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Ifecysta
From Williams et al., 2017:
[Ifecysta, Jan du Chêne and Adediran, 1985, p. 20; Emendation: Antolinez-Delgado and Oboh-Ikuenobe, 2007, p. 55.
Type species: Ifecysta pachyderma, Jan du Chêne and Adediran, 1985 (pl.15, figs.1–2; text-figs.6a–b)]
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Original description: [Jan du Chêne and Adediran, 1985]:
Description:
Cysts with an ellipsoidal to fusiform body showing distinct apical and antapical horn-like protrusions. The endophragm and fibrous periphragm are closely appressed even apically and antapically. The periphragm forms large and solid fibrous penitabular processes which reflect a gonyaulacacean type paratabulation.
The archeopyle is precingular, type P (3" only).
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Modified description:
Stover and Williams, 1987, p. 127, 129:
Synopsis:
Cysts skolochorate, ellipsoidal to fusiform with single apical and antapical protrusions (horns) formed by both wall layers; processes fibrous, penitabular, indicate a paratabulation of ?pr, 4`, 6", 6c, 6```,1 p, 1````; archeopyle precingular, type P, 3".
Description:
Shape: Body ellipsoidal to fusiform with an apical and an antapical protrusion.
Wall relationships: Endophragm and periphragm appressed except where the latter forms processes; polar protrusions (horns) formed by both wall layers.
Wall features: Penitabular processes fibrous; most processes wider than high, elliptical to subquadrate in cross-section; small processes narrowly
elliptical to subcircular in cross-section; apical protrusion may have small, distal, fibrous expansion.
Archeopyle: Precingular, type P, 3" only; operculum free.
Paratabulation: Indicated by penitabular processes; formula: ?4`, 6", 6c, 6```, 1p, 1````, 5s.
Paracingulum: Indicated by a well-defined row of six transversely elongate, narrowly ellipsoidal processes.
Parasulcus: Indicated by five small, generally subcircular processes reflecting the following sulcal paraplates: anterior (as), left (Is), right (rs),
right accessory (ra) and posterior (ps).
Size: Intermediate to large; 75 µm to 110 µm in length.
Affinities:
According to Jan du Chêne and Adediran (1985, p. 20) Ifecysta differs from Turbiosphaera Archangelsky 1969 in having the protrusions formed by both wall layers, whereas in Turbiosphaera they are formed by the periphragm only. Fibrocysta Stover and Evitt 1978, Araneosphaera Eaton 1976 and Cyclapophysis Benson 1976 have ellipsoidal bodies and fibrous processes. Fibrocysta differs from Ifecysta in having nontabular rather than penitabular processes; on Araneosphaera and Cyclapophysis some processes are connected distally by trabeculae.
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Emended description:
Antolinez-Delgado and Oboh-Ikuenobe, 2007:
Diagnosis:
Dinoflagellate cysts with an ellipsoidal to fusiform body, exhibiting distinct apical and antapical horn-like protrusions of approximately equal size. Horn-like protrusions formed by equally appressed endophragm and periphragm. The periphragm may take the form of fibrous nontabular processes, fibrous processes in simulate penitabular complexes, or solid penitabular processes which reflect a gonyaulacacean tabulation.
The archeopyle is precingular, type P3” only.
Affinities/Discussion:
Ifecysta is comparable with genera possessing precingular archeopyles, fibrous periphragm, and distinctive apical and antapical features. Most of these genera belong to the Lanternosphaeridium group (Stover and Evitt, 1978, appendix H, p. 282), which includes taxa such as Damassadinium Fensome et al. 1993, Fibrocysta Stover & Evitt 1978, Kenleyia Cookson & Eisenack 1965, Lanternosphaeridium Morgenroth 1966, Muratodinium Drugg 1970, and Turbiosphaera Archangelsky 1959. Kenleyia and Turbiosphaera are fusiform cysts with distinctive apical and antapical features that are formed by expansions of the periphragm only. By contrast, the hornlike protrusions in Ifecysta are formed by the closely appressed endophragm and periphragm. Some species in Damassadinium, Lanternosphaeridium, and Muratodinium possess horns or bosses at both poles, but are not fusiform like Ifecysta. Fibrocysta includes skolochorate cysts with small to long horn-like protrusions. However, the holotype of Fibrocysta bipolaris Cookson & Eisenack 1965,the type species of the genus, does not exhibit projection of the endophragm outward below the horns. This suggests that the generic description of Fibrocysta may require some additional revision. If is considered that the presence of distinctive horn-like protrusions at the apex and the antapex to be a prime characteristic of Ifecysta. Therefore, it is recommended that those species in Fibrocysta, such as Fibrocysta lappacea, that exhibit horn-like protrusions are transferred to Ifecysta.
