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Freboldinium arctium
From Fensome et al., 2019:
Freboldinium arcticum Below, 1990, p.15–16, pl.1, figs.13–15; pl.2, figs.1–15; text-figs.3a–b. Holotype: Below, 1990, pl.2, figs.1,6–11,15. Contrary to the opinion of Lentin and Williams (1993, p.227), this name is validly published. Below (1987a, p.6) stated that, unless otherwise indicated, all the material is in his personal collection. Since Below (1987a, 1987b, 1990) are parts I to III of a single study, we agree with J. Jansonius (personal communication) that Below's (1987a) repository statement refers to all three publications, fulfilling the requirement of ICN Article 40.7 (see also the discussion on Article 40.7 in the Introduction). Age: Toarcian.
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Original description Below, 1990:
Derivatio nominis: Named after the locality in the Arctic.
Holotype: Specimen S7一1805(KOI)l/l (Plate 2, Figs. 1, 6-11, 15).
Typical locus: Brentskardhaugen Bed, Toarcian.
Typical stratum: Eastern slope of Knerten towards DeGeerdalen, Spitsbergen.
Description:
Vesicle/tablet arrangement of the dinoflagellate amphiesma cop, pop, cap, 4', 3a, 6", 7c, 6'", l"", as, FM, ls, rs, ps; Tegulation 4*, 3**, 6***, 2***, 7c, 3+, 4++, 3+++; growth of thecal plates according to a peridinoidal mode; zygote-cyst habitus proximate, acavate-finicavate, polyhedral, tholiform epicyst distinctly smaller than the coniform hypocyst with flattened antapex, circular in equatorial section, maximum diameter at the posterior cingulate margin; wall composed of thin pedium and luxuriate tegillum; surface coarsely rugulate, granulate, pustulate, partially also reticulate, the course of the finis is marked by densely arranged, partly merging, very delicate granules, these run in the center of wall-like or distally smooth or wavy rib-shaped folds of the tegillum, on the surface of the overlapping Edge of the corresponding theca plate homologous area side, the fold is often broad or not very high and covered with long, solid, coarse, cylindrical, evexate spines; Arranging scheme XPR/cop,-pop, cap, 4', 3a, 6'', 7c , 6'", 1"", as, FM, Is, rs, ps; PR undifferentiated or consisting of a very small, circular to oval cop, which is congruently enclosed by the small pop, tiny cap ventrally adjoining, mostly non-finite; 4 apicals: steno VIII l'(V ), V lll2'(L), camerate 3'(D), VI4'(RDR); 3 anterior intercalary, tiny caroidal la (DL): large vn2a (D) and very small caroidal 3a (RDR), la and 3a often against 2a non-finite; 6 precingulars: anterior geniculate V-nE1" (01VL), anterior bigeniculate VI-nE2" (L), anterior linear IV-nE3" (DDL), anterior linear IV-nE4''(DR), finis 3" /4" dorsal, anterior trigeniculate 5" (RVR), anterior linear IV-nE6"; cingulum left-handed spiral, heptapartite, late lc to 6c and iso 7c; 6 postcingulates: steno V·nE 1"' (V) on a projection covering the sinistral sulcus, posterior linear V-nE 2'" (VL) with contact to the sulcus; posterior linear lV-nE 3"'(LDL), posterior linear IV-nE 4'" (D), posterior line arc lV-nE S"'(RDR), posterior linear V-nE 6"'0/R); 1 pole-positioned VI l'"'; sulcus partit, small VI as, V FM, very small V ls and very small IV rs as well as steno omega-shaped VI ps; archaeopyle precingular/apical, 3" + 4" + la + 2a + 3a + 3'; operculum solvate (pars) and foederate (pars), opercular plates secat, general opercular formula 3''s+4''s+(la + 2a + 3a + 3')s.
Holotype dimensions:
Length 38 μm, width 35 μm, thickness 35 μm.
Note:
So far, only the areas PR, 4', 3a, 7c, 6'', 1'", 1"", as, FM, 1s, rs, ps are known from this species. Areas 1a, 3', and 3a are very rarely finate, finate ornamentation is usually lacking, and the areas of 3', 2', and 4' border openly. 1'' is broad and contacts 2c, as is known in some individuals of Freboldinium regula n.gen. n.sp. (see p. 17). Only one antapic area is developed. 6c, 7c, and rs usually follow one another in series; however, specimen S7-1805(K01)1/1 (Plate 2, Figs. 1, 6, 7; Fig. 3b) shows an anteriorly displaced area 7c, so that rs also borders 6c. The sinistral part of the sulcus (ls and parts of rs) is concealed by a balcony-like projection of area l''', which extends from the sinistral sulcus edge. It extends posteriorly as a self-supporting pedestal (Plate 2, Figs. 7, 11, 12; Fig. 3). The state of preservation—the organic matter in the specimen is extremely brittle—caused the breakage of exposed parts, such as the posterior extension of the sulcal shield, but especially the spines, of which only stubble remains.
Overlapping is only indicated in very well-preserved specimens. The fins are marked by a line of densely spaced, very fine dots. These run along the center of wall-like folds of the luxuriate tegillum. On the side homologous to the overlapping margin of the corresponding thecal plate, the fold is more prominent and also bears spines. On the overlapped side, the fold is often very shallow or completely absent.
Area 2a of specimen S7一1805(K01)1/1 (Plate 1, Fig. 15; Plate 2, Figs. 9, 15) is hololimbat and shows reflected intercalary striations. The homologous thecal plate 2a was overlapped by precingulates. However, it was in turn deposited over 1a, 3' and 3a, i.e. the increase (reflected by the limbus) occurred at both the overlapping and the overlapped edge, thus corresponding to the peridinoidal mode.
