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Riculacysta
From Williams et al., 2017:
[Riculacysta, Stover, 1977, p. 76-77;
Type species: Riculacysta perforata, Stover, 1977 (pl.2, figs.22–24)]
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Original description: [Stover, 1977]:
Diagnosis:
Cysts are chorate with a subspherical body that bears solid, normally isolated processes which arise from the ventrolateral and lateral surfaces and are typically lacking on the midventral and middorsal surfaces. Ventrolateral processes are longer than the lateral ones; all are connected distally by irregularly perforate to trabecular ectophragm that is close or appressed dorsally to the autophragm. Paratabulation indicated by apical type A archeopyle, by paracingulum, and less conspicuously by processes.
Description:
Shape: Body subspherical, outline circular or nearly so or may have shallow, medial antapical concavity between two usually unequally developed antapical lobes.
Wall relationships: Autophragm forms processes on ventrolateral and lateral surfaces; processes are connected distally by thin, perforate to trabecular, discontinuous ectophragm that is near or appressed to the autophragm across the process free middorsal surface and absent over the midventral surface.
Wall features: Processes are solid, typically slender, and usually branched distally. Most processes are isolated, a few arise from low proximal ridges; processes longest on ventrolateral surfaces and diminish gradually in height towards the dorsal surface.
Paratabulation: Indicated by archeopyle and paracingulum, and additionally by process distribution. Some processes appear to be intratabular; exact paratabulation formula unknown.
Archeopyle: Apical, type A, principal suture is angular, operculum is free.
Paracingulum: Indicated on dorsal surface by low, parallel, transverse ridges and some ventrolateral processes may be paracingular.
Parasulcus: Not indicated per se; location suggested by slightly depressed process-free midventral area on autophragm and by absence of ectophragm.
Size: Large, greater than 100 µm.
Affinities:
Riculacysta differs from Adnatosphaeridium Williams and Downie, 1966 by having the ectophragm appressed to the autophragm in the middorsal area, by possessing a skirtlike feature formed by the ectophragm in the dorsal antapical area and by having processes that differ in length depending upon their position on the autocyst. In Adnatosphaeridium, the processes are more or less of the same length so that the trabecular ectophragm is essentially concentric around the cyst body.
Tertiary species of Cyclonephelium Deflandre and Cookson, 1955 emend. Williams and Downie, 1966 differ from Riculacysta by having a lenticular rather than a subspherical body and processes of uniform length or nearly so, regardless of their position on the body.
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Modified description:
Stover and Williams, 1987, p. 189:
Synopsis:
Cysts skolochorate, body subspherical and bears solid, normally isolated processes arising from ventrolateral and lateral surfaces and typically lacking on midventral and middorsal surfaces; ventrolateral processes longer than lateral ones, all processes connected distally by irregularly perforate to trabecular ectophragm that is appressed or close to the autophragm dorsally; paratabulation indicated by apical archeopyle type [tA], by paracingulum and less so by processes.
Description:
Shape: Body subspherical, outline circular or nearly so; with or without medial concavity between two, usually unequally developed, antapical lobes.
Wall relationships: Autophragm and ectophragm close together or appressed middorsally and separated elsewhere, except midventrally where ectophragm is missing; ectophragm trabecular to perforate; discontinuous.
Wall features: Solid, typically slender, usually distally branched processes arise from the ventrolateral and lateral surfaces; most processes isolated, some arise from low proximal ridges; processes longest ventrolaterally, decreasing in height gradually towards the dorsal surface.
Archeopyle: Apical, type [4A], principal suture angular; operculum free.
Paratabulation: Indicated by archeopyle and paracingulum, less so by processes of which some appear to be intratabular.
Paracingulum: Indicated on dorsal surface by low, parallel transverse ridges; some ventrolateral processes may be cingular.
Parasulcus: Location suggested by slightly depressed process-free midventral area on autophragm and by absence of ectophragm.
Size: Large, overall length greater than 100 µm.
Affinities:
Riculacysta differs from Adnatosphaeridium Williams and Downie in Davey et al. 1966 in having the ectophragm appressed to the autophragm in the middorsal area, and in having processes that differ in length depending on their position on the cyst. In Adnatosphaeridium, the processes are more or less of the same length and the trabecular ectophragm is essentially concentric around the cyst body.
Glaphyrocysta Stover and Evitt 1978 differs from Riculacysta in having a lenticular rather than a subspherical body and has processes of more or less uniform length, regardless of their position on the cyst body. Riculacysta differs from Gerdiocysta Liengjaren et al. 1980 in lacking middorsal processes and in not having process complexes.
