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Subtilisphaera habibii

Subtilisphaera? habibii Masure, 1988

Masure, 1988 questionably included this species in Subtilisphaera.
Holotype: Masure, 1988, pl.5, figs.2A-B
Locus typicus: Hole 627B, Leg 101, offshore Bahamas (east of Florida)
Stratum typicum: Cenomanian

Original diagnosis: Masure, 1988, p.129
Bicavate, peridinoid dinoflagellate cyst, dorsoventrally flattened. Three horns: one apical, one well developed left antapical, and one highly reduced riyht antapical. Endophragm subspheroidal, slightly granular. Periphragm thin, with short to long flexous intratabular spine and pandasutural bands. Very low parasutural ridges expressed only o periphragm where endophragm and periphragm are appressed. Peridinoid paratabulation: 1-2? pr, 4, 3a, 7, Xc, 5 , 2 , Xs, with ortho/heta-type paratabulation. Endoarcheopyle, 3I3P, adherent?; periarcheopyle uncertain.
Dimensions: Holotype: length, 64 µm: breadth, 40 µm: length of endocyst, 42 µm; length of apical horn, 12 µm; length of left antapical horn, 10 µm: length of spines, 1-2 µm; 20 specimens measured: length 68 (64) 60 µm: breadth, 44 (40) 38 µm.

Original description: Masure, 1988, p.129
Peridinoid bicavate cyst with well-developed apical an 1 left antapical horns, and truncated right antapical horn. Endophragm granular. Periphragm smooth, with low parasutural ridges present only where the endophragm and periphragm are appressed. Some specimen show only penitabular spines, whereas others have intratabular spines All have pandasutunal bands. 1 paraplate is in contact with the two precingulars 1 and 7, and so is the orthotype; 2a is in contact with 4 and 5, and so is the hexa type.

Affinities:
Masure, 1988, p.129: Subtilisphaera? habibi is a provisionally accepted species of Subtilisphaera because it has a paratabulation indicated by ornamentation. Parasutural ridges, pandasutural bands, and intratabulal spines differentiate Subtilisphaera? habibi from Palaeohystrichophora infusorioides. Pericoels in Subtilisphaena? habibi are more developed than in Chichaouadinium arabicum. The archeopyles of the genera Chichaouadinium (I3P), Luxadinium 3I3P/3I3P, Ladniadinium (3I3P)a, Ginginodinium (3IPa) and Diconodinium (IPa), do not correspond to the archeopyle of Subtilisphaera? habibi.
The paratabulation, which is of the ortho/hexta type, the pandasutural bands, and the intratabular spines suggest that Subtilisphaera? habibi may be related to the cyst of the modern freshwater dinollagellate Pterodinium limbatum. Under the scanning electron microscope no grooves were observed on the inner surface of the endophragn as is found in Pterodinium limbatum, The periarcheopyle of Pterodnium limbatum is (A3I3P)a: that of Subtillsphaera? habibi is uncertain.
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