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Chiropteridium partispinatum
Chiropteridium partispinatum, (Gerlach, 1961), Brosius, 1963
Originally Membranophoridium, subsequently Chiropteridium.
Tax. jr. synonym of Chiropteridium galea (Maier, 1959) Sarjeant, 1983, by implication, according to Matsuoka and Bujak, 1988, who considered Chiropteridium partispinatum to be a tax. jr. synonym of Chiropteridium mespilanum Maier, 1959.
Holotype: Gerlach, 1961, pl.29, fig.6
Age: Middle-Late Oligocene
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Original description Gerlach, 1961 [as Membranophoridium partispinatum]:
Holotype: Pr1170/61 (300), Plate 29, Fig. 6
Paratypes: Pr1170/62 (669) and Pr1170/63 (298)
Locus typicus: Bohrung Emsbüren 7.
Stratum Typicum: Middle Oligocene
Derivation of name: partially spiny because the underside always lacks the appendages.
Diagnosis:
A species of the genus Membranophoridium with the following special characteristics: Theca surrounded by two parallel, meridian-like spiny margins, which may be continuous or interrupted. Upper surface spined with fine, mostly isolated processes. Underside always without spines. Membrane granulated.
Description:
The theca corresponds in outline to M. aspinatum. In two specimens, the initial separation of the operculum is visible through a distinct fissure in the apical first fifth of the theca. Notable differences between M. aspinatum and the present species are the formation of the margins and the spine-covered upper surface. While in M. aspinatum the margins appear entire or slightly serrated, the representatives of the present species are characterized by more or less long, spiny margins. They can be continuous or interrupted by isolated processes. The margins are often filled with pyrite. Consistent with M. aspinatum, the margins on both sides of the antapex are extended into a more or less long, spiny tip. The apical opening is occasionally covered with process stripes on the upper surface. On the unspined underside, the edges rise analogously to M. aspinatum on the fine longitudinal structures, between which the theca appears slightly indented.
The mostly isolated or meridianally fused processes on the upper side of the theca are thin and massive, occasionally hollow, distally blunt, or sometimes multiply forked. The membrane appears granulated and pale yellowish in color. The shells were measured in height and width without seams, as the proportions would otherwise have diverged too much due to the widely varying lengths of the spined seams. Since the operculum was missing in almost all measured specimens, higher measurements were obtained for the width of the shells than for the height. The distribution of the species is limited to the Oligocene. Since M. partispinatum is quite common, the representatives of this species could possibly be used as indicator forms in the differentiation between Oligocene and Miocene.
Affinities:
The upper surface, which is spined on one side, is reminiscent of the genus Areoligera KLUMPP. However, the present species lacks the girdle region characteristic of Areoligera. Furthermore, no areas are formed on the upper surface. M. partispinatum may be closely related to Hystrichosphaeridium lobospinosum Gocht. However, Weiler (1956) only speaks of an equatorial margin that is interrupted several times. According to Gocht (1952), however, flat margins may also be present outside the equator. However, no reliable information is available on this yet. Furthermore, the diagnosis does not allow for any determination as to whether the upper or lower surface of the theca is covered with spines.
The new species also resembles Galea galea Maier in its outline. However, there is no information for that species as to whether one side is spiny or not. The fringed forms of G. galea belong (according to what was discussed in the critical remarks on the genus Galea) to M. partispinatum, as long as the conditions of the indented and unspined underside are met.
Originally Membranophoridium, subsequently Chiropteridium.
Tax. jr. synonym of Chiropteridium galea (Maier, 1959) Sarjeant, 1983, by implication, according to Matsuoka and Bujak, 1988, who considered Chiropteridium partispinatum to be a tax. jr. synonym of Chiropteridium mespilanum Maier, 1959.
Holotype: Gerlach, 1961, pl.29, fig.6
Age: Middle-Late Oligocene
------------------------------------------------------------------------------------------------------------------------------
Original description Gerlach, 1961 [as Membranophoridium partispinatum]:
Holotype: Pr1170/61 (300), Plate 29, Fig. 6
Paratypes: Pr1170/62 (669) and Pr1170/63 (298)
Locus typicus: Bohrung Emsbüren 7.
Stratum Typicum: Middle Oligocene
Derivation of name: partially spiny because the underside always lacks the appendages.
Diagnosis:
A species of the genus Membranophoridium with the following special characteristics: Theca surrounded by two parallel, meridian-like spiny margins, which may be continuous or interrupted. Upper surface spined with fine, mostly isolated processes. Underside always without spines. Membrane granulated.
Description:
The theca corresponds in outline to M. aspinatum. In two specimens, the initial separation of the operculum is visible through a distinct fissure in the apical first fifth of the theca. Notable differences between M. aspinatum and the present species are the formation of the margins and the spine-covered upper surface. While in M. aspinatum the margins appear entire or slightly serrated, the representatives of the present species are characterized by more or less long, spiny margins. They can be continuous or interrupted by isolated processes. The margins are often filled with pyrite. Consistent with M. aspinatum, the margins on both sides of the antapex are extended into a more or less long, spiny tip. The apical opening is occasionally covered with process stripes on the upper surface. On the unspined underside, the edges rise analogously to M. aspinatum on the fine longitudinal structures, between which the theca appears slightly indented.
The mostly isolated or meridianally fused processes on the upper side of the theca are thin and massive, occasionally hollow, distally blunt, or sometimes multiply forked. The membrane appears granulated and pale yellowish in color. The shells were measured in height and width without seams, as the proportions would otherwise have diverged too much due to the widely varying lengths of the spined seams. Since the operculum was missing in almost all measured specimens, higher measurements were obtained for the width of the shells than for the height. The distribution of the species is limited to the Oligocene. Since M. partispinatum is quite common, the representatives of this species could possibly be used as indicator forms in the differentiation between Oligocene and Miocene.
Affinities:
The upper surface, which is spined on one side, is reminiscent of the genus Areoligera KLUMPP. However, the present species lacks the girdle region characteristic of Areoligera. Furthermore, no areas are formed on the upper surface. M. partispinatum may be closely related to Hystrichosphaeridium lobospinosum Gocht. However, Weiler (1956) only speaks of an equatorial margin that is interrupted several times. According to Gocht (1952), however, flat margins may also be present outside the equator. However, no reliable information is available on this yet. Furthermore, the diagnosis does not allow for any determination as to whether the upper or lower surface of the theca is covered with spines.
The new species also resembles Galea galea Maier in its outline. However, there is no information for that species as to whether one side is spiny or not. The fringed forms of G. galea belong (according to what was discussed in the critical remarks on the genus Galea) to M. partispinatum, as long as the conditions of the indented and unspined underside are met.