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Spiniferites solidago
Spiniferites "solidago" de Verteuil and Norris, 1996a, p.144,146,148, pl.10, figs.6–15; pl.11, figs.1–8. Holotype: de Verteuil and Norris, 1996a, pl.10, figs.6–7. Taxonomic senior synonym: Hystrichosphaeridium (as Spiniferites, now Achomosphaera) grallaeformis, according to Strauss et al. (2001, p.412). N.I.A. Age: late Oligocene–late Miocene.
Holotype: Plate 10, f"igs. 6,7
Locus typicus: Scientists Cliffs South, Scientists Cliffs community beach level car park, about 2.5km south of Parker Creek, on the western shore of the Chesapeake Bay, Calvert County, Maryland.
Stratum typicum: Middle Miocene Calvert Formation
Original diagnosis: de Verteuil and Norris, 1996, p. 144: Spiniferites solidago
An intermediate to small species of Spiniferites with the following combination of characteristics: one or more vacoules and associated bulges along the length of most processes; tabulation weakly defined by low, perforate, limbate ridges, that may extend upwards at the bases of processes; variably alveolate luxuriae with irregularly perforate tegillum.
Original description: de Verteuil and Norris, 1996, p. 144: Spiniferites solidago
Cysts intermediate to small, proximochorate with ovoidal to spherical autoblast and a low apical boss. The general structure of the wall is a thin homogeneous pedium ca. 0.5µm thick and a perforate tegillum, separated by an alveolate horizon. The density of alveoles in the wall is variable among specimens, from rare to uniformly common. Alveoles vary in size from barely visible to ca. 1µm in diameter; in most specimens the wall is clearly alveolate but sometimes it appears homogeneous. In intrafield areas the total wall thickness is 0.75 to 2µm and the tegillum is smooth to scabrate and irregularly perforate with circular to ellipsoid lumen that vary from 0.2 to l.5Ám in diameter. Perforations are concentrated along the limbi between processes, thereby partly delimiting the tabulation. The tegillum forms low, wide, ridges across the limbi, with faint, narrow peritabular cusps. Within fields, perforations of the tegillum are generally less common. When distinct pericoels are present at the bases of processes the associated tegillum often has fewer, larger perforations, up to 4µm wide (pl. 11, fig. 1).
Processes are mostly gonal but sometimes also intergonal, particularly on sides 2 and 4 of deltacamerate 3". Processes may have sharply curved, cylindrical bases without pericoels but are usually tapered with some pericoel development. Process shafts are hollow with usually one primary vacuole present one third to two thirds along its length, often with one or more smaller vacuoles distally. Gonal processes are distally trifurcate and intergonal processes bifurcate. Furcations are flat to rounded, about 30% to 50% as long as the shaft and tetrahedronally to orthogonally directed about it. The distally bifid terminations are Y-shaped to recurved. Process shafts excluding the furcations are 15% to 25% of the equatorial diameter. Complex processes are not present, although closely placed processes may be joined by proximal tegillum membranes over a common pericoel, as for example at the as/l " boundary. The simple cingular processes occur in pairs joined by low membranes orthogonal to the cingulum, except at as/lc and ras/6c where more complex process clusters occur involving sulcal fields.
The tabulation of Spiniferites solidago is standard gonyaulacalean, sexiform, S-type. The cingulum is gently laevorotatory without overhang; the sulcus is wide and fairly straight. The archeopyle is simple precingular; 1^2 and 4^5 are sharp and between 90¦ and 110¦; 2^3 and 3^4 are slightly less than 90¦, and there may be a small, anteriorly directed notch at 5^1. Accessory archeopyle sutures are sometimes present.
Dimensions: Length, excluding processes, 40(46.3)52µm; holotype 44µm. Width at cingulum, excluding processes, 36(40.2)44µm; holotype 40µm. Processes excluding trifurcations 7-16µm. Twenty specimens measured.
