Sphaeropylolena tenellispinosa, Zhang & Suzuki, 2017

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 : 40-41

Sphaeropylolena tenellispinosa n. sp.

Figure 23

zoobank.org/ DDE29FB4-665D-4088-94BC-056C12E3200D

1992 Phorticium spp. Sugiyama, Nobuhara, and Inoue, pl. 1, fig. 4 (only).

1999 Phorticium pylonium Haeckel group; Molina-Cruz, Welling, and Caudillo-Bohorquez, pl. 1, figs. 6-7.

2009 Streblacantha circumtexta JØrgensen; Zhang, Chen, Xiang, Zhang, Liu, Huang, and Lu, pl. 1, fig. 2.

2013 Streblacantha cf. circumtexta JØrgensen; Suzuki, Ogawa, Ogane, and Tuji, p. 63-74, figs. 4.1-9, 5.1-21, 6.4, 7.1.

2014d Pylodiscus triangularis Haeckel ; Matsuzaki, Nishi, Suzuki, Takashima, Kawate, and Sakai, pl. 2, fig. 5.

Etymology. The Latin adjective “tenellus” (-a, -um) and “spinosus” (-a, -um), meaning having fragile spines.

Holotype. Specimen in Figure 23.7-10 from the sample YDY05-01.

Paratype. Specimen in Figure 23.5-6 from the sample YDY05-01.

Description. Three girdles join directly on the Sgsides of the 1st pseudo-concentric shell in Type 1 coordinates. Because of this architecture, three apertures are present at the corner of the 2nd pseudo-concentric shell, which is connected to the 1st pseudo-concentric shell by several beams. Approximately eight beams emerge from each of the flat sides of the 1st pseudo-concentric shell, and additional beams extend from the boundary of the girdle with a longitudinal side visible from the Sg-view and a transverse side visible from the Lt-view. These beams from the 1st pseudo-concentric shell pierce through the 2nd pseudo-concentric shell to form radial spines. Partial girdles are developed between these beams in some specimens. One apical and two sagittal rods extend from the central combination to pierce through the 2nd pseudo-concentric shell as radial spines. Further radial spines arise radially from the 2nd pseudo-concentric shell. All of these spines are cylindrical and relatively thin. However, the radial spines from the central combination tend to be longer than the radial spines from the 1st pseudo-concentric shell, and the latter is longer than those from the 2nd pseudo-concentric shell. The 2nd pseudo-concentric shell is twice as large as the 1st pseudo-concentric shell. The pores are elliptical to polygonal in shape in the 2nd pseudo-concentric shell. Pores of the 1st pseudo-concentric shell are 7–11 μm in diameter, and those of the 2nd pseudo-concentric shell are10–23 μm in diameter.

Remarks. Sphaeropylolena tenellispinosa n. sp. is easily distinguished from Sphaeropylolena laxa n. sp. based on its more tightly concentric 1st and 2nd pseudo-concentric shells and its shorter and more fragile radial spines. Although S. tenellispinosa n. sp. is characterized by an inflated triangular 2nd pseudo-concentric shell, it is difficult apply for identifying the species because its appearance is variable in different orientations. Sphaeropylolena tenellispinosa n. sp. differs from Sphaeropylolena circumtexta ( JØrgensen, 1899) in that the former’s radial spines are more robust and its pseudo-concentric shells longer and more tightly concentric.

Dimensions. Based on the holotype specimen. The height of the 1st pseudo-concentric shell: 47.8 μm; The height of the 2nd pseudo-concentric shell: 105.6 μm. The height ratio of the the 2nd pseudo-concentric shell to the 1st pseudo-concentric shell: ca. 2.2. Diameter of pores: 7–11 μm (1st pseudo-concentric shell), and 10–23 μm (2nd pseudo-concentric shell).

Figures

FIGURE 23. Photographs of the encountered morphotypes of Sphaeropylolena tenellispinosa n. sp. All are Fr-view at Type 2. Scale bar equals 0.1 mm. All specimens are from YDY05-01.