Netzelia corona
Netzelia corona with some spines and a number of teeth

 

 

Netzelia corona (Wallich, 1864) Gooma et al., 2017

Syn.: Protocucurbitella coroniformis Gauthier-Lièvre & Thomas, 1960

 

Diagnosis: shell spherical to sub-spherical. The shell wall is composed of mineral grains, quartz and diatom  frustules, which are agglutinated together by an organic cement. The shell is ornamented by conical hollow spines at the posterior third. The aperture is circular, surrounded by a variable number of inward-oriented angular crenulations (tooth-like structures). Shells ornated with tuberculate structures similar to Netzelia tuberculata have been observed by Vucetich (1973) and Siemensma (2013, see http://www.arcella.nl/difflugia-corona,http://www.arcella.nl/difflugia-urceolata).

 

Dimensions: 140-320 µm (Leidy); 200-250 µm (Penard); 180-310 µm (Awerinzew); 180-230 µm (Cash); 155-200 µm(Hoogenraad & De Groot); 80-380 µm (Lahr & Lopes); my measurements 105-193 µm, mean 156 µm.

 

Ecology: Fresh water, in different water types; in sediments, in sphagnum, on waterplants, often very common. This species has been found in icefield lakes high in the mountains (Monti 1906).

 

Remarks: Sometimes the shell has a tuberculate structure as in D. tuberculata. The number of conical spines I counted in Dutch specimen is commonly 4-6.

 

Netzelia corona
Netzelia corona
Shell, dorsal and apertural view
Netzelia corona Difflugia corona
Netzelia corona Difflugia corona
Small spine, 33 µm long and spine with a mineral grain in the opening
Netzelia corona
Drawing: Penard, in Faune Rhizopodique du Bassin du Léman, 1902
Netzelia corona
Aperture with 12 denticulate lobes.
Netzelia corona
Each lobe is a hollow structure at the outer most part.
Netzelia corona
Shell with tubercular structure
Netzelia corona
Shell with tubercular structure - stacked image
Netzelia corona

 

Shell with crenulate structure, drawing Vucetich, 1973.
Netzelia corona

 

Netzelia corona; collection of individuals to show the variation in size and form; in number, length and shape of the spines, and the like. All drawn to the same scale. In: Jennings, 1916.