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Rhiptocorys
From Williams et al., 2017:
[Rhiptocorys, Lejeune-Carpentier and Sarjeant, 1983, p. 5; Emendations: Lentin and Vozzhennikova, 1990, p. 110–111; Slimani, 1994, p. 51.
Tax. sr. syn.: Phanerodinium, according to Below (1987b, p.36) — however, Lentin and Williams (1989, p.316) retained Rhiptocorys.
Type species: originally as Micrhystridium veligerum, Deflandre, 1937b (pl.12 (al. pl.9), fig.9)] ; Rhiptocorys veligera, (Deflandre 1937); Lejeune-Carpentier and Sarjeant, 1983
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Original description: [Lejeune-Carpentier and Sarjeant, 1983]
Description:
Proximate to proximochorate cysts, typically of small size. Cyst spheroidal to ovoidal or subpolygonal, with epitract markedly smaller than hypotract.
Paratabulation: 7, ?5-6``, 6c, 6```, 1 Pl 1``` [sic]. Epitractal paraplates marked feebly by lines or low ridges, or not at all; hypotractal paraplates demarcated by high crests which may be suturocavate.
Cingulum either represented by a single suturocavate structure on its anterior margin or bounded by variably developed crests on both sides. Sulcus of variable breadth, often discernible only on the hypotract. Ornamentation of phragma also variable.
Archaeopyle epitractal, formed either by the loss of a single operculum or by progressive loss of opercular pieces.
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Modified description:
Stover and Williams, 1987, p. 187:
Synopsis:
Cysts proximate to proximochorate, spherical to subpolygonal; epicyst significantly smaller than hypocyst; parasutural features delineate paratabulation, formula: ?`, ?5-6", 6c, 6```, 2````, 1 or more s; hypocystal paratabulation arranged in typical microdinioid pattern, partiform; archeopyle type uncertain, possibly epicystal.
Description:
Shape: Spherical to subpolygonal.
Wall relationships: Cysts apparently composed of two closely appressed wall layers that may be separated locally beneath some parasutural features.
Wall features: Faint parasutural features may be present on epicyst; prominent parasutural septa developed along paracingulum and on hypocyst.
Surface, exclusive of parasutural features, variously ornamented.
Archeopyle: Possibly epicystal, but definitive confirmation lacking.
Paratabulation: Indicated on hypocyst by conspicuous parasutural crests, formula: 6```, 2````; paraplates 1``` and 6``` prominent and of about equal size; posterior sulcal paraplate large, teardropshaped, antapical configuration partiform. Paratabulation on epicyst unexpressed or indicated by faint, low, parasutural features; so far, only four precingular paraplates have been recognized.
Paracingulum: Indicated either by a single, transverse crest or by two transverse crests; possibly subdivided longitudinally.
Parasulcus: Indicated by single, large, posteriorly widened paraplate on hypocyst. Epicystal expression not known.
Size: Small, 25 to 35 μm in diameter.
Affinities:
Based solely on the hypocystal paratabulation, Rhiptocorys appears to be allied to Microdinium Cookson and Eisenack 1960a emended Stover and Evitt 1978, Histiocysta Davey 1969a, Druggidium Habib 1973 and Cladopyxidium McLean 1972.
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Emended description:
Slimani, 1994:
Diagnosis:
Small proximate to proximochorate cyst, spheroidal to ovoidal or subpolygonal, the epicyst remarkably smaller than the hypocyst. The paratabulation is gonyaulacoid: 1pr, 4`, 4a, 6``, 6c, 6```, 1p, 1````. The hypocystal paraplates are delimited by prominent suturocavate crests. The paracingulum is indicated by a single suturocavate crest on the anterior margin, joined or not on the posterior margin by a line or low crest. The intratabular ornamentation is variable. The epicyst, having the shape of a convex lens, is remarkably smaller than the hypocyst and without parasutural relief or shows delicate, nearly indiscernable crests; however, the precingular paraplates are discernable, and are indicated by principal and accessory archaeopyle sutures, and may also be indicated by gonal protruberances on the anterior crests of the paracingulum. The parasulcus is mostly delimited by lines or low crests, and presents 2 to 5 paraplates. The hypocystal configuration is partiform. The archaeopyle is apical-intercalary type (tAtI), the operculum is attached and composed of one preapical paraplate, 4 apical paraplates, and 4 anterior intercalary paraplates.
