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Hystrichokolpoma mentitum
Hystrichokolpoma mentitum McLean, 1974
Tax. jr. synonym of Alisocysta circumtabulata (Drugg, 1967) Stover and Evitt, 1978, according to Schumacker-Lambry, 1978. Lentin and Williams, 1981, retained Hystrichokolpoma mentitum as a separate species.
Holotype: McLean, 1974, pl.8, figs.1-5
Locus typicus: Outcrop localities along the Potomac River, South of Washington
Stratum typicum: Late Paleocene
Original diagnosis: McLean, 1974, p.68
A species of Hystrichokolpoma, the main body of which, in size, shape, and tabulation, resembles specimens of Eisenackia.
Original description: McLean, 1974, p.68-69
Cyst main body spheroidal to slightly ellipsoidal, bearing simulate, hollow, box-like processes. Cyst wall bi-layered; processes formed of the periphragm, reflect tabulation of 4", 0a, 6", 6c, 6""", 1p, 1"""". Archeopyle apical (Type A) with simple, free operculum; corresponds to four apical plates and an apical pore closing platelet. Cingulum and sulcus reflected by processes. Cingulum levorotatory, ends separated vertically about one half cingulum width and transversely about two cingulum widths. Sulcal area reflected at top and bottom by anterior and posterior sulcal processes, respectively, and in between by two pairs of small processes. Of the anterior-most pair the left member is the larger and is designated as the 1""" the other pair is between the 6""" and 1p processes.
Wall layers appressed except under processes. Endophragm c. 2.0 Ám thick, and externally smooth. Periphragm c. 0.5 Ám thick, and externally micro-reticulate on main body, muri 0.5 - 1Á across. Processes simulate, one per plate-equivalent, hollow and box-like, closed at tips, nearly parallel sided, faintly punctate externally, and do not communicate with endocoel. Precingular processes nearly equidimensional except for relatively small 6"; processes 2" and 4" have four-sided bases, and 1", 3", and 5" are five-sided. Cingular process bases rectangular. Postcingular processes variable in size and shape; processes 3""", 4""", and 5""", are largest of series, are nearly equidimensional, and contain distinctive U-shaped partitions, which open upward, in their anterior portions; process 6""" is intermediate in size and 1""" is the smallest of the series, postcingular process bases are commonly four-sided except for 4""" and 6""" which may be five-sided. Process 1p and the posterior sulcal process bases are four-sided. Antapical process base pentagonal.
Dimensions: Holotype main body L x W: 48x45 Ám, process length up to 15 Ám. Observed range main body length 48-50 Ám, width 42-45 Ám.
Tax. jr. synonym of Alisocysta circumtabulata (Drugg, 1967) Stover and Evitt, 1978, according to Schumacker-Lambry, 1978. Lentin and Williams, 1981, retained Hystrichokolpoma mentitum as a separate species.
Holotype: McLean, 1974, pl.8, figs.1-5
Locus typicus: Outcrop localities along the Potomac River, South of Washington
Stratum typicum: Late Paleocene
Original diagnosis: McLean, 1974, p.68
A species of Hystrichokolpoma, the main body of which, in size, shape, and tabulation, resembles specimens of Eisenackia.
Original description: McLean, 1974, p.68-69
Cyst main body spheroidal to slightly ellipsoidal, bearing simulate, hollow, box-like processes. Cyst wall bi-layered; processes formed of the periphragm, reflect tabulation of 4", 0a, 6", 6c, 6""", 1p, 1"""". Archeopyle apical (Type A) with simple, free operculum; corresponds to four apical plates and an apical pore closing platelet. Cingulum and sulcus reflected by processes. Cingulum levorotatory, ends separated vertically about one half cingulum width and transversely about two cingulum widths. Sulcal area reflected at top and bottom by anterior and posterior sulcal processes, respectively, and in between by two pairs of small processes. Of the anterior-most pair the left member is the larger and is designated as the 1""" the other pair is between the 6""" and 1p processes.
Wall layers appressed except under processes. Endophragm c. 2.0 Ám thick, and externally smooth. Periphragm c. 0.5 Ám thick, and externally micro-reticulate on main body, muri 0.5 - 1Á across. Processes simulate, one per plate-equivalent, hollow and box-like, closed at tips, nearly parallel sided, faintly punctate externally, and do not communicate with endocoel. Precingular processes nearly equidimensional except for relatively small 6"; processes 2" and 4" have four-sided bases, and 1", 3", and 5" are five-sided. Cingular process bases rectangular. Postcingular processes variable in size and shape; processes 3""", 4""", and 5""", are largest of series, are nearly equidimensional, and contain distinctive U-shaped partitions, which open upward, in their anterior portions; process 6""" is intermediate in size and 1""" is the smallest of the series, postcingular process bases are commonly four-sided except for 4""" and 6""" which may be five-sided. Process 1p and the posterior sulcal process bases are four-sided. Antapical process base pentagonal.
Dimensions: Holotype main body L x W: 48x45 Ám, process length up to 15 Ám. Observed range main body length 48-50 Ám, width 42-45 Ám.