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Operculodinium javanum
From Fensome et al., 2019:
Operculodinium javanum Morgenroth et al., 2008, p.118, pl.1, figs.1–6. Holotype: Morgenroth et al., 2008, pl.1, figs.1–2. Age: Middle Miocene.
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Derivation of name: The species is named after the Indonesian island of Java.
Holotype: Pl. 1, Figs 1, 2. Single grain slide N-2/3 from sample N 2.
Paratypes: Single grain slides N-7/1, N-7/2, N-7/3 and N-7/4 from sample N-7, N-8/40 from sample N-8, CP-20/6 and CP-25/27 from samples CP-20 and CP-25.
Type locality: Cijarian River, West Java (fext-fig. 5). Cimandiri Formation, Middle Miocene, Age N13.
Diagnosis: An intermediate species of Operculodinium characterized by ovoidal to subspherical, proximochorate cysts with a reticulate wall and numerous nontabular, evenly distributed processes. Processes slender, usually tapered, some possibly bifid, rarely acuminate. The size of the cysts and the length of processes show little variation. Archeopyle precingular, simple.
Description: The intermediate cysts are usually ovoidal, rarely subspherical. The cyst wall is about 2 μm thick and reticulated. The dimensions of the cysts do not vary strongly, but are rather consistent as is the length of the processes. The numerous processes are slender, tapered or possibly bifid. A few processes seem to be acuminate. Indications of field boundaries have not been observed. Almost all specimens show a simple precingular archeopyle.
Dimensions: Length excluding processes, 50 (56) 62 μm, holotype 61 μm, width excluding processes, 45 (49) 56 μm, holotyp e-56 μm. Processes 7-10 μm, rarely 12 μm. 50 specimens measured.
Comparison: This species resembles Operculodinium echigoense MATSUOKA 1983 from the early Middle Miocene of Japan. However, O. echigoense is larger (67-86 μm), its processes longer (12-21 μm) (MATSUOKA, 1983: 126) All of the many specimens studied in the Miocene of Java are considerably smaller, and it is therefore preferred not to include them into the species O. echigoense. Operculodinium wallii MATSUOKA 1983 and Operculodinium crassum HARLAND 1979 are also larger and have longer and different processes (MATSUOKA 1983: 126, 127). The species Operculodinium piaseckii (STRAUSS and LUND 1992) DE VERTEUIL and NORRIS 1996 and Operculodinium placitum DRUGG and LOEBLICH 1967 are considerably smaller and have conical or tapered processes, which are very short: Operculodinium placitum has processes 1.25-2 μm long, Operculodinium piaseckii has short (3-5 μm) subconical to conical clavate virgae (DE VERTEUIL & NORRIS 1996: 122, 124, 126).
Operculodinium javanum Morgenroth et al., 2008, p.118, pl.1, figs.1–6. Holotype: Morgenroth et al., 2008, pl.1, figs.1–2. Age: Middle Miocene.
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Derivation of name: The species is named after the Indonesian island of Java.
Holotype: Pl. 1, Figs 1, 2. Single grain slide N-2/3 from sample N 2.
Paratypes: Single grain slides N-7/1, N-7/2, N-7/3 and N-7/4 from sample N-7, N-8/40 from sample N-8, CP-20/6 and CP-25/27 from samples CP-20 and CP-25.
Type locality: Cijarian River, West Java (fext-fig. 5). Cimandiri Formation, Middle Miocene, Age N13.
Diagnosis: An intermediate species of Operculodinium characterized by ovoidal to subspherical, proximochorate cysts with a reticulate wall and numerous nontabular, evenly distributed processes. Processes slender, usually tapered, some possibly bifid, rarely acuminate. The size of the cysts and the length of processes show little variation. Archeopyle precingular, simple.
Description: The intermediate cysts are usually ovoidal, rarely subspherical. The cyst wall is about 2 μm thick and reticulated. The dimensions of the cysts do not vary strongly, but are rather consistent as is the length of the processes. The numerous processes are slender, tapered or possibly bifid. A few processes seem to be acuminate. Indications of field boundaries have not been observed. Almost all specimens show a simple precingular archeopyle.
Dimensions: Length excluding processes, 50 (56) 62 μm, holotype 61 μm, width excluding processes, 45 (49) 56 μm, holotyp e-56 μm. Processes 7-10 μm, rarely 12 μm. 50 specimens measured.
Comparison: This species resembles Operculodinium echigoense MATSUOKA 1983 from the early Middle Miocene of Japan. However, O. echigoense is larger (67-86 μm), its processes longer (12-21 μm) (MATSUOKA, 1983: 126) All of the many specimens studied in the Miocene of Java are considerably smaller, and it is therefore preferred not to include them into the species O. echigoense. Operculodinium wallii MATSUOKA 1983 and Operculodinium crassum HARLAND 1979 are also larger and have longer and different processes (MATSUOKA 1983: 126, 127). The species Operculodinium piaseckii (STRAUSS and LUND 1992) DE VERTEUIL and NORRIS 1996 and Operculodinium placitum DRUGG and LOEBLICH 1967 are considerably smaller and have conical or tapered processes, which are very short: Operculodinium placitum has processes 1.25-2 μm long, Operculodinium piaseckii has short (3-5 μm) subconical to conical clavate virgae (DE VERTEUIL & NORRIS 1996: 122, 124, 126).