The ecological and taxonomical study on the living ostracods from coral reefs in the Sckisci-sho area, Ryukyu Islands, Japan

本研究旨在揭示琉球群岛sekisei - shoo地区珊瑚礁介形类物种的生态分布，并对未被描述的物种进行系统描述。1990年9月，通过水肺潜水从10个地点（约3至15米深）收集了30个活体介形类样本；5个地点在泻湖，5个地点在礁坡。结果鉴定出足足目40属76种，肌足目2种。根据频繁出现的30种足足类的分布格局，根据底物种类可划分出3个类群；第一类与砂底密切相关，第二类几乎局限于岩石或砾石等硬底上的大型藻类或丝状微小藻类，第三类与特定种类的基质没有明显的关系。根据砂底粒度分布、大型藻类和丝状藻类生长的岩石或砾石的形状，第一类和第二类的物种组成各有不同。一些物种的丰度也因周围水体（如海洋或泻湖）的性质而异。对超过50种未描述物种的分类工作仍在进行中。在本研究中，附属物和男性性器官等通常不作为化石保存的柔软部位也与甲壳一起作为重要的分类学特征。

The purpose of this study is to reveal the ecological distributions of ostracod species from coral reefs in the Sekisei-sho area, Ryukyu Islands, and to carry out the systematic descriptions on the undescribed species. In September, 1990, 30 samples for living ostracods were collected by SCUBA diving from 10 locations (about 3 to 15 meters deep); 5 locations in the lagoon and 5 in the reef slope. As a result, 76 species belonging to 40 genera of Podocopa and 2 species of Myodocopa were identified. Based on the distribution patterns of 30 podocopid species occurring frequently, three species groups in relation to the kinds of substrates can be distinguished; the first group appear in close relation to sand bottom, and the second is almost confined to macroalgae or filamentous minute algae on hard bottom such as rocks or gravels, and the third have no distinct relation to particular kinds of substrates. The species composition of the first and second groups are respectively variable to some extent, depending on the grain size distribution of sand bottom and the shape of macroalgae and rocks or gravels on which filamentous algae grow. Some species also differ in abundance depending on the nature of surrounding water mass such as oceanic or lagoonal. Taxonomical work on undescribed species over 50 are still ongoing. In this study, soft parts such as appendages and male sexual organs, which are not usually preserved as fossils, are also used as important taxonomical characters with carapace.