Microworld

world of amoeboid organisms

Menu

Genus Microheliella Cavalier-Smith and Chao, 2012

Diagnosis: As for the order Microhelida.

 

Microheliella maris Cavalier-Smith and Chao, 2012

Diagnosis: Characters of the genus; cell body about 4 µm, axopodia about twice that but so slender that easily overlooked.

Ecology: brackish habitat. River Ebro Delta, Spain

Remarks: Microheliella maris is so small that it is hard to see morphological characteristics under the light microscope, but it can be recognized by four:

1) radiating axopodia,
2) central centrosome,
3) the nucleus situated aside from the cell centre,
4) absence of cilia.

This morphological combination is shared only with centrohelid heliozoa and gymnosphaerids; in the light microscope alone one cannot see their tiny extrusomes and cannot tell that the axopodia actually have microtubules, as shown here for the first time. Gymnosphaerids are far larger, more complicated and adaptively quite distinct; none of those known could be confused with Microheliella. It would be hard to separate Microheliella from the smallest scale-free centrohelids (Oxnerella, Chlamydaster); the smallest of these so far described is typically three times as large as Microheliella, but there is a new species of Oxnerella which is nearly as small (7 µm as opposed to Microheliella’s 4 µm (Chao and Cavalier-Smith, unpubl. observ.). It can be distinguished from Microheliella by careful light microscopy that reveals its much larger and more obvious extrusomes (Cavalier-Smith and Chao, 2012).

Similar looking amoeboids are specimens of the genus Limnofila, which are also very small, but lack microtubules.

Recent posts

Haplomyxa spec.

Main cell body Haplomyxa spec. Description: The cell had a cylindrical flattened body from which numerous granuloreticulopodia emerged. The common shape was more or less

Read More »

Valkanovia delicatula

V. delicatula, after Valkanov, 1962 Genus Valkanovia  Tappan, 1966 Diagnosis: Shell ovoid, oblate, elliptical in cross-section, composed of elongated elliptical hyaline scales arranged in a

Read More »

Gocevia pontica

Gocevia pontica, after Valkanov, 1934 Gocevia pontica Valkanov, 1934 Diagnosis: Clearly addressed bipolarity. Body covered by a weakly flexible tectum covered with foreign bodies. The

Read More »

Nabranella

N. brevis, after Snegovaya and Alekperov, 2009 Genus Nabranella Snegovaya and Alekperov, 2009 Diagnosis: Shell oval or spherical shape without neck. Apical top flat and

Read More »

Armipyxis

Genus Armipyxis Dekhtiar, 2009 Genus Armipyxis was created by Dekhtiar (2009) to accommodate all species with internal struts. However, C. aculeata may also have struts, although

Read More »

Netzelia pseudolimnetica

N. pseudolimnetica, after Penard, 1902 Netzelia pseudolimnetica Ogden and Meisterfeld, 1989 Synonym Difflugia limnetica (Levander, 1900) Penard, 1902. D. limnetica – Pejler, 1962, Oikos, 12,

Read More »

Cylindrifflugia hiraethogii

C. hiraethogii, after Ogden. 1983 Cylindrifflugia hiraethogii (Ogden, 1983) González-Miguéns et al., 2022 Diagnosis: the shell is light yellow or transparent, thin pyriform with a distinct

Read More »

Cylindrifflugia bacillariarum

  C. bacillariarum, 103 – 114 µm – Fochteloërveen, Netherlands   Cylindrifflugia bacillariarum (Perty, 1849) n. comb. González-Miguéns et al., 2022 Diagnosis: shell transparent, colorless or

Read More »

Cylindrifflugia elegans

C. elegans, length 84-102 µm, Gaasterland Cylindrifflugia elegans (Penard, 1890) n. comb. González-Miguéns et al., 2022 Basionym: Difflugia elegans Penard, 1890 Diagnosis: shell outline rough, pyriform

Read More »

Cylindrifflugia lanceolata

C. lanceolata, shells 153-169 µm long, nuclei 23-26 µm (Naardermeer, Netherlands) Cylindrifflugia lanceolata (Penard, 1890) n. comb. González-Miguéns et al., 2022 Basionym: Difflugia lanceolata Penard,

Read More »