Timiriasevia aratra Almeida-Lima, Guzmán, Maia, Jesus & Piovesan, 2024, sp. nov.

Timiriasevia aratra sp. nov. (Fig. 4K–M; Fig. 5C)

2022 Timiriasevia? sp.—Guzmán et al., p. 21, fig. 13P–R.

2023 Timiriasevia? sp.—Guzmán et al., p. 27, fig. 7O–P.

Zoobank-link: urn:lsid:zoobank.org:act: DD8D7EEE-5537-4A24-8425-B29D637F2590

Holotype: LMA-00319, L: 0.40 mm, H: 0.24 mm, W: 0.22 mm.

Material: One carapace.

Derivation of name: In reference to the outline of the anteroventral region, with morphology similar to a “plough” or, in latin, aratra.

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

Type horizon: Crato Formation, Santana Group, Araripe Basin, Brazil. 2-AR-SR-1A-CE well core sample, depth interval 121.28–121.31 m.

Stratigraphic and geographic distribution: Aptian:Crato Formation,Araripe Basin, Nova Olinda Municipality, Ceará State, Brazil (Guzmán et al. 2022, 2023; this study).

Diagnosis: A Timiriasevia species with reticulated carapace, sub-trapezoidal in lateral view and sub-oval in dorsal view with the anteroventral region showing a morphology like a “plough”.

Description: Carapace sub-trapezoidal in lateral view; sub-oval in dorsal view. Dorsal margin slightly convex to straight, in front of the anterior cardinal angle a straight slope on the anterodorsal region; ventral margin convex at the posterior region and middle third and concave at the anteroventral region; posterior margin weakly rounded, almost straight and infracurvate.The anteroventral region shows a morphology similar to a well-developed “plough”. Greater height at mid-length, greater length just below mid-height and greater width at the median region. LV overlapping RV along the dorsal, anterodorsal and posterodorsal margins. Surface ornamented with sub-rounded to sub-hexagonal reticulation, thick muri, shallow fossae, punctuated sola more densely at the dorsomedian region, a few intramural pore canals scattered throughout the carapace, and at the ventral region elongated reticulations, forming subparallel rows. Cardinal angles obtuse. Sexual dimorphism and internal features not observed.

Remarks: The new species Timiriasevia aratra has an anteroventral region described as a “plough” morphology, this structure resembling the general shape described for Aratrocypris Whatley et al., 1985, although in this marine genus, it is more blade-like than in the species described in this paper. This is the first species described for Timiriasevia in the Araripe Basin, however, the occurrence of the genus has already been reported for the Sanfrasciscana Basin, where the species Timiriasevia sanfranciscanensis Leite et al., 2018 was recovered in samples from the Quiricó Formation, Lower Cretaceous (Leite et al. 2018) and differs from Timiriasevia aratra sp. nov. mainly in its oval to rounded outline in lateral view, it has punctuated ornamentation and does not have the “plough” structure in the anteroventral region.