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Phallocysta granosa
Phallocysta granosa Riding and Helby 2001c, p.61–62, figs.1A–I.
Holotype: Riding and Helby 2001c, figs.1G–I.
Age: Bathonian.
Stratigraphical distribution: Phallocysta granosa ranges from the Bathonian, lower part of the Caddasphaera halosa Zone (subzone 7cii) to the middle part of the Wanaea verrucosa Zone (subzone 7ciaii) in Australia (Foster, this volume; Helby & partridge, in prep.). The species has been tentatively identified in the Callovian Oraka Sandstone of New Zealand (Helby et al. 1988).
Original description (Riding & Helby, 2001c)
Description:
A small to intermediate sized (Stover & Evitt, 1978, p.5) species of Phallocysta with an elongate subconical outline. The pericyst is cone shaped, the distal extremity of the apical horn is blunt to sharply pointed and the anatpex is rounded. The endocyst is ellipsoidal to subcircular n outline and fills most of the pericyst, apart from the apical part of the pericoel. The endophragm is relatively think (c. 1 µm) and microscabrate to microgranulate. By contrast, the periphragm is thinner (c. 0.5 µm) and ornamented by granules and/or spinules. Where spinules are developed, they are irregular in density and short, simple and solid. They vary from 0.5 to 1 µm in length and are c. 0.5 µm in width at the base. Both granules and spinules are nontabular and normally are of moderate density. Both cyst layers are susceptible to folding.
Dimensions (µm; n=20): Min (Mean) Max.
Length of pericyst: 37 (43) 59
Length of pericoel: 8 (14) 20
Length of endocyst: 20 (30) 42
Equatorial width: 22 (32) 40
The measured specimens are form core from Sunrise-2 well at 2122.25 m and Sunset-1 well at 2216.67 m , 2216.66m , 221420m, 2208.65m and 2204.80m.
Comments:
This species of Phallocysta has a densely granulate to spinose periphragm. The ornamentational style is somewhat variable in that some forms have an irregular covering of short spinules and others are largely microgranulate. The apical horn varies from being sharply-pointed to rounded. Both cyst layers are closely appressed in the hypocyst; the species is consistently epicavate and the thin periphragm separates from the more robust endophragm above the equator. There is no manifestation of paratabulation apart from the anterior intercalary periarchaeopyle.
Comparison:
Phallocysta granosa differs from the other species of the genus by its relatively small size and the granulate/spinose ornamentation. Phallocysta arctica (Below, 1987) Riding 1984 is more elongate tha P. granosa (the holotype is 52µm long according to Below, 1987, p. 113), and the former is extremely densely granulate to icrogranulate (Below, 1987). The Early-Mid Jurassic (latest Toarcian-early Bajocian) species Phallocysta elongata (Beju 1971) Riding 1994 is also more elongate than P. granosa, the former is also psilate to occasionally scabrate and is typically flask-shaped (Riding, 194). Phallocysta elongata may be relatively sparsely ornamented and has a distinct apical horn. Rare late Toarcian to Aalenian specimens of P. elongata may be microgranulate; for example, those illustated as P. minuta Prauss 1989 by Riding et al. (1991, pl.2, figs 23-25). However Lentin & Williams (1993) pointed out that P. minuta was invalid and proposed P. subconica as a substitute name. Subsequently, Riding (1994) synonymised P. subconica with P. elongata. The species P. granuosa and P. elongata are clearly similar. However, the latter is generally smooth and rarely micrograulate, whereas the former is distinctly granulate to occasionally spinose and is generally more squat. The only other Australian species of Phallocysta is P? erregulensis (Filatoff 1975) Stover & Helby 1987. This species is larger than P. granosa, commonly antapically bilobate, may have a rounded apical extremity and has a smooth, granulate to spinose periphragm and rarely, a spinose endophragm (Stover & Helby, 1987, fig. 10E). Phallocysta eumekes is significantly larger than P. granosa. The former also has a consistently smooth endophragm, frequently has a smooth periphragm, and has a distinct lobate hypocyst (Dörhöfer & Davies, 1980; Riding 1984). Phallocysta frommernensis Below 1987 from the Aalenian of southern Germany is relatively small and squat. It also has a spongy, densely gemmate/verrucate periphragm (Below, 1987, pl.22, figs 9-18). The Aalenian-Bajocian species Phallocysta thomasii Smelror 1991 is similar in size to P. granosa and has a spinose periphragm. However the former taxon has a strongly differentiated apical horn and is antapically bilobate. Helby et al. (1988, fig. 3B) illustrated as "gen. et sp. indet. AR", a single specimens from the Callovian Oraka Sandstone of New Zealand which closely resembles Phallocysta granosa.
