Gooday, A.J., Bowser, S.S., Bett, B.J., Smith, C.R. (2000). A large testate protist, Gromia sphaerica sp. nov. (Order Filosea), from the bathyal Arabian Sea. Deep-Sea Research II. 47: 55-73.

408308

Gooday, A.J., Bowser, S.S., Bett, B.J., Smith, C.R.

2000

47: 55-73

Publication

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 o! Oman (NW Arabian Sea) during RRS Discovery Cruise 211. Specimens consist of an organic envelope, with numerous tiny apertures, enclosing a mass of "ne waste pellets (stercomata). On the basis of its wall ultrastructure (revealed by high-voltage transmission electron microscopy), this organism is identi"ed as a member of the "losean 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 "rst 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 sea#oor 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.

Northern Indian Ocean

Foraminifera

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