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Trithyrodinium verrucosum
Original description (Heisecke, 1970) Translation PKB 2025:
DIAGNOSIS. Cyst excavated in subcircular to rhomboidal contour composed of two layers. Endophragm
thick, opaque, infragranulated, with warty sculpture; periphragm delicate, hyaline, forming an apical horn and two small antiapical horns. In the equatorial zone, a poorly defined cingulum is observed. It has a precingular archeopyle.
HOLOTYPE. Slide 429(1), coordinates 35.7/104.2.
DIMENSIONS. Holotype: total length 84 μm, polled length 68 μm, width 67 μm, apical horn length 8 μm, greater antiapical horn length 9 μm, lesser antiapical horn length 4 μm.
DESCRIPTION. Subspherical excavated cyst with a circular to subcircular contour with a tendency to rhomboidal,
composed of two layers. The endophragm, opaque, reddish brown, presents warty sculpture; The warts are distributed in a fairly spaced and irregular manner, and the shapes of these warts are diverse, with irregular contours, in some cases elongated, with one wart joining another. The periphragm is delicate, hyaline and forms a small apical protuberance or horn and two antiapical horns, one larger than the other, also small. Both layers are separated forming a period of 1-1.5 μm. wide, except in the apical and antiapical area, where they separate to form the horns. In the equatorial zone, irregular thickenings of the wall are observed, which would indicate the presence of a little characteristic or defined angle. It has a precingular archeopyle. irregular pentagonal.
DIMENSIONS. Total length 84-86 μm, length (without horns) 64-68 μm, width 67-68 μm, apical horn length 8-10 μm, length of major antiapical horn 9-15 μm, length of the minor antiapical horn 4-7 μm, Number of specimens measured: 2.
STUDY MATERIAL. slide 67( 4 ), coordinates 46.2/111.8 and slide 429( 1 ), coordinates
35.7/104.2.
DISCUSSION. This new species differs from those observed corresponding to the same genus, mainly in the warty structure of the endophragm and the great contrast between the thick and opaque endophragm and the delicate and hyaline periphragm. Deflandrea endopapillata Archangelsky, 1959, is the only species comparable to the one described here because of its endophragm provided with papillae. However, Scriniodinium verrucosum differs from this form due to the position of the archaeopil; The horns of the new species are relatively small, the periphragm is smooth (it does not present more condensed granules in the horns and in the pericingular region as in D. endopapillata) and the size is smaller.
HORIZON. Samples MH6 and MH2.
DERIVATIO NOMINIS. From the Latin verrucosus, warty, referring to the warty sculpture of the endophragm.
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Emended diagnosis Estebenet and Guler, 2023:
Emended diagnosis. Peridiniacean (deflandreoid) dinoflagellate cyst. The cyst wall is composed of two layers: the periphragm thin and hyaline, and the endophragm moderately thick, bearing irregularly spaced non-tabular, spherical verrucae of moderate relief.
Emended description. Proximate peridiniacean cysts, bicavate to circumcavate, spherical to subspherical in shape. The wall has two layers closely appressed except at the horns. A thin, hyaline periphragm forms a short apical horn (~10 μm) and two scarcely developed unequal antapical horns (Fig. 3.13, 3.15–3.16). A pigmented moderately thick (up to 2 μm) endophragm presents irregularly spaced non-tabular spherical (as “pearls”) of similar size verrucae of moderate relief, 1.3 (1.8) 2.6 μm in diameter, occasionally joined at their bases (e.g., Fig. 3.1). In some specimens an alignment of the verrucae is observed at the paracingulum (Figs. 3.2– 3.3, 3.7). Archeopyle is intercalary type 3I with formula I(1–3a); most of the operculum is often attached (Figs. 2.1–2.11, 3.1–3.13).
Dimensions. Central body length 60 (67) 73 μm, width 61 (68) 72 μm; spherical verrucae of 1.3 (1.7) 2.6 μm of diameter. Number of specimens measured= 11.
Occurrence. Valdés Basin: YPF-CH-PV.es-1 borehole (42° 44’ 46.26” S; 63° 39’ 26.58” W), from level 825–830 mbgs to 850–855 mbgs. Neuquén Basin (Roca Formation): Cerro Caracol locality (37° 50’ S; 68° 25’ W), sample MH6b; Sierra Blanca locality (38° 10’ S; 68° 25’ W), sample MH6 (Heisecke, 1970).
