Wolburgiopsis magnafossa, Almeida-Lima & Guzmán & Maia & Jesus & Piovesan, 2024

Wolburgiopsis magnafossa sp. nov. ( Fig. 4Q–S View FIGURE 4 ; Fig. 5E View FIGURE 5 )

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Holotype: LMA-00514, L: 0.38 mm, H: 0.20 mm, W: 0.16 mm.

Paratype: LMA-00515, 0.20 mm, H: 0.11 mm, W: 0.09 mm.

Material: Four carapaces.

Derivation of name: In reference to the deep fossae present in the ornamentation of the carapace of this species.

Type locality: Ipubi Formation, Araripe Basin, Nova Olinda Municipality, Ceará State, Brazil.

Type horizon: Ipubi Formation , Araripe Basin, Nova Olinda Municipality, Ceará State, Brazil. 2-AR-SR-1A-CE well core sample, depth interval 54.40–54.43 m .

Stratigraphic and geographic distribution: Aptian:Ipubi Formation,Araripe Basin, Nova Olinda Municipality, Ceará State, Brazil (this study).

Diagnosis: A species with sub-trapezoidal to sub-rectangular outline in lateral view, ellipsoidal in dorsal view; surface ornamentation with deep fossae and punctuated muri; prominent overlap of the valves at the cardinal angle regions.

Description: Carapace sub-trapezoidal to sub-rectangular in lateral view; ellipsoidal in dorsal view. Ventral margin straight to slightly concave; dorsal margin almost straight, with a slight slope to the posterior margin. Anterior margin asymmetrically rounded; posterior margin sub-rounded and equicurvate. Two shallow sulci, the first one smaller and located at the anterodorsal region and the second one at mid-length extending from dorsal margin to mid-height. LV overlapping RV at the anterodorsal and posterodorsal regions, more prominently at the cardinal angle regions and subtly at the anteroventral region. Maximum height at the anterior cardinal angle; greater length at mid-height; greater width behind the second sulci. Well-defined and obtuse cardinal angles. Ornamented surface with reticula formed by thick and punctuated muri; deep and sub-rounded fossae at the median region, with deformities near the sulci; however, to the anterolateral, posterolateral, ventrolateral and ventral outlines, the reticulation becomes more elongated forming subparallel rows without punctuation; the hinge margin has no ornamentation. Sexual dimorphism and internal features not observed.

Remarks: This is the first record of Wolburgiopsis for the Araripe Basin, but the genus had already been recovered in the Sanfranciscana Basin (Lower Cretaceous) ( Do Carmo et al. 2004) and the Paraná Basin (Upper Cretaceous) ( Dias-Brito et al. 2001; Gobbo & Bertini 2023; Gobbo-Rodrigues et al. 1999). Do Carmo et al. (2004) identified two species in their study, Wolburgiopsis plastica ( Musacchio, 1970) , which is similar to Wolburgiopsis magnafossa sp. nov., but differs from it by having an almost straight dorsal margin along its entire length and a more pronounced concave ventral margin and Wolburgiopsis chinamuertensis ( Musacchio, 1970) , a species that has an ornamented carapace with tubercles (three dorsal and two ventrolateral) joined together by a crest that expands in the ventral region, which distinguishes it from the new species. Dias-Brito et al. (2001) and Gobbo & Bertini (2023) identify the species Wolburgiopsis neocretacica ( Bertels, 1972) , which has a completely reticulated carapace (composed of fine muri) and an almost straight dorsal margin along its entire length and Wolburgiopsis vicinalis Uliana & Musacchio, 1978 , which has a subelliptical lateral outline. These features distinguish them from the new species here presented.