Pompholyxophrys Archer, 1869 (ref. ID; 3691) or Archer, 1869 emend. Roijackers & Siemensma, 1988 (ref. ID; 4747)
Phylum Rhizopoda von Siebold, 1845: Class Filosea Leidy, 1879: Order Cristidiscoidida Page, 1987: Family Pompholyxophryidae Page, 1987 (ref. ID; 4747)

Synonym Hyalolampe Greeff, 1869 (ref. ID; 3541, 3691, 4149)

[ref. ID; 1618]
Spherical; outer mucilaginous envelope with minute colorless spherical granules arranged in concentric layers; contractile vacuoles; pseudopodia long, straight, acicular; fresh water. (ref. ID; 1618)

[ref. ID; 1923]
Nucleus eccentric, generally a central corpuscle from which the axial filaments arise. Spicules closely united. Skeletal elements globular, forming a compact envelope completely surrounding the body. (ref. ID; 1923)

[ref. ID; 4149]
The genus Pompholyxophrys contains three species of amoeboid organisms which have rounded bodies, fine radiating pseudopodia, and a layer of small adhering siliceous spheres ("perles") (Rainer, 1968). Organisms belonging to this genus were initially described in the same year by Archer under the name Pompholyxophrys punicea and by Greeff as Hyalolampe fenestrata. Greeff later assigned priority to Archer's name. Two further species have been assigned to the genus: P. exigua (Hertwig & Lesser, 1874) and P. ovuligera (Penard, 1904). (ref. ID; 4149)

[ref. ID; 4747]
Emended diagnosis; Cells covered with a layer of siliceous structures in the form of spherical, ovoid, discoid or bone-shaped elements of a single type within a species. The term "scales" is preferred for these structures, rather than "plate-scales" or "spicules". Scales up to 8 um long. The scales wall consists of many small beads, arranged in a hexagonal pattern. The scales are hollow; within the scales of some species internal struts may be observed, which can interconnect the upper and lower plates of the flattened scales. 7 species, all EM studied. (ref. ID; 4747)
Type species; Pompholyxophrys punicea (ref. ID; 4747)

