Psammina multiloculata Kamenskaya, Gooday, Tendal 2015
Creators: name: Holzmann, Maria
name: Barrenechea-Angeles, Inés
name: Lim, Swee-Cheng
name: Pawlowski, Jan
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Chromista
Foraminifera
Monothalamea
Psamminidae
Psammina
Psammina multiloculata

description: Psammina aff. multiloculata Kamenskaya, Gooday, Tendal, 2015
Supplementary Figs S4, S 5
Material examined (morphology only). BC044, RC1830
Shipboard observations. The specimen was found lying flat on the surface of the box core and was probably incomplete. In shipboard photographs it formed a flat plate, fairly elongated, more than 57 mm long and ~ 29 mm in maximum width, making it the largest specimen in our collection (Supplementary Fig. S4A). One of the longer sides was convex and probably included parts of the intact margin. The opposite side of the test was concave and appeared broken, as did the two irregularly shaped ends.
Preserved specimen. On arrival in Geneva, the plate had broken into several fragments, the largest about 13.5 mm long and 1.1–1.5 mm thick (Supplementary Fig. S5A). The following description is based mainly on observations made at this stage, since the fragments themselves had almost totally disintegrated by the time they reached Southampton.
The surface showed concentric lineations following a rather irregular, wavy course, in places comprising a series of short, curved sections to create a scalloped effect. The lineations are sometimes joined by faint transverse lines, reflecting the cell-like compartments that occupy the test interior. The outer wall is very thin (30–68 µm), delicate and easily damaged (Supplementary Fig. S5B–D). It is composed of very small mineral grains, which include a scattering of tiny orange and white grains, together with sponge spicule fragments and occasional radiolarians. The internal compartments are clearly visible in broken sections (Supplementary Fig. S5E, F) and are defined by partitions with the same thickness and composition as the external walls, with which they merge. Some of the partitions span the two outer walls more or less transversely, but overall, the compartments are not particularly regular and the partitions between them are orientated in various directions with respect to the outer walls.
Remarks. This specimen resembles Psammina multiloculata in terms of its wall structure and composition, as well as the compartmentalised test interior. However, although damaged, it is still much larger than the specimen described above (57 mm compared to only 7.5 mm!), and has a flat, plate-like morphology with no sign of a stalk or multiple radiating plates. Nevertheless, the holotype of P. multiloculata was originally described as being flat and plate-like (Kamenskaya et al., 2015). It was much smaller (24 mm) than the present specimen, although an intact example of the species described in a later study (Kamenskaya et al., 2017), which was also flat and plate-like, was closer in size (45 mm compared to 57 mm). It is therefore possible that this large plate should be assigned to P. multiloculata. However, this and the specimen described above are so different morphologically that in the absence of genetic data we prefer to keep them separate.
description: Published as part of Holzmann, Maria, Barrenechea-Angeles, Inés, Lim, Swee-Cheng & Pawlowski, Jan, 2024, New xenophyophores (Foraminifera, Monothalamea) from the eastern Clarion-Clipperton Zone (equatorial Pacific), pp. 151-188 in Zootaxa 5419 (2) on page 176, DOI: 10.11646/zootaxa.5419.2.1, http://zenodo.org/record/10792055