Discussion: de Verteuil and Norris, 1996, p. 144
Spiniferites solidago shows a considerable range of morphological variability in certain characters. The most important of these are process length relative to autoblast diameter, the degree of separation of the tegillum from the alveolate horizon at process bases and consequent pericoel development, the density of tegillum perforations and alveoles in the wall, and the tendency to have intergonal processes. Specimens with shorter processes, about 15% of equatorial diameter, tend to have relatively shorter furcations as well. Pericoel development varies from none to moderate. The density of alveoles varies from almost none to a well developed horizon between the pedium and tegillum. The wall, however, is never thicker than 2.5µm and never develops an intense multilevel vacuolate texture. Intergonal processes, not exceeding one per side, may be present on any of the adcingular series field boundaries, but tend to be rare on the dorsal hypocyst. On some specimens, an intergonal process is present on one side of the archeopyle, 2 or 4, but not on the other. The spiniferites solidago style of simple paired cingular processes, particularly at the laterally positioned of 2c and 5c field boundaries, is in contrast to another common cingular process morphology in Spiniferites and Achomosphaera. In that style, which is characteristic of Achomosphaera ramulifera, a single main process shaft bifurcates once to form two secondary shafts which are each trifurcate.
Comparison: de Verteuil and Norris, 1996, p. 144
Spiniferites solidago from the United States Atlantic margin compares well with the specimens described as Achomospharea sp. A by Martin (1991) from Oligocene and undifferentiated lower to middle Miocene sediments of the Murray Basin, southwestern Australia. It is not clear whether an apical boss is present in the Australian material; optical sections of Martin"s specimens indicate that the reticulate surface pattern he describes results from the internally alveolate wall structure, the outer surface of the tegillum being essentially smooth.
The ovoidal shape and clear apical boss of Spiniferites solidago make it similar in this respect to Spiniferites bentorii, to which it may be allied. Spiniferites solidago is a relatively small species that does not seem to vary much in size. Shape and size therefore distinguish Spiniferites solidago from many species of Spiniferites and Achomosphaera. The alveolate wall, vacuolate processes and perforate tegillum, together with its distinctive size, shape and cingular process structure distinguish Spiniferites solidago form all other taxa in this complex. In particular, Achomosphaera ramulifera has complex lateral cingular processes; Achomosphaera crassipellis and Achomosphaera sagena have thicker, reticulate walls formed by columellae; Achomosphaera spongiosa has spongy luxuriae and lacks an apical boss and consistent vacuoles in the process.
Occurrence: Upper Oligocene to upper Miocene (DN 9) in the Salisbury Embayment. Most commonly present in the Plum Point Marls Member of the Calvert Formation and in the Choptank Formation.
Holotype: Plate 10, f"igs. 6,7
Locus typicus: Scientists Cliffs South, Scientists Cliffs community beach level car park, about 2.5km south of Parker Creek, on the western shore of the Chesapeake Bay, Calvert County, Maryland.
Stratum typicum: Middle Miocene Calvert Formation
Original diagnosis: de Verteuil and Norris, 1996, p. 144: Spiniferites solidago
An intermediate to small species of Spiniferites with the following combination of characteristics: one or more vacoules and associated bulges along the length of most processes; tabulation weakly defined by low, perforate, limbate ridges, that may extend upwards at the bases of processes; variably alveolate luxuriae with irregularly perforate tegillum.
Original description: de Verteuil and Norris, 1996, p. 144: Spiniferites solidago
Cysts intermediate to small, proximochorate with ovoidal to spherical autoblast and a low apical boss. The general structure of the wall is a thin homogeneous pedium ca. 0.5µm thick and a perforate tegillum, separated by an alveolate horizon. The density of alveoles in the wall is variable among specimens, from rare to uniformly common. Alveoles vary in size from barely visible to ca. 1µm in diameter; in most specimens the wall is clearly alveolate but sometimes it appears homogeneous. In intrafield areas the total wall thickness is 0.75 to 2µm and the tegillum is smooth to scabrate and irregularly perforate with circular to ellipsoid lumen that vary from 0.2 to l.5Ám in diameter. Perforations are concentrated along the limbi between processes, thereby partly delimiting the tabulation. The tegillum forms low, wide, ridges across the limbi, with faint, narrow peritabular cusps. Within fields, perforations of the tegillum are generally less common. When distinct pericoels are present at the bases of processes the associated tegillum often has fewer, larger perforations, up to 4µm wide (pl. 11, fig. 1).
