Tholomura, Haeckel, 1887 sensu emend. Suzuki

Zhang, Lanlan & Suzuki, Noritoshi, 2017, Taxonomy and species diversity of Holocene pylonioid radiolarians from surface sediments of the northeastern Indian Ocean, Palaeontologia Electronica (Cambridge, England: 2003) 7 (8), pp. 1-68 : 57

Genus THOLOMURA Haeckel, 1887 sensu emend. Suzuki in Matsuzaki, Suzuki, and Nishi, 2015a

*1887 Tholomura Haeckel , p. 672.

2015a Tholomura Haeckel ; Matsuzaki, Suzuki, and Nishi, p. 36 (See the full synonymy).

Type species. Tholomura (Tholomura) metallasson Haeckel, 1887 (SD by Campbell, 1954).

Description. Test consists of an S1a (microsphere) and several levels of three sets of dome-shaped cupolas. A set of dome-shaped cupolas consists of twin cupolas positioned at opposite sides along one of the axes of Type 1 coordinates. Three sets of dome-shaped cupolas are mutually oriented to form one level of the test, equivalent to a pseudo-concentric shell. This mutually arranged cupola system is repeated in the same way to form successive pseudo-concentric shells. Rods extend from both sides of the S1a to pierce through the twin cupolas along the Lt-axis under Type 1 coordinates. Two types of radial spines are recognizable as polar spines and main spines. Polar spines extend along the Type 1 coordinate axes, whereas main spines pierce through the joint zones of the four cupolas. The development state of radial spines varies with different ontogenetic stages. The sutures between the cupolas develop in varying degrees.

Remarks. To identify Tholomura species, the apparent difference based on the orientation of the test and on ontogenetic growth stages must be carefully examined. Specifying the orientation of the test is essential to identify the specimen in the first stage. In the next step, the corresponding relationships among differently oriented specimens is determined based on the size of the same pseudo-concentric shells, pore patterns, and the development of the sutures between cupolas. This genus differs from the family Larnacillidae Haeckel, 1887 , in having dome-shaped cupolas instead of girdles with gates.