Back
Geonettia
From Williams et al., 2017:
[Geonettia, de Verteuil and Norris, 1996b, p. 265-267.
The name Geonettia was not validly published in de Verteuil and Norris (1996a, p.171) since these authors did not give a description.
Type species: Geonettia clineae, de Verteuil and Norris, 1996b (pl.1, figs.1A-B,2A-B)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [de Verteuil and Norris, 1996b]:
Diagnosis:
Goniodomacean dinocysts without processes or other chorate luxuriae; first apical field is an insert and omegaform; excystment occurs by irregular disruption of the dorsal surface and apical series along field boundaries.
Description:
Spherical to ovoidal proximate quinqueform cysts having three fundital fields and a prominent omegacamerate, insert, first apical field. Excystment occurs through irregular disintegration of the dorsal surface among field boundaries, into polyplacoid opercular pieces. Sulcal and adjacent fields are less prone to disruption but structural weakness in the pedium along field boundaries is characteristic. The wall comprises thin pedium and smooth, granulate, reticulate or otherwise constructed proximate luxuriae, with or without vigrae, verrucae or ridges. Small angular re-entrants and acute projections are a conspicuous feature of field geometries and where present indicate the imbrication.
The tabulation is L-type quinqueform; three funditals occupy the antapex and form a dorsally directed triad. There are four climactals including a wide mid-ventral insert first apical, plus well defined apical pore field and one or two smaller Q-fields. Adcingular series comprise six precingulars in standard gonyaulacalean topology and five postcingulars; however, the inferred first postcingular homologue lies within the sulcus. The sixth precingular is irregularly thetacamerate with a long 6"/1' boundary. The second and fourth postcingular fields are posteriorly geniculate and each contact two funditals.
Cingulum narrow and gently laevorotatory, displaced approximately one cingulum width; cingulum without overhang. Six cingular fields and a distal transitional field are present.
The mid-ventral sulcus is straight and wide and does not extend much above the proximal end of the cingulum; it is not noticeably indented. Several small sulcal fields surround a central field having two flagellar scars; sulcals include an anterior, a left accessory (inferred *1"), right and left sulcals having poorly defined anterior field boundaries, and two or more right accessory sulcals excluding the transitional cingular field. The quinqueform hypotabulation may result in minor sinistral torsion.
[Geonettia, de Verteuil and Norris, 1996b, p. 265-267.
The name Geonettia was not validly published in de Verteuil and Norris (1996a, p.171) since these authors did not give a description.
Type species: Geonettia clineae, de Verteuil and Norris, 1996b (pl.1, figs.1A-B,2A-B)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [de Verteuil and Norris, 1996b]:
Diagnosis:
Goniodomacean dinocysts without processes or other chorate luxuriae; first apical field is an insert and omegaform; excystment occurs by irregular disruption of the dorsal surface and apical series along field boundaries.
Description:
Spherical to ovoidal proximate quinqueform cysts having three fundital fields and a prominent omegacamerate, insert, first apical field. Excystment occurs through irregular disintegration of the dorsal surface among field boundaries, into polyplacoid opercular pieces. Sulcal and adjacent fields are less prone to disruption but structural weakness in the pedium along field boundaries is characteristic. The wall comprises thin pedium and smooth, granulate, reticulate or otherwise constructed proximate luxuriae, with or without vigrae, verrucae or ridges. Small angular re-entrants and acute projections are a conspicuous feature of field geometries and where present indicate the imbrication.
The tabulation is L-type quinqueform; three funditals occupy the antapex and form a dorsally directed triad. There are four climactals including a wide mid-ventral insert first apical, plus well defined apical pore field and one or two smaller Q-fields. Adcingular series comprise six precingulars in standard gonyaulacalean topology and five postcingulars; however, the inferred first postcingular homologue lies within the sulcus. The sixth precingular is irregularly thetacamerate with a long 6"/1' boundary. The second and fourth postcingular fields are posteriorly geniculate and each contact two funditals.
Cingulum narrow and gently laevorotatory, displaced approximately one cingulum width; cingulum without overhang. Six cingular fields and a distal transitional field are present.
The mid-ventral sulcus is straight and wide and does not extend much above the proximal end of the cingulum; it is not noticeably indented. Several small sulcal fields surround a central field having two flagellar scars; sulcals include an anterior, a left accessory (inferred *1"), right and left sulcals having poorly defined anterior field boundaries, and two or more right accessory sulcals excluding the transitional cingular field. The quinqueform hypotabulation may result in minor sinistral torsion.