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Wetzeliella summissa
From Fensome et al., 2019:
Wetzeliella summissa Harland, 1979
Originally Wetzeliella subgenus Apectodinium, subsequently (and now) Apectodinium, thirdly Krutzschidinium (combination not validly published).
Holotype: Harland, 1979, pl.1, fig.12
Locus typicus: North Sea Basin
Stratum typicum: Late Paleocene
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Original diagnosis: Harland, 1979, p.66: Wetzeliella (Apectodinium) summissa
Small sub-pentagonal cyst having two wall layers fairly closely adpressed except at the apex and sometimes in the lateral areas. Apical horn usually prominent; all other horns absent, incipient, or very poorly developed. Processes -randomly developed, some sutural, hollow slender to flexuous, may be branched, distallv evexate, bulbous and opening distally with a small pore. Cingulum planar outlined by sutural processes. Archeopyle [I2a/I2a], ?reduced.
Original description: Harland, 1979, p.66-67: Wetzeliella (Apectodinium) summissa
Cyst compressed dorso-ventrally, the two wall layers thin and the endophragm often crumpled, the endophragm always smooth but the periphragm may be smooth, microreticulate or microgranulate, with the ornamentation present on the processes. A periceol always developed in the apex and sometimes laterally according to the prominence of any lateral incipient horns. If no lateral structures are apparent the cyst can assume a more rounded ambitus. The processes appear randomly distributed but some are clearly sutural. Sutural process outline the planar, non-indented, cingulum. Processes composed of periphragm, tapering, distally evexate, sometimes with a distal pore; some have a bulbous tip, many branched. Process length very variable from 1/10 to 1/4 of the cyst diameter. A larger proccss, often branched, may occupy the site of the left antapical horn.
Discussion. This form represents an initial morphological step from W. (A.) homomorpha towards W. (A.) quinquelata and ultimately W. (W.) articuleta. It is a distinct form that can be recognized in Palaeocene sediments, and is characterized by its usually prominent apical horn and sub-pentagonal ambitus.
Dimensions:
Holotype. Length, excluding apical horn, 58.75 µm; breadth 55.00 µm.
Range--Length, excluding apical horn, 48.75 (53.96) 57.5 µm breadth 45.0 (50.0) 52.50 µm. Six specimens measured.
Variation: Intraspecific variation confined to overall shape and process length, and linked to the former by the incipient development of lateral horns.
Wetzeliella summissa Harland, 1979
Originally Wetzeliella subgenus Apectodinium, subsequently (and now) Apectodinium, thirdly Krutzschidinium (combination not validly published).
Holotype: Harland, 1979, pl.1, fig.12
Locus typicus: North Sea Basin
Stratum typicum: Late Paleocene
---------------------------------------------------------------------------------------------------
Original diagnosis: Harland, 1979, p.66: Wetzeliella (Apectodinium) summissa
Small sub-pentagonal cyst having two wall layers fairly closely adpressed except at the apex and sometimes in the lateral areas. Apical horn usually prominent; all other horns absent, incipient, or very poorly developed. Processes -randomly developed, some sutural, hollow slender to flexuous, may be branched, distallv evexate, bulbous and opening distally with a small pore. Cingulum planar outlined by sutural processes. Archeopyle [I2a/I2a], ?reduced.
Original description: Harland, 1979, p.66-67: Wetzeliella (Apectodinium) summissa
Cyst compressed dorso-ventrally, the two wall layers thin and the endophragm often crumpled, the endophragm always smooth but the periphragm may be smooth, microreticulate or microgranulate, with the ornamentation present on the processes. A periceol always developed in the apex and sometimes laterally according to the prominence of any lateral incipient horns. If no lateral structures are apparent the cyst can assume a more rounded ambitus. The processes appear randomly distributed but some are clearly sutural. Sutural process outline the planar, non-indented, cingulum. Processes composed of periphragm, tapering, distally evexate, sometimes with a distal pore; some have a bulbous tip, many branched. Process length very variable from 1/10 to 1/4 of the cyst diameter. A larger proccss, often branched, may occupy the site of the left antapical horn.
Discussion. This form represents an initial morphological step from W. (A.) homomorpha towards W. (A.) quinquelata and ultimately W. (W.) articuleta. It is a distinct form that can be recognized in Palaeocene sediments, and is characterized by its usually prominent apical horn and sub-pentagonal ambitus.
Dimensions:
Holotype. Length, excluding apical horn, 58.75 µm; breadth 55.00 µm.
Range--Length, excluding apical horn, 48.75 (53.96) 57.5 µm breadth 45.0 (50.0) 52.50 µm. Six specimens measured.
Variation: Intraspecific variation confined to overall shape and process length, and linked to the former by the incipient development of lateral horns.