Xenophyophores (Rhizaria, Foraminifera), including four new species and two new genera, from the western Clarion-Clipperton Zone (abyssal equatorial Pacific)

Andrew J Gooday,Jennifer M Durden,Maria Holzmann,Jan Pawlowski,Craig R Smith

doi:10.1016/j.ejop.2020.125715

Abstract

The Clarion-Clipperton Zone (CCZ) occupies a vast swathe of the Pacific with extensive polymetallic nodule deposits. Eastern and central parts host diverse assemblages of xenophyophores (megafaunal agglutinated foraminifera). Here we describe xenophyophores obtained using a Remotely Operated Vehicle from the western CCZ. Eleven distinct forms include two known species, Stannophyllum zonarium Haeckel, 1888 and Aschemonella monile Gooday and Holzmann in Gooday et al., 2017b. Another four are described as new species based on morphological and genetic data. In Abyssalia foliformis gen. nov., sp. nov. and Abyssalia sphaerica sp. nov. the flattened or spherical test comprises a homogeneous framework of sponge spicules. Psammina tenuis sp. nov. has a delicate, thin, plate-like test. Moanammina semicircularis gen. nov., sp. nov. has a stalked, fan-shaped test and is genetically identical to ‘Galatheammina sp. 6’ of Gooday and co-workers from the eastern CCZ. Sequence data revealed a spherical ‘mudball’, which disintegrated and cannot be formally described, to be a novel xenophyophore. Finally, four morphospecies are represented by dead tests: Psammina spp., Reticulammina sp., and an unknown genus with a unique test structure. This collection enhances our knowledge of Pacific xenophyophore diversity and provides the first genetic confirmation of wide geographic ranges for abyssal species.

Highlights

1912) described further species and introduced the name ‘Xenophyophora’, regarding them as a distinct group of large agglutinated rhizopod protists
In addition to the contract areas, the International Seabed Authority (ISA) recognises a system of Areas of Particular Environmental Interest (APEIs), areas ∼100,000 km2 in extent that are currently protected from mining (Lodge et al 2014)
The third clade comprises Galatheammina spp., Semipsammina mattaeformis and an Aschemonella-like form. This small collection of xenophyophores from abyssal plains in the western Clarion-Clipperton Zone (CCZ) includes 11 morphological species, only two of which could be assigned to known species (Aschemonella monile and Stannophyllum zonarium)

Summary

Introduction

1912) described further species and introduced the name ‘Xenophyophora’, regarding them as a distinct group (order) of large agglutinated rhizopod protists. The works of Haeckel (1889), Goës (1892) and Schulze (1907) showed that xenophyophores were diverse in the abyssal equatorial Pacific; early studies described more species from here than from any other part of the deep ocean (Plate VIII in Schulze 1907) In recent years, this area, and the Clarion-Clipperton Zone (CCZ), has acquired considerable potential economic importance because it hosts rich deposits of polymetallic nodules (Petersen et al 2016). Morphological and genetic analyses of collected specimens have led to the description of new species and genera (Gooday et al 2017b, 2017c, 2018; Kamenskaya 2005; Kamenskaya et al 2015, 2017) These studies have been concentrated in the central and eastern parts of the CCZ, mainly the Russian, UK-1 and Ocean Mineral Singapore (OMS) contract areas and APEI-6 (Fig. 1 in Gooday et al 2017a). We have two main goals: 1) to describe new and known xenophyophore species based on molecular and genetic data; and 2) to compare these species with those recorded from the central and eastern CCZ

Methods

Results

Conclusion