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Xylochoarion
From Williams et al., 2017:
[Xylochoarion, Erkmen and Sarjeant, 1978, p.401,403–404
Type species: Xylochoarion hacknessense, Erkmen and Sarjeant, 1978 (figs.1,5–6)]
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Original description: [Erkman and Sarjeant, 1978]:
Description:
Proximate to proximochorate dinoflagellate cysts. Ambitus spheroidal to elongate ellipsoidal. One pole of the cyst may exhibit the development of two asymmetrical outbuiges or prominences. Numerous nontabulate processes, of variable form and relative length, are present generally over the cyst surface but may be lacking from the paracingulum. Paraplate boundaries are not marked, though the paratabulation is in part indicated by the shape of the archaeopyle. Archaeopyle formation by schism at about two thirds along the long axis of the cyst, a single operculum being thrown off.
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Modified description:
Stover and Williams, 1987, p. 401:
Synopsis:
Cysts proximochorate, elongate ellipsoidal with numerous nontabular processes that are not interconnected distally; principal archeopyle suture angular and occurs at approximately one-third the longitudinal distance from one pole; archeopyle type uncertain.
Description:
Shape: Broadly to elongate ellipsoidal.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Numerous nontabular processes are open or closed distally, highly variable in shape, typically about one fourth cyst body width in length and not interconnected by trabeculae.
Archeopyle: Exact type unknown; stated as involving paraplates from at least two series and with separation between two paraplate series; single opercular piece free.
Paratabulation: Indicated by principal and accessory archeopyle sutures only; precise identification of paraplates uncertain.
Paracingulum: Stated as being rather narrow and indicated by absence of processes. Paracingulum not clearly evident on illustrated specimens.
Parasulcus: Not indicated.
Size: Intermediate, total length about 80 µm.
Affinities:
Xylochoarion differs from Prolixosphaeridium Davey and Williams in Davey et al. 1966 emended Davey 1969a in having more numerous and variable processes, and an archeopyle suture much farther from one pole. In Prolixosphaeridium, the archeopyle is apical, type [tA]. In Xylochoarion, the archeopyle suture is about one-third the longitudinal distance from one pole, and it is uncertain whether the nearer pole is apical or antapical.
[Xylochoarion, Erkmen and Sarjeant, 1978, p.401,403–404
Type species: Xylochoarion hacknessense, Erkmen and Sarjeant, 1978 (figs.1,5–6)]
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Original description: [Erkman and Sarjeant, 1978]:
Description:
Proximate to proximochorate dinoflagellate cysts. Ambitus spheroidal to elongate ellipsoidal. One pole of the cyst may exhibit the development of two asymmetrical outbuiges or prominences. Numerous nontabulate processes, of variable form and relative length, are present generally over the cyst surface but may be lacking from the paracingulum. Paraplate boundaries are not marked, though the paratabulation is in part indicated by the shape of the archaeopyle. Archaeopyle formation by schism at about two thirds along the long axis of the cyst, a single operculum being thrown off.
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Modified description:
Stover and Williams, 1987, p. 401:
Synopsis:
Cysts proximochorate, elongate ellipsoidal with numerous nontabular processes that are not interconnected distally; principal archeopyle suture angular and occurs at approximately one-third the longitudinal distance from one pole; archeopyle type uncertain.
Description:
Shape: Broadly to elongate ellipsoidal.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Numerous nontabular processes are open or closed distally, highly variable in shape, typically about one fourth cyst body width in length and not interconnected by trabeculae.
Archeopyle: Exact type unknown; stated as involving paraplates from at least two series and with separation between two paraplate series; single opercular piece free.
Paratabulation: Indicated by principal and accessory archeopyle sutures only; precise identification of paraplates uncertain.
Paracingulum: Stated as being rather narrow and indicated by absence of processes. Paracingulum not clearly evident on illustrated specimens.
Parasulcus: Not indicated.
Size: Intermediate, total length about 80 µm.
Affinities:
Xylochoarion differs from Prolixosphaeridium Davey and Williams in Davey et al. 1966 emended Davey 1969a in having more numerous and variable processes, and an archeopyle suture much farther from one pole. In Prolixosphaeridium, the archeopyle is apical, type [tA]. In Xylochoarion, the archeopyle suture is about one-third the longitudinal distance from one pole, and it is uncertain whether the nearer pole is apical or antapical.