海蝶螺屬

海蝶螺屬，又叫明螺屬，是玉黍螺目海蝶螺科之下一個全浮游海洋腹足綱軟體動物的屬，也是海蝶螺科的模式屬。分佈.除Atlanta californiensis外，全部19種都生活在熱帶和亞熱帶水域。大多數物種是世界性的，其餘的9種物種中，有5種在印度太平洋，有2種只限於太平洋，1種在印度-大西洋，1種只限於大西洋。它們是在熱帶和亞熱帶海洋中漂浮或游泳的蝸牛。大多數都具有全球性的分佈，但是A. brunnea，A. pulchella和A. quoyi僅在美國水域中發現。 A. fusca、A. pacifica和A. rosea只生活在日本週圍的海洋中。描述.It has been recognized by several authors that identification of species in this genus is difficult and is dependent on their morphology of eyes, radula and operculum.Main diagnostic features include: the shell and keel are calcareous; larval shell becomes the spire in the adult shell.Snails of this genus are very small. Their coiled, calcareous shell has a diameter of less than 1 cm. The protoconch of the larval shell is retained after metamorphosis and becomes the spire of the adult shell. The number of spire whirls varies from 2½ (in the "A. lesueuri"- group) to 6 ("A. gibbosa") and is thus also helpful in the identification of a species. The spire shape differs between the species groups, from very small ("A. lesueuri"- group), to inflated or flat ("A. inflata"- group ) to large ("A.inclinata"- group and "A. gibbosa"- group).They can retract into their shell and close it off with an operculum. This operculum is cartilaginous and flexible. In 1961 Richter distinguished three types of the operculum in which the larval gyre of the operculum is apical. This gyre can be relatively somewhat larger (macro-oligogyre), smaller (micro-oligogyre) or a single gyre (monogyre).The eye morphology also consists of three types with differences in pigmented region between the lens and the retina.The radula is typically taenioglossate with one central (rachidian) tooth, with on each side one lateral tooth and two marginal teeth. In 13 species the number of tooth rows increases during growth (Type I), while in 8 species the radula has a limited number of tooth rows (Type II).Identification.Many authors (e.g., Thiriot-Quiévreux, 1973, p. 240; Richter, 1974, p. 60; Seapy, 1990, p. 107) admit that identification of Atlanta species is difficult and including soft-part features (eyes, radula, operculum) or application of transmitted light to observe inner shell structures (Richter, 1987, p. 178) are very helpful in distinguishing species with similar shells. However, such methods are unavailable for fossil material. This makes identifying fossil species of "Atlanta" quite difficult and even well-preserved specimens occasionally can only be related to existing taxa with a query (e.g., "Atlanta" sp. in Janssen, 2004, p. 108; "Atlanta" cf. "echinogyra" in Jansen 2007). Advantageous in this study of fossil atlantids, however, is the fact that all specimens are preserved as opaque aragonitic shells as a result of recrystallisation, which facilitates assessing protoconch shape and ornament with a normal 25 or 50× binocular magnification, they are thus much easier studied than in the usually very transparent and shiny Recent specimens. Still, here, too, study of the larval shell shape and micro-ornamentation by SEM is highly desirable or even indispensable.物種."Atlanta" includes a large number of Recent species. Lalli &amp; Gilmer (1989) listed 14 species, but Richter &amp; Seapy (1999) recognised 21 extant species, provisionally subdivided into seven ‘species groups’ (and one species unassigned). A further Recent species was described since; "Atlanta selvagensis" de Vera &amp; Seapy, 2006.截至2018年 (2018)[ [update]]，WoRMS紀錄本屬物種如下：Based on similar morphologies, these species have been placed in seven species groups:Tesch (1908) was the first to group together the species of "Atlanta" sharing similar morphologies. He recognized four species groups; the "Atlanta peronii"-, "Atlanta inflata"-, "Atlanta turriculata"-, and "Atlanta inclinata"-groups. In addition to these four, three additional ones are currently recognized; the "Atlanta lesueurii"-, "Atlanta gaudichaudi"- and "Atlanta gibbosa" groups. Except for Tesch's "Atlanta turriculata"-group, the composition of Tesch's species groups has changed by species invalidations, the addition of new species over time, and addition of three new species groups. The main changes in Tesch's species groups have occurred in the "Atlanta peronii"-group (with "Atlanta gaudichaudi" and "Atlanta lesueurii" now forming their own species groups) and the "Atlanta inclinata"-group (the "Atlanta gibbosa" now forming its own group).This article incorporates CC BY-3.0 text from references.