Remarks and comparison. Heisecke (1970) described this species as Scriniodinium verrucosum, as having precingular archeopyle. However, the new well-preserved specimens recovered from the PV borehole and the re-studied of the original material of the Roca Formation allowed us to identify an unequivocal intercalary archeopyle type 3I that led us to transfer the species to the genus Trithyrodinium. The emendation of the species also modified the original definition of the ornamentation. Whereas Heisecke (1970) includes broader reference to the variability of the verrucae, specimens herein analyzed exhibit only spherical verrucae. Because slides with the holotype material could not be located, a lectotype is designated (Fig. 2.9–2.10). Senegalinium sp. from the Jagüel Formation, Neuquén Basin (38° 08’ S; 68° 26’ W) illustrated by Papú et al. (1999, fig. 1.3) might be a specimen of Trithyrodinium verrucosum; the specimen shows an intercalary archeopyle of type 3I, and the endophragm ornamented with verrucae. This specimen should be designated at least as Trithyrodinium also that it does not satisfy the criteria for being considered Senegalinium genus.
Trithyrodinium verrucosum is similar to Trithyrodinium verrucatum Vieira & Mahdi, 2021 in having an endophragm with verrucae, but in Trithyrodinium verrucosum the endophragm is less thick and verrucae are smaller and more irregularly spaced distributed (less quantity) than in Trithyrodinium verrucatum (Vieira & Mahdi, 2021). Both species differ from all other species of Trithyrodinium by the presence of a verrucate ornamented endophragm. Trithyrodinium ioannidesii Vieira & Mahdi, 2021 bears numerous non-tabular grana and coni of variable size; Trithyrodinium suspectum (Manum & Cookson, 1964) Davey, 1969 contain rod-shaped elements of unequal length; Trithyrodinium zakkii Pearce et al., 2019 possessed short, minutely non-tabular bifurcating spines; Trithyrodinium evittii is finely punctate ornamented; Trithyrodinium striatum Benson, 1976 is longitudinally striate, and Trithyrodinium partridgei Willumsen & Vajda, 2010 presents a foveolate mesophragm.
DIAGNOSIS. Cyst excavated in subcircular to rhomboidal contour composed of two layers. Endophragm
thick, opaque, infragranulated, with warty sculpture; periphragm delicate, hyaline, forming an apical horn and two small antiapical horns. In the equatorial zone, a poorly defined cingulum is observed. It has a precingular archeopyle.
HOLOTYPE. Slide 429(1), coordinates 35.7/104.2.
DIMENSIONS. Holotype: total length 84 μm, polled length 68 μm, width 67 μm, apical horn length 8 μm, greater antiapical horn length 9 μm, lesser antiapical horn length 4 μm.
DESCRIPTION. Subspherical excavated cyst with a circular to subcircular contour with a tendency to rhomboidal,
composed of two layers. The endophragm, opaque, reddish brown, presents warty sculpture; The warts are distributed in a fairly spaced and irregular manner, and the shapes of these warts are diverse, with irregular contours, in some cases elongated, with one wart joining another. The periphragm is delicate, hyaline and forms a small apical protuberance or horn and two antiapical horns, one larger than the other, also small. Both layers are separated forming a period of 1-1.5 μm. wide, except in the apical and antiapical area, where they separate to form the horns. In the equatorial zone, irregular thickenings of the wall are observed, which would indicate the presence of a little characteristic or defined angle. It has a precingular archeopyle. irregular pentagonal.
DIMENSIONS. Total length 84-86 μm, length (without horns) 64-68 μm, width 67-68 μm, apical horn length 8-10 μm, length of major antiapical horn 9-15 μm, length of the minor antiapical horn 4-7 μm, Number of specimens measured: 2.
STUDY MATERIAL. slide 67( 4 ), coordinates 46.2/111.8 and slide 429( 1 ), coordinates
35.7/104.2.
DISCUSSION. This new species differs from those observed corresponding to the same genus, mainly in the warty structure of the endophragm and the great contrast between the thick and opaque endophragm and the delicate and hyaline periphragm. Deflandrea endopapillata Archangelsky, 1959, is the only species comparable to the one described here because of its endophragm provided with papillae. However, Scriniodinium verrucosum differs from this form due to the position of the archaeopil; The horns of the new species are relatively small, the periphragm is smooth (it does not present more condensed granules in the horns and in the pericingular region as in D. endopapillata) and the size is smaller.