[Rhiptocorys, Lejeune-Carpentier and Sarjeant, 1983, p. 5; Emendations: Lentin and Vozzhennikova, 1990, p. 110–111; Slimani, 1994, p. 51.
Tax. sr. syn.: Phanerodinium, according to Below (1987b, p.36) — however, Lentin and Williams (1989, p.316) retained Rhiptocorys.
Type species: originally as Micrhystridium veligerum, Deflandre, 1937b (pl.12 (al. pl.9), fig.9)] ; Rhiptocorys veligera, (Deflandre 1937); Lejeune-Carpentier and Sarjeant, 1983
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Lejeune-Carpentier and Sarjeant, 1983]
Description:
Proximate to proximochorate cysts, typically of small size. Cyst spheroidal to ovoidal or subpolygonal, with epitract markedly smaller than hypotract.
Paratabulation: 7, ?5-6``, 6c, 6```, 1 Pl 1``` [sic]. Epitractal paraplates marked feebly by lines or low ridges, or not at all; hypotractal paraplates demarcated by high crests which may be suturocavate.
Cingulum either represented by a single suturocavate structure on its anterior margin or bounded by variably developed crests on both sides. Sulcus of variable breadth, often discernible only on the hypotract. Ornamentation of phragma also variable.
Archaeopyle epitractal, formed either by the loss of a single operculum or by progressive loss of opercular pieces.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 187:
Synopsis:
Cysts proximate to proximochorate, spherical to subpolygonal; epicyst significantly smaller than hypocyst; parasutural features delineate paratabulation, formula: ?`, ?5-6", 6c, 6```, 2````, 1 or more s; hypocystal paratabulation arranged in typical microdinioid pattern, partiform; archeopyle type uncertain, possibly epicystal.
Description:
Shape: Spherical to subpolygonal.
Wall relationships: Cysts apparently composed of two closely appressed wall layers that may be separated locally beneath some parasutural features.
Wall features: Faint parasutural features may be present on epicyst; prominent parasutural septa developed along paracingulum and on hypocyst.
Surface, exclusive of parasutural features, variously ornamented.
Archeopyle: Possibly epicystal, but definitive confirmation lacking.
Paratabulation: Indicated on hypocyst by conspicuous parasutural crests, formula: 6```, 2````; paraplates 1``` and 6``` prominent and of about equal size; posterior sulcal paraplate large, teardropshaped, antapical configuration partiform. Paratabulation on epicyst unexpressed or indicated by faint, low, parasutural features; so far, only four precingular paraplates have been recognized.
Paracingulum: Indicated either by a single, transverse crest or by two transverse crests; possibly subdivided longitudinally.
Parasulcus: Indicated by single, large, posteriorly widened paraplate on hypocyst. Epicystal expression not known.
Size: Small, 25 to 35 μm in diameter.
Affinities:
Based solely on the hypocystal paratabulation, Rhiptocorys appears to be allied to Microdinium Cookson and Eisenack 1960a emended Stover and Evitt 1978, Histiocysta Davey 1969a, Druggidium Habib 1973 and Cladopyxidium McLean 1972.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Slimani, 1994:
Diagnosis:
Small proximate to proximochorate cyst, spheroidal to ovoidal or subpolygonal, the epicyst remarkably smaller than the hypocyst. The paratabulation is gonyaulacoid: 1pr, 4`, 4a, 6``, 6c, 6```, 1p, 1````. The hypocystal paraplates are delimited by prominent suturocavate crests. The paracingulum is indicated by a single suturocavate crest on the anterior margin, joined or not on the posterior margin by a line or low crest. The intratabular ornamentation is variable. The epicyst, having the shape of a convex lens, is remarkably smaller than the hypocyst and without parasutural relief or shows delicate, nearly indiscernable crests; however, the precingular paraplates are discernable, and are indicated by principal and accessory archaeopyle sutures, and may also be indicated by gonal protruberances on the anterior crests of the paracingulum. The parasulcus is mostly delimited by lines or low crests, and presents 2 to 5 paraplates. The hypocystal configuration is partiform. The archaeopyle is apical-intercalary type (tAtI), the operculum is attached and composed of one preapical paraplate, 4 apical paraplates, and 4 anterior intercalary paraplates.