Atsumi Masako O, Saito Yasunori
Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan.
Zoolog Sci. 2011 Jul;28(7):532-42. doi: 10.2108/zsj.28.532.
Botrylloides simodensis, belonging to the family Botryllidae, is a common species on the rocky shore around Shimoda. Since this species was first reported in 1981, it has been noticed that some B. simodensis colonies have distinctly different ground colors and color patterns from colonies including type specimens (holotype and all of paratypes) of B. simodensis. However, as there is no remarkable difference among them in morphology other than the colonial colors and color patterns, they have been considered to belong to the same species. In the present work, colonies of B. simodensis sensu lato were divided into three groups, two major and one minor, based on their color-morphs and periods of sexual reproduction. In one of the major groups, B. simodensis sensu strict, the period of sexual reproduction was limited from July to September, as shown in the original description. The other major group engaged in sexual reproduction for much longer than the former group, and they frequently made clusters of vascular vessels and underwent vascular budding. Therefore, the group with the long period of sexual reproduction was described as a new species of the genus Botrylloides here. In addition, phylogenetic analysis based on mtDNA sequences of these groups indicated that each group had a peculiar sequence, and that they were genetically separated.
下田拟菊海鞘（Botrylloides simodensis）属于菊海鞘科（Botryllidae），是下田周边岩岸常见的物种。自1981年首次报道该物种以来，人们注意到一些下田拟菊海鞘群体与包括下田拟菊海鞘模式标本（正模和所有副模）在内的群体相比，具有明显不同的底色和颜色图案。然而，除了群体颜色和颜色图案外，它们在形态上没有显著差异，因此被认为属于同一物种。在本研究中，广义的下田拟菊海鞘群体根据其颜色形态和有性繁殖时期被分为三组，两组主要的和一组次要的。在其中一个主要组，即狭义的下田拟菊海鞘中，有性繁殖时期如原始描述所示，限制在7月至9月。另一个主要组的有性繁殖时间比前一组长得多，它们经常形成血管簇并进行血管出芽。因此，这里将有性繁殖时期长的组描述为拟菊海鞘属的一个新物种。此外，基于这些群体的线粒体DNA序列的系统发育分析表明，每个组都有独特的序列，并且它们在基因上是分离的。
