Penardeugenia huelsmannii Dumack, Siemensma and Bonkowski, 2018
Diagnosis: Cells spherical, ovoid or pyriform, 24.0-30.4 X 16.1-27.3 µm in diameter, surrounded by a layer of siliceous scales of two types: plate-scales and spine-scales. Plate-scales consist of two triangular plates with broadly rounded vertices, 1.45-1.68 µm in diameter, joined together by three pillars, each 0.26 µm high and 0.21 µm wide, narrowing to 0.16 µm where they are attached to the proximal plate. On the distal surface of both plates the points of attachment of the pillars are revealed as holes, 50 nm in diameter, in the surface of the plates. The distance between these holes varies between 0.51 and 0.63 µm. The pillars are not hollow. Spine-scales are 6.7-7.1 µm long, excluding the basal structure. This basal structure consists of two triangular plates with rounded vertices, 0.96-1.18 µm in diameter, which are joined together by three struts, each 0.26 µm long, and their position on the distal surface is visible as a hole. The shaft of the spine is attached to the upper plate where it is eccentrically placed; the spine shaft is not hollow, tapering from 0.23 µm above the upper basal plate to 0.16 µm below the sharply pointed apex. The spine seems to be an extension of a pillar. Number of spine-scales usually 10-30. The aperture is flexible, but usually elliptical elongated, 20-24 X 6.9-7.8 µm. Pseudopodia are elongated conical and sharply pointed, up to 14 µm long and at the base up to 1.8 µm broad. Nucleus vesicular, slightly granular, with relatively small nucleolus. Nucleolus with some lacunae. Diameter of nucleus 10 µm, nucleolus 3 µm.
Dimensions: Cells are c. 20-25 µm in diameter and up to 30 µm long. There is one nucleus which is granulated with a relatively small spherical central nucleolus.
Ecology: I found these species in moss on a rock in a beech wood near Ayl, Saarburg, Germany. In my lab the moss was washed with rain water and the residue was kept in a jar. At first specimens came up in a wet mount which was kept for some days in a moist chamber.
Remarks: Though this species resembles Cochliopodium, it never spreads it tectum. The tectum also bears some spines, but it is not clear if these rods are bacteria. They can well be observed in water and also around dried specimens, but dried cells embedded in Aquamount® never showed these spines, probably because of the refractive index of that medium. After some weeks, there were a lot of specimens in the jar.
Reference: Dumack, K., Siemensma, F., Bonkowski, M., 2018. Rediscovery of the Testate Amoeba Genus Penardeugenia (Thaumatomonadida, Imbricatea). Protist, 169, 1, 29-42.