Molecular Invertebrate of Systematics and Ecology (MISE) Lab, Graduate School of Engineering and Science, University of the Ryukyus, Nishihara, Okinawa, Japan.
Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa, Japan.
PeerJ. 2022 Jul 19;10:e13720. doi: 10.7717/peerj.13720. eCollection 2022.
Species of the genus Fleming, 1822, are air-breathing onchidiid sea slugs that inhabit intertidal reef flats of temperate to tropical zones. In the Ryukyu Islands of southern subtropical Japan, species are a traditional food source for local people. To date, there have been three species recorded around Okinawajima Island; and , along with recently described , which was described as possibly endemic to Okinawajima Island. This study aimed to map the distribution ranges of these three species within the Ryukyu Islands using molecular analyses in order to understand the specific distribution of each species. Since species are generally indistinguishable by gross external morphology, a DNA barcoding approach was employed to identify specimens. The molecular data showed that there are four species present in the Ryukyu Islands. (unit #1 Dayrat et al., 2020) was dominant at almost all locations, while was present in much lower numbers than , but found across a relatively wide range in the Ryukyu Islands. We newly record and from Amami Oshima Island and from several places around Okinawajima Island, and also identified high levels of genetic variation within . and have been thought to be endemic to Okinawajima Island and to Honshu, mainland Japan, respectively. However, as both species were observed around Okinawajima and Amami Oshima islands, other islands of the Ryukyus are also likely to harbor these species, and their distribution ranges are wider than previously thought. Based on the results from molecular analyses, we provide general descriptions of each species. Sizes of specimens were consistently smaller for and relatively larger for specimens. On the other hand, and had similar size ranges, but had comparatively much more distinct papillae. This study revealed that the Ryukyu Islands are the only region currently known with four sympatric species, and this work provides a basis for future research on these species throughout the northwest Pacific Ocean, representing the first step in more effective management of the local fisheries in the Ryukyu Islands.
Fleming，1822 年属的物种是呼吸空气的 Onchididae 海蛞蝓，栖息在温带至热带地区的潮间带珊瑚礁平原。在日本亚热带的琉球群岛，这些物种是当地人的传统食物来源。迄今为止，在冲绳岛周围已记录到三种物种；和 ，以及最近描述的 ，被描述为可能是冲绳岛的特有种。本研究旨在利用分子分析绘制这三种 物种在琉球群岛的分布范围，以了解每个物种的特定分布。由于 物种通常无法通过外部形态进行区分，因此采用 DNA 条形码方法来识别标本。分子数据显示，琉球群岛有四种物种。（单位#1 Dayrat 等人，2020）在几乎所有地点都占主导地位，而 则比 少得多，但在琉球群岛的广泛范围内都有发现。我们新记录了 和 来自奄美大岛和冲绳岛周围的几个地方，并且在 内也发现了高水平的遗传变异。 和 分别被认为是冲绳岛和本州大陆日本的特有种。然而，由于这两个物种在冲绳岛和奄美大岛周围都有观察到，其他琉球群岛的岛屿也可能存在这些物种，它们的分布范围比以前认为的要广。基于分子分析的结果，我们对每个物种进行了一般描述。标本的大小对于 和 始终较小，而对于 标本则相对较大。另一方面， 和 具有相似的大小范围，但 具有明显更多的乳突。本研究表明，琉球群岛是目前唯一已知存在四种共生 物种的地区，这为未来在西北太平洋地区对这些 物种进行研究提供了基础，这是在琉球群岛更有效地管理当地 渔业的第一步。
