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A new genus of xenophyophores (Foraminifera) from Japan Trench: morphological description, molecular phylogeny and elemental analysis

A new genus of xenophyophores (Foraminifera) from Japan Trench: morphological description, molecular phylogeny and elemental analysis
A new genus of xenophyophores (Foraminifera) from Japan Trench: morphological description, molecular phylogeny and elemental analysis
The deep-sea floor is inhabited by a number of unusual and enigmatic taxa, unknown in shallow waters. These include the xenophyophores, a group of giant protists that construct fragile agglutinated tests. Here, we describe Shinkaiya lindsayigen. et sp. nov., a new xenophyophore collected by the submersible Shinkai 6500 at a depth of 5435 m near the Japan Trench. The phylogenetic analysis performed on its complete small-subunit ribosomal DNA (SSU rDNA) sequence confirms that Sh. lindsayisp. nov. is a foraminiferan that is closely related to another xenophyophore, Syringammina corbicula Richardson, 2001, and to a monothalamous (single-chambered) foraminiferan Rhizammina algaeformis Brady, 1879. In terms of morphology, the new genus resembles Syringammina, but its test wall is thicker, softer, and more weakly cemented. Moreover, the SSU rDNA sequences of the two genera are highly divergent. Mass spectra analyses reveal unusually high concentrations of some elements, such as lead, uranium, and mercury. The granellare system (the cytoplasm and the organic sheath that encloses it) is apparently devoid of barite crystals, which are usually abundant as intracellular inclusions in xenophyophores, but is rich in mercury (with 12 times the concentration of mercury found in the surrounding sediment). Fecal pellets retained within a tubular system (stercomare) concentrate heavy metals, including lead and uranium (respectively, two and six times more than that of the sediment). Based on a comparison of the compositions of the agglutinated test wall, the granellare, the stercomare, and the surrounding sediment, we discuss the impact of xenophyophores on their habitat.
0024-4082
455-464
Lecrocq, Beatrice
5f312f29-540b-47d7-bd31-2afb65da04eb
Gooday, Andrew John
d9331d67-d518-4cfb-baed-9df3333b05b9
Tsuchiya, Masashi
ee230900-9e97-4a3a-95ec-fc9e0b87ddc6
Pawlowski, Jan
c3b6b0e6-fb24-4452-a762-770f7eb91d72
Lecrocq, Beatrice
5f312f29-540b-47d7-bd31-2afb65da04eb
Gooday, Andrew John
d9331d67-d518-4cfb-baed-9df3333b05b9
Tsuchiya, Masashi
ee230900-9e97-4a3a-95ec-fc9e0b87ddc6
Pawlowski, Jan
c3b6b0e6-fb24-4452-a762-770f7eb91d72

Lecrocq, Beatrice, Gooday, Andrew John, Tsuchiya, Masashi and Pawlowski, Jan (2009) A new genus of xenophyophores (Foraminifera) from Japan Trench: morphological description, molecular phylogeny and elemental analysis. Zoological Journal of the Linnean Society, 156 (3), 455-464. (doi:10.1111/j.1096-3642.2008.00493.x).

Record type: Article

Abstract

The deep-sea floor is inhabited by a number of unusual and enigmatic taxa, unknown in shallow waters. These include the xenophyophores, a group of giant protists that construct fragile agglutinated tests. Here, we describe Shinkaiya lindsayigen. et sp. nov., a new xenophyophore collected by the submersible Shinkai 6500 at a depth of 5435 m near the Japan Trench. The phylogenetic analysis performed on its complete small-subunit ribosomal DNA (SSU rDNA) sequence confirms that Sh. lindsayisp. nov. is a foraminiferan that is closely related to another xenophyophore, Syringammina corbicula Richardson, 2001, and to a monothalamous (single-chambered) foraminiferan Rhizammina algaeformis Brady, 1879. In terms of morphology, the new genus resembles Syringammina, but its test wall is thicker, softer, and more weakly cemented. Moreover, the SSU rDNA sequences of the two genera are highly divergent. Mass spectra analyses reveal unusually high concentrations of some elements, such as lead, uranium, and mercury. The granellare system (the cytoplasm and the organic sheath that encloses it) is apparently devoid of barite crystals, which are usually abundant as intracellular inclusions in xenophyophores, but is rich in mercury (with 12 times the concentration of mercury found in the surrounding sediment). Fecal pellets retained within a tubular system (stercomare) concentrate heavy metals, including lead and uranium (respectively, two and six times more than that of the sediment). Based on a comparison of the compositions of the agglutinated test wall, the granellare, the stercomare, and the surrounding sediment, we discuss the impact of xenophyophores on their habitat.

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Published date: 2009

Identifiers

Local EPrints ID: 71832
URI: http://eprints.soton.ac.uk/id/eprint/71832
ISSN: 0024-4082
PURE UUID: d3fb11f6-fb19-414e-aa99-aeb6b36f1415

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Date deposited: 04 Jan 2010
Last modified: 13 Mar 2024 20:48

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Contributors

Author: Beatrice Lecrocq
Author: Andrew John Gooday
Author: Masashi Tsuchiya
Author: Jan Pawlowski

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