Taxonomical and Ecological Study on alpheid shrimps living in tunnel bored in rock at the Ryukyu Islands

2002年至2004年，在琉球的奄美大岛、冲绳岛和石垣岛等地多处采集了岩洞生活的虾类标本。虾和小螃蟹也生活在隧道中，这些岩石被切成几片，以获得有关隧道细节的信息。隧道的形状并不总是恒定的，在较大的居民中变得更厚更复杂，但可以肯定的是，他们无法走出隧道，因为开口的直径只有1.5-2.5毫米，比虾的大小要小得多。隧道的内壁是光滑的，可能是用锤状的活动手指把它弄得更宽更长。所收集的标本被鉴定为分布在热带印度洋-西太平洋珊瑚礁中的肥胖Alpheus obesomanus。在野外破岩时，常见的是梯形蝇科Jonesius属的小蟹。很明显，他们不能自己在岩石中挖隧道，因此他们使用了阿尔菲斯·奥贝斯马努斯的废弃隧道。对它们的详细检查显示，它们是指两个不同的属，彼此不同。

During this study from 2002 to 2004, many specimens of alpheid shrimps living tunnels bored in rocks were collected in many places in Amami-Oshima Island, Okinawa-jima Islands and Ishigaki-jima Islands in the Ryukyu Islands. The shrimps and the small crabs also living in tunnels were identified, and the rocks were cut into several slices to get information about details of the tunnels. Shape of the tunnels are not always constant, becoming thicker and more complicated in the larger inhabitants, but it is sure that they cannot go out of the tunnel, because the diameter of the opening(s) is (are) only 1.5-2.5 mm much smaller than the size of the shrimps. The tunnel is smooth at the inside wall, and probably made wider and longer using the strong hammer-shaped movable finger. The collected specimens were identified with Alpheus obesomanus distributed in the tropical Indo-West Pacific coral reefs.On breaking the rock in the field, small crabs referable to the genus Jonesius of the family Trapeziidae were rather commonly found. It is apparent that they cannot dig the tunnel into rock by themselves, and therefore they use the abandoned tunnel of Alpheus obesomanus. Detailed examination of them revealed that they are referred to two different genera distinct from each other.