Larcopyle, Dreyer, 1889

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 : 27-28

Genus LARCOPYLE Dreyer, 1889 sensu emend. herein

*1889 Larcopyle Dreyer , p. 128.

1954 Larcopyle Dreyer ; Campbell, p. D96.

2005 Larcopyle Dreyer ; Lazarus, Faust, and Popova-Goll, p. 106.

2015a Larcopyle Dreyer ; Matsuzaki, Suzuki, and

Nishi, p. 33 (See full synonymy).

Type species. Larcopyle buetschlii Dreyer (SD by Campbell, 1954).

Description. Test is ellipsoid to spherical in shape, and comprises a central combination and continuous or intermittent spiral girdles. Robust or fragile coverage develops in the fully mature forms of some species. A bore pylome may be present on one end of the test, but no specific internal structure associated with the pylome has been recognized inside the test. The bore pylome, if present, opens along the Lt-axis. A bore pylome may be surrounded by spinules. The longest direction of the Ug-axis is parallel to the Lt-axis. A central combination consists of an S1a and a pylodiscid-type triangular G1 girdle (see the type specimen image shown in figure 70 in Dreyer [1889]). Based on the definitions, both the Pl- and Sg-axes in Type 1 coordinates can be determined based on the central combination, but the Pr- and Fr-axes cannot be differentiated without pyloniid-type gates. Single or twin girdles coil variably several times from the central combination. The G1 girdle consists of three caps placed on the Sg-plane, and two of these caps develop from both lateral ends of the central combination along the Lt-axis, while the remaining cap is below the S1a (microsphere) along the Pl-axis in Type 1 coordinates. The S1a and G1 girdle form the 1st pseudo-concentric shell, which resembles an elongated ellipse from the Pl-view and a rounded triangle from the Sg-view or another oblique view.

Remarks. The original definition of the genus Larcopyle puts emphasis on the presence of a pylome, but this structure is only present in the fully mature morphotypes with discrete outermost coverage shell. Even if the outermost coverage shell has a pylome, no special related structures have been recognized inside the outermost coverage shell, as described above. In addition, the outermost coverage shell does not always have a pylome even in the same species. Therefore, the presence or absence of a pylome is not used as a taxonomic criterion for this genus. Following this revised definition, Tholospira dendrophora Haeckel, 1887 , moves into the same genus as Larcopyle buetschlii Dreyer, 1889 . The former is the type species of Tholospira Haeckel, 1887 , whereas the latter is that of the genus Larcopyle Dreyer, 1889 , which suggests that Larcopyle would logically be synonymized with Tholospira . However, because the internal structure of Tholospira dendrophora has not been well examined, the name Tholospira has not been formally prioritized over Larcopyle . The internal structures of L. buetschlii and L. cervicornis are shown in Figure 5.4 . The genus name is derived from the grammatical Latin female noun “pyle”; therefore, this genus is a grammatically female noun.

Figures

FIGURE 5. The structure of central combination in genera Tetrapyle (1-3), Larcopyle (4) and Circodiscus (5). 1, Sgview at Type 1, Fr-view at Type 2; 2, Pl-view at Type 1, Fr-view at Type 2; 3, Lt-view at Type 1, Pr-view at Type 2. G1, G2, S1a, and S1a-girdle are the morphological terminology, of which the definitions have been shown in Table 1.