[Ifecysta, Jan du Chêne and Adediran, 1985, p. 20; Emendation: Antolinez-Delgado and Oboh-Ikuenobe, 2007, p. 55.
Type species: Ifecysta pachyderma, Jan du Chêne and Adediran, 1985 (pl.15, figs.1–2; text-figs.6a–b)]
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Original description: [Jan du Chêne and Adediran, 1985]:
Description:
Cysts with an ellipsoidal to fusiform body showing distinct apical and antapical horn-like protrusions. The endophragm and fibrous periphragm are closely appressed even apically and antapically. The periphragm forms large and solid fibrous penitabular processes which reflect a gonyaulacacean type paratabulation.
The archeopyle is precingular, type P (3" only).
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Modified description:
Stover and Williams, 1987, p. 127, 129:
Synopsis:
Cysts skolochorate, ellipsoidal to fusiform with single apical and antapical protrusions (horns) formed by both wall layers; processes fibrous, penitabular, indicate a paratabulation of ?pr, 4`, 6", 6c, 6```,1 p, 1````; archeopyle precingular, type P, 3".
Description:
Shape: Body ellipsoidal to fusiform with an apical and an antapical protrusion.
Wall relationships: Endophragm and periphragm appressed except where the latter forms processes; polar protrusions (horns) formed by both wall layers.
Wall features: Penitabular processes fibrous; most processes wider than high, elliptical to subquadrate in cross-section; small processes narrowly
elliptical to subcircular in cross-section; apical protrusion may have small, distal, fibrous expansion.
Archeopyle: Precingular, type P, 3" only; operculum free.
Paratabulation: Indicated by penitabular processes; formula: ?4`, 6", 6c, 6```, 1p, 1````, 5s.
Paracingulum: Indicated by a well-defined row of six transversely elongate, narrowly ellipsoidal processes.
Parasulcus: Indicated by five small, generally subcircular processes reflecting the following sulcal paraplates: anterior (as), left (Is), right (rs),
right accessory (ra) and posterior (ps).
Size: Intermediate to large; 75 µm to 110 µm in length.
Affinities:
According to Jan du Chêne and Adediran (1985, p. 20) Ifecysta differs from Turbiosphaera Archangelsky 1969 in having the protrusions formed by both wall layers, whereas in Turbiosphaera they are formed by the periphragm only. Fibrocysta Stover and Evitt 1978, Araneosphaera Eaton 1976 and Cyclapophysis Benson 1976 have ellipsoidal bodies and fibrous processes. Fibrocysta differs from Ifecysta in having nontabular rather than penitabular processes; on Araneosphaera and Cyclapophysis some processes are connected distally by trabeculae.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Antolinez-Delgado and Oboh-Ikuenobe, 2007:
Diagnosis:
Dinoflagellate cysts with an ellipsoidal to fusiform body, exhibiting distinct apical and antapical horn-like protrusions of approximately equal size. Horn-like protrusions formed by equally appressed endophragm and periphragm. The periphragm may take the form of fibrous nontabular processes, fibrous processes in simulate penitabular complexes, or solid penitabular processes which reflect a gonyaulacacean tabulation.
The archeopyle is precingular, type P3” only.
Affinities/Discussion:
Ifecysta is comparable with genera possessing precingular archeopyles, fibrous periphragm, and distinctive apical and antapical features. Most of these genera belong to the Lanternosphaeridium group (Stover and Evitt, 1978, appendix H, p. 282), which includes taxa such as Damassadinium Fensome et al. 1993, Fibrocysta Stover & Evitt 1978, Kenleyia Cookson & Eisenack 1965, Lanternosphaeridium Morgenroth 1966, Muratodinium Drugg 1970, and Turbiosphaera Archangelsky 1959. Kenleyia and Turbiosphaera are fusiform cysts with distinctive apical and antapical features that are formed by expansions of the periphragm only. By contrast, the hornlike protrusions in Ifecysta are formed by the closely appressed endophragm and periphragm. Some species in Damassadinium, Lanternosphaeridium, and Muratodinium possess horns or bosses at both poles, but are not fusiform like Ifecysta. Fibrocysta includes skolochorate cysts with small to long horn-like protrusions. However, the holotype of Fibrocysta bipolaris Cookson & Eisenack 1965,the type species of the genus, does not exhibit projection of the endophragm outward below the horns. This suggests that the generic description of Fibrocysta may require some additional revision. If is considered that the presence of distinctive horn-like protrusions at the apex and the antapex to be a prime characteristic of Ifecysta. Therefore, it is recommended that those species in Fibrocysta, such as Fibrocysta lappacea, that exhibit horn-like protrusions are transferred to Ifecysta.