Microworld

world of amoeboid organisms

Menu

Cercozoa Cavalier-Smith 1998, emend. Adl et al. 2005; emend. Cavalier-Smith 2018

Diagnosis: Diverse clade lacking distinctive morphological or behavioural characters; biciliated and/or amoeboid, usually with filopodia; most with tubular mitochondrial cristae; cysts common; kinetosomes connecting to nucleus with cytoskeleton; usually with microbodies and extrusomes.

Imbricatea Cavalier-Smith 2011
Test proteinaceous, with calcified inner layer, or completely chitinoid with recycled mineral particles; pseudopodia conical, pointed, clearly ectoplasmatic, sometimes branched and may anastomose; Cryptodifflugia stands out by having orthomitosis, but it is unclear if this feature is characteristic for the group.

Thecofilosea Cavalier-Smith 2003, emend. Cavalier-Smith 2011
With robust organic extracellular theca, unlike most other Cercozoa, which are usually naked or with scales; ventral filose pseudopodia emerge from ventral groove; two cilia with divergent kinetosomes, secondarily lost in Rhizaspidae and the euglyphid amoebae, and restricted to zoospores in phaeodarians; ancestrally benthic gliding on posterior cilium only, but some secondarily planktonic swimmers amongst which ebriids have lost pseudopodia; theca with perforations for cilia and for pseudopodia, and three perforations in phaeodaria (thus also called Tripylea Hertwig 1879), which have surrounded it by a pseudopodial net containing a pigmented phaeodium, thus converting it into a ‘central capsule’, but not homologous with that of Polycystinea of Radiolaria; silica scales absent, unlike many Imbricatea, but hollow silica endoskeleton in all ebriids and most phaeodarians.

Granofilosea Cavalier-Smith & Bass 2009
With very fine branching or unbranched granuloreticulopodia bearing obvious extrusomes as the granules at frequent rather regular intervals, or with radiating, sometimes branched, axopodia with similar granules; pseudopodia supported by internal microtubules and typically appressed to the substratum during feeding, in a semi-immobile state; in most species, pseudopodia do not anastomose; some with biciliated swimming or gliding stage.

Incertae sedis: Chlamydophryidae de Saedeleer 1934: Capsellina, Chlamydophrys, Clypeolina, Diaphoropodon, Lecythium, Leptochlamydophrys, Penardeugenia.


Note: this is not a complete overview of Cercozoa.

After Adl et al, Revised Classification of Protozoa, 2012

Cercozoa is a diverse, increasingly well characterized phylum of protists founded mainly on the basis of 18S rDNA phylogenies that revealed a phylogenetic relationship between a variety of gliding zooflagellates and filose amoebae and the plasmodiophorid plant parasites. This diversity of cercozoan body forms includes:

• filose testate amoebae
• amoeboflagellate algae
• zooflagellates with pseudopodia and siliceous scales
• diverse parasites
• naked reticulose amoebae
• testate reticulose amoebae
• colonial flagellates
• planktonic swimming flagellates
• numerous small gliding flagellates
• helioflagellates
• soft-bodied amoeboflagellates
• thecate or scaly amoeboflagellates with a marked groove or cleft
• and even protists with axopodia

Recent posts

Organic-walled species

Specimen with an optical cross-section of the peduncle (left) Organic-walled species Diagnosis: Multinucleated organic-walled monothalamous foraminifera. Test spherical to oval shaped, with a hyaline, flexible,

Read More »

Velamentofex tyrolensis

V. tyrolensis, two specimens Velamentofex tyrolensis Völcker and Clauß, 2020 April 2022, I found two specimens in a sample from the pond in Crailoo, Netherlands. I could

Read More »

Raphidiophrys spec. nov.

Raphidiophrys n. sp. Raphidiophrys n. sp. Diagnosis: Plate-scales canoe-shaped, elongated, with tapering, rounded poles, slightly curved upwardly. Light microscopically, these plate-scales show a clear rim;

Read More »

Lacogromia spec. Naardermeer

Lacogromia sp., Naardermeer, the Netherlands, 2022 (n=nucleus) Lacogromia sp. Six living specimens were found in an old sediment sample from a freshwater ditch in nature

Read More »

Sphenoderia rhombophora

S. rhombophora , after Bonnet, 1966 Sphenoderia rhombophora Bonnet, 1966 Diagnosis: Test hyaline, ellipsoidal, very slightly compressed. Fundus relatively narrow. Pseudostome largely truncated. Neck very

Read More »

Sphenoderia ovoidea

S. ovoidea , after Jung, 1942 Sphenoderia ovoidea Jung, 1942 Diagnosis: Shell with four layers of plate-scales. Distinguished from S. fissirostris by the ovoid tapering

Read More »

Sphenoderia truncata

S. truncata , after Van Oye, 1949 Sphenoderia truncata Van Oye, 1949 Diagnosis: Shell smooth and diaphanous, with usually pentagonal, sometimes hexagonal, inconspicuous plates. The

Read More »

Nebela gimlii

N. gimlii, from Singer and Lara, 2015 Nebela gimlii Singer and Lara, 2015 Diagnosis: Test wide pyriform or drop-shaped, laterally compressed, with a protruding narrow

Read More »

Sphenoderia, with granules

Overview Sphenoderia S. compressa S. fissirostris S. labiata S. lenta S. macrolepis S. minuta S. ovoidea S. rhombophora S. sphaerica S. splendida S. truncata

Read More »

Nebela overview

Nebela overview N. acolla N. aliciae N. aliciae N. barbata N. bohemica N. carinatella N. collaris N. flabellulum N. gimlii N. golemanskyi N. nebeloides N.

Read More »