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Operculodinium bahamense
Operculodinium bahamense Head in Head and Westphal, 1999, p.12–13, fig.9, nos.9–14; fig.10, nos.1–5. Emendation: Paez-Reyes and Head, 2013, p.789,791.
Holotype: Head and Westphal, 1999, fig.9, nos.9–12.
Age: Pliocene.
Original description (Head & Westpal, 1999):
Operculadinium Bahamaense Head, new species Figures 9.9-9.14, 10.1-10.5
Operculodinium sp. 3. Manum, Boulter, Gunnarsdottir Rangnes, and Scholze, 1989, pl. 13, figs. 5, 6.
Diagnosis.-A large species of Operculodinium with long, sparsely distributed processes; tabulation relatively completely expressed by low sutural ridges that appear as dark narrow lines on surface.
Description.-Central body broadly egg-shaped to nearly spherical, the wall consisting of thin, solid pedium, and thicker, distally open, spongy-fibrous to fibro-microreticulate luxuria. Gonyaulacacean tabulation indicated by low (ca. 1 µm or less) sutural ridges composed of coalesced fibers or granules, appearing as dark narrow lines on surface. Cingulum narrow, equatorial, and descending with displacement of about one width. A flagellar scar may be indicated by elongate indentation in midsulcal area. Processes are slender and solid, with fibrous, expanded bases; and terminate distally in small aculeate platforms, each with up to eight or more aculeae. Process distribution sparse and nontabular, with process bases sometimes crossing sutural ridges. Process length variable on individual specimens, some processes being up to 32 µm in length. Archeopyle precingular Type 1P (3"), enlarged, has rounded angles. Operculum free.
Dimensions.-Holotype: length (excluding process), 81 µm; process length, 6-11 µm; wall thickness, ca. 1.7 µm. Range: Maximum diameter (excluding process), 80(89.7)106 µm; average process length, 7(15.0)24 µm. Wall thickness, ca. 0.6(1.1)1.7 µm. Thirty specimens measured.
Etymology. -Named with reference to the Great Bahama Bank, type locality of this species.
Holotype.-Fig. 9.9-9.12. Sample CUS-K 11, slide 3; England Finder reference G18/2. ROM 53304. Clino core, 234.12 m (768.13 ft) below mud pit; upper upper Pliocene.
Comparison.-Operculodinium giganteum Wall, 1967 may also have sutural lines, but processes are shorter (2-4 µm) and more densely distributed. Operculodinium wallii Matsuoka, 1983 lacks sutural lines or ridges. Operculodinium floridium Warny and Wrenn, 1997 has shorter (2-10 µm) processes whose distribution is dense and distinctly intratabular, and lacks sutural lines or ridges. Previous records.-Upper middle and upper Miocene of the Norwegian Sea (as Operculodinium sp. 3 in Manum et al., 1989).
Emended description (Paez-Reyes and Head, 2013):
1989 Operculodinium sp. 3; Manum, Boulter, Gunnarsdottir, Rangnes, and Scholze, p. 13, figs. 5, 6.
1999 Operculodinium bahamense Head in Head and Westphal, p. 12, 13, figs. 9.9–9.14, 10.1–10.5.
Emended diagnosis: a large species of Operculodinium with spherical to subspherical central body whose spongy-fibrous luxuria bears sparsely-distributed, solid to fibrous processes with expanded fibrous bases, terminating distally in minute expansions with aculeate margins. Low sutural ridges demarcate gonyaulacacean, sexiform tabulation with modified L-type ventral organization, neutrally contorted dorsal tabulation, and episert 1’. Plate formula is 2’þ*2’, 6’’, 6c, 5s, *6’’’, 1p, 1’’’’. Archeopyle large, angles rounded, formed by loss of third precingular plate; operculum free.
