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Semicavidinium
From Williams et al., 2017:
[Semicavidinium, Dodekova, 1994, p. 28
Type species: Meiourogonyaulax mitra, Dürr, 1987 (pl.4, fig.2)]
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Original description: [Dodekova 1994]:
Diagnosis:
At the present knowledge the generic diagnosis coincides with that of the type species. The cyst is proximate, sutural and hypocavate, slightly dorso-ventrally compressed. Endocyst subspherical, endophragm thick, smooth or finely ornamented. Pericyst roundly subpolyhedral with subpentagonal outline. Periphragm thin, variously ornamented with features of low relief, finely to rugoreticulate. It is appressed to the endophragm locally in the intratabular areas and it is inconstant separated from the latter in the places of the sutures, slightly at the apex and particularly in the antapex. It is difficult to establish if exist supporting structures within the pericoels. The superficial rugoreticulation on the periphragm hinder their establishment Relatively wide helicoidal cingulum divides the cyst. The epicyst is almost twice smaller than the hypocyst. The sulcus is straight, devoids of the coarse ornamentation ans sulcal tabulation. It starts from the middle of the epicyst and reaches the antapical plate. The tabulation is gonyaulacacean indicated by low external ridges and sutural cavities. The tabulation formula: pr?, 4`, 6", `6c, 6"`, lp, 1"``. The archeopyle is apical, type tA, the principal archeopyle suture zig-zag with sulcal notch and a free operculum. The size is intermediate, at the upper part of the measured range.
Remarks:
The combination of subspherical inner body, subpentagonal outer ambitus, apical archeopyle, gonyallacacean tabulation, sutural and antapical cavities differentiates Semicavidinium gen. n. from all previously described genera.
[Semicavidinium, Dodekova, 1994, p. 28
Type species: Meiourogonyaulax mitra, Dürr, 1987 (pl.4, fig.2)]
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Original description: [Dodekova 1994]:
Diagnosis:
At the present knowledge the generic diagnosis coincides with that of the type species. The cyst is proximate, sutural and hypocavate, slightly dorso-ventrally compressed. Endocyst subspherical, endophragm thick, smooth or finely ornamented. Pericyst roundly subpolyhedral with subpentagonal outline. Periphragm thin, variously ornamented with features of low relief, finely to rugoreticulate. It is appressed to the endophragm locally in the intratabular areas and it is inconstant separated from the latter in the places of the sutures, slightly at the apex and particularly in the antapex. It is difficult to establish if exist supporting structures within the pericoels. The superficial rugoreticulation on the periphragm hinder their establishment Relatively wide helicoidal cingulum divides the cyst. The epicyst is almost twice smaller than the hypocyst. The sulcus is straight, devoids of the coarse ornamentation ans sulcal tabulation. It starts from the middle of the epicyst and reaches the antapical plate. The tabulation is gonyaulacacean indicated by low external ridges and sutural cavities. The tabulation formula: pr?, 4`, 6", `6c, 6"`, lp, 1"``. The archeopyle is apical, type tA, the principal archeopyle suture zig-zag with sulcal notch and a free operculum. The size is intermediate, at the upper part of the measured range.
Remarks:
The combination of subspherical inner body, subpentagonal outer ambitus, apical archeopyle, gonyallacacean tabulation, sutural and antapical cavities differentiates Semicavidinium gen. n. from all previously described genera.