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Aprobolocysta reticulata ssp. imparilis
Original description Duxbury, 2024:
Plate 9, Figures 11, 12, 18, 19
Holotype: Plate 9, Figures 11, 12
Paratype: Plate 9, Figure 19
Type Locality: Vergol outcrop, late Valanginian, Bed V112M, verrucosum ammonite Zone, pronecostatum Sub-zone. Holotype:
Slide V112M(1), E.F. F32.4. Paratype: Slide V112M (schulze), E.F. S50.0.
Derivation of Name: From the Latin imparilis, odd, different - in reference to markedly different cingular crests.
Diagnosis: A subspecies of Aprobolocysta reticulata where the anterior cingular crest is markedly higher than the posterior but which otherwise conforms to other morphological characteristics of this species, including a reticulate periphragm and a prominent apical projection. In some specimens, undulation of the higher cingular crest is particularly clear. The operculum is usually retained.
Dimensions: Holotype (complete): 68 × 51 μm. Paratype (operculum lost): 61 × 48 μm.
Overall – Complete specimens (4): 71 (70) 68 μm × 51 (46) 38 μm.
Operculum lost (paratype only): 61 × 48 μm.
Specimens measured – 5.
Remarks: The distinctive, high anterior cingular crest displayed by this subspecies and its wavy nature can be reminiscent of the cingular fold in Aprobolocysta eilema Duxbury 1977, a significantly younger species (see Duxbury 2023). The presence of a clearly reticulate periphragm and a prominent apical projection distinguish A. reticulata imparilis, however.
This subspecies was recorded in the early and late Valanginian at Vergol, beds V45M to V112M, neocomiensiformis Zone, neocomiensiformis Sub-zone to verrucosum Zone, pronecostatum Sub-zone. Monteil (1985) recorded this subspecies as a rarity, as Aprobolocysta aff. varigranosa Duxbury 1977, with a similar range (pertransiens to campylotoxum ammonite zones), and at Angles in the same stratigraphic interval (Monteil 1986).
Plate 9, Figures 11, 12, 18, 19
Holotype: Plate 9, Figures 11, 12
Paratype: Plate 9, Figure 19
Type Locality: Vergol outcrop, late Valanginian, Bed V112M, verrucosum ammonite Zone, pronecostatum Sub-zone. Holotype:
Slide V112M(1), E.F. F32.4. Paratype: Slide V112M (schulze), E.F. S50.0.
Derivation of Name: From the Latin imparilis, odd, different - in reference to markedly different cingular crests.
Diagnosis: A subspecies of Aprobolocysta reticulata where the anterior cingular crest is markedly higher than the posterior but which otherwise conforms to other morphological characteristics of this species, including a reticulate periphragm and a prominent apical projection. In some specimens, undulation of the higher cingular crest is particularly clear. The operculum is usually retained.
Dimensions: Holotype (complete): 68 × 51 μm. Paratype (operculum lost): 61 × 48 μm.
Overall – Complete specimens (4): 71 (70) 68 μm × 51 (46) 38 μm.
Operculum lost (paratype only): 61 × 48 μm.
Specimens measured – 5.
Remarks: The distinctive, high anterior cingular crest displayed by this subspecies and its wavy nature can be reminiscent of the cingular fold in Aprobolocysta eilema Duxbury 1977, a significantly younger species (see Duxbury 2023). The presence of a clearly reticulate periphragm and a prominent apical projection distinguish A. reticulata imparilis, however.
This subspecies was recorded in the early and late Valanginian at Vergol, beds V45M to V112M, neocomiensiformis Zone, neocomiensiformis Sub-zone to verrucosum Zone, pronecostatum Sub-zone. Monteil (1985) recorded this subspecies as a rarity, as Aprobolocysta aff. varigranosa Duxbury 1977, with a similar range (pertransiens to campylotoxum ammonite zones), and at Angles in the same stratigraphic interval (Monteil 1986).