A new late Eocene Bicornucythere species (Ostracoda, Crustacea) from Myanmar, and its significance for the evolutionary history of the genus.
A new late Eocene Bicornucythere species (Ostracoda, Crustacea) from Myanmar, and its significance for the evolutionary history of the genus.
复制标题
DOI：
10.11646/zootaxa.3919.2.4
复制
发表时间：
2015-02
期刊：
影响因子：
0.9
通讯作者：
T. Yamaguchi;Hisashi Suzuki;A. Soe;Thaung Htike;R. Nomura;M. Takai
中科院分区：
文献类型：
--
作者：
T. Yamaguchi;Hisashi Suzuki;A. Soe;Thaung Htike;R. Nomura;M. Takai
介形虫属Bicornucythere（Ostracoda，Crustacea）在现代富营养化的海湾中非常丰富，广泛分布于东亚的河口和内湾，包括中国、韩国、日本和俄罗斯远东。对双角子树的进化历史了解甚少。本文报道了同心双角介（Bicornucythereconcentica sp. nov.）来自缅甸盆地中部始新世Yaw地层。已知最古老的Bicornucythere分类群，Bicornucythere secedens，是在印度中新世地层中发现的，尽管分子生物学研究表明该属最早出现在白垩纪晚期。同心双角介Bicornucythere concentricica sp. nov.比已知最早的B至少早1090万年。分离新物种与亚颗粒氨（Ammonium subgranulosa）一起出现，亚颗粒氨是一种底栖有孔虫，是现代亚洲海湾咸水条件的代表。我们的研究结果表明，现存的属居住在亚洲海湾晚始新世以来。Bicornucythere的古生物地理学表明，该分类群在印度和欧亚板块之间的碰撞期间分散到印度海岸。
The ostracode genus Bicornucythere (Ostracoda, Crustacea) is abundant in modern-day eutrophic marine bays, and is widely distributed in estuaries and inner bays throughout East Asia, including in China, Korea, Japan, and the Russian Far East. The evolutionary history of Bicornucythere is poorly understood. Here, we report on a new species of Bicornucythere (Bicornucythere concentrica sp. nov.) from the upper Eocene Yaw Formation in the Central Myanmar Basin. The oldest previously known Bicornucythere taxon, Bicornucythere secedens, was reported from lower Miocene strata in India, although a molecular phylogeny suggests that the genus first appeared in the Late Cretaceous. Bicornucythere concentrica sp. nov. is at least 10.9 million years older than the earliest known B. secedens. The new species occurs with Ammonia subgranulosa, a benthic foraminifer, an association that is representative of brackish water conditions in modern Asian bays. Our findings indicate that extant genera have inhabited Asian bays since the late Eocene. The paleobiogeography of Bicornucythere indicates that the taxon was dispersed onto Indian coasts during the collision between the Indian and Eurasian plates.