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A large testate protist, Gromia sphaerica sp.nov. (Order Filosea), from the bathyal Arabian Sea

A large testate protist, Gromia sphaerica sp.nov. (Order Filosea), from the bathyal Arabian Sea
A large testate protist, Gromia sphaerica sp.nov. (Order Filosea), from the bathyal Arabian Sea
The deep ocean provides a habitat for several large testate protistan taxa, e.g., xenophyophores and komokiaceans. However, testate amoebae (orders Lobosea and Filosea) have never been reliably reported from below 270 m depth. Here we describe large spherical protists, up to almost 40 mm diameter, recovered in box core, multicore, and epibenthic sledge samples taken on the continental slope off Oman (NW Arabian Sea) during RRS Discovery Cruise 211. Specimens consist of an organic envelope, with numerous tiny apertures, enclosing a mass of fine waste pellets (stercomata). On the basis of its wall ultrastructure (revealed by high-voltage transmission electron microscopy), this organism is identified as a member of the filosean genus Gromia. It is described herein as Gromia sphaerica sp. nov. The wall is layered and includes the ‘honeycomb membrane', a structure that is unique to this genus. The new species is the first gromiid to be reported from the deep sea. It lives between about 1200 and 1630 m below the main oxygen minimum zone, in an area where bottom-water oxygen concentrations are around 0.47 ml l?1. The new gromiid species is clearly visible in bottom photographs taken at 1273 m (2.7 individuals m?2), 1318 m (2.7 indiv. m?2), 1624 m (17.3 indiv. m?2) and 1633 m (76.5 indiv. m?2). They lie partly embedded in the seafloor and are sometimes grouped in twos and threes. Specimens are typically surrounded by an apron of lighter-coloured sediment, possibly resulting from their feeding activities. Where they lie in very close proximity, the apron around one specimen typically obscures adjacent tests.
PROTISTS, ARABIAN SEA, OMAN MARGIN, "DISCOVERY", OXYGEN MINIMUM ZONE
0967-0645
55-73
Gooday, A.J.
d9331d67-d518-4cfb-baed-9df3333b05b9
Bowser, S.S.
dd6f39ad-d90e-431d-aed1-6dc75c4fef56
Bett, B.J.
61342990-13be-45ae-9f5c-9540114335d9
Smith, C.R.
4438caca-acef-42d2-a57b-1a1b3c1f8f27
Gooday, A.J.
d9331d67-d518-4cfb-baed-9df3333b05b9
Bowser, S.S.
dd6f39ad-d90e-431d-aed1-6dc75c4fef56
Bett, B.J.
61342990-13be-45ae-9f5c-9540114335d9
Smith, C.R.
4438caca-acef-42d2-a57b-1a1b3c1f8f27

Gooday, A.J., Bowser, S.S., Bett, B.J. and Smith, C.R. (2000) A large testate protist, Gromia sphaerica sp.nov. (Order Filosea), from the bathyal Arabian Sea. Deep Sea Research Part II: Topical Studies in Oceanography, 47 (1/2), 55-73. (doi:10.1016/S0967-0645(99)00100-9).

Record type: Article

Abstract

The deep ocean provides a habitat for several large testate protistan taxa, e.g., xenophyophores and komokiaceans. However, testate amoebae (orders Lobosea and Filosea) have never been reliably reported from below 270 m depth. Here we describe large spherical protists, up to almost 40 mm diameter, recovered in box core, multicore, and epibenthic sledge samples taken on the continental slope off Oman (NW Arabian Sea) during RRS Discovery Cruise 211. Specimens consist of an organic envelope, with numerous tiny apertures, enclosing a mass of fine waste pellets (stercomata). On the basis of its wall ultrastructure (revealed by high-voltage transmission electron microscopy), this organism is identified as a member of the filosean genus Gromia. It is described herein as Gromia sphaerica sp. nov. The wall is layered and includes the ‘honeycomb membrane', a structure that is unique to this genus. The new species is the first gromiid to be reported from the deep sea. It lives between about 1200 and 1630 m below the main oxygen minimum zone, in an area where bottom-water oxygen concentrations are around 0.47 ml l?1. The new gromiid species is clearly visible in bottom photographs taken at 1273 m (2.7 individuals m?2), 1318 m (2.7 indiv. m?2), 1624 m (17.3 indiv. m?2) and 1633 m (76.5 indiv. m?2). They lie partly embedded in the seafloor and are sometimes grouped in twos and threes. Specimens are typically surrounded by an apron of lighter-coloured sediment, possibly resulting from their feeding activities. Where they lie in very close proximity, the apron around one specimen typically obscures adjacent tests.

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Published date: 2000
Keywords: PROTISTS, ARABIAN SEA, OMAN MARGIN, "DISCOVERY", OXYGEN MINIMUM ZONE

Identifiers

Local EPrints ID: 8782
URI: https://eprints.soton.ac.uk/id/eprint/8782
ISSN: 0967-0645
PURE UUID: 6efbe904-4b1e-4b98-9493-42a97367281e

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Date deposited: 25 Aug 2004
Last modified: 17 Jul 2017 17:12

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Contributors

Author: A.J. Gooday
Author: S.S. Bowser
Author: B.J. Bett
Author: C.R. Smith

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