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Nematosphaeropsis lilaensis
Nematosphaeropsis lilaensis sp. nov.; Slimani, H. et al. 2021
Holotype: Sample KBL7, slide 2, England Finder (EF) coordinates S58/1 (Plate IIIA–D); Slimani, H. et al. 2021
Age: upper Campanian
Original description: Slimani, H. et al. 2021: Nematosphaeropsis lilaensis sp. nov.:
Diagnosis:
Characterized by a smooth central body wall and numerous sutural (gonal and intergonal) processes that are joined proximally by low and discontinuous sutural ridges and
distally by pairs of thin penitabular trabeculae. The paratabulation is expressed by a precingular archeopyle type P (3′′), sutural processes on the central body, penitabular trabeculae and partially by sutural ridges.
Description:
This species is of an intermediate to a large size and a subspheroidal to an egg-shaped central body.
Wall of the central body: is smooth, hyaline and thin (0.5–1 μm thick) and gives rise to sutural gonal and intergonal processes that are distally slightly expanded, reflecting a tabulation
Processes: (8–10 μm in length) are slender, hollow and smooth to finely fibrous, generally circular in cross-section and connected distally by paired of thin penitabular trabeculae. The distal ends of the intergonal processes are bifurcate, whereas those of the gonal processes are trifurcate. Each process furcation gives rise to two thin penitabular trabeculae that are mostly rounded in cross-section. The bases of processes may be connected by low sutural ridges.
Tabulation: gonyaulacoid, indicated mostly by the sutural processes and by the trabecular shell surrounding the central body: 4′, 6′′, 6c, 6′′′, 1p, 1′′′′, 2–xs (Fig. 4). The tabulation is delineated on well-preserved specimens, but may be obscured when the trabeculae are destroyed or deformed. The tabulation may also be partially delineated by the low sutural ridges on the central body. The cingulum is slightly laevorotatory and bordered by two parallel rows of sutural processes. Every row ends distally with a pair of penitabular trabeculae. The sulcusis relatively large, with well-differentiated posterior sulcal plate ps and rarely well-expressed anterior sulcal plate as. The postcingular plate 1′′′ is very narrow. The postcingular plate 2′′′ does not contact the antapical plate 1′′′′ and also the posterior sulcal plate ps does not contact the
postcingular plate 5′′′. The antapical plate 1′′′′ is subhexagonal and forms a sexiform hypocystal plate arrangement with the posterior intercalary (1p), the posterior sulcal (ps) and the postcingular (3′′, 4′′, 5′′, 6′′) plates (Fig. 4, Plate IIIA, H, L).
Archeopyle: precingular (type P), formed by the loss of the plate 3′′. The operculum is free or in place.
Dimensions:
Range for 10 specimens measured: overall length without 70(75)80 μm, overall width 62(71)90 μm, central body length 45(51)55 μm, central body width 42(46)50 μm, length of processes 8–16 μm.
Holotype: overall length 80 μm, overall width 75 μm, central body length 57 μm, central body width 50 μm, height of septa 8–13 μm.
Remarks:
N. lilaensis may be a probable ancestor of N. silsila, a possible evolutionary relationship may exist between the two species.
Affinities:
The new species differs from Nematosphaeropsis silsila Guédé and Slimani in Guédé et al., 2014, mainly by the presence of pairs of simple and thin penitabular trabeculae, connecting the gonal and intergonal processes distally, rather than chain-like pairs of thin penitabular trabeculae. Nematosphaeropsis silsila bears
more numerous, shorter and equidistantly spaced sutural processes than those observed in Nematosphaeropsis lilaensis.
Unipontidinium grande (Davey, 1975) Wrenn, 1988can be distinguished by having pairs of penitabular trabeculae rather than a single membranous sutural trabeculum. Nematosphaeropsis lativittatus Wrenn, 1988 possesses also relatively spaced gonal and?intergonal processes, but they are connected distally by very broad, often fused,
ribbon-like trabeculae rather than paired thin trabeculae of the new species.
Nematosphaeropsis lilaensis differs from Nematosphaeopsis rigida Wrenn, 1988 in being larger and in having flexible and hollow rather than solid and stiff gonal and?intergonal processes, with less pronounced distal furcations. In N. rigida, trabeculae shell resists deformation (Wrenn, 1988), however in N. lilaensis, trabeculae are often deformed or destroyed.
The new species resembles Nematosphaeropsis philippotii (Deflandre, 1947) De Coninck, 1969 in having hollow processes connected distally by pairs of thin penitabular trabeculae, but the latter is distinguished by its more widely spaced Spiniferite-like processes (probably only gonal) (see also Slimani, 1994, p. 77–78, pl. 11, figs. 18–19). In general, Nematosphaeropsis lilaensis differs from the formally published species of the genus Nematosphaeropsis, by its large size, large central body, largest central
body/process length ratio, smooth central body wall and its tabulation delineated generally by pairs of thin penitabular trabeculae, relatively spaced sutural (gonal and intergonal) processes, and also partially by discontinuous sutural ridges (Table 1).
