Molecular Invertebrate Systematics and Ecology Laboratory, Graduate School of Engineering and Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan.
R&D Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology, Yokosuka 237-0061, Japan; Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, 905-0227 Okinawa, Japan.
Mol Phylogenet Evol. 2015 Aug;89:73-90. doi: 10.1016/j.ympev.2015.04.002. Epub 2015 Apr 8.
Currently the genera Parazoanthus (family Parazoanthidae) and Epizoanthus (family Epizoanthidae) are the only sponge-associated zoantharians (Cnidaria, Anthozoa). The Parazoanthidae-sponge associations are widely distributed in tropical and subtropical waters from the intertidal to the deep sea in the Atlantic and Indo-Pacific Oceans. However, the taxonomic identification of both parties is often confused due to variable morphology and wide ecological ranges. In particular, Parazoanthidae species diversity remains poorly understood in the Indo-Pacific. In the present study, the diversity of the sponge-zoanthid association in the Indo-Pacific was investigated with 71 Parazoanthidae specimens collected from 29 different locations in Japan (n=22), Australia (n=6) and Florida, USA (n=1). For all specimens morphological analyses were performed and total DNA was extracted and amplified for four DNA markers (COI-mtDNA, mt 16S-rDNA, ITS-rDNA and ALG11-nuDNA). The combined data demonstrate that the specimens of this study are clearly different from those of all described Parazoanthus species, and lead us to erect Umimayanthus gen. n., within family Parazoanthidae, containing the three newly described species U. chanpuru sp. n., U. miyabi sp. n., U. nakama sp. n. The new genus also includes the previously described species U. parasiticus (Duchassaing and Michelotti, 1860; comb. nov.), previously belonging to the genus Parazoanthus. Neighbor joining, maximum likelihood and Bayesian posterior probability phylogenetic trees clearly demonstrate the monophyly of Umimayanthus gen. n. to the exclusion of all outgroup sequences. The phylogenetic results were also compared to morphological features, and polyp sizes, amount of sand content in tissues, types of connections between polyps, and cnidae data, in particular holotrichs-1, were useful in distinguishing the different species within this new genus. This new genus can be distinguished from all other Zoantharia by a unique and conserved 9 bp insertion and a 14 bp deletion in the mt 16S-rDNA region. Additionally, compared to Parazoanthus sensu stricto (i.e. P. axinellae [Schmidt, 1862]), Umimayanthus spp. are only found associated to sponges, and have a coenenchyme much less developed than Parazoanthus sensu stricto. Each new species can be distinguished from other congeners by a unique DNA sequence, numbers of tentacle, maximum sizes of holotrichs, associated sponge morphology, and colony morphology. The identification of the host sponge species is the next logical step in this research as this may also aid in the distinction of Umimayanthus species.
目前，Parazoanthus 属（Parazoanthidae 科）和 Epizoanthus 属（Epizoanthidae 科）是唯一与海绵共生的珊瑚虫（刺胞动物门，珊瑚纲）。Parazoanthidae 科与海绵的共生关系广泛分布于大西洋和印度洋太平洋的热带和亚热带水域，从潮间带到深海。然而，由于形态变化和广泛的生态范围，双方的分类鉴定常常混淆。特别是，Parazoanthidae 物种多样性在印度洋-太平洋地区仍知之甚少。在本研究中，从日本（n=22）、澳大利亚（n=6）和美国佛罗里达州（n=1）的 29 个不同地点采集了 71 个 Parazoanthidae 标本，研究了印度洋-太平洋地区海绵-珊瑚虫共生体的多样性。对所有标本进行形态分析，并提取和扩增了四个 DNA 标记（COI-mtDNA、mt16S-rDNA、ITS-rDNA 和 ALG11-nuDNA）的总 DNA。综合数据表明，本研究的标本与所有已描述的 Parazoanthus 物种明显不同，这促使我们在 Parazoanthidae 科内建立了一个新属，名为 Umimayanthus gen. n.，其中包含三个新描述的物种：U. chanpuru sp. n.、U. miyabi sp. n.和 U. nakama sp. n.。这个新属还包括以前描述的 U. parasiticus（Duchassaing 和 Michelotti，1860；组合新属），以前属于 Parazoanthus 属。基于邻接法、最大似然法和贝叶斯后验概率构建的系统发育树清楚地表明，Umimayanthus gen. n.是单系的，排除了所有的外群序列。系统发育结果还与形态特征、组织中沙含量、珊瑚虫的大小、珊瑚虫之间的连接类型以及 cnidae 数据进行了比较，特别是 holotrichs-1，在区分这个新属内的不同物种方面非常有用。这个新属与所有其他 Zoantharia 类群的区别在于 mt 16S-rDNA 区域的一个独特且保守的 9 个碱基插入和 14 个碱基缺失。此外，与严格意义上的 Parazoanthus（即 P. axinellae [Schmidt，1862]）相比，Umimayanthus spp.仅与海绵共生，并且 coenenchyme 的发育程度远低于严格意义上的 Parazoanthus。每个新种都可以通过独特的 DNA 序列、触须数量、holotrichs 的最大大小、相关海绵形态和群体形态与其他同属种区分开来。鉴定宿主海绵物种是这一研究的下一步，因为这也有助于区分 Umimayanthus 物种。
