Cocinocassis pontigulasiformis
C. pontigulasiformis, c. 60 µm large - Tirol, Austria, stacked image



Genus Cocinocassis  Nasser and Anderson, 2015


Diagnosis: A genus of Centropyxidae characterized by dorsoventrally symmetric, ovoid to subspherical test typically comprised of agglutinated particles obtained from the environment, round aperture and diagnostic very large and asymmetrically oriented conical to funnel-like apertural flange extending from a small circular aperture.


Description: Test free; unilocular; ovoid to subspherical to spherical; subcircular in cross section; test dorsoventrally symmetrical in most cases; test wall comprised of agglutinated particles derived from mineral or biologic sources bound together with an organic cement; aperture circular; proportionately very large conical to funnel-shaped and typically asymmetrically oriented flange extends from aperture; broad apertural rim recurved inward and comprised of fine agglutinated grains.


Types and Occurrence: Very wet mosses and aquatic environments in High Arctic regions of Europe and North America; lacustrine environments in the Central Northwest Territories of Canada; and peatlands in Germany, the Netherlands and Austria.


Dimensions: Length: 90–150 μm; width: 50–100 μm. Main test body: 50–100 μm across in all dimensions; funnel-shaped apertural flange: 25–50 μm across.


Remarks: Many of the diagnostic test features characterizing members of the family Centropyxidae (e.g., dorsoventral symmetry, chitinoid test and circular to oval aperture) are maintained in the new genus, Conicocassis. Therefore, Conicocassis is recognized as a member of the family Centropyxidae along with the genus Centropyxis. However, the new genus is readily distinguished from Centropyxis in having a two-component test comprised of an ovoid to subspherical main body, and a relatively very large conical to funnel-like and asymmetrically positioned flange extending out from a small circular aperture. In contrast Centropyxis tests tend to be beret-like to discoidal shaped with an invaginated ventral aperture.


Reference: Nasser, N,. A. and Patterson, R. T. 2015. Conicocassis, a new genus of Arcellinina (testate lobose amoebae). Palaeontologia Electronica 18.3.46A: 1-11