Description.—Central body spherical to subspherical, wall consisting of thin, solid pedium, and thicker, distally open, spongy-fibrous luxuria. Surface spongy-fibrous to punctate (Fig. 6.7, 6.10–6.12), may become smoother on sulcus (Fig. 6.12). Scattered granules may also occur over surface (Fig. 6.8). Processes slender, solid to fibrous, circular in cross-section, with fibrous expanded bases; terminate distally in minute, flared platforms with recurved, aculeate margins, each bearing up to about eight aculeae. Process distribution sparse, apparently intratabular, with the largest plates bearing up to around seven processes (e.g., seven on plate *4’’’, Fig. 5.1, 5.2; six on plate 3’’, Head and Westphal, 1999, fig. 10.4, 10.5), usually up to four or five processes on other large plates (e.g., 1’’ and *3’’’), and usually no more than one on smaller plates (e.g., *2’’’). Process bases observed to cross plate boundaries only in the midventral region (Fig. 6.8) and occasionally along the cingulum. Process distribution irregular within plate boundaries, adjacent processes may be widely separated or so close as to be fused at base. Processes up to ~35 µm long, with length sometimes variable on individual specimens; some specimens devoid of processes (Figs. 2, 6.1–6.6). Shorter, more slender processes may occur in the sulcal area (Fig. 6.8). Gonyaulacacean tabulation indicated by low (~1.0 lm or less) sutural ridges composed of coalesced fibers or granules, appearing under bright field microscopy as dark narrow lines on surface. Apical pore complex (apc) located at anterior pole, slightly left of sulcal midline; individual constituents of apc not distinguishable under light microscopy (Fig. 5.7–5.9) or SEM (Fig. 6.10). Third apical homologue (*3’) does not reach apc owing to narrow 2’/*4’ contact (Figs. 5.7–5.9, 9.1, 9.3–9.5). First apical plate (1’) either a trapezium reaching 6’’ where 1’/ 6’’shorter than 1’/2’ (Fig. 9.1, 9.4) representing episert type I topology (Fig. 10.4), or inverted isosceles triangle not reaching 6’’ owing to narrow *4’/1’’ contact (Fig. 9.5) representing episert type II topology (Fig. 10.5). Plate *4’ somewhat larger than plate *3’. Plate 3’’, lost in archeopyle formation, directly opposite sulcus. Left margin of plate 6’’ curves to left, over anterior sulcal plate (as), causing broad 6’’/1’’ contact. Plate 1’’ always contacts the anterior sulcal plate. Cingulum narrow, equatorial, descending with displacement of about one width. Sulcus broad, aligned, modified L-type (see Remarks); sulcal plates poorly expressed, but anterior sulcal (as), right accessory sulcal (ras), right sulcal (rs), left sulcal (ls), posterior sulcal (ps) plates may all be partially delineated by faint traces, though not necessarily on every cyst; flagellar scar indicated by elongate indentation left of ras; posterior margin of ps convex where contacting first antapical plate (1’’’’). First postcingular homolog (*1’’’) small, does not contact cingulum (Fig. 6.12, 9.4, 9.5); labeled as such because occurs within sulcal area; remaining five plates in series obligatorily labeled postcingular homologs. Neutral torsion on dorsal surface indicated by approximate alignment of *4’’’/*5’’’ with 3’’/4’’ at cingulum, although *4’’’/*5’’’ typically offset slightly to left of 3’’/4’’ (as for holotype; Fig. 3.1–3.3). Boundary *3’’’/*4’’’ offset conspicuously to left of 2’’/3’’ at cingulum (e.g., Fig. 5.1–5.3). Sexiform hypocystal tabulation; antapical plate (1’’’’) six sided but approximately trapezoidal, widening ventrally; 1’’’’/*6’’’ longer than 1’’’’/1p (Fig. 9.2). Archeopyle large, precingular Type 1P (3’’), has rounded angles; low sutural crests, where visible, closely follow entire archeopyle margin including rounded angles (Fig. 6.7); operculum free.
Measurements.—Holotype: central body length, 81 µm; process length, 6–11, µm; wall thickness, ~1.7 µm (Head and Westphal, 1999). Upper Pliocene and lower Pleistocene, Great Bahama Bank: central body maximum diameter, 80(89.7)106 µm; average process length, 7(15.0)24 µm; wall thickness, ~0.6(1.1)1.7 µm; 30 specimens measured (Head and Westphal, 1999). ODP Site 1007 (Miocene): central body maximum diameter, 55(84.0)110 µm; average process length, 0(17.2)35.2 µm; wall thickness, ~0.5–1.3 µm; 25 specimens measured. ODP Site 1007 (Pliocene): central body maximum diameter, 68(86.1)106 µm; average process length, 0(10.5)31.8 µm; wall thickness, ~0.8–3.0 µm; 14 specimens measured. ODP Site 1007 (Pleistocene): central body maximum diameter, 74(84.1)96 µm; average process length, 0(6.0)13.6 µm; wall thickness, ~0.8–2.0 µm; seven specimens measured.
