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Membranophoridium aspinatum
Membranophoridium aspinatum Gerlach, 1961
Lentin and Williams, 1993, followed Fensome et al., 1993, in accepting this species name as validly published in Gerlach, 1961.
Originally (and now) Membranophoridium, subsequently Chiropteridium.
Holotype: Gerlach, 1961, pl.29, figs.7-8 (two specimens designated)
Lectotype: Gerlach, 1961, pl.2, fig.7 (designated by Gocht, 1969)
Paratypes: Gerlach, 1961
Locus typicus: Emsb³ren 7 bore, Germany
Stratum typicum: Middle Oligocene
Translation Gerlach, 1961: Fensome et al., 1993
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Membranophoridium aspinatum Gerlach, 1961. See generic diagnosis. Size: overall length 74-110 µm, width 84-118 µm.
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Original diagnosis: Gerlach, 1961, p.199
Type species of the genus Membranophoridium with the following characteristics: theca surrounded on both sides by two parallel membranes which run meridionally. Upper and lower sides of the shell always lacking spines. Membrane granulate.
Original description: Gerlach, 1961, p.199-200
The outline of the theca is almost always semicircular. Based on abundant material (more than 300 specimens of this genus were prepared, all of which are open apically), it is evident that, although the apical cap is missing, the shells are not damaged accidentally. More likely, the polar cap is shed in consequence of the release of the protoplast, a pylome thus being formed. Moreover, this is unequivocally shown by the presence of some specimens of this genus, in an uncommon state of preservation, in which the polar cap is still loosely connected to the remaining part of the theca.
This mode of pylome formation, as occurring predominantly in the genus Membranophoridium, is not uncommon in other hystrichosphaerids. It has been described for Tenua hystrix Eisenack, Hystrichosphaeridium tiara Klumpp, Hystrichosphaera [i.e. Histiophora] ornata Klement and for six species which Maier assigned to the genus Galea.
The apical-antapical orientation of the shells results from the position of the escape hole. The dorsal-ventral orientation was guided by the weak depression on one side, which is arbitrarily defined as the ventral or lower surface. Characteristic of the new species M. aspinatum is the lack of isolated spines on the upper and lower sides of the theca. Laterally the shell is surrounded by two parallel, meridionally trending membranes, which are not interconnected antapically. On the lower side ..., broad, lobate, highly disrupted borders are set off from the two vertically running structures; their external margins are more or less smooth or marked by fine denticles. Ventrally, the theca is weakly indented between the structures. The two parts of the membrane separating the upper and lower sides are considerably smaller than the two ventrally situated membranes. At the antapex, they are prolonged into flaps, one of which distinctly surmounts the other.
The shell wall is granulate and of a yellow-brown colour.
Size: Holotype: overall length 93 Ám, overall width 110 Ám, endocyst length 74 Ám, endocyst width 84 Ám. Range of 20 specimens: overall length 74-110 Ám, overall width 84-118 Ám. See Gerlach, 1961, p.200 for further measurements.
Supplemental description: Mao Shaozhi and Norris, 1988, p.33
Cyst proximate, dorsoventrally compressed, with a short obtuse apical horn and two more or less unequal antapical lobes or horns--the left one always larger.
Central body ellipsoidal, with slightly protruding apex. Periphragm thin and membranous; its margin generally smooth to slightly sinuous, seldom bearing isolated bifurcate processes. Middorsally and midventrally appressed to endophragm (indicated by line of contact), separated elsewhere. Width of pericoel varying from 0 to 16 Ám in one individual. Pericoel usually complete.
Endophragm smooth to granulate. Archeopyle apical, type (tA) or (tA)a; archeopyle suture ragged, its accessory sutures indicating six precingular plates. Operculum more commonly free than attached dorsally. Sulcal notch offset to left.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 469, pl.12,fig.4: Membranophoridium cf. aspinatum
The specimens recovered from the Lutetian section in Wursterheide are considerably smaller than typical for this species.
