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

Wolburgiopsis magnafossa sp. nov. (Fig. 4Q–S; Fig. 5E) Zoobank-link: urn:lsid:zoobank.org:act: D4B54EA7-84C0-4C28-B31E-B3BDD65134BF 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.