Astroperula dumacki Siemensma and Holzmann, 2023
Diagnosis: Multinucleate organic-walled monothalamous foraminifera. Cells spherical to pyriform bi-symmetrical with curved dorsal side and flatter ventral side. Shell wall flexible, colorless and smooth. Aperture terminal, oblique. Peduncle more or less trumpet-shaped, eccentrically located and varying in length, surrounded by a hyaline peduncular sheath. Radiating network of granuloreticulopodia. Cytoplasm with numerous yellowish crystalline birefringent crystalline rod-shaped bodies.
Ecology (Type locality): On submerged basalt rocks at the base of a dike along the northern part of Gooimeer, a freshwater lake in the Netherlands (52°18’18.5″N 5°18’50.1″E).
Description. The test is monothalamous and organic walled, hyaline and colorless, flexible, smooth and delicate. The stationary cell is spherical, during locomotion it is bi-symmetrical, with the pseudopodial peduncle located on the ventral side. The maximum length of the observed specimen is 122 µm, the ventral-dorsal distance about 75 µm. The peduncle is almost half the length of the cell, approximately 60 µm, and 4-6 µm thick. The aperture is located terminally. From the peduncle radiate some long granuloreticulopodia, forming one or two leading strands and one or more trailing ones. The cytoplasm flows continuously in all directions within the cell, containing food vacuoles, some contractile vacuoles, many small spherical granules, about 1 µm in diameter, and numerous yellow, birefringent rod-shaped crystalline inclusions, each attached to a spherical non-refractive body. It was not possible to detect any nucleus or nuclei in the living cell.
Differential diagnosis. Astroperula dumacki is distinguished from A. parvipila by its larger size, approximately 122 µm versus approximately 65 µm, these measurements, however, are based on single individuals in each species. It is distinguished from Lieberkuehnia wageneri and C. lachmannii by yellow, birefringent rod-shaped crystalline cell inclusions that are absent in the latter two species. Based on observed morphological characters it cannot be distinguished with certainty from Velamentofex species. A. dumacki branches with A. parvipila and environmental clone LCSA1 obtained from a French agricultural soil sediment (Lejzerowicz et al., 2010). The branching is supported by a bootstrap value of 100%. The group clusters at the base of Lieberkuehniidae and Limnogromiidae, albeit without bootstrap support. Sequence length of A. dumacki is 1194 nucleotides, the GC content is 41%.
Observed food. Diatoms.