Overall dimensions: central body maximum diameter, 55(86.1)110 µm; average process length, 0(13.9)35.2 µm; wall thickness, ~0.5–3.0 µm; 76 specimens measured.
Holotype: Head and Westphal, 1999, fig.9, nos.9–12.
Age: Pliocene.
Original description (Head & Westpal, 1999):
Operculadinium Bahamaense Head, new species Figures 9.9-9.14, 10.1-10.5
Operculodinium sp. 3. Manum, Boulter, Gunnarsdottir Rangnes, and Scholze, 1989, pl. 13, figs. 5, 6.
Diagnosis.-A large species of Operculodinium with long, sparsely distributed processes; tabulation relatively completely expressed by low sutural ridges that appear as dark narrow lines on surface.
Description.-Central body broadly egg-shaped to nearly spherical, the wall consisting of thin, solid pedium, and thicker, distally open, spongy-fibrous to fibro-microreticulate luxuria. Gonyaulacacean tabulation indicated by low (ca. 1 µm or less) sutural ridges composed of coalesced fibers or granules, appearing as dark narrow lines on surface. Cingulum narrow, equatorial, and descending with displacement of about one width. A flagellar scar may be indicated by elongate indentation in midsulcal area. Processes are slender and solid, with fibrous, expanded bases; and terminate distally in small aculeate platforms, each with up to eight or more aculeae. Process distribution sparse and nontabular, with process bases sometimes crossing sutural ridges. Process length variable on individual specimens, some processes being up to 32 µm in length. Archeopyle precingular Type 1P (3"), enlarged, has rounded angles. Operculum free.
Dimensions.-Holotype: length (excluding process), 81 µm; process length, 6-11 µm; wall thickness, ca. 1.7 µm. Range: Maximum diameter (excluding process), 80(89.7)106 µm; average process length, 7(15.0)24 µm. Wall thickness, ca. 0.6(1.1)1.7 µm. Thirty specimens measured.
Etymology. -Named with reference to the Great Bahama Bank, type locality of this species.
Holotype.-Fig. 9.9-9.12. Sample CUS-K 11, slide 3; England Finder reference G18/2. ROM 53304. Clino core, 234.12 m (768.13 ft) below mud pit; upper upper Pliocene.
Comparison.-Operculodinium giganteum Wall, 1967 may also have sutural lines, but processes are shorter (2-4 µm) and more densely distributed. Operculodinium wallii Matsuoka, 1983 lacks sutural lines or ridges. Operculodinium floridium Warny and Wrenn, 1997 has shorter (2-10 µm) processes whose distribution is dense and distinctly intratabular, and lacks sutural lines or ridges. Previous records.-Upper middle and upper Miocene of the Norwegian Sea (as Operculodinium sp. 3 in Manum et al., 1989).
Emended description (Paez-Reyes and Head, 2013):
1989 Operculodinium sp. 3; Manum, Boulter, Gunnarsdottir, Rangnes, and Scholze, p. 13, figs. 5, 6.
1999 Operculodinium bahamense Head in Head and Westphal, p. 12, 13, figs. 9.9–9.14, 10.1–10.5.
Emended diagnosis: a large species of Operculodinium with spherical to subspherical central body whose spongy-fibrous luxuria bears sparsely-distributed, solid to fibrous processes with expanded fibrous bases, terminating distally in minute expansions with aculeate margins. Low sutural ridges demarcate gonyaulacacean, sexiform tabulation with modified L-type ventral organization, neutrally contorted dorsal tabulation, and episert 1’. Plate formula is 2’þ*2’, 6’’, 6c, 5s, *6’’’, 1p, 1’’’’. Archeopyle large, angles rounded, formed by loss of third precingular plate; operculum free.