Processes are mostly gonal but sometimes also intergonal, particularly on sides 2 and 4 of deltacamerate 3". Processes may have sharply curved, cylindrical bases without pericoels but are usually tapered with some pericoel development. Process shafts are hollow with usually one primary vacuole present one third to two thirds along its length, often with one or more smaller vacuoles distally. Gonal processes are distally trifurcate and intergonal processes bifurcate. Furcations are flat to rounded, about 30% to 50% as long as the shaft and tetrahedronally to orthogonally directed about it. The distally bifid terminations are Y-shaped to recurved. Process shafts excluding the furcations are 15% to 25% of the equatorial diameter. Complex processes are not present, although closely placed processes may be joined by proximal tegillum membranes over a common pericoel, as for example at the as/l " boundary. The simple cingular processes occur in pairs joined by low membranes orthogonal to the cingulum, except at as/lc and ras/6c where more complex process clusters occur involving sulcal fields.
The tabulation of Spiniferites solidago is standard gonyaulacalean, sexiform, S-type. The cingulum is gently laevorotatory without overhang; the sulcus is wide and fairly straight. The archeopyle is simple precingular; 1^2 and 4^5 are sharp and between 90¦ and 110¦; 2^3 and 3^4 are slightly less than 90¦, and there may be a small, anteriorly directed notch at 5^1. Accessory archeopyle sutures are sometimes present.
Dimensions: Length, excluding processes, 40(46.3)52µm; holotype 44µm. Width at cingulum, excluding processes, 36(40.2)44µm; holotype 40µm. Processes excluding trifurcations 7-16µm. Twenty specimens measured.
Discussion: de Verteuil and Norris, 1996, p. 144
Spiniferites solidago shows a considerable range of morphological variability in certain characters. The most important of these are process length relative to autoblast diameter, the degree of separation of the tegillum from the alveolate horizon at process bases and consequent pericoel development, the density of tegillum perforations and alveoles in the wall, and the tendency to have intergonal processes. Specimens with shorter processes, about 15% of equatorial diameter, tend to have relatively shorter furcations as well. Pericoel development varies from none to moderate. The density of alveoles varies from almost none to a well developed horizon between the pedium and tegillum. The wall, however, is never thicker than 2.5µm and never develops an intense multilevel vacuolate texture. Intergonal processes, not exceeding one per side, may be present on any of the adcingular series field boundaries, but tend to be rare on the dorsal hypocyst. On some specimens, an intergonal process is present on one side of the archeopyle, 2 or 4, but not on the other. The spiniferites solidago style of simple paired cingular processes, particularly at the laterally positioned of 2c and 5c field boundaries, is in contrast to another common cingular process morphology in Spiniferites and Achomosphaera. In that style, which is characteristic of Achomosphaera ramulifera, a single main process shaft bifurcates once to form two secondary shafts which are each trifurcate.
Comparison: de Verteuil and Norris, 1996, p. 144
Spiniferites solidago from the United States Atlantic margin compares well with the specimens described as Achomospharea sp. A by Martin (1991) from Oligocene and undifferentiated lower to middle Miocene sediments of the Murray Basin, southwestern Australia. It is not clear whether an apical boss is present in the Australian material; optical sections of Martin"s specimens indicate that the reticulate surface pattern he describes results from the internally alveolate wall structure, the outer surface of the tegillum being essentially smooth.
The ovoidal shape and clear apical boss of Spiniferites solidago make it similar in this respect to Spiniferites bentorii, to which it may be allied. Spiniferites solidago is a relatively small species that does not seem to vary much in size. Shape and size therefore distinguish Spiniferites solidago from many species of Spiniferites and Achomosphaera. The alveolate wall, vacuolate processes and perforate tegillum, together with its distinctive size, shape and cingular process structure distinguish Spiniferites solidago form all other taxa in this complex. In particular, Achomosphaera ramulifera has complex lateral cingular processes; Achomosphaera crassipellis and Achomosphaera sagena have thicker, reticulate walls formed by columellae; Achomosphaera spongiosa has spongy luxuriae and lacks an apical boss and consistent vacuoles in the process.
Occurrence: Upper Oligocene to upper Miocene (DN 9) in the Salisbury Embayment. Most commonly present in the Plum Point Marls Member of the Calvert Formation and in the Choptank Formation.