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New species of Leptohalysis (Rhizaria, Foraminifera) from an extreme hadal site in the western Pacific Ocean

New species of Leptohalysis (Rhizaria, Foraminifera) from an extreme hadal site in the western Pacific Ocean
New species of Leptohalysis (Rhizaria, Foraminifera) from an extreme hadal site in the western Pacific Ocean
Leptohalysis kaikoi sp. nov., a new hormosinacean foraminiferan, is described from a core sample collected using the Japan Agency for Marine-Earth Science and Technology’s Remote Operated Vehicle, KAIKO, in the Challenger Deep (10,896 m water depth, Izu-Bonin-Mariana-Arc-trench system). The agglutinated test is <130 ?m long and approximately 20 ?m wide, and more or less confined to the 32-63 ?m sieve fraction. It consists of a linear series of chambers with a simple terminal aperture. The new species differs from typical members of the genus Leptohalysis in the following features: 1) the chambers are rounded and abut closely with a distinct suture between them, rather than being flask-shaped with more or less flat, truncated bases; 2) the wall structure is less regular and consists mainly of grains with flat exposed faces that abut to create an outer surface resembling an uneven pavement, the edges of the grains being obscured by copious amounts of organic cement; 3) the proloculus is sometimes followed by a single “adventitious”chamber, located to one side of the axis of growth. A second species with similar characteristics is represented by a single individual in our material. These two species may represent a new genus. However, we prefer to retain them within Leptohalysis pending a detailed comparison of their wall structure with that of typical members of this genus. We also briefly describe a single specimen of a typical Leptohalysis morphotype. Leptohalysis kaikoi sp. nov. was the most common multilocular agglutinated foraminiferan in the 32-63 ?m sieve fraction of the Challenger Deep sample. It has not been found in the same size fraction of samples from abyssal depths in the North and eastern equatorial Pacific Ocean.
Benthic foraminifera, agglutinated, Hormosinacea, deep-sea trench, West Pacific, Remote Operated Vehicle (ROV)
1175-5334
23-32
Kitazato, Hiroshi
1acb8558-98a8-45eb-8e0b-37e299033032
Uematsui, Katsuyuki
f667010a-d91c-4bb4-b829-ebd11301cde6
Todo, Yuko
9fb80b39-5ea6-44af-b293-3c5c305c6f6d
Gooday, Andrew J.
d9331d67-d518-4cfb-baed-9df3333b05b9
Kitazato, Hiroshi
1acb8558-98a8-45eb-8e0b-37e299033032
Uematsui, Katsuyuki
f667010a-d91c-4bb4-b829-ebd11301cde6
Todo, Yuko
9fb80b39-5ea6-44af-b293-3c5c305c6f6d
Gooday, Andrew J.
d9331d67-d518-4cfb-baed-9df3333b05b9

Kitazato, Hiroshi, Uematsui, Katsuyuki, Todo, Yuko and Gooday, Andrew J. (2009) New species of Leptohalysis (Rhizaria, Foraminifera) from an extreme hadal site in the western Pacific Ocean. Zootaxa, 2059, 23-32.

Record type: Article

Abstract

Leptohalysis kaikoi sp. nov., a new hormosinacean foraminiferan, is described from a core sample collected using the Japan Agency for Marine-Earth Science and Technology’s Remote Operated Vehicle, KAIKO, in the Challenger Deep (10,896 m water depth, Izu-Bonin-Mariana-Arc-trench system). The agglutinated test is <130 ?m long and approximately 20 ?m wide, and more or less confined to the 32-63 ?m sieve fraction. It consists of a linear series of chambers with a simple terminal aperture. The new species differs from typical members of the genus Leptohalysis in the following features: 1) the chambers are rounded and abut closely with a distinct suture between them, rather than being flask-shaped with more or less flat, truncated bases; 2) the wall structure is less regular and consists mainly of grains with flat exposed faces that abut to create an outer surface resembling an uneven pavement, the edges of the grains being obscured by copious amounts of organic cement; 3) the proloculus is sometimes followed by a single “adventitious”chamber, located to one side of the axis of growth. A second species with similar characteristics is represented by a single individual in our material. These two species may represent a new genus. However, we prefer to retain them within Leptohalysis pending a detailed comparison of their wall structure with that of typical members of this genus. We also briefly describe a single specimen of a typical Leptohalysis morphotype. Leptohalysis kaikoi sp. nov. was the most common multilocular agglutinated foraminiferan in the 32-63 ?m sieve fraction of the Challenger Deep sample. It has not been found in the same size fraction of samples from abyssal depths in the North and eastern equatorial Pacific Ocean.

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More information

Published date: 2009
Keywords: Benthic foraminifera, agglutinated, Hormosinacea, deep-sea trench, West Pacific, Remote Operated Vehicle (ROV)

Identifiers

Local EPrints ID: 71939
URI: http://eprints.soton.ac.uk/id/eprint/71939
ISSN: 1175-5334
PURE UUID: b58903e0-1904-4f6f-897d-6092310af8da

Catalogue record

Date deposited: 11 Jan 2010
Last modified: 22 Jul 2022 17:10

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Contributors

Author: Hiroshi Kitazato
Author: Katsuyuki Uematsui
Author: Yuko Todo
Author: Andrew J. Gooday

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