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Capillicysta fusca

Capillicysta fusca, Matsuoka and Bujak in Matsuoka et al., 1987

Holotype: Matsuoka et al. 1987: plate 1, figures 1, 2
Locus typicus: Onnagawa, Oga Peninsula, Akita Prefecture, North Japan.
Stratum typicum: Shinzan Diatomite Member of Funakawa Formation, upper part of the Middle Miocene to the Upper Miocene.
Age: Middle-Late Miocene

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Original description: [Matsuoka et al. 1987 p. 226, 228]:

Diagnosis:
Proximate cyst with roundly peridinioid shape cornucavate and moderately compressed dorsoventrally.
Cyst wall consisting of thick, smooth, pigmented endophragm and thin, mostly colorless spinose periphragm.
Spines varying in shape and length from short conical to longer and distally bifurcate. Apical horn columnar with short spines at the apex. One or two symmetrically located antapical horns are generally reflected by larger spinose ornament but may be absent. Low parasutures are occasionally visible on parts of the cyst including the cingulum, sulcus and archeopyle, but the paratabulation is indeterminate.
Cingulum wide, circular to slightly helicoidal, marked by parallel rows of processes. Sulcus deep and bordered by crests, becoming broader toward the antapex.
Archeopyle steno-deltaform hexa-intercalary, formed by the loss of paraplate 2a.

Dimensions (in µm):
Holotype: cyst length 63.8, width 60, length of apical horn 5.6, spine length 1.9.
Range: cyst length47.5-63.8, width 43.9-63.2, spine length 1.9-3.5. Number of measured specimens: 20.

Remarks:
Capillicysta fusca is similar to Trinovantedinium capitatum and Votadinium spinosum, both of which are attributed to the modern Protoperidinium. However, T. capitatum is distinguished by the combination of a distinct paracingulum, apical and antapical horns, and a brownish pigmented cyst wall.
The thecal affinity for this species is unknown, but it is probably related to the modern Protoperidinium.

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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.

Capillicysta fusca Matsuoka and Bujak in Matsuoka et al., 1987, has a thick endophragm and a thin, colourless, spinose periphragm. Spines may be short conical to longer and distally bifurcate. One or two symmetrically located antapical horns are generally reflected by larger spinose ornamentation but may be absent. Cingulum wide marked by parallel rows of processes, sometimes low parasutures. Archeopyle intercalary resulting from the loss of the steno-deltaform 2a.
Size: length 48-64 µm, width 44-63 µm, spine length 2-3.5 µm.
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