Back
Eisenackia brevivallata
From Fensome et al., 2019:
Eisenackia brevivallata (Harker and Sarjeant in Harker et al., 1990, p.97–98, pl.5, figs.5,9–17; text-figs.20a–b ex Harker and Sarjeant, 1991, p.708) Quattrocchio and Sarjeant, 2003, p.146. Holotype: Harker et al., 1990, pl.5, figs.11–12; textfigs. 20a–b. Originally Alisocysta, subsequently (and now) Eisenackia. The name Alisocysta brevivallata was not validly published in Harker et al. (1990), since the lodgement of the holotype was not cited (ICN Article 40.7). Age: late Campanian.
---------------------------------------------------------------------------------------------------
Original description (Harker et al., 1990):
Alisocysta brevivallata sp. nov.
Plate 5, Figs. 5, 9-17; Text-fig. 20
Derivation of name: Latin brevis, short, vallatus, to surround with a wall; with reference to the low penitabular crests.
Diagnosis: Small proximate cysts having a spheroidal to ovoidal ambitus. Phragma thin, composed of two closely adpressed layers; endophragm smooth to finely granular, periphragm giving rise to short capitate spines that support low connecting crests forming simulate complexes. These penitabular crests outline the paratabulation 4', (?)6", 6c, 1-5s(?), 6'", 1p, 1"". The complexes are separated by fossae that are generally bare of ornamentation other than rare isolate, coarse granules but are in places traversed by low ridges. Poorly developed accessory crests give rise to a partial reticulation on some paraplates. Cingulum slightly laevorotatory; sulcus of moderate breadth.
Archaeopyle apical, with deep parasutural notches and a free operculum.
Description: The low penitabular crests are supported by short capitate spines (PI. 5, Fig. 17), a structure very similar to that observed in Cassiculospbaeridia magna and C. ovalis sp. nov. (PI. 2, Fig. 10 and Pl. 2, Fig. 12). Since the penitabular crests are often poorlv developed in the apical and ventral regions and since the apex is missing in most specimens, the full paratabulation is diffcult to determine; however, it appears to be that typical for the genus. The cingular paraplate series is easily recognized and is slightly laevorotatory, sulcal displacement being by about one cingulum width. A partial reticulation is produced by poorly developed, discontinuous spine-supported crests; this feature is not equally developed on every specimen (compare PI. 5, Fig. l2 and l. J, Fig. 14). 1ne rossae separating the paraplates are generally smooth with only a few, scattered granules (relief less than 0.5 um). howeve, they are in places traversed by low ridges related in position to accessory crests on adjacent peniplates; these surely correspond to lines demarcating grOwth phases of the motile dinoflagellate. The archaeopyle is formed by loss of all the apical paraplates: its angular margin has deep parasutural notches (PI. 5, Fig. 16).
Remarks: The low, spine-supported crests distinguish this from all other species of Alisoysta. A. ornata (COOKSON & EISENACK 1965a) STOVER & EVITT 1978 and A. circumtabulata (DRUGG 1967) STOVER & EVITT 1978 similar, but differ respectively in having smooth, distally tapering penitabular ridges or high, membranous penitabular crests. The specimens illustrated by LEOPOLD & TSCHUDY (1965, Figs. 237, 238) appear similar in size and morphology to those observed.
This species is rare in the upper Millwood Member and rare to common in the Odanah Member, Pierre Formation, Manitoba; rare to common in the Mitten Black Shale and lower Red Bird Members, Pierre Shale, Wyoming.
Figured Material: Holotype GMUS Pd 37, PI. 5, Figs. 11, 12; Text-fig. 20: Slide 2183/1, 20.0/105.4; Odanah Member, Pierre Formation, La Riviere, Manitoba. Other specimens: (a) Pl. 5, Figs. 5, 9: Slide 2573/1, 21.2/1 18.1; Pierre Shale, Red Bird, Wyoming. (b) PI. 5, Figs. 10, 13, 14: Slide 2235/1, 18.9/105.0; Millwood Member, Pierre Formation, Millwood, Manitoba. (c) P. 5, Fig. 16: Slide 2204/1, 5.9/101.2; PI. 5, Fig. 15: Slide 2204/1, 15.2/194.1; Odanah Member, Pierre Formation, Harrowby, Manitoba.
Dimensions: Holotype: length (apex missing) 26 μm, breadth 29 μm, height of crests 0.5-1.5 um, width 0.5-1.0 μm. Range of 61 measurable specimens: length (apex missing) 25-37 μm, mean 31 μm; breadth 25-37 μm, mean 29 μm; height of crests 0.5-2.0 μm; width 0.5-1.0 μm. 123 specimens were counted.
