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Vesperopsis dolabella
Vesperopsis dolabella (Duxbury, 1983) Bint, 1986
Originally Australisphaera, subsequently (and now) Vesperopsis, thirdly Vesperopsis?.
Bint, 1986, suggested that Vesperopsis dolabella and Vesperopsis digitata (Duxbury, 1983) Bint, 1986 may be conspecific.
Lentin and Williams, 1989, stated incorrectly that Bint, 1986, questionably included this species in Vesperopsis. Lentin and Williams, 1993, followed Bint, 1986, in including the species in Vesperopsis without question.
Holotype: Duxbury, 1983, pl.3, fig.11; text-fig.7
Locus typicus: Redcliff section, Isle of Wight, England
Stratum typicum: Early Albian
Original diagnosis: Duxbury, 1983, p.25: Australisphaera dolabella
A very thin-walled species of Australisphaera having two lateral and two antapical horns. The lateral horns are short, broad and distally bear two short, digitate projections which are of approximately equal length. The distal termination of each lateral horn is characteristically hatchet-shaped. The antapical horns comprise one which is long and curved and one which is short and digitate. The body surface has isolated, usually linear, granular areas and the archeopyle is apical.
Observed Dimensions: Holotype - 70 x 70 µm. Complete specimens - 84 (78) 75 x 73 (64) 58 µm. Operculum detached - 67 (61) 52 x 81 (73) 61 µm.
Affinities:
Duxbury, 1983, p. 26: Australisphaera dolabella
This is a most distinctive species, particularly in the nature of the lateral horns and in having a very thin cyst wall. The most comparable species is Muderongia? digitata Duxbury, particularly in the presence of digitate extensions to the lateral horns. Both A. dolabella and M? digitata are, however, very thinwalled and the possible second body layer remarked in the latter (see below) may be due to folding of a single layer. However, until better specimens of M? digitata are observed to establish the number of body layers present, that species must tentatively remain in Muderongia.
Originally Australisphaera, subsequently (and now) Vesperopsis, thirdly Vesperopsis?.
Bint, 1986, suggested that Vesperopsis dolabella and Vesperopsis digitata (Duxbury, 1983) Bint, 1986 may be conspecific.
Lentin and Williams, 1989, stated incorrectly that Bint, 1986, questionably included this species in Vesperopsis. Lentin and Williams, 1993, followed Bint, 1986, in including the species in Vesperopsis without question.
Holotype: Duxbury, 1983, pl.3, fig.11; text-fig.7
Locus typicus: Redcliff section, Isle of Wight, England
Stratum typicum: Early Albian
Original diagnosis: Duxbury, 1983, p.25: Australisphaera dolabella
A very thin-walled species of Australisphaera having two lateral and two antapical horns. The lateral horns are short, broad and distally bear two short, digitate projections which are of approximately equal length. The distal termination of each lateral horn is characteristically hatchet-shaped. The antapical horns comprise one which is long and curved and one which is short and digitate. The body surface has isolated, usually linear, granular areas and the archeopyle is apical.
Observed Dimensions: Holotype - 70 x 70 µm. Complete specimens - 84 (78) 75 x 73 (64) 58 µm. Operculum detached - 67 (61) 52 x 81 (73) 61 µm.
Affinities:
Duxbury, 1983, p. 26: Australisphaera dolabella
This is a most distinctive species, particularly in the nature of the lateral horns and in having a very thin cyst wall. The most comparable species is Muderongia? digitata Duxbury, particularly in the presence of digitate extensions to the lateral horns. Both A. dolabella and M? digitata are, however, very thinwalled and the possible second body layer remarked in the latter (see below) may be due to folding of a single layer. However, until better specimens of M? digitata are observed to establish the number of body layers present, that species must tentatively remain in Muderongia.