Phorticium, Haeckel, 1887

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 : 41-42

Genus PHORTICIUM Haeckel, 1887 sensu emend.

*1887 Phorticium Haeckel , p. 709.

1954 Phorticium Haeckel ; Campbell, p. D100.

Type species. Phorticium (Phortopyle) pylonium Haeckel, 1887 (SD by Campbell, 1954).

Description. Test is rounded, flat, and quadrangular in shape and consists of a central combination with one or two pseudo-concentric shells. The central combination is ellipsoid in shape and comprises an S1a with a twin girdle that is designated the G1 girdle. Each of these twin girdles has a circular to ellipsoid aperture. The Lt-, Pl-, and Sg-axes are clearly determined based on their definitions. The shape of the 1st pseudo-concentric shell is similar to that of the central combination. The 1st pseudo-concentric shell is fully latticed or has twin opposite gates. The gates open on both sides of the 1st pseudo-concentric shell along the Ug-axis direction. Polar beams may or may not be present along the Ug-axis from one or both sides of the 1st pseudo-concentric shell. The 1st and 2nd pseudo-concentric shells are connected with numerous thick pillar beams on both sides of the shells. Pillar beams are sparse in the gates between adjacent pseudo-concentric shells.

Remarks. A good reference for the internal structure of Phorticium is Sugiyama et al. (1992, plate 10, figures 1-9). Phorticium is characterized by gates between each pseudo-concentric shell oriented in nearly the same direction. Phorticium and Tetrapyle can be differentiated based on the presence or absence of the S1a-girdle, but Phorticium also tends to have numerous pillar beams between pseudo-concentric shells. This criterion is applicable for these two genera.