Nipponacmea is a genus of sea snails, the true limpets, marine gastropod mollusks in the family Lottiidae.[2]
These species are very common among the Japanese gastropod fauna on rocks and boulders in the intertidal zone of Japanese waters and adjacent islands.
The shape of the thin shell is limpet-like or patelliform. It has a medium size and has a low to medium height. The base (the aperture) has an oval shape and is longer than wide.
The color of the shell is greenish brown and characteristically bedecked with granules of fine radial riblets. . The interior is greenish blue and has a shining luster. The thin and broad interior shell margin exhibits a distinct color and texture from the adjoining area.
The shell is constituted of five layers of different structure, while the genus Notoacmea has six layers.
The gill is flaplike with a bipectinate ctenidium situated in the nuchal cavity and lacks secondary pallial gills. The radula has typically three pairs of lateral teeth and one pair of marginal teeth that is either lacks any function or is degenerated with growth or is lacking from the beginning.
Until 1993 the species of these Japanese limpets were allocated in the genus Notoacmea.[1] They were reassigned based on different anatomical characters and shell structure and their endemism to the Japonic zoogeographical province (Japanese waters and adjacent island chains). There wasn't just enough similarity with the New Zealand species from Notoacmea. Also the radula characters were different. Lindberg (in 1986) had pointed out that the genus Notoacmea was restricted to species from New Zealand and Australia and that the North American species belonged in Tectura. The eight Japanese species had been unsettled until this study. Some authors consider them color variations, others regard them as subspecies or as independent species.[1]
Species within the genus Nipponacmea include:
Nipponacmea is a genus of sea snails, the true limpets, marine gastropod mollusks in the family Lottiidae.
Nipponacmea is een geslacht van weekdieren uit de klasse van de Gastropoda (slakken).
Nipponacmea is een geslacht van weekdieren uit de klasse van de Gastropoda (slakken).
日本青螺屬（學名：Nipponacmea），又名背尖貝屬[2]，是一個海螺的屬，是一個海生笠螺類的腹足綱軟體動物青螺科（或蓮花笠螺科[3]）之下的成員[4]。舊屬原始腹足目[3][5]，今屬笠形腹足類支序[4]。
這些物種在生活於日本水域及鄰近島嶼潮間帶的岩石與礫石的腹足綱動物當中非常常見。不過亦有見於台灣[6]及南韓[5]的水域。
本屬物種有着一般笠形腹足類物種的螺殼，但外殼比較薄，尺寸中等，殼高低到中等。
截至1993年，本屬的各種來自日本的笠螺物種仍然屬於Notoacmea屬[1]。由於牠們在解剖上的特徵及螺殼的構造 都與其他物種有所不同[1][6]。
