Abstract Atlanticodinium n. gen. accommodates small- to medium-sized proximate dinoflagellate cysts with a spherical or subspherical central body having a nonfibrous wall with a smooth to finely ornamented surface bearing numerous, short, hollow, unbranched, nontabular, nonfibrous processes. The archeopyle is precingular, its margins having well defined angles. Atlanticodinium striaticonulum n. gen., n. sp. has a IP archeopyle, and distinctive short, distally closed processes with internal striations. This species has a confirmed Lower Pleistocene record, possibly extending to at least upper Lower Pliocene, and occurs widely in modern marine sediments. Atlanticodinium janduchenei (Head et al., 1989) n. comb., here reassigned from the genus Operculodinium Wall, 1967, has smooth-shafted processes that can be distally open or closed, as confirmed by re-examination of the holotype and paratype from the Upper Miocene of the Labrador Sea. Atlanticodinium janduchenei has a reported stratigraphic range of Lower Miocene to Lower Pleistocene, but this requires reevaluation. Atlanticodinium striaticonulum has been widely mistaken for Atlanticodinium janduchenei in modern sediments. Atlanticodinium striaticonulum has a tropical to temperate modern distribution, and is particularly associated with offshore to oceanic settings where conditions are oligotrophic.

中文翻译：

---

Atlanticodinium striaticonulum n. gen., n. sp.，一种来自新生代晚期的广泛存在的甲藻囊肿，及其与 Atlanticodinium janduchenei 的比较（Head 等，1989）n。梳子

摘要 Atlanticodinium n. 将军 容纳小到中等大小的近端甲藻囊肿，具有球形或亚球形中心体，具有非纤维壁，表面光滑至精细装饰，表面带有许多短的、空心的、不分枝的、非扁平的、非纤维状突起。始孔是前缘，其边缘有明确的角度。Atlanticodinium striaticonulum n. gen., n. sp. 有一个 IP 原始孔，以及独特的短、远端闭合的带有内部条纹的突起。该物种具有确认的下更新世记录，可能至少延伸到上新世，广泛存在于现代海洋沉积物中。Atlanticodinium janduchenei (Head et al., 1989) n. 梳子，这里从 1967 年的 Operculodinium Wall 属重新分配，具有光滑的轴突，可以在远端打开或关闭，对拉布拉多海上中新世的正模和副模的重新检查证实了这一点。Atlanticodinium janduchenei 已报告了下中新世至下更新世的地层范围，但这需要重新评估。Atlanticodinium striaticonulum 在现代沉积物中被广泛误认为是 Atlanticodinium janduchenei。Atlanticodinium striaticonulum 具有热带到温带的现代分布，特别与近海到海洋条件贫营养的环境有关。