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Riculacysta amplexa
Riculacysta amplexa Kirsch, 1991, p.127–128, pl.33, figs.1,5–6,9–13; pl.43, figs.1,4,7; text-figs.60a–b. Holotype: Kirsch, 1991, pl.33, figs.5,9; Fauconnier and Masure, 2004, pl.67, figs.7–8. Age: late Maastrichtian.
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Original description: [Kirsch, 1991]:
Riculacysta amplexus sp. nov.
Plate 33, Figs. 1, 5, 6, 9-13; Plate 43, Figs. 1, 4, 7;
Fig. 60a, b
Derivation nominis: From amplexus, Latin = embrace.
Referring to the thin membrane that encloses the central body.
Holotype: Specimen 210.1, EF: M 53/2.
Paratype: Specimen 210.1, EF: G 43/4.
Locus typicus: Nussdorf, Graben SSE Waidach; Austria.
Stratum typicum: Upper Maastricht (mayaroensis zone).
Diagnosis: Scolochorate cyst with a subspheroidal, ellipsoculate, smooth to weakly granulated central body and a smooth, rarely weakly perforated, distinct outer membrane connected to the central body by very slender, massive processes.
These processes occur in the lateral and ventrolateral regions of the cyst and are longest posterior-laterally, corresponding to the maximum distance between the central body and the outer membrane. The archaeopyle is apically (4A) with a secated operculum.
Description: This chorate cyst has a subspheroidal central body, which can sometimes form two unequal, weakly defined lobes antapically. The surface of the central body is smooth to weakly granulated. The membrane is usually also smooth and imperforate. However, variation ranges from a slightly perforated membrane to the appearance of individual oval perforations of varying sizes. The course of the outer membrane is characteristic; it occupies the entire dorsal region and surrounds the central body in a wing-like (amplexate) manner, migrating over the antapex to the ventral side of the cyst. However, the midventral region remains free of any processes or deposits of the outer membrane. This is often interrupted or torn due to preservation. The distal edges can be straight or serrated.
The thin, narrow, distally also split, and massive processes connect the central body to the outer membrane only at certain points. They may indicate tabulation. Crucially, the processes are also present dorsally in the region of the archaeopyle margin, meaning that the two layers are not completely pressed together. Apart from the archaeopyle (apical; 4A) and the serrated archaeopyle margin, no signs of tabulation are visible.
Tabulation: 4, 6", ?c, ?"', ?p, ?"", Operculum secat and foederat.
The cysts are predominantly preserved dorsal-ventral or apical-antapical, less frequently laterally compressed.
Note: In this case, the terms "individual wall layers" according to EVITT (1985) are not used, as the relationship between the individual layers has not yet been clearly established and various classifications are in use (cf. BELOW 1987a). STOVER (1977),
for example, uses the terms "autophragm" and "ectophragm," while BUJAK (1980: 48) uses the neutral term "membrane" for Riculacysta semitecta (BUJAK 1980). In contrast to STOVER's (1977) original diagnosis for Riculacysta, this species lacks a cingulum.
Comparison: Riculacysta amplexus sp. nov. differs from the type species in the development of a smooth, rarely irregularly perforated membrane and very slender processes. Compared to Riculacysta semitecta (BUJAK 1980), the large perforations within the membrane, which is also strongly asymmetrically elongated posteriorly, are missing. Riculacysta? pala sp. nov. possesses a reticulated periphragm and a more lenticular central body.
Dimensions: Holotype: Size of the central body (without operculum; L x W) 44 x 48 u; total size (without operculum) 64 x 83 u.
Variation: Size of the central body (without operculum; L x W) 40-44 x 46-50 u; length of the membrane 20-30 u;
total size (without operculum) 56-66 x 68-80 u.
Material: 30 specimens.
Occurrence: Moos-Graben II locality (BMS): Graben profile SSE Waidach (Oichinger Strata).
Age: Upper Maastrichtian (mayaroensis zone).
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Original description: [Kirsch, 1991]:
Riculacysta amplexus sp. nov.
Plate 33, Figs. 1, 5, 6, 9-13; Plate 43, Figs. 1, 4, 7;
Fig. 60a, b
Derivation nominis: From amplexus, Latin = embrace.
Referring to the thin membrane that encloses the central body.
Holotype: Specimen 210.1, EF: M 53/2.
Paratype: Specimen 210.1, EF: G 43/4.
Locus typicus: Nussdorf, Graben SSE Waidach; Austria.
Stratum typicum: Upper Maastricht (mayaroensis zone).
Diagnosis: Scolochorate cyst with a subspheroidal, ellipsoculate, smooth to weakly granulated central body and a smooth, rarely weakly perforated, distinct outer membrane connected to the central body by very slender, massive processes.
These processes occur in the lateral and ventrolateral regions of the cyst and are longest posterior-laterally, corresponding to the maximum distance between the central body and the outer membrane. The archaeopyle is apically (4A) with a secated operculum.
Description: This chorate cyst has a subspheroidal central body, which can sometimes form two unequal, weakly defined lobes antapically. The surface of the central body is smooth to weakly granulated. The membrane is usually also smooth and imperforate. However, variation ranges from a slightly perforated membrane to the appearance of individual oval perforations of varying sizes. The course of the outer membrane is characteristic; it occupies the entire dorsal region and surrounds the central body in a wing-like (amplexate) manner, migrating over the antapex to the ventral side of the cyst. However, the midventral region remains free of any processes or deposits of the outer membrane. This is often interrupted or torn due to preservation. The distal edges can be straight or serrated.
The thin, narrow, distally also split, and massive processes connect the central body to the outer membrane only at certain points. They may indicate tabulation. Crucially, the processes are also present dorsally in the region of the archaeopyle margin, meaning that the two layers are not completely pressed together. Apart from the archaeopyle (apical; 4A) and the serrated archaeopyle margin, no signs of tabulation are visible.
Tabulation: 4, 6", ?c, ?"', ?p, ?"", Operculum secat and foederat.
The cysts are predominantly preserved dorsal-ventral or apical-antapical, less frequently laterally compressed.
Note: In this case, the terms "individual wall layers" according to EVITT (1985) are not used, as the relationship between the individual layers has not yet been clearly established and various classifications are in use (cf. BELOW 1987a). STOVER (1977),
for example, uses the terms "autophragm" and "ectophragm," while BUJAK (1980: 48) uses the neutral term "membrane" for Riculacysta semitecta (BUJAK 1980). In contrast to STOVER's (1977) original diagnosis for Riculacysta, this species lacks a cingulum.
Comparison: Riculacysta amplexus sp. nov. differs from the type species in the development of a smooth, rarely irregularly perforated membrane and very slender processes. Compared to Riculacysta semitecta (BUJAK 1980), the large perforations within the membrane, which is also strongly asymmetrically elongated posteriorly, are missing. Riculacysta? pala sp. nov. possesses a reticulated periphragm and a more lenticular central body.
Dimensions: Holotype: Size of the central body (without operculum; L x W) 44 x 48 u; total size (without operculum) 64 x 83 u.
Variation: Size of the central body (without operculum; L x W) 40-44 x 46-50 u; length of the membrane 20-30 u;
total size (without operculum) 56-66 x 68-80 u.
Material: 30 specimens.
Occurrence: Moos-Graben II locality (BMS): Graben profile SSE Waidach (Oichinger Strata).
Age: Upper Maastrichtian (mayaroensis zone).