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Hystrichostrogylon
From Fensome et al., 2019:
Hystrichostrogylon, Agelopoulos, 1964, p.673–674.
Emendation: Stover and Evitt, 1978, p.164.
Taxonomic senior synonym: Achomosphaera, by implication in Eaton (1976, p.237), who transferred the "type species" of Hystrichostrogylon, Hystrichostrogylon membraniphorum, to Achomosphaera -- however, Stover and Evitt (1978, p.165) retained Hystrichostrogylon; Spiniferites, according to Duxbury (2019, p.202) -- however, we retain Hystrichostrogylon, which can be distinguished by its partial cavation..
Taxonomic junior synonym: Diphasiosphaera, according to Stover and Williams (1987, p.81) -- however, Duxbury (2019, p.187) retained
Diphasiosphaera.
Type: Agelopoulos, 1964, text-fig.1, as Hystrichostrogylon membraniphorum.
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Original description: [Agelopoulos, 1964]: (Translation: Stover and Evit, 1978, p. 164):
Diagnosis:
Central shell spherical to oval, apparently slightly flattened, provided with forked spines, and enclosed by a delicate, transparent, only antapically developed, somewhat concentric outer shell that lies close to the inner shell ventrally and dorsally. Slender, long, hollow processes occur in the region of the apex which is indicated by a pylome, whereas wide, broad-surfaced processes are confined to the region of the antapex and therefore to the outer shell. The central shell within the outer shell possesses no processes.
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Emended description:
Stover and Evitt, 1978:
Synopsis:
Cysts skolochorate, camocavate; endocyst subspherical; periphragm and endophragm appressed over a portion of the cyst but separated elsewhere by a pericoel that is not limited to the polar areas; processes gonal or gonal and intergonal, their shafts differing in length according to extent of pericoel development beneath them; paratabulation gonyaulacacean, indicated mainly by processes but also by faint parasutural lines or ridges; archaeopyle precingular, Type P.
Description:
Shape: Endocyst subspherical; outline of periphragm varies in size and shape, consistent with degree of separation between endophragm and periphragm.
Wall relationships: Cysts camocavate; periphragm and endophragm always appressed dorsally, narrowly to widely separated elsewhere; size and shape of pericoel vary.
Wall features: Faint parasutural lines or ridges may be present on periphragm. Gonal and intergonal processes typically furcate, tips not interconnected; process shafts normally long where pericoel is least developed or not at all, short where pericoel is most developed. Endophragm and periphragm smooth or faintly ornamented.
Paratabulation: Indicated by processes and additionally by faint parasutural lines or ridges; gonyaulacacean, formula: 3-4`, 6``, 6c, 5-6```, 0-1p, 1````; rarely expressed completely.
Archaeopyle: Precingular, type P (3`` only); operculum free.
Paracingulum: Position indicated by locations of processes and, additionally, by faint parasutural lines or ridges.
Parasulcus: Not indicated, or outlined by parasutural features.
Size: Intermediate.
Affinities:
Hystrichostrogylon differs from Achomosphaera and Spiniferites in that the periphragm and endophragm are separated over a substantial portion of the cyst; further, length of the process shafts varies according to the degree off separation. In Achomosphaera and Spiniferites the pericoels, when developed, are usually small and limited to areas beneath process bases. A few species show more inflated pericoels, although they are local and may occur inconsistently. Moreover, the process shafts on Achomosphaera and Spiniferites are of approximately uniform length. Hystrichostrogylon differs from Rottnestia in having the pericoel developed mainly along the dorsal side, not restricted to the polar areas as in the latter genus.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Hystrichostrogylon Agelopoulos, 1964, emend. Stover and Evitt, 1978. According to Stover and Evitt (1978, p.164), Hystrichostrogylon is skolochorate, camocavate, with a subspherical endocyst. Periphragm and endophragm appressed over a portion of the cyst but separated elsewhere by a pericoel that is not limited to the polar areas. Processes gonal or gonal and sutural, their shafts differing in length according to extent of pericoel development beneath them. Paratabulation gonyaulacacean indicated mainly by processes but also by faint parasutural lines or ridges.
