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''Atlanta lesueurii'' is a species of sea snail, a holoplanktonic marine gastropod mollusk in the family Atlantidae. ==Description== The maximal shell size of ''Atlanta lesueurii'' appears to vary geographically (from 2 mm in Hawaiian and eastern Australian waters to 6 mm in the tropical western Pacific).〔 The shell is transparent, thin and fragile, with a smooth surface (lacking raised sculpture). The spire is very small, somewhat elevated and compact, consisting of about 2½ whorls.〔 Spire sutures are deep, with the result that the whorls are somewhat rounded in profile and can easily be distinguished.〔 After metamorphosis the outermost whorl enlarges and inflates rapidly and the keel becomes progressively taller, becoming very tall in large adults and having a truncate leading edge.〔 The keel base and spire sutures are colorless.〔 Main features for the recognition of this species are the protoconch composed of just 2¼-3 convex whorls, separated by an incised suture and the absence of any ornament.〔 The first teleoconch whorl expands rapidly and bears a well-developed flange-like keel.〔 In the largest specimens the final three quarters of the teleoconch separates from the penultimate whorl.〔 Eyes are type b, with a large lens.〔 The Operculum is the type b.〔 Radula is type I, with a narrowly triangular shape.〔 ''Atlanta lesueurii'' is the large species in the genus ''Atlanta'', but ''Atlanta peronii'' is larger. ''Atlanta lesueurii'' resembles closely ''Atlanta oligogyra'', in which, however, the first whorls are separated by a superficial suture and the shell remains much smaller.〔 Overview of description: * Maximal shell size appears to vary geographically, between 2 and 6 mm〔〔Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". ''PLoS ONE'' 5(1): e8776. .〕 * Shell transparent with a thin, fragile walls〔 * Shell surface smooth; lacking surface sculpture〔 * Spire compact, consisting of about 2½ whorls〔 * Spire sutures incised, enabling distinction of whorls〔 * Keel tall, with a truncate leading edge〔 * Eyes type b; lens large〔 * Operculum type b〔 * Radula type I, narrowly triangular shape〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Atlanta lesueurii」の詳細全文を読む スポンサード リンク
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