Polyaxone monaxonids: revision of raspailiid sponges with polyactine megascleres ( Cyamon and Trikentrion)
Polyaxone monaxonids: revision of raspailiid sponges with polyactine megascleres ( Cyamon and Trikentrion)
复制标题
Polyaxone monaxonids：用聚肌动蛋白巨巩膜（Cyamon 和 Trikentrion）改良拉斯帕利海绵
作者：
R. V. VAN SOEST;J. Carballo;J. Hooper
摘要 在数千种非四肢海绵动物中，只有不到二十种拥有多肌动蛋白（通常为三或四包层）巨巩膜。这些目前被分配给两个密切相关的属，即。 Cyamon Gray 和 Trikentrion Ehlers，均为树莓亚科 Cyamoninae 的成员。由于多轴针针的形状和装饰的差异，这两个属被认为是有效的。 Cyamon 主要具有四包层等角骨针，所有分支都有刺或有皱纹，而 Trikentrion 通常具有大多数三包层针，其中仅在单个基部分支上发现刺。然而，这两个属之间的差异似乎在几个已知和新发现的物种中重叠，因此有必要对这两个类进行修订。在毛里塔尼亚海岸附近的近海砂岩平台上发现了两种新的 Cyamon 物种。新物种之一，Cyamon amphipolyactinum sp。 n.，除了 Cyamon 所特有的常见的类角果多肌动蛋白巨巩膜外，还拥有独特的小型“双”多肌动蛋白针状体。第二个新种，Cyamon arguinense sp。 n.，拥有聚肌动巨巩膜，其中只有一个分支有刺，其余三个或更多分支是光滑的，这一特征被认为是 Trikentrion 属海绵的特征。 Cyamon 的模式种 Cyamon vickersii (Bowerbank) 似乎被误解为加勒比海物种，因为间接证据强烈表明其起源于印度洋。结果是，随后来自西大西洋各地以 Cyamon vickersii 名称记录的标本被重新分配给 Cyamon agnani (Boury-Esnault)，该物种最初描述于巴西。一种新物种，被报道为来自印度东海岸的 Cyamon vickersii sensu Burton & Rao，我们只能以安装在载玻片上的单个厚切片的形式获得，它被命名为 Cyamon hamatum sp。名词唯一的深海物种 Cyamon spinispinosum (Topsent) 的 Cyamon 成员资格由于与主流 Cyamon 存在相当大的形态偏差而受到质疑。 Trikentrion 的模式种 Trikentrion muricatum (Pallas) 被广泛描述和讨论，并指定了一个新型。西非 Trikentrion laeve（卡特）自最初的描述以来首次根据模型材料进行了正确的重新描述。伯顿记录的来自刚果的标本 Trikentrion laeve 结果与卡特的原始材料不同，并被分配到一个新物种，Trikentrion africanum sp。名词被认为有效的两个属的所有物种都经过审查，主要基于对类型或其他原始标本的检查。我们的修订显示存在 12 种 Cyamon 物种和 6 种 Trikentrion 物种。提供了该物种的索引，并对两个属的地理分布进行了评论。根据我们的研究，重新评估了 Cyamon 和 Trikentrion 之间的差异。只有一个特征可以绝对地区分这两个属，即Trichodragmata 的存在（Trikentrion）或不存在（Cyamon）。另一个区别特征是拥有短而粗的花柱（大多数 Cyamon 物种）与粗的 oxea（许多 Trikentrion），但由于三个 Trikentrion 物种中缺乏 oxea，情况变得复杂。尽管聚肌针本身的刺状结构不能准确地区分这两个属，但 Trikentrion 的刺状刺通常可以通过过多的钩状刺与 Cyamon 的细刺状刺来识别。两个类群的聚肌动蛋白针状体可能是非同源的，Cyamon 聚肌动蛋白源自花柱，而 Trikentrion 聚肌动蛋白则源自 oxea，但这仍有待进一步研究。
Abstract Among the thousands of non-tetractinellid (monaxonid) Demospongiae species, less than twenty possess polyactine (usually three- or four-claded) megascleres. These are currently assigned to two closely related genera, viz. Cyamon Gray and Trikentrion Ehlers, both members of the raspailiid subfamily Cyamoninae. The two genera are considered valid on account of differences in the shape and the ornamentation of the polyaxone spicules. Cyamon predominantly has four-claded equiangular spicules with all cladi spined or rugose, whereas Trikentrion usually has a majority of three-claded spicules on which spines are found only on a single basal clade. Nevertheless, the differences between the two genera appear to overlap in several known and newly discovered species, necessitating a revision of the two groups. Two new species of Cyamon were found to occur on inshore sandstone platforms off the coast of Mauritania. One of the new species, Cyamon amphipolyactinum sp. n., possesses unique small ‘double’ polyactine spicules in addition to the usual calthrops-like polyactine megascleres characteristic for Cyamon. The second new species, Cyamon arguinense sp. n.,possesses polyactine megascleres of which only one of the cladi is spined the remaining three or more cladi being smooth, a feature that is considered characteristic of sponges of the genus Trikentrion. The type species of Cyamon, Cyamon vickersii (Bowerbank) appears to have been misinterpreted as a Caribbean species, because circumstantial evidence strongly indicates an Indian Ocean origin. This has the consequence that specimens recorded subsequently under the name Cyamon vickersii from various Western Atlantic localities are reassigned to Cyamon agnani (Boury-Esnault), a species originally described from Brazil. A new species, reported as Cyamon vickersii sensu Burton & Rao from the east coast of India, and available to us only as a single thick section mounted on a glass slide, is named Cyamon hamatum sp. n. The Cyamon membership of the only deep-sea species, Cyamon spinispinosum (Topsent) is drawn in doubt due to considerable morphological deviation from mainstream Cyamon. The type species of Trikentrion, Trikentrion muricatum (Pallas), is extensively described and discussed, and a neotype is assigned. West African Trikentrion laeve (Carter) is for the first time since its original description properly redescribed from the type material. The specimen recorded by Burton as Trikentrion laeve from Congo turned out to be different from the original material of Carter and is assigned to a new species, Trikentrion africanum sp. n. All species of both genera considered valid are reviewed, mostly based on the examination of type or other original specimens. Our revision shows the existence of twelve species of Cyamon and six species of Trikentrion. A key to the species is provided and remarks on the geographic distribution of both genera are made. Based on our study, the differences between Cyamon and Trikentrion are re-evaluated. Only one character absolutely distinguishes the two genera, the presence (Trikentrion) or absence (Cyamon) of trichodragmata. A further discriminating character is the possession of short thick styles (most Cyamon species) versus thick oxeas (many Trikentrion), but this is complicated by absence of the oxeas in three Trikentrion species. Although spination of the polyactine spicules in itself cannot serve to distinguish the two genera with certainty, those of Trikentrion are usually recognizable by excessive hook-like spines against a finer spination in Cyamon. Possibly, the polyactine spicules of both groups are non-homologous, with Cyamon polyactines derived from styles and Trikentrion polyactines from oxeas, but this remains to be further investigated.