Freboldinium arcticum Below, 1990, p.15–16, pl.1, figs.13–15; pl.2, figs.1–15; text-figs.3a–b. Holotype: Below, 1990, pl.2, figs.1,6–11,15. Contrary to the opinion of Lentin and Williams (1993, p.227), this name is validly published. Below (1987a, p.6) stated that, unless otherwise indicated, all the material is in his personal collection. Since Below (1987a, 1987b, 1990) are parts I to III of a single study, we agree with J. Jansonius (personal communication) that Below's (1987a) repository statement refers to all three publications, fulfilling the requirement of ICN Article 40.7 (see also the discussion on Article 40.7 in the Introduction). Age: Toarcian.
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Original description Below, 1990:
Derivatio nominis: Named after the locality in the Arctic.
Holotype: Specimen S7一1805(KOI)l/l (Plate 2, Figs. 1, 6-11, 15).
Typical locus: Brentskardhaugen Bed, Toarcian.
Typical stratum: Eastern slope of Knerten towards DeGeerdalen, Spitsbergen.
Description:
Vesicle/tablet arrangement of the dinoflagellate amphiesma cop, pop, cap, 4', 3a, 6", 7c, 6'", l"", as, FM, ls, rs, ps; Tegulation 4*, 3**, 6***, 2***, 7c, 3+, 4++, 3+++; growth of thecal plates according to a peridinoidal mode; zygote-cyst habitus proximate, acavate-finicavate, polyhedral, tholiform epicyst distinctly smaller than the coniform hypocyst with flattened antapex, circular in equatorial section, maximum diameter at the posterior cingulate margin; wall composed of thin pedium and luxuriate tegillum; surface coarsely rugulate, granulate, pustulate, partially also reticulate, the course of the finis is marked by densely arranged, partly merging, very delicate granules, these run in the center of wall-like or distally smooth or wavy rib-shaped folds of the tegillum, on the surface of the overlapping Edge of the corresponding theca plate homologous area side, the fold is often broad or not very high and covered with long, solid, coarse, cylindrical, evexate spines; Arranging scheme XPR/cop,-pop, cap, 4', 3a, 6'', 7c , 6'", 1"", as, FM, Is, rs, ps; PR undifferentiated or consisting of a very small, circular to oval cop, which is congruently enclosed by the small pop, tiny cap ventrally adjoining, mostly non-finite; 4 apicals: steno VIII l'(V ), V lll2'(L), camerate 3'(D), VI4'(RDR); 3 anterior intercalary, tiny caroidal la (DL): large vn2a (D) and very small caroidal 3a (RDR), la and 3a often against 2a non-finite; 6 precingulars: anterior geniculate V-nE1" (01VL), anterior bigeniculate VI-nE2" (L), anterior linear IV-nE3" (DDL), anterior linear IV-nE4''(DR), finis 3" /4" dorsal, anterior trigeniculate 5" (RVR), anterior linear IV-nE6"; cingulum left-handed spiral, heptapartite, late lc to 6c and iso 7c; 6 postcingulates: steno V·nE 1"' (V) on a projection covering the sinistral sulcus, posterior linear V-nE 2'" (VL) with contact to the sulcus; posterior linear lV-nE 3"'(LDL), posterior linear IV-nE 4'" (D), posterior line arc lV-nE S"'(RDR), posterior linear V-nE 6"'0/R); 1 pole-positioned VI l'"'; sulcus partit, small VI as, V FM, very small V ls and very small IV rs as well as steno omega-shaped VI ps; archaeopyle precingular/apical, 3" + 4" + la + 2a + 3a + 3'; operculum solvate (pars) and foederate (pars), opercular plates secat, general opercular formula 3''s+4''s+(la + 2a + 3a + 3')s.
Holotype dimensions:
Length 38 μm, width 35 μm, thickness 35 μm.
Note:
So far, only the areas PR, 4', 3a, 7c, 6'', 1'", 1"", as, FM, 1s, rs, ps are known from this species. Areas 1a, 3', and 3a are very rarely finate, finate ornamentation is usually lacking, and the areas of 3', 2', and 4' border openly. 1'' is broad and contacts 2c, as is known in some individuals of Freboldinium regula n.gen. n.sp. (see p. 17). Only one antapic area is developed. 6c, 7c, and rs usually follow one another in series; however, specimen S7-1805(K01)1/1 (Plate 2, Figs. 1, 6, 7; Fig. 3b) shows an anteriorly displaced area 7c, so that rs also borders 6c. The sinistral part of the sulcus (ls and parts of rs) is concealed by a balcony-like projection of area l''', which extends from the sinistral sulcus edge. It extends posteriorly as a self-supporting pedestal (Plate 2, Figs. 7, 11, 12; Fig. 3). The state of preservation—the organic matter in the specimen is extremely brittle—caused the breakage of exposed parts, such as the posterior extension of the sulcal shield, but especially the spines, of which only stubble remains.
Overlapping is only indicated in very well-preserved specimens. The fins are marked by a line of densely spaced, very fine dots. These run along the center of wall-like folds of the luxuriate tegillum. On the side homologous to the overlapping margin of the corresponding thecal plate, the fold is more prominent and also bears spines. On the overlapped side, the fold is often very shallow or completely absent.
Area 2a of specimen S7一1805(K01)1/1 (Plate 1, Fig. 15; Plate 2, Figs. 9, 15) is hololimbat and shows reflected intercalary striations. The homologous thecal plate 2a was overlapped by precingulates. However, it was in turn deposited over 1a, 3' and 3a, i.e. the increase (reflected by the limbus) occurred at both the overlapping and the overlapped edge, thus corresponding to the peridinoidal mode.