Phorticium polycladum Tan and Tchang, 1976

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 : 43-45

Phorticium polycladum Tan and Tchang, 1976

Figure 25

1976 Phorticium polycladum Tan and Tchang , p.

267, text-fig. 39a-b. 1980 Pylospira octopyle Haeckel ; Boltovskoy and

Riedel, pl. 4, fig. 7. non 1983 Phorticium polycladum Zhiyuan et Tso-run

(author’s names are wrong); Srinivasan,

Lombari, and Dave, p. 11, pl. 2, figs. 9. non 1984 Phorticium polycladum Tan and Tchang ;

Nigrini and Lombari, p. S83-84, pl. 12, fig.

1a-b. non 1987 Phorticium polycladum Tan and Tchang ;

Akers, Marolt, and Navarette, p. 16, pl. 3,

figs. 9, 11. non 1988 Phorticium polycladum Tan and Tchang ;

Sharma and Sharma, pl. 2, fig. 9. non 1992 Phorticium polycladum Tan and Tchang ;

Gupta and Srinivasan, pl. 2, fig. 15. non 1993 Phorticium polycladum Tan and Tchang ;

Sharma and Singh, pl. 2, fig. 20. 1995 Pylonidae gen. et sp. indet. van de Paverd,

pl. 58, fig. 11 (only). 1996 Phorticium polycladum Tan and Tchang ;

Chen and Tan, p. 199-200, pl. 23, figs. 12-

13. non 1999 Phorticium polycladum Tan and Tchang ;

Sharma, Singh, and Rawal, pl. 3, fig. 7.

1999 Phorticium polycladum Tan and Tchang ; Tan and Chen, p. 255, text-fig. 5.168.

non 2003 Phorticium polycladum Tan and Tchang ; Sharma and Ram, pl. 3, figs. 16-17.

2008 Phorticium polycladum Tan and Tchang ; Kamikuri, Motoyama, and Nishimura, pl. 2, fig. 15.

2009 Phorticium polycladum Tan and Tchang ; Itaki, p. 47, pl. 11, fig. 4.

2013 Phorticium clevei (JØrgensen); Hernández-Almeida, BjØrklund, Sierro, Filippelli, Cacho, and Flores, pl. 3, fig. 2 (only).

2014a Phorticium pylonium Haeckel ; Matsuzaki, Nishi, Hayashi, Suzuki, Ikehara, Gyawali, Tanaka, and Takashima, fig. 2.9.

2014c Phorticium polycladum Tan and Tchang ; Matsuzaki, Nishi, Suzuki, Kawate, Takashima, and Sakai, pl. 1, fig. 20.

2014d Phorticium polycladum Tan and Tchang ; Matsuzaki, Nishi, Suzuki, Takashima, Kawate, and Sakai, pl. 2, fig. 3.

non 2015a Phorticium polycladum Tan and Tchang ; Matsuzaki, Suzuki, and Nishi, p. 32, fig. 6.13-14.

2015b Phorticium polycladum Tan and Tchang ; Matsuzaki, Suzuki, Nishi, Hayashi, Gyawali, Takashima, and Ikehara, fig. 7.13-14.

Description. The test is large and ellipsoid in shape (the length ratio of the Ug-axis to the Pr-axis in Type 2 coordinates: ca. 1.1–1.2) in Sg-view, and it consists of an elongate central combination, a rounded rectangular 1st pseudo-concentric shell, a large 2nd pseudo-concentric shell with two large apertures in one side of the test in Sg-view, numerous pillar beams between the central combination and 1st pseudo-concentric shell and between the 1st and 2nd pseudo-concentric shells, and numerous radial spines. An incomplete 3rd pseudo-concentric shell develops in the fully mature form. The 1st and 2nd pseudo-concentric shells are arranged in a common orientation. The 1st pseudo-concentric shell has two gates in the juvenile form in the absence of the 2nd pseudo-concentric shell, and it is completely latticed in the mature form with a partial 2nd pseudo-concentric shell. Many pillar beams are present between the central combination and the 1st pseudo-concentric shell, and between the 1st and 2nd pseudo-concentric shells. Some pillar beams from the 1st pseudo-concentric shell pierce through the 2nd pseudo-concentric shell to form cylindrical radial spines. The spines between the adjacent girdles of each pseudo-concentric shell tend to be longer than other radial spines. Pores are subcircular and small (5–8 μm in diameter) on the 1st pseudo-concentric shell, polygonal and

ZHANG & SUZUKI: TAXONOMY OF HOLOCENE PYLONIOID moderate in size (8–16 μm in diameter) on the 2nd pseudo-concentric shell, and polygonal and large (16–35 μm in diameter) on the 3rd pseudo-concentric shell. Four or five pores are aligned along the Lt-axis at the joint between the 1st and 2nd pseudo-concentric shells, and 10 to 14 pores are aligned along the Pl-axis on the 2nd pseudo-concentric shell. The pore frames of the 1st and 2nd pseudo-concentric shells are very thin. The size ratio of the 2nd pseudo-concentric shell to the 1st pseudo-concentric shell is 1.8–2.0 along the Lt-axis and 1.9–2.3 along the Pl-axis.

Remarks. Phorticium polycladum Tan and Tchang, 1976 , is characterized by its large 1st and 2nd pseudo-concentric shells, the large size ratio between the 2nd pseudo-concentric shell to the 1st pseudo-concentric shell, and its many radial spines. Nigrini and Lombari (1984) included a morphotype with a smaller size ratio of the 2nd pseudo-concentric shell to the 1st pseudo-concentric shell (1.7 along the longer axis of the test and 1.8 along the middle axis of the test, as shown in plate 12, figure 1a and 1b) and a higher number of pores on the 2nd pseudo-concentric shell (7–8 pores and 14 pores are visible along the Fr-axis and the Pr-axis, respectively), but this smaller morphotype is inferred to be a different species because no intermediate forms were detected in our samples. Phorticium polycladum is distinguishable from Phorticium pylonium Haeckel, 1887 , because the former has larger pores on the 2nd pseudo-concentric shell, robust pillar beams between the 1st and 2nd pseudo-concentric shell, and robust radial spines.

Figures

FIGURE 25. Photographs of the encountered morphotypes of Phorticium polycladum Tan and Tchang, 1976. 1-10, Sg-view at Type 1; 11-14, Pl-view at Type 1. Scale bar equals 0.1 mm. All specimens are from YDY05-01.