Pattersoncypris minima Almeida-Lima & Piovesan, 2020

Almeida-Lima, Débora Soares De, Piovesan, Enelise Katia, Sayão, Juliana Manso & Lima, Flaviana Jorge De, 2020, Description and ontogeny of Pattersoncypris minima sp. nov. (Crustacea Ostracoda), Araripe Basin, Northeast Brazil, Zootaxa 4851 (1), pp. 171-179 : 174-176

Pattersoncypris minima Almeida-Lima & Piovesan sp. nov.

( Fig. 4 A–R)

ZooBank-link: urn:lsid:zoobank.org:pub:D609D813-B9CB-4284-ADBC-98246162332E

Etymology: In reference to the small size.

Type-locality: Santana do Cariri Municipality, Ceará State, Northeast Brazil.

Type-horizon: Outcrop sample, coordinates 07º11’32”S– 39º42’52”W. Aptian. Romualdo Formation, Araripe Basin.

Material: 722 carapaces (92 adults; 630 juveniles).

Holotype: LMA-00020, Adult L: 0.49 mm, H: 0.29 mm, W: 0.24 mm ( Fig. 4 : A-B).

Paratypes: LMA-00021, A-1 L: 0.41 mm, H: 0.26 mm. W: 0.17 mm; LMA-00022, A-2 L: 0.34 mm, H: 0.20 mm, W: 0.16 mm; LMA-00023, A-3 L: 0.29 mm, H: 0.18 mm, W: 0.14 mm; LMA-00024, A-4 L: 0.26 mm, H: 0.16 mm, W: 0.13 mm; LMA-00025, A-5 L: 0.23 mm, H: 0.14 mm, W: 0.12 mm; LMA-00026, A-6 L: 0.21 mm, H: 0.14 mm, W: 0.10 mm; LMA-00027, A-7 L: 0.18 mm, H: 0.12 mm, W: 0.09 mm; LMA-00028, A-8 L: 0.15 mm, H: 0,11 mm, W: 0.07 mm ( Fig. 4 : C-R).

Repository: Collection from Laboratório de Micropaleontologia Aplicada [Applied Micropaleontology Laboratory] (LMA) from UFPE, Recife, Brazil (Av. Da Arquitetura Cidade Universitária, Recife PE, CEP: 50740-540)

Diagnosis: A small-shelled species of Pattersoncypris , suboval in lateral view, hump barely pronounced. LV overlapping the RV along the anterodorsal and ventral margins, except in the oral region.

Description: Carapace small, suboval in lateral view; ellipsoid in dorsal view. Ventral margin straight; dorsal margin slightly concave, steep posteriorly. Anterior margin broadly rounded; posterior margin infracurvate (sensu Lüttig 1962). Greater length at mid-height, greater height and greater width in the median region. LV larger than RV, overlapping along anterodorsal, anterior and almost all the ventral margins, except for the anteroventral portion. Carapace smooth. Sexual dimorphism and internal characters not observed. The instars A-2 to A-7 have a more triangular lateral outline and from A-1 to A-8 a symmetrical dorsal view.

Remarks: Pattersoncypris minima sp. nov. differs from other species of the genus mainly in the size, by being significantly smaller. This new species was proposed based on the occurrence of complete ontogenetic series, which supports the hypothesis that it is a new taxon instead of an instar of a previously described species. Moreover, morphological differences are noticed when P. minima sp. nov. is compared to other species of the genus. Compared to P. crepata ( Do Carmo et al., 2013) from the Aptian-Albian of Araripe and Potiguar basins, Brazil, the new species is distinguished by the absence of the prominent hump, the less rounded posterior margin and the positions of greatest height and width. P. alta ( Antonietto et al., 2012) from the Aptian-Albian of Araripe, Pará-Maranhão and Potiguar basins, Brazil, is highest in the anteromedian region, its posterior portion is slightly supracurvate, and it is ornamented. P. minima sp. nov. differs from P. salitrensis ( Krömmelbein & Weber, 1971) recorded in Aptian-Albian of Araripe and São Luís-Grajaú basins, Brazil, by the absence of the dorsal pronounced hump. Additionally, in P. salitrensis the greatest width is positioned at the postero-median region and presents a more subtriangular outline in lateral view, when compared with the new species presented here. Pattersoncypris sinuata ( Krömmelbein & Weber, 1971) from the Aptian-Albian of Araripe, Potiguar and Sergipe-Alagoas basins, Brazil, differs from P. minima sp. nov. by its dorsal hump and its bigger size. Pattersoncypris micropapillosa Bate, 1972 , from the Aptian-Albian of Araripe, Potiguar, Cedro and Jatobá basins, Brazil, features a pronounced dorsal hump, an equicurvate posterior margin and a typical carapace ornamentation, thus distinguishing it from P. minima sp. nov.

Stratigraphic distribution: Brazil, Araripe Basin, Romualdo Formation, Aptian.

Figures

FIGURE 4. (A–R) Pattersoncypris minima sp. nov. (A–B) LMA-00020, holotype, C, right and dorsal views; (C–D) LMA- 00021, paratype A-1, C, right and dorsal views; (E–F) LMA-00022, paratype A-2, C, right and dorsal views; (G–H) LMA- 00023, paratype A-3, C, right and dorsal views; (I–J) LMA-00024, paratype A-4, C, right and dorsal views; (K–L) LMA-00025, paratype A-5, C, right and dorsal views; (M–N) LMA-00026, paratype A-6, C, right and dorsal views; (O–P) LMA-00027, paratype A-7, C, right and dorsal views; (Q–R) LMA-00028, paratype A-8, C, right and dorsal views.