Acanthocystis pectinata
Scales of A. pectinata, the Netherlands, REM photomicrograph – Eckhard Voelcker

Acanthocystis pectinata Penard, 1889, emend. Siemensma & Roijackers, 1988

Diagnosis: Cell diameter 15-20 µm. Periplast with plate-scales and two kinds of spine-scales: short and long spine-scales. Short spine-scales all of the same length, 2.1-3.1 µm long, with a cylindrical, hollow and straight shaft, 0.25 µm thick; apex cup-shaped, 0.8-1.4 µm wide and with 4-6 long, diverging sharp teeth, interconnected by a thin membrane; basal plate 0.43-1.2 µm in diameter, conical, circular, with a fairly thick margin. Long spine-scales not abundantly present, 6.0-10.2 µm long with the apex terminating in 2-3 short teeth; no intermediate lengths between the short and the long spine-scales were observed. Plate-scales 1.6-2.5 X 1.3-1.6 µm, oblong to slightly ovoid with faintly concave sides with a broad marginal area ornamented with a pattern of small granules arranged in more or less concentric or radial rows. Similar plate-scales were observed by Dürrschmidt (1987a) and assigned to a new subspecies, A. pectinata ceylanica.

Remarks: I have studied many specimens in vivo. Their habitus was in every aspect as described by Penard (1889, 1904) and Rainer (1968). The ring of short spine-scales is very helpful in identifying this species by light microscopy. In all specimens I detected a few thin, long spine-scales as reported by Rainer (1968). In vivo these spines are hardly detectable between the axopods. The diagnosis given by Penard (1889, 1904) and emended by Rainer (1968) is therefore sufficient to identify this species, even by light microscopy.

Acanthocystis pectinata
Acanthocystis pectinata, light microscope; arrows indicate v-shaped apex.
a long spine-scale; b short spine-scale, apical view; c plate-scales
Recent posts

Microcorycia spec. 4

Microcorycia spec. , folded Microcorycia spec.? I found this specimen in a sample from moss on a fallen tree in a marsh in the Naardermeer,

Read More »

Microchlamys spec.

Microchlamys spec., the same cell in lateral view Microchlamys spec. Diagnosis: Shell relatively high compared with all described species. The diameter is twice the height.

Read More »


Infraorder Excentrostoma Kosakyan et al., 2016   Diagnosis: Testate amoebae with an eccentrically placed aperture; test organic with few or many xenosomes. Family Centropyxidae Jung, 1942  

Read More »


Infraorder Longithecina Kosakyan et al., 2016   Diagnosis: Testate amoebae with a more or less tubular or cylindrical test and a terminal aperture; test with

Read More »