腹吸盘，在前缘的中线处有一个小凹口。在珊瑚的肠道和薄壁组织中，有大量的线虫囊和共生甲藻。个体成虫在珊瑚骨骼上产下多批卵，每批卵有20-26个卵囊，每个卵囊含有3-7个胚胎。胚胎发育大约需要21天，在此期间，远洋生活阶段的特征（叶和纤毛簇）发展，但在孵化前丢失。幼体能够游泳，但很快就定居在底栖生物中，在这个阶段没有在动物身上观察到虫黄藻。我们认为，囊内变态限制了孵化的扩散潜力，并促进招聘到纳塔尔地的后代。讨论了胚胎中保留叶和纤毛簇的进化和生态学意义。Camphelage，高繁殖力和可能的分散二型性可能解释如何Amakusaplana acroporae可以导致鹿角珊瑚。死亡率在水族馆的自然捕食者可能缺席。
Efforts to culture and conserve acroporid corals in aquaria have led to the discovery of a corallivorous polyclad flatworm (known as AEFW – Acropora-eating flatworm), which, if not removed, can eat entire colonies. Live observations of the AEFW, whole mounts, serial histological sections and comparison of 28S rDNA sequences with other polyclads reveal that this is a new species belonging to the family Prosthiostomidae Lang, 1884 and previously monospecific genus Amakusaplana (Kato 1938). Amakusaplana acroporae is distinguished from Amakusaplana ohshimai by a different arrangement and number of eyes, a large seminal vesicle and dorsoventrally compressed shell gland pouch. Typical of the genus, A. acroporae, lacks a ventral sucker and has a small notch at the midline of the anterior margin. Nematocysts and a Symbiodinium sp. of dinoflagellate from the coral are abundantly distributed in the gut and parenchyma. Individual adults lay multiple egg batches on the coral skeleton, each egg batch has 20–26 egg capsules, and each capsule contains between 3–7 embryos. Embryonic development takes approximately 21 days, during which time characteristics of a pelagic life stage (lobes and ciliary tufts) develop but are lost before hatching. The hatchling is capable of swimming but settles to the benthos quickly, and no zooxanthellae were observed in the animal at this stage. We suggest that intracapsular metamorphosis limits the dispersal potential of hatchlings and promotes recruitment of offspring into the natal habitat. The evolutionary and ecological significance of retaining lobes and ciliary tufts in the embryo are discussed. Camouflage, high fecundity and possible dispersal dimorphisms probably explain how Amakusaplana acroporae can cause Acropora sp. mortality in aquaria where natural predators may be absent.