Pompholyxophrys degrooti Roijackers & Siemensma, 1988 (ref. ID; 4747 original paper)
Diagnosis; Cells covered with a layer of broadly elliptical or circular, discoid scales. Diameter of the scales 2.8-6.6 um. Scales hollow, with internal struts that connect the upper and lower plates of the scales. There are 13 beads per micrometre on the cell surface. The struts have the form of a pillar, with both ends branched like the roots of tree. We have seen these structures with the SEM in broken scales. The existence of these pillar-like struts is also indicated by the surface structure of the scales. This surface shows many pale spots, obviously the position where the struts are fused to the scales wall. From SEM-observations we conclude that the stellate pillars are identical with the stellate structures observed by TEM. (ref. ID; 4747)
Etymology; This species is named after the late Dr. A.A. De Groot, a Dutch pioneer in the field of rhizopods. (ref. ID; 4747)
Type locality; freshwater in Sweden. (ref. ID; 4747)
Pompholyxophrys exigua (Hertwig & Lesser, 1874) (ref. ID; 3541, 3691), (Hertwig & Lesser, 1874) Penard, 1904 (ref. ID; 4747)
Syn; Hyalolampe exigua Hertwig & Lesser, 1874 (ref. ID; 3541, 3691); Pompholyxophrys exigua Penard, 1904 (ref. ID; 3541)
Diagnosis; Cells with covering of scales 15-29 um in diameter. Cells covered by a layer of small spherical scales, 0.8-3.2 um in diameter. The scales of individual cells are more or less of uniform in size, differing from those of P. punicea, which vary in size. Air-dried scales are commonly dented, but it is not clear if these dented scales are common present in living cells or are the result of preparation procedures. Dented scales were also noticed and illustrated by Nicholls and Durrschmidt (1985) and they indicate the probability of a specific character. The 15 beads per 10 um, reported by those workers, is obviously a misprint and should be 15 per 1 um. (ref. ID; 4747)
Pompholyxophrys ovuligera Penard, 1904 (ref. ID; 3541, 3691 original paper, 4731, 4747)
Description; The scales observed were of similar size and shape variability to those pictured by Nicholls and Durrschmidt (1985) with most being ovoid, 1.1-2.2 um, wide x 1.7 to 2.8 um long, with pores 0.04-0.05 um in diameter. (ref. ID; 4731)
Cells covered with layer of hollow, ovoid scales. These scales are 0.7-3.2 um in diameter, without any internal struts. Ca. 10 beads per micrometre on the cell surface. Air-dried scales easily collapse. This species must be carefully distinguished from P. stammeri, which has also ovoid scales. In side view, the difference is obvious: scales of P. ovuligera have distinctly convex sides, whereas the distal and proximal layer of the scales of P. stammeri run nearly parallel. (ref. ID; 4747)
Pompholyxophrys punicea Archer, 1869 (ref. ID; 3541, 3691, 4149, 4747) reported year? (ref. ID; 1618, 1923, 3497)
Syn; Hyalolampe fenestrata Greeff, 1869 (ref. ID; 3691); Hyalolampe fenestrate Greeff, 1869 (ref. ID; 3541)
Description; Body colorless or reddish, with usually many colored granules and green or brown food particles; solitary, active; in pools. (ref. ID; 1618)
The siliceous spherical globules usually in 3 rows about the body. Endoplasm usually reddish, containing numerous colored granules and vegetable food particles. Nucleus spherical, large, eccentric. Pseudopodia very tenuous and indistinct. Habitat ponds and swamps. (ref. ID; 1923)
The cell has a large nucleus with a small karyosome and no common contractile vacuole. Pores of the reticulate test are numerous, small and round. (ref. ID; 3497)
[Light microscopy]: Living cells have spherical bodies. Those observed in this study had diameters from 25 to 40 um. The body supported a layer, 5-7 um thick, of siliceous spheres ("perles"). The perles of any individual cell varied in size, with the largest having a diameter of 5 um. Ultrastructural examination showed that 70% of the profiles fell within a range of 1.0 to 2.5 um. Long, immotile bacteria adhered to the layer of perles. The cytoplasm was tinged with an orange color and filled with numerous food vacuoles. Each cell contained a single eccentric nucleus with a prominent nucleolus. The pseudopodia were fine and relatively stiff. They were able to bend and bore occasional blebs, but they were not seen to divide or fuse. No axonemes or extrusomes were evident. No cysts were seen. (ref. ID; 4149)
[Ultrastructural observations]: Each cell was surrounded by a layer of perles. In any one cell the perles were of varying sizes, with the largest lying centrifugally. Different cells exhibited slight differences in the sizes of perles that were present. The perles were evident after resin embedding and their presence used to identify cells for sectioning. The eccentric nucleus was surrounded by a layer of closely adpressed dictyosomes. The bulk of the cytoplasm was occupied by food vacuoles, which often contain recognizable remains of algal cells such as diatom frustules. Mitochondria, which were distributed throughout the cytoplasm, had flat cristae with pedicel-like supports. Lipid droplets were often associated with irregularly shaped, membrane-bounded organelles. Ribosomes occurred both in association with rough endoplasmic reticulum and as cytoplasmic clusters. The most superficial layer of cytoplasm was often homogenous and finely filamentous. Most organelles were excluded from it. The same consistency characterized the cytoplasm of pseudopodia. A patchy coat of fine treads was sometimes seen on the outer surface of the plasma membrane. The perles were comprised of two layers of fused beads of silicon. In grazing sections tangential to the surface, the silicon may be seen to be arrayed in a roughly hexagonal lattice. The cytoplasm typically contained many perles in stage of development and/or recycling, as perles may be taken into food vacuoles. Most perles tended to have a spherical or ovoid profile. Even at the earliest identifiable stages of development, presumptive perles fall within the size range of those lying outside the cell. At the onset of perle development, a layer of fine filamentous (organic?) material may be found adhering to the luminal face of the membranes of the perle-forming vacuoles, and this material is highly patterned. Silicon accretes on this material until a substantial two-layered structure is formed. The vacuole containing the completed structure is then surrounded by a layer of homogeneous cytoplasm and moved to the surface of the cell prior to expulsion to the outer surface. No cytoplasmic microtubules were seen at any time, nor were identifiable microtubule-organizing organelles or extrusomes. (ref. ID; 4149)
Cells 24-42 um in diameter; including the covering of scales 24-65 um in diameter. Cells covered with spherical scales, 1-7.5 um in diameter and hollow; no internal structures are observed. Ca. 11 beads per micrometre were counted on the cell surface. When air-dried, the scales hardly collapse, nor do they show irregularities in their outline. This species differs from P. exigua in having scales which vary strongly in size on any individual cell. (ref. ID; 4747)
Type locality; Freshwaters in the Netherlands, Denmark and Sweden. (ref. ID; 4747)
Measurements; Diameter 25-35 um; outer envelope 5-10 um larger. (ref. ID; 1618)
Diameter 25-30 um. (ref. ID; 1923)
Diameter of a test 20-30 um. (ref. ID; 3497)
Pompholyxophrys stammeri (Rainer, 1968) Roijackers & Siemensma, 1988 (ref. ID; 4747 redescribed paper)
Emended diagnosis; Cells 27-66 um in diameter, including the scales. Cells covered with a layer of overlapping, elliptical flattened, hollow scales, 2-6 um in diameter. There are 11-12 beads pro micron on the scale surface. This species was described by Rainer (1968) as Pinaciophora stammeri. The scales were described by Rainer (1968) as scales of irregular, commonly elliptical shape with are irregularly bordered central hole, which has a somewhat collar-like raised border. The identity of the Dutch and Swedish specimens with the species designated by Rainer (1968) as Pinaciophora stammeri is beyond doubt. The specimens were often studied in vivo by light microscopy (Siemensma 1981). Electron microscopic examination of this species revealed two interesting points. The scales were very different in structure from those in the genera Pinaciophora and Rabdiophrys, but were very much like those in the genus Pompholyxophrys. Furthermore, most of the scales were collapsed in their central part, obviously due to preparation procedures (air-drying); these collapsed scales even showed the collar-like raised borders as described by Rainer (1968). It was in fact these collapsed scales that were described by Rainer (1968) as Pinaciophora scales. This species is therefore transferred to the genus Pompholyxophrys. (ref. ID; 4747)
Pompholyxophrys stellata Durrschmidt & Nicholls, 1985 (ref. ID; 4747)
Emended diagnosis; Scales with intercalary pillar-like struts are described for P. degrooti. Both ends of the struts have stellate structures. Nicholls and Durrschmidt (1985) gave excellent photomicrographs in which these stellate pillars are visible in TEM. In SEM these struts are visible in broken scales or indicated by a spotted surface structure. Scales with such internal struts hardly collapse when air-dried. Only the central part of the scale surface may collapse, as struts are lacking. (ref. ID; 4747)
Type locality; Freshwaters in the Netherlands and Sweden. (ref. ID; 4747)