Pattersoncypris trapezium, Filho & Ceolin & Fauth & Lima, 2023

Filho, Marcos Antonio Batista Dos Santos, Ceolin, Daiane, Fauth, Gerson & Lima, Francisco Henrique De Oliveira, 2023, Ostracods from the Barbalha and Crato formations, Aptian of the Araripe Basin, northeast Brazil, Zootaxa 5319 (3), pp. 332-350 : 343

Pattersoncypris trapezium sp. nov.

Fig 5.1A–O

Etymology: From the Latin “ trapezium ”, in reference to the sub-trapezoidal lateral outline that is characteristic of this species.

Material: 222 specimens.

Figured specimens: ULVG-14198, adult; ULVG-14199, A-1; ULVG-14200, A-1; ULVG-14201, A-2; ULVG-14202, A-3; ULVG-14203, A-4; ULVG-14204, A-5; ULVG-14205, A-6.

Dimensions:

Diagnosis: A species of Pattersoncypris with a distinctly sub-trapezoidal to sub-triangular outline that is less inflated in dorsal view when compared to other Pattersoncypris species.

Description: Medium size carapace of sub-trapezoidal to sub-triangular outline in lateral view and a fusiform outline in dorsal view. Anterior margin broadly rounded, posterior margin rounded and infracurvate. Ventral margin sinuous with a concavity between its mid-length and posterior third, dorsal margin convex.

LV larger than RV, visibly overlapping along the entire carapace margin. RV has a slight concavity in the antero-dorsal margin, typical of the genus. Anterior cardinal angle obtuse, gently sloping towards the anterior margin. Greatest height slightly anterior, greatest length just below mid-height, greatest width at mid-length.

Carapace surface smooth. Sexual dimorphism not observed. Juveniles greatly resemble the adults, except for their smaller size.

No internal characteristics were observed, as only tightly closed carapaces were recovered.

Remarks: This species was attributed to genus Pattersoncypris due to the slight concavity present in the antero-dorsal margin of the right valve, creating the characteristic hump of the genus. This species differs from other Pattersoncypris species by being more elongated in lateral view, having a more distinctly sub-trapezoidal to sub-triangular lateral outline, and being less inflated in dorsal view when compared to other Pattersoncypris species. This species somewhat resembles Pattersoncypris crepata ( Do Carmo, Coimbra, Whatley, Antonietto & Citon, 2013) , with both being fusiform in dorsal view and both having their dorsal margin sloping towards the posterior margin. However, in P. trapezium sp. nov., the angle in which the dorsal margin slopes is more pronounced, and the posterior margin is more infracurvate than that of P. crepata . This species has some similarities to Candonopsis ? alagoensis Tomé, Lima Filho and Neumann, 2014 , but it differs due to the dorsal margin of the adult instar sloping towards the posterior margin instead of it being straight, and by its fusiform outline in dorsal view compared to the more ovoid outline of C.? alagoensis .

Occurrences: 1PS-06-CE: AM-10 (108.06 m), AM-11 (106.62 m), AM-12 (106.05 m), AM-14 (103.6 m), AM-17 (99.8 m), AM-18 (99.3 m), AM-23 (92.4 m), AM-41 (60.5 m), AM-51 (12. 6 m), AM-54 (3.3 m).

Stratigraphic and geographic distribution: Aptian, Barbalha Formation, Araripe Basin, Brazil (this study).

Figures

FIGURE 5. Plate illustrating the ostracod species recovered from the Barbalha and Crato formations, Araripe Basin. 1. Pattersoncypris trapezium sp. nov. A–B, ULVG-14198, adult, holotype, RLV, LLV; C, ULVG-14199, A-1, paratype, DV; D– E, ULVG-14200, A-1, paratype, RLV and DV; F–G, ULVG-14201, A-2, paratype, RLV and DV; H–I, ULVG-14202, A-3, paratype, RLV and DV; J–K, ULVG-14203, A-4, paratype, RLV and DV; L–M, ULVG-14204, A-5, paratype, RLV and DV; N–O, ULVG-14205, A-6, paratype, RLV and DV. 2. Looneyellopsis? sagittensis sp. nov. ULVG-14212, adult.A—RLV, B—DV. 3. Theriosynoecum silvai (Silva, 1978). A—ULVG-13487, adult male, RLV, B–C, ULVG-13683, adult female, RLV and DV.