Back
Cribroperidinium granomembranaceum
From Fensome et al., 2019:
Cribroperidinium? granomembranaceum (Matsuoka, 1983b, p.121–122, pl.1, figs.1a–c,2,3a–b,4a–b,5a–b; text-figs.14A–B) Lentin and Williams, 1985, p.78. Holotype: Matsuoka, 1983b, pl.1, figs.1a–c; Jan du Chêne et al., 1986a, pl.27, figs.1–2. Originally Millioudodinium, subsequently (and now) Cribroperidinium?. Questionable assignment: Lentin and Williams (1985, p.78). Age: Early-Middle Miocene.
---------------------------------------------------------------------------------------------------
Original description: [Matsuoka, 1983b]:
Millioudodinium granomembranaceum sp. nov.
PI. 1, figs. 1-5, Text-Fig. 14
?1972 Gonyanlagsta sp. cf. giuseppei (MORGENROTH) BENEDEK, p. 18-19, pl. 4, fig. 7.
Derivation of name: Latin, granum + membranaceus, grain + membraneous, with the reference to granular autophragm.
Diagnosis: Cyst with granular surface, rounded fusiform to ellipsodal and consisting of autophragm. One apical born originally short, acuminate and closed distally. Parasutural septa relatively high, sometimes reliculate. Acessory parasutural septa partially observed. Archeopyle somewhat enlarged precingular and formed by loss of the 3" paraplate. Paraplates constituting the paracingulum hardly observed. Paratabulation 4' (?), 0a, 6", Xc, 5'", 1p, 1"" and Xs.
Holotype: KMD slide NNA 1-1 (5.0/130.4), pl. 1, fig. 1. Sample NNA 1, Nashinoki Formation equivalent to the Nanatani Formation - late Early to early Middle Miocene. Loc.: Nashinoki, Kurokuwa-mura, Niigata Prefecture, Central Japan.
Description: The large proximate cyst is rounded fusiform to ellipsoidal and composed of an autophragm with a granular surface. The conial epicyst has a short apical horn which is originally acuminate and has a closed distal end. In ill-preserved specimens, the end of the apical horn is sometimes truncated and opened. Except for the paracingulum, parasutural septa are moderately high and sometimes granular. Some corroded specimens show apparently micro-perfomations on the autophragm. In some specimens, parasutural septa are partially developed.
Parallel ridges of the autophragm distributed equatorially indicate the paracingulum. The parasulcus is also well marked by parasutural septa. The paratabulation is represented as 4' (?), 0a, 6", Xc, 5'", 1p, 1"" and Xs. If the first postcingular paraplate is much reduced as in other gonyaulacacean cysts, the postcingulum might have six paraplates originally. The archeopyle is an enlarged precingular type marked by the hexagonal shape of the 3" paraplate.
Dimensions: Holotype: Length of cyst 90 μm, width of cyst 76 μm, width of paracingulum 5 μm, length of apical horn 7 μm (this specimen is slightly damaged and its apical horn is opened distally), diameter of archeopyle 38 μm x 22 μm. Other specimens; Length of cyst 81-95 μm, width of cyst 64-93 μm, width of paracingulum 4-6 μm, length of acuminate and closed apical horn up to 12 μm. Number of specimens measured: 25.
Occurrence: A few to abundant in the Nanatani Formation and its equivalent formations (late Early to Early Middle Miocene).
Remarks: Many specimens of Millioudodinium granomembranaceum obtained from the Nigata district are somewhat corroded, and apparently show a granular surface of the autophragm. But this species is distinguishable other species in having a rounded fusiform to ellipsoidal cyst body. Gonyaulacysta sp. cf. guiseppei (MORGENROTH) described by BENEDEK (1972) may be assignable to this new species on the basis of its
characteristic apical horn and cyst shape, but BENEDEK'S specimens are smaller than the present ones.
Cribroperidinium? granomembranaceum (Matsuoka, 1983b, p.121–122, pl.1, figs.1a–c,2,3a–b,4a–b,5a–b; text-figs.14A–B) Lentin and Williams, 1985, p.78. Holotype: Matsuoka, 1983b, pl.1, figs.1a–c; Jan du Chêne et al., 1986a, pl.27, figs.1–2. Originally Millioudodinium, subsequently (and now) Cribroperidinium?. Questionable assignment: Lentin and Williams (1985, p.78). Age: Early-Middle Miocene.
---------------------------------------------------------------------------------------------------
Original description: [Matsuoka, 1983b]:
Millioudodinium granomembranaceum sp. nov.
PI. 1, figs. 1-5, Text-Fig. 14
?1972 Gonyanlagsta sp. cf. giuseppei (MORGENROTH) BENEDEK, p. 18-19, pl. 4, fig. 7.
Derivation of name: Latin, granum + membranaceus, grain + membraneous, with the reference to granular autophragm.
Diagnosis: Cyst with granular surface, rounded fusiform to ellipsodal and consisting of autophragm. One apical born originally short, acuminate and closed distally. Parasutural septa relatively high, sometimes reliculate. Acessory parasutural septa partially observed. Archeopyle somewhat enlarged precingular and formed by loss of the 3" paraplate. Paraplates constituting the paracingulum hardly observed. Paratabulation 4' (?), 0a, 6", Xc, 5'", 1p, 1"" and Xs.
Holotype: KMD slide NNA 1-1 (5.0/130.4), pl. 1, fig. 1. Sample NNA 1, Nashinoki Formation equivalent to the Nanatani Formation - late Early to early Middle Miocene. Loc.: Nashinoki, Kurokuwa-mura, Niigata Prefecture, Central Japan.
Description: The large proximate cyst is rounded fusiform to ellipsoidal and composed of an autophragm with a granular surface. The conial epicyst has a short apical horn which is originally acuminate and has a closed distal end. In ill-preserved specimens, the end of the apical horn is sometimes truncated and opened. Except for the paracingulum, parasutural septa are moderately high and sometimes granular. Some corroded specimens show apparently micro-perfomations on the autophragm. In some specimens, parasutural septa are partially developed.
Parallel ridges of the autophragm distributed equatorially indicate the paracingulum. The parasulcus is also well marked by parasutural septa. The paratabulation is represented as 4' (?), 0a, 6", Xc, 5'", 1p, 1"" and Xs. If the first postcingular paraplate is much reduced as in other gonyaulacacean cysts, the postcingulum might have six paraplates originally. The archeopyle is an enlarged precingular type marked by the hexagonal shape of the 3" paraplate.
Dimensions: Holotype: Length of cyst 90 μm, width of cyst 76 μm, width of paracingulum 5 μm, length of apical horn 7 μm (this specimen is slightly damaged and its apical horn is opened distally), diameter of archeopyle 38 μm x 22 μm. Other specimens; Length of cyst 81-95 μm, width of cyst 64-93 μm, width of paracingulum 4-6 μm, length of acuminate and closed apical horn up to 12 μm. Number of specimens measured: 25.
Occurrence: A few to abundant in the Nanatani Formation and its equivalent formations (late Early to Early Middle Miocene).
Remarks: Many specimens of Millioudodinium granomembranaceum obtained from the Nigata district are somewhat corroded, and apparently show a granular surface of the autophragm. But this species is distinguishable other species in having a rounded fusiform to ellipsoidal cyst body. Gonyaulacysta sp. cf. guiseppei (MORGENROTH) described by BENEDEK (1972) may be assignable to this new species on the basis of its
characteristic apical horn and cyst shape, but BENEDEK'S specimens are smaller than the present ones.