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Horologinella spinosa
Horologinella? spinosa Cookson, 1965
NOW Paucilobimorpha (Acritarch). Originally Horologinella?, subsequently (and now) Paucilobimorpha (Acritarch). Questionable assignment: Cookson (1965a, p.89). Pestchevitskaya (2003, p.53) included this species in Horologinella but did not mention its transfer to Paucilobimorpha.
Holotype: Cookson, 1965a, pl.10, fig.11; Pestchevitskaya, 2003, pl.2, fig.14.
Locus typicus: Brown"s Creek, SW. Victoria, Australia
Stratum typicum: Late Eocene
Original description: Cookson, 1965, p.89
Cyst without fields, with deeply concave sides and straight to slightly concave ends (cf. H. incurvata Pl. 11, fig. 13). Wall c. 0.5-1µ, thick mainly smooth, except at the distal rounded ends of the 4 arrns where it is ornamented with small, solid, spine-like projections. One of the arms at the "anterior" end is slightly longer than the other 3 and sometimes narrows slightly towards the apex. In 2 examples (cf. Pl. 11, fig. 10) the apex of the longer arm is open, apparently as the result of a natural transverse break.
Dimensions: Holotype c. 42 µm long, 39 µm broad. Range c. 23-42 µm long, c. 23-39 µm broad.
Affinities:
Cookson, 1965, p.89: This form is doubtfully referred to Horologinella on account of its resemblance to the capsule of Halophoridia xena Cookson and Eisenack 1962, especially as regards the greater prominence and narrower shape of one of the "anterior" arms. However, in H. xena the capsule is enclosed in a hyaline membrane whereas, in the 10 specimens of Horologinella? spinosa seen, no trace of such a membrane has been present.
H.? spinosa differs from the cysts of the described species of Horologinella Cookson and Eisenack 1962 and the capsules of Halophoridia xerla in the development of spines at and adjacent to the apices of the 4 arms. In 3 specimens (Pl. 10, fig. 10) minute dot-like thickenings are scattered over the general surface; in the holotype (Pl. 10, fig. 11) 2 groups of dots are present, one at each end of the "waist"-like region.
NOW Paucilobimorpha (Acritarch). Originally Horologinella?, subsequently (and now) Paucilobimorpha (Acritarch). Questionable assignment: Cookson (1965a, p.89). Pestchevitskaya (2003, p.53) included this species in Horologinella but did not mention its transfer to Paucilobimorpha.
Holotype: Cookson, 1965a, pl.10, fig.11; Pestchevitskaya, 2003, pl.2, fig.14.
Locus typicus: Brown"s Creek, SW. Victoria, Australia
Stratum typicum: Late Eocene
Original description: Cookson, 1965, p.89
Cyst without fields, with deeply concave sides and straight to slightly concave ends (cf. H. incurvata Pl. 11, fig. 13). Wall c. 0.5-1µ, thick mainly smooth, except at the distal rounded ends of the 4 arrns where it is ornamented with small, solid, spine-like projections. One of the arms at the "anterior" end is slightly longer than the other 3 and sometimes narrows slightly towards the apex. In 2 examples (cf. Pl. 11, fig. 10) the apex of the longer arm is open, apparently as the result of a natural transverse break.
Dimensions: Holotype c. 42 µm long, 39 µm broad. Range c. 23-42 µm long, c. 23-39 µm broad.
Affinities:
Cookson, 1965, p.89: This form is doubtfully referred to Horologinella on account of its resemblance to the capsule of Halophoridia xena Cookson and Eisenack 1962, especially as regards the greater prominence and narrower shape of one of the "anterior" arms. However, in H. xena the capsule is enclosed in a hyaline membrane whereas, in the 10 specimens of Horologinella? spinosa seen, no trace of such a membrane has been present.
H.? spinosa differs from the cysts of the described species of Horologinella Cookson and Eisenack 1962 and the capsules of Halophoridia xerla in the development of spines at and adjacent to the apices of the 4 arms. In 3 specimens (Pl. 10, fig. 10) minute dot-like thickenings are scattered over the general surface; in the holotype (Pl. 10, fig. 11) 2 groups of dots are present, one at each end of the "waist"-like region.