HORIZON. Samples MH6 and MH2.
DERIVATIO NOMINIS. From the Latin verrucosus, warty, referring to the warty sculpture of the endophragm.
----------------------------------------------------------------------------------------------------------------
Emended diagnosis Estebenet and Guler, 2023:
Emended diagnosis. Peridiniacean (deflandreoid) dinoflagellate cyst. The cyst wall is composed of two layers: the periphragm thin and hyaline, and the endophragm moderately thick, bearing irregularly spaced non-tabular, spherical verrucae of moderate relief.
Emended description. Proximate peridiniacean cysts, bicavate to circumcavate, spherical to subspherical in shape. The wall has two layers closely appressed except at the horns. A thin, hyaline periphragm forms a short apical horn (~10 μm) and two scarcely developed unequal antapical horns (Fig. 3.13, 3.15–3.16). A pigmented moderately thick (up to 2 μm) endophragm presents irregularly spaced non-tabular spherical (as “pearls”) of similar size verrucae of moderate relief, 1.3 (1.8) 2.6 μm in diameter, occasionally joined at their bases (e.g., Fig. 3.1). In some specimens an alignment of the verrucae is observed at the paracingulum (Figs. 3.2– 3.3, 3.7). Archeopyle is intercalary type 3I with formula I(1–3a); most of the operculum is often attached (Figs. 2.1–2.11, 3.1–3.13).
Dimensions. Central body length 60 (67) 73 μm, width 61 (68) 72 μm; spherical verrucae of 1.3 (1.7) 2.6 μm of diameter. Number of specimens measured= 11.
Occurrence. Valdés Basin: YPF-CH-PV.es-1 borehole (42° 44’ 46.26” S; 63° 39’ 26.58” W), from level 825–830 mbgs to 850–855 mbgs. Neuquén Basin (Roca Formation): Cerro Caracol locality (37° 50’ S; 68° 25’ W), sample MH6b; Sierra Blanca locality (38° 10’ S; 68° 25’ W), sample MH6 (Heisecke, 1970).
Remarks and comparison. Heisecke (1970) described this species as Scriniodinium verrucosum, as having precingular archeopyle. However, the new well-preserved specimens recovered from the PV borehole and the re-studied of the original material of the Roca Formation allowed us to identify an unequivocal intercalary archeopyle type 3I that led us to transfer the species to the genus Trithyrodinium. The emendation of the species also modified the original definition of the ornamentation. Whereas Heisecke (1970) includes broader reference to the variability of the verrucae, specimens herein analyzed exhibit only spherical verrucae. Because slides with the holotype material could not be located, a lectotype is designated (Fig. 2.9–2.10). Senegalinium sp. from the Jagüel Formation, Neuquén Basin (38° 08’ S; 68° 26’ W) illustrated by Papú et al. (1999, fig. 1.3) might be a specimen of Trithyrodinium verrucosum; the specimen shows an intercalary archeopyle of type 3I, and the endophragm ornamented with verrucae. This specimen should be designated at least as Trithyrodinium also that it does not satisfy the criteria for being considered Senegalinium genus.
Trithyrodinium verrucosum is similar to Trithyrodinium verrucatum Vieira & Mahdi, 2021 in having an endophragm with verrucae, but in Trithyrodinium verrucosum the endophragm is less thick and verrucae are smaller and more irregularly spaced distributed (less quantity) than in Trithyrodinium verrucatum (Vieira & Mahdi, 2021). Both species differ from all other species of Trithyrodinium by the presence of a verrucate ornamented endophragm. Trithyrodinium ioannidesii Vieira & Mahdi, 2021 bears numerous non-tabular grana and coni of variable size; Trithyrodinium suspectum (Manum & Cookson, 1964) Davey, 1969 contain rod-shaped elements of unequal length; Trithyrodinium zakkii Pearce et al., 2019 possessed short, minutely non-tabular bifurcating spines; Trithyrodinium evittii is finely punctate ornamented; Trithyrodinium striatum Benson, 1976 is longitudinally striate, and Trithyrodinium partridgei Willumsen & Vajda, 2010 presents a foveolate mesophragm.