Description.—Central body spherical to subspherical, wall consisting of thin, solid pedium, and thicker, distally open, spongy-fibrous luxuria. Surface spongy-fibrous to punctate (Fig. 6.7, 6.10–6.12), may become smoother on sulcus (Fig. 6.12). Scattered granules may also occur over surface (Fig. 6.8). Processes slender, solid to fibrous, circular in cross-section, with fibrous expanded bases; terminate distally in minute, flared platforms with recurved, aculeate margins, each bearing up to about eight aculeae. Process distribution sparse, apparently intratabular, with the largest plates bearing up to around seven processes (e.g., seven on plate *4’’’, Fig. 5.1, 5.2; six on plate 3’’, Head and Westphal, 1999, fig. 10.4, 10.5), usually up to four or five processes on other large plates (e.g., 1’’ and *3’’’), and usually no more than one on smaller plates (e.g., *2’’’). Process bases observed to cross plate boundaries only in the midventral region (Fig. 6.8) and occasionally along the cingulum. Process distribution irregular within plate boundaries, adjacent processes may be widely separated or so close as to be fused at base. Processes up to ~35 µm long, with length sometimes variable on individual specimens; some specimens devoid of processes (Figs. 2, 6.1–6.6). Shorter, more slender processes may occur in the sulcal area (Fig. 6.8). Gonyaulacacean tabulation indicated by low (~1.0 lm or less) sutural ridges composed of coalesced fibers or granules, appearing under bright field microscopy as dark narrow lines on surface. Apical pore complex (apc) located at anterior pole, slightly left of sulcal midline; individual constituents of apc not distinguishable under light microscopy (Fig. 5.7–5.9) or SEM (Fig. 6.10). Third apical homologue (*3’) does not reach apc owing to narrow 2’/*4’ contact (Figs. 5.7–5.9, 9.1, 9.3–9.5). First apical plate (1’) either a trapezium reaching 6’’ where 1’/ 6’’shorter than 1’/2’ (Fig. 9.1, 9.4) representing episert type I topology (Fig. 10.4), or inverted isosceles triangle not reaching 6’’ owing to narrow *4’/1’’ contact (Fig. 9.5) representing episert type II topology (Fig. 10.5). Plate *4’ somewhat larger than plate *3’. Plate 3’’, lost in archeopyle formation, directly opposite sulcus. Left margin of plate 6’’ curves to left, over anterior sulcal plate (as), causing broad 6’’/1’’ contact. Plate 1’’ always contacts the anterior sulcal plate. Cingulum narrow, equatorial, descending with displacement of about one width. Sulcus broad, aligned, modified L-type (see Remarks); sulcal plates poorly expressed, but anterior sulcal (as), right accessory sulcal (ras), right sulcal (rs), left sulcal (ls), posterior sulcal (ps) plates may all be partially delineated by faint traces, though not necessarily on every cyst; flagellar scar indicated by elongate indentation left of ras; posterior margin of ps convex where contacting first antapical plate (1’’’’). First postcingular homolog (*1’’’) small, does not contact cingulum (Fig. 6.12, 9.4, 9.5); labeled as such because occurs within sulcal area; remaining five plates in series obligatorily labeled postcingular homologs. Neutral torsion on dorsal surface indicated by approximate alignment of *4’’’/*5’’’ with 3’’/4’’ at cingulum, although *4’’’/*5’’’ typically offset slightly to left of 3’’/4’’ (as for holotype; Fig. 3.1–3.3). Boundary *3’’’/*4’’’ offset conspicuously to left of 2’’/3’’ at cingulum (e.g., Fig. 5.1–5.3). Sexiform hypocystal tabulation; antapical plate (1’’’’) six sided but approximately trapezoidal, widening ventrally; 1’’’’/*6’’’ longer than 1’’’’/1p (Fig. 9.2). Archeopyle large, precingular Type 1P (3’’), has rounded angles; low sutural crests, where visible, closely follow entire archeopyle margin including rounded angles (Fig. 6.7); operculum free.
Measurements.—Holotype: central body length, 81 µm; process length, 6–11, µm; wall thickness, ~1.7 µm (Head and Westphal, 1999). Upper Pliocene and lower Pleistocene, Great Bahama Bank: central body maximum diameter, 80(89.7)106 µm; average process length, 7(15.0)24 µm; wall thickness, ~0.6(1.1)1.7 µm; 30 specimens measured (Head and Westphal, 1999). ODP Site 1007 (Miocene): central body maximum diameter, 55(84.0)110 µm; average process length, 0(17.2)35.2 µm; wall thickness, ~0.5–1.3 µm; 25 specimens measured. ODP Site 1007 (Pliocene): central body maximum diameter, 68(86.1)106 µm; average process length, 0(10.5)31.8 µm; wall thickness, ~0.8–3.0 µm; 14 specimens measured. ODP Site 1007 (Pleistocene): central body maximum diameter, 74(84.1)96 µm; average process length, 0(6.0)13.6 µm; wall thickness, ~0.8–2.0 µm; seven specimens measured.
Overall dimensions: central body maximum diameter, 55(86.1)110 µm; average process length, 0(13.9)35.2 µm; wall thickness, ~0.5–3.0 µm; 76 specimens measured.