Larcopyle eccentricanoides, 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 : 37

Larcopyle eccentricanoides n. sp.

Figure 18.13-18

zoobank.org/ B6634317-B65C-4542-8745-7F8F95946E2F

cf. 1987 Sponguras? sp. (wrong spelling of the genus name); Akers, Marolt, and Navarette, pl. 1, fig. 9.

Etymology. Similar to Larcopyle eccentrica .

Holotype. Specimen in Figure 18.13-14 from the sample YDY05-01.

Paratype. Specimen in Figure 18.15-16 from the sample YDY05-01.

Description. Test is spindle-shaped to ellipsoid and consists of a pylodiscid-type central combination, two ellipsoid pseudo-concentric shells, and an outermost coverage shell with a slender bore pylome. The central combination is spherical in shape. The 1st pseudo-concentric shell appears rectangular in shape from some directions but spherical from other directions. The relationship between the central combination and the remaining pseudo-concentric shell is unknown. The 2nd pseudo-concentric shell is also rectangular in shape. The longest axis of the 1st pseudo-concentric shell is parallel to that of the 2nd pseudo-concentric shell. In contrast, the longest axis of the outermost shell is variably oriented in the direction of the 2nd pseudo-concentric shell. The stage of development of the outermost coverage shell is also variable from a complete ellipsoid to spindle-like coverage to incomplete conditions at the joint with the 2nd pseudo-concentric shell. Because of these irregular orientations and developmental conditions of the outermost coverage shell, the space between the 2nd pseudo-concentric shell and the outermost coverage shell is different around the 2nd pseudo-concentric shell. The pore frames of the 2nd pseudo-concentric shell are robust with relatively large pores (ca. 5 μm in diameter).

Remarks. Larcopyle eccentricanoides n. sp. is similar to Larcopyle eccentrica Lazarus, Faust and Popova-Goll, 2005 , with a rectangular 2nd pseudo-concentric shell and a slender bore pylome. The former is distinguishable from the latter in that the latter has more pores in former’s thick-walled outermost coverage shell, as well as sufficient space between the outermost coverage shell and the preceding pseudo-concentric shell. Larcopyle eccentricanoides n. sp. is distinguishable from other Larcopyle species based on the former’s presence of the quadrangular 2nd pseudo-concentric shell. The direction of the outermost coverage shell is less important for determining the species name.

Dimensions. Based on the holotype specimen. The length and width of the 1st pseudo-concentric shell: 24.4 μm and 17.1μm; The length and width of the 2nd pseudo-concentric shell: 42.0 μm and 35.1μm. The length and width of the outermost coverage shell: 73.9 μm and 45.8 μm. The ratio of length to width of the outermost coverage shell: 1.6.

Figures

FIGURE 18. Photographs of the encountered morphotypes of Larcopyle. 1-6, Larcopyle variabile (Dreyer, 1889) sensu emend.; 7-12, Larcopyle molle n. sp.; 13-18, Larcopyle eccentricanoides n. sp.; 19-22, Larcopyle pulchella n. sp. All are Fr-view at Type 2. Scale bar equals 0.1 mm. All specimens are from YDY05-01.