Holotype: Riding and Helby 2001c, figs.1G–I.
Age: Bathonian.
Stratigraphical distribution: Phallocysta granosa ranges from the Bathonian, lower part of the Caddasphaera halosa Zone (subzone 7cii) to the middle part of the Wanaea verrucosa Zone (subzone 7ciaii) in Australia (Foster, this volume; Helby & partridge, in prep.). The species has been tentatively identified in the Callovian Oraka Sandstone of New Zealand (Helby et al. 1988).
Original description (Riding & Helby, 2001c)
Description:
A small to intermediate sized (Stover & Evitt, 1978, p.5) species of Phallocysta with an elongate subconical outline. The pericyst is cone shaped, the distal extremity of the apical horn is blunt to sharply pointed and the anatpex is rounded. The endocyst is ellipsoidal to subcircular n outline and fills most of the pericyst, apart from the apical part of the pericoel. The endophragm is relatively think (c. 1 µm) and microscabrate to microgranulate. By contrast, the periphragm is thinner (c. 0.5 µm) and ornamented by granules and/or spinules. Where spinules are developed, they are irregular in density and short, simple and solid. They vary from 0.5 to 1 µm in length and are c. 0.5 µm in width at the base. Both granules and spinules are nontabular and normally are of moderate density. Both cyst layers are susceptible to folding.
Dimensions (µm; n=20): Min (Mean) Max.
Length of pericyst: 37 (43) 59
Length of pericoel: 8 (14) 20
Length of endocyst: 20 (30) 42
Equatorial width: 22 (32) 40
The measured specimens are form core from Sunrise-2 well at 2122.25 m and Sunset-1 well at 2216.67 m , 2216.66m , 221420m, 2208.65m and 2204.80m.
Comments:
This species of Phallocysta has a densely granulate to spinose periphragm. The ornamentational style is somewhat variable in that some forms have an irregular covering of short spinules and others are largely microgranulate. The apical horn varies from being sharply-pointed to rounded. Both cyst layers are closely appressed in the hypocyst; the species is consistently epicavate and the thin periphragm separates from the more robust endophragm above the equator. There is no manifestation of paratabulation apart from the anterior intercalary periarchaeopyle.
Comparison:
Phallocysta granosa differs from the other species of the genus by its relatively small size and the granulate/spinose ornamentation. Phallocysta arctica (Below, 1987) Riding 1984 is more elongate tha P. granosa (the holotype is 52µm long according to Below, 1987, p. 113), and the former is extremely densely granulate to icrogranulate (Below, 1987). The Early-Mid Jurassic (latest Toarcian-early Bajocian) species Phallocysta elongata (Beju 1971) Riding 1994 is also more elongate than P. granosa, the former is also psilate to occasionally scabrate and is typically flask-shaped (Riding, 194). Phallocysta elongata may be relatively sparsely ornamented and has a distinct apical horn. Rare late Toarcian to Aalenian specimens of P. elongata may be microgranulate; for example, those illustated as P. minuta Prauss 1989 by Riding et al. (1991, pl.2, figs 23-25). However Lentin & Williams (1993) pointed out that P. minuta was invalid and proposed P. subconica as a substitute name. Subsequently, Riding (1994) synonymised P. subconica with P. elongata. The species P. granuosa and P. elongata are clearly similar. However, the latter is generally smooth and rarely micrograulate, whereas the former is distinctly granulate to occasionally spinose and is generally more squat. The only other Australian species of Phallocysta is P? erregulensis (Filatoff 1975) Stover & Helby 1987. This species is larger than P. granosa, commonly antapically bilobate, may have a rounded apical extremity and has a smooth, granulate to spinose periphragm and rarely, a spinose endophragm (Stover & Helby, 1987, fig. 10E). Phallocysta eumekes is significantly larger than P. granosa. The former also has a consistently smooth endophragm, frequently has a smooth periphragm, and has a distinct lobate hypocyst (Dörhöfer & Davies, 1980; Riding 1984). Phallocysta frommernensis Below 1987 from the Aalenian of southern Germany is relatively small and squat. It also has a spongy, densely gemmate/verrucate periphragm (Below, 1987, pl.22, figs 9-18). The Aalenian-Bajocian species Phallocysta thomasii Smelror 1991 is similar in size to P. granosa and has a spinose periphragm. However the former taxon has a strongly differentiated apical horn and is antapically bilobate. Helby et al. (1988, fig. 3B) illustrated as "gen. et sp. indet. AR", a single specimens from the Callovian Oraka Sandstone of New Zealand which closely resembles Phallocysta granosa.