Holotype: Sample KBL7, slide 2, England Finder (EF) coordinates S58/1 (Plate IIIA–D); Slimani, H. et al. 2021
Age: upper Campanian
Original description: Slimani, H. et al. 2021: Nematosphaeropsis lilaensis sp. nov.:
Diagnosis:
Characterized by a smooth central body wall and numerous sutural (gonal and intergonal) processes that are joined proximally by low and discontinuous sutural ridges and
distally by pairs of thin penitabular trabeculae. The paratabulation is expressed by a precingular archeopyle type P (3′′), sutural processes on the central body, penitabular trabeculae and partially by sutural ridges.
Description:
This species is of an intermediate to a large size and a subspheroidal to an egg-shaped central body.
Wall of the central body: is smooth, hyaline and thin (0.5–1 μm thick) and gives rise to sutural gonal and intergonal processes that are distally slightly expanded, reflecting a tabulation
Processes: (8–10 μm in length) are slender, hollow and smooth to finely fibrous, generally circular in cross-section and connected distally by paired of thin penitabular trabeculae. The distal ends of the intergonal processes are bifurcate, whereas those of the gonal processes are trifurcate. Each process furcation gives rise to two thin penitabular trabeculae that are mostly rounded in cross-section. The bases of processes may be connected by low sutural ridges.
Tabulation: gonyaulacoid, indicated mostly by the sutural processes and by the trabecular shell surrounding the central body: 4′, 6′′, 6c, 6′′′, 1p, 1′′′′, 2–xs (Fig. 4). The tabulation is delineated on well-preserved specimens, but may be obscured when the trabeculae are destroyed or deformed. The tabulation may also be partially delineated by the low sutural ridges on the central body. The cingulum is slightly laevorotatory and bordered by two parallel rows of sutural processes. Every row ends distally with a pair of penitabular trabeculae. The sulcusis relatively large, with well-differentiated posterior sulcal plate ps and rarely well-expressed anterior sulcal plate as. The postcingular plate 1′′′ is very narrow. The postcingular plate 2′′′ does not contact the antapical plate 1′′′′ and also the posterior sulcal plate ps does not contact the
postcingular plate 5′′′. The antapical plate 1′′′′ is subhexagonal and forms a sexiform hypocystal plate arrangement with the posterior intercalary (1p), the posterior sulcal (ps) and the postcingular (3′′, 4′′, 5′′, 6′′) plates (Fig. 4, Plate IIIA, H, L).
Archeopyle: precingular (type P), formed by the loss of the plate 3′′. The operculum is free or in place.
Dimensions:
Range for 10 specimens measured: overall length without 70(75)80 μm, overall width 62(71)90 μm, central body length 45(51)55 μm, central body width 42(46)50 μm, length of processes 8–16 μm.
Holotype: overall length 80 μm, overall width 75 μm, central body length 57 μm, central body width 50 μm, height of septa 8–13 μm.
Remarks:
N. lilaensis may be a probable ancestor of N. silsila, a possible evolutionary relationship may exist between the two species.
Affinities:
The new species differs from Nematosphaeropsis silsila Guédé and Slimani in Guédé et al., 2014, mainly by the presence of pairs of simple and thin penitabular trabeculae, connecting the gonal and intergonal processes distally, rather than chain-like pairs of thin penitabular trabeculae. Nematosphaeropsis silsila bears
more numerous, shorter and equidistantly spaced sutural processes than those observed in Nematosphaeropsis lilaensis.
Unipontidinium grande (Davey, 1975) Wrenn, 1988can be distinguished by having pairs of penitabular trabeculae rather than a single membranous sutural trabeculum. Nematosphaeropsis lativittatus Wrenn, 1988 possesses also relatively spaced gonal and?intergonal processes, but they are connected distally by very broad, often fused,
ribbon-like trabeculae rather than paired thin trabeculae of the new species.
Nematosphaeropsis lilaensis differs from Nematosphaeopsis rigida Wrenn, 1988 in being larger and in having flexible and hollow rather than solid and stiff gonal and?intergonal processes, with less pronounced distal furcations. In N. rigida, trabeculae shell resists deformation (Wrenn, 1988), however in N. lilaensis, trabeculae are often deformed or destroyed.
The new species resembles Nematosphaeropsis philippotii (Deflandre, 1947) De Coninck, 1969 in having hollow processes connected distally by pairs of thin penitabular trabeculae, but the latter is distinguished by its more widely spaced Spiniferite-like processes (probably only gonal) (see also Slimani, 1994, p. 77–78, pl. 11, figs. 18–19). In general, Nematosphaeropsis lilaensis differs from the formally published species of the genus Nematosphaeropsis, by its large size, large central body, largest central
body/process length ratio, smooth central body wall and its tabulation delineated generally by pairs of thin penitabular trabeculae, relatively spaced sutural (gonal and intergonal) processes, and also partially by discontinuous sutural ridges (Table 1).