Back
Vesperopsis mayi
Vesperopsis mayii Bint, 1986
Holotype: Bint, 1986, pl.5, figs.9, 12-13, text-fig.5
Locus typicus: Kiowa Formation, Western Interior, USA
Stratum typicum: Late Albian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Vesperopsis mayi Bint, 1986. is intermediate to large, with an apical, two lateral and two antapical horns. Apical horn long, narrow and distally rounded. Lateral horns about equal in size, with anterior rounded shoulder, vague cingular indentation and posterior extension. Left antapical horn long and narrow, right antapical horn reduced. Operculum adnate and usually in place. Muderongia asymmetrica differs in having an endocyst, a free operculum and a right postcingular horn that is longer than the left. Size: length (with operculum) 88-120 µm, length (without operculum) 60-67 µm, width 64-96 µm, approximate length of horns, apical 20-37 µm, postcingular 6-16 µm, left antapical 15-32 µm, right antapical 0-11 µm.
--------------------------------------------------
Original description: Bint, 1986, p.157
Intermediate to large, dorso-ventrally compressed cysts with an apical, two lateral, and two antapical horns. Apical horn is long, narrow, and distally rounded. Lateral horns about equal in size; a prominent to rather short laterally extending portion terminates in an anterior rounded shoulder, a clear to vague cingular indentation, and a posterior consistently developed narrow postcingular extension which is narrowly rounded distally. Rarely, a short precingular extension may be present. Left antapical horn long and narrow, nearly as long as the apical horn, and narrowly rounded distally. Right antapical horn short, usually the shortest horn of all, and pointed or narrowly rounded; it may be absent. Acavate, autophragm smooth and extremely thin.
Paratabulation not expressed. Cingulum indicated by indentation of the lateral horns, and sometimes by faint transverse lines near the lateral margins of the cyst; sulcus not indicated. Archeopyle apical, operculum usually in place and adnate, but may be broken away. Archeopyle suture weakly angular, incomplete, and developed to varying extents ranging from short lateral nicks between the apical and precingular series to a fully developed state in which only a mid-ventral attachment area remains between the operculum and cyst body.
Size. Length of complete specimen 88(103)120 µm, 18 measurements; length of two specimens with operculum broken away 60 and 67 µm; total width 64(77)96 µm; 20 specimens measured. Approximate lengths of horns: apical 20-37 µm, postcingular 6-16 µm, left antapical 15-32 µm, right antapical 0-11 µm.
Remarks. Because of its very thin autophragm, specimens of V. mayi are also very fragile. They were always badly damaged by SEM mounting procedures and consequently were not suitable for photography.
Affinities:
Bint, 1986, p.157: Vesperopsis mayii is superficially similar to Muderongia asymmetrica Brideaux 1977 which differs in having an inner body, a free apical operculum, and a right postcingular horn which is longer than the left postcingular horn. V. nebulosa is distinguished from V. mayi by having all horns about equal in size and rounded conical in shape. Vesperopsis digitata and V. dolabella both differ in having prominent precingular projections arising from the lateral horns.
Holotype: Bint, 1986, pl.5, figs.9, 12-13, text-fig.5
Locus typicus: Kiowa Formation, Western Interior, USA
Stratum typicum: Late Albian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Vesperopsis mayi Bint, 1986. is intermediate to large, with an apical, two lateral and two antapical horns. Apical horn long, narrow and distally rounded. Lateral horns about equal in size, with anterior rounded shoulder, vague cingular indentation and posterior extension. Left antapical horn long and narrow, right antapical horn reduced. Operculum adnate and usually in place. Muderongia asymmetrica differs in having an endocyst, a free operculum and a right postcingular horn that is longer than the left. Size: length (with operculum) 88-120 µm, length (without operculum) 60-67 µm, width 64-96 µm, approximate length of horns, apical 20-37 µm, postcingular 6-16 µm, left antapical 15-32 µm, right antapical 0-11 µm.
--------------------------------------------------
Original description: Bint, 1986, p.157
Intermediate to large, dorso-ventrally compressed cysts with an apical, two lateral, and two antapical horns. Apical horn is long, narrow, and distally rounded. Lateral horns about equal in size; a prominent to rather short laterally extending portion terminates in an anterior rounded shoulder, a clear to vague cingular indentation, and a posterior consistently developed narrow postcingular extension which is narrowly rounded distally. Rarely, a short precingular extension may be present. Left antapical horn long and narrow, nearly as long as the apical horn, and narrowly rounded distally. Right antapical horn short, usually the shortest horn of all, and pointed or narrowly rounded; it may be absent. Acavate, autophragm smooth and extremely thin.
Paratabulation not expressed. Cingulum indicated by indentation of the lateral horns, and sometimes by faint transverse lines near the lateral margins of the cyst; sulcus not indicated. Archeopyle apical, operculum usually in place and adnate, but may be broken away. Archeopyle suture weakly angular, incomplete, and developed to varying extents ranging from short lateral nicks between the apical and precingular series to a fully developed state in which only a mid-ventral attachment area remains between the operculum and cyst body.
Size. Length of complete specimen 88(103)120 µm, 18 measurements; length of two specimens with operculum broken away 60 and 67 µm; total width 64(77)96 µm; 20 specimens measured. Approximate lengths of horns: apical 20-37 µm, postcingular 6-16 µm, left antapical 15-32 µm, right antapical 0-11 µm.
Remarks. Because of its very thin autophragm, specimens of V. mayi are also very fragile. They were always badly damaged by SEM mounting procedures and consequently were not suitable for photography.
Affinities:
Bint, 1986, p.157: Vesperopsis mayii is superficially similar to Muderongia asymmetrica Brideaux 1977 which differs in having an inner body, a free apical operculum, and a right postcingular horn which is longer than the left postcingular horn. V. nebulosa is distinguished from V. mayi by having all horns about equal in size and rounded conical in shape. Vesperopsis digitata and V. dolabella both differ in having prominent precingular projections arising from the lateral horns.