Lentin and Williams, 1993, followed Fensome et al., 1993, in accepting this species name as validly published in Gerlach, 1961.
Originally (and now) Membranophoridium, subsequently Chiropteridium.
Holotype: Gerlach, 1961, pl.29, figs.7-8 (two specimens designated)
Lectotype: Gerlach, 1961, pl.2, fig.7 (designated by Gocht, 1969)
Paratypes: Gerlach, 1961
Locus typicus: Emsb³ren 7 bore, Germany
Stratum typicum: Middle Oligocene
Translation Gerlach, 1961: Fensome et al., 1993
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Membranophoridium aspinatum Gerlach, 1961. See generic diagnosis. Size: overall length 74-110 µm, width 84-118 µm.
--------------------------------------------------
Original diagnosis: Gerlach, 1961, p.199
Type species of the genus Membranophoridium with the following characteristics: theca surrounded on both sides by two parallel membranes which run meridionally. Upper and lower sides of the shell always lacking spines. Membrane granulate.
Original description: Gerlach, 1961, p.199-200
The outline of the theca is almost always semicircular. Based on abundant material (more than 300 specimens of this genus were prepared, all of which are open apically), it is evident that, although the apical cap is missing, the shells are not damaged accidentally. More likely, the polar cap is shed in consequence of the release of the protoplast, a pylome thus being formed. Moreover, this is unequivocally shown by the presence of some specimens of this genus, in an uncommon state of preservation, in which the polar cap is still loosely connected to the remaining part of the theca.
This mode of pylome formation, as occurring predominantly in the genus Membranophoridium, is not uncommon in other hystrichosphaerids. It has been described for Tenua hystrix Eisenack, Hystrichosphaeridium tiara Klumpp, Hystrichosphaera [i.e. Histiophora] ornata Klement and for six species which Maier assigned to the genus Galea.
The apical-antapical orientation of the shells results from the position of the escape hole. The dorsal-ventral orientation was guided by the weak depression on one side, which is arbitrarily defined as the ventral or lower surface. Characteristic of the new species M. aspinatum is the lack of isolated spines on the upper and lower sides of the theca. Laterally the shell is surrounded by two parallel, meridionally trending membranes, which are not interconnected antapically. On the lower side ..., broad, lobate, highly disrupted borders are set off from the two vertically running structures; their external margins are more or less smooth or marked by fine denticles. Ventrally, the theca is weakly indented between the structures. The two parts of the membrane separating the upper and lower sides are considerably smaller than the two ventrally situated membranes. At the antapex, they are prolonged into flaps, one of which distinctly surmounts the other.
The shell wall is granulate and of a yellow-brown colour.
Size: Holotype: overall length 93 Ám, overall width 110 Ám, endocyst length 74 Ám, endocyst width 84 Ám. Range of 20 specimens: overall length 74-110 Ám, overall width 84-118 Ám. See Gerlach, 1961, p.200 for further measurements.
Supplemental description: Mao Shaozhi and Norris, 1988, p.33
Cyst proximate, dorsoventrally compressed, with a short obtuse apical horn and two more or less unequal antapical lobes or horns--the left one always larger.
Central body ellipsoidal, with slightly protruding apex. Periphragm thin and membranous; its margin generally smooth to slightly sinuous, seldom bearing isolated bifurcate processes. Middorsally and midventrally appressed to endophragm (indicated by line of contact), separated elsewhere. Width of pericoel varying from 0 to 16 Ám in one individual. Pericoel usually complete.
Endophragm smooth to granulate. Archeopyle apical, type (tA) or (tA)a; archeopyle suture ragged, its accessory sutures indicating six precingular plates. Operculum more commonly free than attached dorsally. Sulcal notch offset to left.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 469, pl.12,fig.4: Membranophoridium cf. aspinatum
The specimens recovered from the Lutetian section in Wursterheide are considerably smaller than typical for this species.