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Pseudoceratium interiorense
Pseudoceratium interiorense Bint, 1986
Holotype: Bint, 1986, pl.3, fig.3,9
Locus typicus: Kiowa Formation, Western Interior, USA
Stratum typicum: Late Albian
Original description: Bint, 1986, p.146
Large cysts with ceratioid outline and three prominent, pointed or narrowly rounded horns: apical, antapical, and a shorter right lateral. Right lateral horn is postcingular and is unusually close to the antapical horn for the genus. Specimens are usually flattened (secondarily) and the varied views presented suggest that primary biological dorso-ventral compression was not strong.
Cyst wall two-layered; ectophragm linked to autophragm by connecting structures over the cyst body, except at the horn tips where cornucavation develops. Autophragm extending almost to tips of hypocystal horns, but not as far into the apical horn, so that the apical ectocoel is largest and quite obvious, whereas the hypocystal ectocoels are much smaller and usually difficult to discern. Autophragm smooth or scabrate, ectophragm very finely perforate (0.5-1 µm) with occasional larger perforations. Perforations diminish in density toward ends of horns and are rare in the terminal cavate portion. Structures linking autophragm and ectophragm appear to consist of the muri of an irregular, sometimes incomplete, reticulum with lumina about 3-8 µm across. This reticulation appears more closely connected with the ectophram than the autophragm because remnants of it are present in at least part of the cavate portion of the apical horn.
Archeopyle apical, type (tA), operculum adnate ventrally in some specimens but possibly free in others. Archeopyle suture weakly angular to zigzag, sulcal notch offset to the left. Paratabulation not expressed. Cingulum partially indicated in some specimens by transverse alignment of reticulate connecting elements; sulcus not delimited.
Size. Length of complete specimen 105(123)146 µm, 11 measurements; length with operculum detached 70(83)93 µm, 9 measurements; width 45(53)61 µm, 19 measurements; dorso-ventral width of one specimen in lateral view, partly flattened laterally, 40 µm; 20 specimens measured. Approximate lengths of horns: apical 29-50 µm, lateral 8-20 µm, and antapical 19-38 µm; length of apical pericoel 12-30 µm. Length of five detached opercula 46-75 µm.
Remarks. The unusual positioning of the right postcingular horn close to the antapical horn in Pseudoceratium interiorense results in some specimens appearing to have two antapical horns. However, most specimens have one hypocystal horn shorter and closer to the cingulum than the other indicating that one is postcingular and the other is antapical.
Affinities:
Bint, 1986, p.148: The presence of an ectophragm in P. interiorense distinguishes it from other species of Pseudoceratium with long pointed horns, namely P. pelliferum, P. gochtii, and P. nudum. P. polymorphum has an ectophragm but has low rounded horns.
Holotype: Bint, 1986, pl.3, fig.3,9
Locus typicus: Kiowa Formation, Western Interior, USA
Stratum typicum: Late Albian
Original description: Bint, 1986, p.146
Large cysts with ceratioid outline and three prominent, pointed or narrowly rounded horns: apical, antapical, and a shorter right lateral. Right lateral horn is postcingular and is unusually close to the antapical horn for the genus. Specimens are usually flattened (secondarily) and the varied views presented suggest that primary biological dorso-ventral compression was not strong.
Cyst wall two-layered; ectophragm linked to autophragm by connecting structures over the cyst body, except at the horn tips where cornucavation develops. Autophragm extending almost to tips of hypocystal horns, but not as far into the apical horn, so that the apical ectocoel is largest and quite obvious, whereas the hypocystal ectocoels are much smaller and usually difficult to discern. Autophragm smooth or scabrate, ectophragm very finely perforate (0.5-1 µm) with occasional larger perforations. Perforations diminish in density toward ends of horns and are rare in the terminal cavate portion. Structures linking autophragm and ectophragm appear to consist of the muri of an irregular, sometimes incomplete, reticulum with lumina about 3-8 µm across. This reticulation appears more closely connected with the ectophram than the autophragm because remnants of it are present in at least part of the cavate portion of the apical horn.
Archeopyle apical, type (tA), operculum adnate ventrally in some specimens but possibly free in others. Archeopyle suture weakly angular to zigzag, sulcal notch offset to the left. Paratabulation not expressed. Cingulum partially indicated in some specimens by transverse alignment of reticulate connecting elements; sulcus not delimited.
Size. Length of complete specimen 105(123)146 µm, 11 measurements; length with operculum detached 70(83)93 µm, 9 measurements; width 45(53)61 µm, 19 measurements; dorso-ventral width of one specimen in lateral view, partly flattened laterally, 40 µm; 20 specimens measured. Approximate lengths of horns: apical 29-50 µm, lateral 8-20 µm, and antapical 19-38 µm; length of apical pericoel 12-30 µm. Length of five detached opercula 46-75 µm.
Remarks. The unusual positioning of the right postcingular horn close to the antapical horn in Pseudoceratium interiorense results in some specimens appearing to have two antapical horns. However, most specimens have one hypocystal horn shorter and closer to the cingulum than the other indicating that one is postcingular and the other is antapical.
Affinities:
Bint, 1986, p.148: The presence of an ectophragm in P. interiorense distinguishes it from other species of Pseudoceratium with long pointed horns, namely P. pelliferum, P. gochtii, and P. nudum. P. polymorphum has an ectophragm but has low rounded horns.