Eisenackia brevivallata (Harker and Sarjeant in Harker et al., 1990, p.97–98, pl.5, figs.5,9–17; text-figs.20a–b ex Harker and Sarjeant, 1991, p.708) Quattrocchio and Sarjeant, 2003, p.146. Holotype: Harker et al., 1990, pl.5, figs.11–12; textfigs. 20a–b. Originally Alisocysta, subsequently (and now) Eisenackia. The name Alisocysta brevivallata was not validly published in Harker et al. (1990), since the lodgement of the holotype was not cited (ICN Article 40.7). Age: late Campanian.
---------------------------------------------------------------------------------------------------
Original description (Harker et al., 1990):
Alisocysta brevivallata sp. nov.
Plate 5, Figs. 5, 9-17; Text-fig. 20
Derivation of name: Latin brevis, short, vallatus, to surround with a wall; with reference to the low penitabular crests.
Diagnosis: Small proximate cysts having a spheroidal to ovoidal ambitus. Phragma thin, composed of two closely adpressed layers; endophragm smooth to finely granular, periphragm giving rise to short capitate spines that support low connecting crests forming simulate complexes. These penitabular crests outline the paratabulation 4', (?)6", 6c, 1-5s(?), 6'", 1p, 1"". The complexes are separated by fossae that are generally bare of ornamentation other than rare isolate, coarse granules but are in places traversed by low ridges. Poorly developed accessory crests give rise to a partial reticulation on some paraplates. Cingulum slightly laevorotatory; sulcus of moderate breadth.
Archaeopyle apical, with deep parasutural notches and a free operculum.
Description: The low penitabular crests are supported by short capitate spines (PI. 5, Fig. 17), a structure very similar to that observed in Cassiculospbaeridia magna and C. ovalis sp. nov. (PI. 2, Fig. 10 and Pl. 2, Fig. 12). Since the penitabular crests are often poorlv developed in the apical and ventral regions and since the apex is missing in most specimens, the full paratabulation is diffcult to determine; however, it appears to be that typical for the genus. The cingular paraplate series is easily recognized and is slightly laevorotatory, sulcal displacement being by about one cingulum width. A partial reticulation is produced by poorly developed, discontinuous spine-supported crests; this feature is not equally developed on every specimen (compare PI. 5, Fig. l2 and l. J, Fig. 14). 1ne rossae separating the paraplates are generally smooth with only a few, scattered granules (relief less than 0.5 um). howeve, they are in places traversed by low ridges related in position to accessory crests on adjacent peniplates; these surely correspond to lines demarcating grOwth phases of the motile dinoflagellate. The archaeopyle is formed by loss of all the apical paraplates: its angular margin has deep parasutural notches (PI. 5, Fig. 16).
Remarks: The low, spine-supported crests distinguish this from all other species of Alisoysta. A. ornata (COOKSON & EISENACK 1965a) STOVER & EVITT 1978 and A. circumtabulata (DRUGG 1967) STOVER & EVITT 1978 similar, but differ respectively in having smooth, distally tapering penitabular ridges or high, membranous penitabular crests. The specimens illustrated by LEOPOLD & TSCHUDY (1965, Figs. 237, 238) appear similar in size and morphology to those observed.
This species is rare in the upper Millwood Member and rare to common in the Odanah Member, Pierre Formation, Manitoba; rare to common in the Mitten Black Shale and lower Red Bird Members, Pierre Shale, Wyoming.
Figured Material: Holotype GMUS Pd 37, PI. 5, Figs. 11, 12; Text-fig. 20: Slide 2183/1, 20.0/105.4; Odanah Member, Pierre Formation, La Riviere, Manitoba. Other specimens: (a) Pl. 5, Figs. 5, 9: Slide 2573/1, 21.2/1 18.1; Pierre Shale, Red Bird, Wyoming. (b) PI. 5, Figs. 10, 13, 14: Slide 2235/1, 18.9/105.0; Millwood Member, Pierre Formation, Millwood, Manitoba. (c) P. 5, Fig. 16: Slide 2204/1, 5.9/101.2; PI. 5, Fig. 15: Slide 2204/1, 15.2/194.1; Odanah Member, Pierre Formation, Harrowby, Manitoba.
Dimensions: Holotype: length (apex missing) 26 μm, breadth 29 μm, height of crests 0.5-1.5 um, width 0.5-1.0 μm. Range of 61 measurable specimens: length (apex missing) 25-37 μm, mean 31 μm; breadth 25-37 μm, mean 29 μm; height of crests 0.5-2.0 μm; width 0.5-1.0 μm. 123 specimens were counted.