Leptohalysis sp. 1

Kitazato, Hiroshi, Uematsui, Katsuyuki, Todo, Yuko & Gooday, Andrew J., 2009, New species of Leptohalysis (Rhizaria, Foraminifera) from an extreme hadal site in the western Pacific Ocean, Zootaxa 2059 (1), pp. 23-32 : 29

Leptohalysis sp. 1

Fig. 3

Material examined: A single specimen mounted on an SEM stub

Description. Test morphology. Test comprises straight, linear series of 10 chambers. Overall length 113 µm; length:width ratio 4.8. Spherical proloculus 7.1 µm diameter. Chambers more tightly pressed against each other than in L. kaikoi , and sutures between them less pronounced, so that overall appearance is more compact. Smallest (proximal) chamber 11.2 µm diameter; largest (distal) chamber 23.5 µm diameter. Aperture not clearly visible, but appears to be simple opening at end of final chamber, as in L. kaikoi .

Wall structure and composition. Wall comprises tiny agglutinated particles and fibrous organic cement. Particles thin, flake-like, irregular in shape, measuring from <1 micron to several microns in size. They are embedded haphazardly in cement, which is dominant test component and typically forms rounded, coalescing, sponge-like, hummocky masses. As in L. kaikoi , cement consists largely of anastomosing, bar-like elements with small, flat areas, probably tiny clay particles. X-ray microanalyses of particles reveals dominant peaks for Al and Si and also presence of Mg, Mn, Fe, Ca, K and Na in varying amounts. Peaks more numerous than in L. kaikoi , reflecting smaller grain size and consequent contamination of signal by surrounding area.

Proloculus covered by thin veneer of particles; most rod-like and <0.5 µm in length but few larger (~1.5 µm), plate-like grains also present. X-ray microanalyses similar to those for L. kaikoi proloculus, with peaks for Si and Al as well as Mg, Ca and Fe.

Remarks. Compared to L. kaikoi , this species has a more compressed test and the divisions between the chambers are less distinct. Moreover, the wall structure as seen in the SEM is distinctly different from that of L. kaikoi . In particular, the agglutinated particles are smaller and are stuck haphazardly into the masses of cement, rather than lying flat.

Figures

FIGURE 3: Leptohalysis sp. 1, scanning electron micrographs. A: Complete specimen. B: Proximal end showing organic-walled proloculus with some plate-like grains. C: Final chamber. D–E: Progressively closer views of final chamber showing mesh-like masses of organic cement and flake-like mineral grains. F: Central part of test. G: Close view showing cement and agglutinated grains.