[Riculacysta, Stover, 1977, p. 76-77;
Type species: Riculacysta perforata, Stover, 1977 (pl.2, figs.22–24)]
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Original description: [Stover, 1977]:
Diagnosis:
Cysts are chorate with a subspherical body that bears solid, normally isolated processes which arise from the ventrolateral and lateral surfaces and are typically lacking on the midventral and middorsal surfaces. Ventrolateral processes are longer than the lateral ones; all are connected distally by irregularly perforate to trabecular ectophragm that is close or appressed dorsally to the autophragm. Paratabulation indicated by apical type A archeopyle, by paracingulum, and less conspicuously by processes.
Description:
Shape: Body subspherical, outline circular or nearly so or may have shallow, medial antapical concavity between two usually unequally developed antapical lobes.
Wall relationships: Autophragm forms processes on ventrolateral and lateral surfaces; processes are connected distally by thin, perforate to trabecular, discontinuous ectophragm that is near or appressed to the autophragm across the process free middorsal surface and absent over the midventral surface.
Wall features: Processes are solid, typically slender, and usually branched distally. Most processes are isolated, a few arise from low proximal ridges; processes longest on ventrolateral surfaces and diminish gradually in height towards the dorsal surface.
Paratabulation: Indicated by archeopyle and paracingulum, and additionally by process distribution. Some processes appear to be intratabular; exact paratabulation formula unknown.
Archeopyle: Apical, type A, principal suture is angular, operculum is free.
Paracingulum: Indicated on dorsal surface by low, parallel, transverse ridges and some ventrolateral processes may be paracingular.
Parasulcus: Not indicated per se; location suggested by slightly depressed process-free midventral area on autophragm and by absence of ectophragm.
Size: Large, greater than 100 µm.
Affinities:
Riculacysta differs from Adnatosphaeridium Williams and Downie, 1966 by having the ectophragm appressed to the autophragm in the middorsal area, by possessing a skirtlike feature formed by the ectophragm in the dorsal antapical area and by having processes that differ in length depending upon their position on the autocyst. In Adnatosphaeridium, the processes are more or less of the same length so that the trabecular ectophragm is essentially concentric around the cyst body.
Tertiary species of Cyclonephelium Deflandre and Cookson, 1955 emend. Williams and Downie, 1966 differ from Riculacysta by having a lenticular rather than a subspherical body and processes of uniform length or nearly so, regardless of their position on the body.
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Modified description:
Stover and Williams, 1987, p. 189:
Synopsis:
Cysts skolochorate, body subspherical and bears solid, normally isolated processes arising from ventrolateral and lateral surfaces and typically lacking on midventral and middorsal surfaces; ventrolateral processes longer than lateral ones, all processes connected distally by irregularly perforate to trabecular ectophragm that is appressed or close to the autophragm dorsally; paratabulation indicated by apical archeopyle type [tA], by paracingulum and less so by processes.
Description:
Shape: Body subspherical, outline circular or nearly so; with or without medial concavity between two, usually unequally developed, antapical lobes.
Wall relationships: Autophragm and ectophragm close together or appressed middorsally and separated elsewhere, except midventrally where ectophragm is missing; ectophragm trabecular to perforate; discontinuous.
Wall features: Solid, typically slender, usually distally branched processes arise from the ventrolateral and lateral surfaces; most processes isolated, some arise from low proximal ridges; processes longest ventrolaterally, decreasing in height gradually towards the dorsal surface.
Archeopyle: Apical, type [4A], principal suture angular; operculum free.
Paratabulation: Indicated by archeopyle and paracingulum, less so by processes of which some appear to be intratabular.
Paracingulum: Indicated on dorsal surface by low, parallel transverse ridges; some ventrolateral processes may be cingular.
Parasulcus: Location suggested by slightly depressed process-free midventral area on autophragm and by absence of ectophragm.
Size: Large, overall length greater than 100 µm.
Affinities:
Riculacysta differs from Adnatosphaeridium Williams and Downie in Davey et al. 1966 in having the ectophragm appressed to the autophragm in the middorsal area, and in having processes that differ in length depending on their position on the cyst. In Adnatosphaeridium, the processes are more or less of the same length and the trabecular ectophragm is essentially concentric around the cyst body.
Glaphyrocysta Stover and Evitt 1978 differs from Riculacysta in having a lenticular rather than a subspherical body and has processes of more or less uniform length, regardless of their position on the cyst body. Riculacysta differs from Gerdiocysta Liengjaren et al. 1980 in lacking middorsal processes and in not having process complexes.