Circodiscus microporus ( Stöhr, 1880 )

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 : 56

Circodiscus microporus ( Stöhr, 1880)

Figure 31.5-14

1880 Trematodiscus microporus Stöhr , p. 108, pl. 4, fig. 17.

1954 Spongodiscus a sp. Nakaseko, pl. 2, fig. 4.

1955 Ommatodiscus cf. stÖhrii Haeckel (violation error in the species name for ICZN Article 35.2.2); Nakaseko, p. 94, pl. 7, fig. 4.

1972 Circodiscus microporus (Stöhr) ; Petrushevskaya and Kozlova, p. 526, pl. 19, figs. 1-7.

1976 Porodiscidae gen. et spp. indet. Berggren, Benson, Riedel, Sanfilippo, Schrader, and Tjalsma, pl. 12, fig. 8 (only).

1976 Porodiscus microporus (Stöhr) ; Renz, p. 109, pl. 3, fig. 15.

1978 Stylodictya centrospira Haeckel ; McMillen and Casey, pl. 2, fig. 15.

1981 Ommatodiscus murrayi Dreyer ; Takahashi and Honjo, p. 150, pl. 5, fig. 11.

non 1983 Circodiscus microporus Petrushevskaya and Kozlova (wrong authors’ name); Srinivasan, Lombari, and Dave, pl. 2, fig. 3.

1984 Circodiscus microporus (Stöhr) group; Nigrini and Lombari, p. S73-74, pl. 10, fig. 3.

1984b Porodiscus microporus (Stöhr) ; Nishimura and Yamauchi, pl. 53, fig. 4.

1987 Circodiscus microporus (Stöhr) ; Akers, Marolt, and Navarette, pl. 1, fig. 10.

non 1991 Circodiscus microporus (Stöhr) group; Taketani and Aita, pl. 2, fig. 4.

1992 Circodiscus microporus (Stöhr) ; Gupta and Srinivasan, pl. 1, fig. 25.

1992 Circodiscus cf. C. microporus (Stöhr) ; Ling and Kobayashi, fig. 2.5.

1993 Circodiscus microporus (Stöhr) ; Hull, pl. 4, fig. 10.

non 1996 Circodiscus microporus (Stöhr) ; Bak, Lee, and Yun, pl. 4, fig. 1.

non 1999 Circodiscus microporus (Stöhr) group; Sharma, Singh, and Rawal, p. 257, pl. 2, fig. 28.

2002 Circodiscus spp. Anma, Kawakami, and Yamamoto, fig. 12.20.

non 2003 Circodiscus microporus (Stöhr) ; Sharma and Ram, pl. 3, fig. 14.

2009 Circodiscus microporus (Stöhr) ; Itaki, p. 45- 46, pl. 7, fig. 8.

2009 Porodiscus circularis Clark and Campbell ; Motoyama and Kawamura, fig. 8.1.

2009 Circodiscus microporus (Stöhr) ; Sono, Suzuki, Yoshimura, Kano, and Takeda, pl. 1, fig. 22.

2015a Circodiscus microporus (Stöhr) ; Matsuzaki, Suzuki, and Nishi, p. 32-33, fig. 4.16.

2015b Circodiscus microporus (Stöhr) ; Matsuzaki, Suzuki, Nishi, Hayashi, Gyawali, Takashima, and Ikehara, fig. 7.5.

Remarks. The length ratio between the diameters of the Ug- and Pr-axes of the 2nd ring is similar to those of different specimens, and the shape of the

2nd ring shows a nearly circular outline of the rounded quadrangular appearance. Benson (1983)

synonymized “ Ommatodiscus pantanellii Carnevale, 1908 ” with Circodiscus microporus ( Stöhr,

1880), but we separate out the former because no

Circodiscus specimens with robust pylomate 3rd

rings were found in our samples. The overall appearance of “ Ommatodiscus murrayi Dreyer ”

reported by Takahashi and Honjo (1981) is similar to that of Circodiscus pseudomicroprus n. sp., but this specimen should be identified as C. microporus based on its rings with fine pores. The type image of the representative species shows small pores on the 2nd and 3rd rings, which are different from those of specimens previously identified as this species (e.g., Sharma and Ram, 2003). Circodiscus microporus differs from Circodiscus circularis ( Campbell and Clark, 1944) because the rings are apparently wider in the former than in the latter.

Figures

FIGURE 31. Photographs of the encountered morphotypes of Circodiscus. 1-2, Circodiscus amphitrites (Ehrenberg, 1854b); 3-4, Circodiscus biorbiculus n. sp.; 5-14, Circodiscus microporus (Stöhr, 1880); and 15-16, Circodiscus pseudomicroporus n. sp. All are Sg-view at Type1, Fr-view at Type 2. Scale bar equals 0.1 mm. All specimens are from YDY05-01.