Hystrichostrogylon, Agelopoulos, 1964, p.673–674.
Emendation: Stover and Evitt, 1978, p.164.
Taxonomic senior synonym: Achomosphaera, by implication in Eaton (1976, p.237), who transferred the "type species" of Hystrichostrogylon, Hystrichostrogylon membraniphorum, to Achomosphaera -- however, Stover and Evitt (1978, p.165) retained Hystrichostrogylon; Spiniferites, according to Duxbury (2019, p.202) -- however, we retain Hystrichostrogylon, which can be distinguished by its partial cavation..
Taxonomic junior synonym: Diphasiosphaera, according to Stover and Williams (1987, p.81) -- however, Duxbury (2019, p.187) retained
Diphasiosphaera.
Type: Agelopoulos, 1964, text-fig.1, as Hystrichostrogylon membraniphorum.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Agelopoulos, 1964]: (Translation: Stover and Evit, 1978, p. 164):
Diagnosis:
Central shell spherical to oval, apparently slightly flattened, provided with forked spines, and enclosed by a delicate, transparent, only antapically developed, somewhat concentric outer shell that lies close to the inner shell ventrally and dorsally. Slender, long, hollow processes occur in the region of the apex which is indicated by a pylome, whereas wide, broad-surfaced processes are confined to the region of the antapex and therefore to the outer shell. The central shell within the outer shell possesses no processes.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Stover and Evitt, 1978:
Synopsis:
Cysts skolochorate, camocavate; endocyst subspherical; periphragm and endophragm appressed over a portion of the cyst but separated elsewhere by a pericoel that is not limited to the polar areas; processes gonal or gonal and intergonal, their shafts differing in length according to extent of pericoel development beneath them; paratabulation gonyaulacacean, indicated mainly by processes but also by faint parasutural lines or ridges; archaeopyle precingular, Type P.
Description:
Shape: Endocyst subspherical; outline of periphragm varies in size and shape, consistent with degree of separation between endophragm and periphragm.
Wall relationships: Cysts camocavate; periphragm and endophragm always appressed dorsally, narrowly to widely separated elsewhere; size and shape of pericoel vary.
Wall features: Faint parasutural lines or ridges may be present on periphragm. Gonal and intergonal processes typically furcate, tips not interconnected; process shafts normally long where pericoel is least developed or not at all, short where pericoel is most developed. Endophragm and periphragm smooth or faintly ornamented.
Paratabulation: Indicated by processes and additionally by faint parasutural lines or ridges; gonyaulacacean, formula: 3-4`, 6``, 6c, 5-6```, 0-1p, 1````; rarely expressed completely.
Archaeopyle: Precingular, type P (3`` only); operculum free.
Paracingulum: Position indicated by locations of processes and, additionally, by faint parasutural lines or ridges.
Parasulcus: Not indicated, or outlined by parasutural features.
Size: Intermediate.
Affinities:
Hystrichostrogylon differs from Achomosphaera and Spiniferites in that the periphragm and endophragm are separated over a substantial portion of the cyst; further, length of the process shafts varies according to the degree off separation. In Achomosphaera and Spiniferites the pericoels, when developed, are usually small and limited to areas beneath process bases. A few species show more inflated pericoels, although they are local and may occur inconsistently. Moreover, the process shafts on Achomosphaera and Spiniferites are of approximately uniform length. Hystrichostrogylon differs from Rottnestia in having the pericoel developed mainly along the dorsal side, not restricted to the polar areas as in the latter genus.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Hystrichostrogylon Agelopoulos, 1964, emend. Stover and Evitt, 1978. According to Stover and Evitt (1978, p.164), Hystrichostrogylon is skolochorate, camocavate, with a subspherical endocyst. Periphragm and endophragm appressed over a portion of the cyst but separated elsewhere by a pericoel that is not limited to the polar areas. Processes gonal or gonal and sutural, their shafts differing in length according to extent of pericoel development beneath them. Paratabulation gonyaulacacean indicated mainly by processes but also by faint parasutural lines or ridges.