Zonocypris dorsoconvexa, Piovesan & Melo & Cabral & Guzmán, 2022

Piovesan, Enelise Katia, Melo, Gustavo Dias, Cabral, Maria Cristina & Guzmán, Juliana, 2022, New Early Cretaceous species of Zonocypris G. W. Müller, 1898 (Crustacea: Ostracoda) from the Crato Formation, Brazil, Zootaxa 5141 (6), pp. 581-591 : 586-587

Zonocypris dorsoconvexa sp. nov.

( Fig. 3 )

ZooBank-link: urn:lsid:zoobank.org:act:F2A2EDDA-1D45-4290-8FB4-89C3D10B00C2

Etymology: The specific name is derived from Latin convexus (meaning convex) and refers to the dorsal outline.

Type-locality: Crato Municipality, Ceará State, Northeast Brazil.

Type-horizon: Late Aptian. Crato Formation, Santana Group , Araripe Basin, Brazil. 2-AR-SR-1A-CE well core (coordinates: 7°17’29.88” S and 39°23’34.84” W) sample, depth interval 134.00– 134.05 m .

Material: three carapaces (two adults; one juvenile).

Holotype: LMA-00333 , adult male; L: 0.42 mm, H: 0.24 mm, W: 0.27 mm ( Figs 3A–D ). 2-AR-SR-1A-CE well core sample, depth interval 134.00– 134.05 m.

Paratypes: LMA-00306, female, L: 0.41 mm, H: 0.27 mm, W: 0.27 mm ( Fig. 3E ), 2-AR-SR-1A-CE well core sample, depth interval 134.00– 134.05 m. LMA-00334, C, juvenile, L: 0.33 mm, H: 0.21 mm. W: 0.22 mm ( Figs 3F–H ), 2-AR-SR-1A-CE well core sample, depth interval 124.55–124.58 m.

Repository: Collection from Laboratório de Micropaleontologia Aplicada [Applied Micropaleontology Laboratory] ( LMA) from UFPE, Recife, Brazil.

Diagnosis: A species of Zonocypris with a small, sub-rectangular to sub-ovate carapace in lateral view, with the typical ornamentation of concentric ribs almost horizontal in the central and ventral areas; intercostal areas smooth and slightly thicker than the ribs.

Description: Small carapace, sub-rectangular to sub-ovate in lateral view. Carapace ovoid, in dorsal and ventral views, posteriorly broadened, anteriorly acuminate. LV larger than RV, uniformly overlapping it along all margins, except in the ventral margin. Greatest height at mid-length in females, in front of middle in males. Greatest length below mid-height. Greatest width in posterior third. Dorsal margin convex, ventral margin almost straight; anterior margin sub-rounded, posterior margin truncated and projected downwards. Sexual dimorphism pronounced, with females higher, less elongated, more inflated and dorsally more convex than males.

Concentric ribs parallel to margins on carapace periphery. In central region of carapace, ribs more triangular shape, being almost horizontal in ventral zone. Intercostal areas smooth and slightly thicker than ribs. On ribs, or adjacent to them, simple normal pore canals (type A’ of Puri & Dickau 1969 and A1 of Danielopol et al. 2018) are abundant, some of which seemingly with marginal lip (type A” of Puri & Dickau 1969 and A2 of Danielopol et al. 2018), bad preservation of specimens not allowing for more detailed description ( Fig. 3H ). Marginal pore canals also present, more densely arranged ( Fig. 3D ).

Internal features not seen.

Remarks: This species differs from the previous Z onocypris berthoui sp. nov. in general outline, mainly the dorsal one, less robust ribs and the posterior position of greatest width. Zonocypris dorsoconvexa sp. nov. resembles Zonocypris sp. 1 from the Early Aptian of Portugal ( Cabral 1995), but the latter has a straighter ventral margin and a more marked posterior end; the ornamentation is also slightly different with the ribs more inclined in the ventral area. The species Zonocypris sp. , recorded from the Early Cretaceous from Argentina ( Carignano et al. 2017), differs from Zonocypris dorsoconvexa sp. nov. in the more rounded anterior margin, and position of the greatest width in the posterior quarter of the carapace.

Occurrence: Late Aptian, Crato Formation, Araripe Basin, Crato Municipality, Ceará State, Brazil (this study).

Figures

FIGURE 3. Zonocypris dorsoconvexa sp. nov. (A–D), LMA-00333, holotype, male carapace, (A) general ventral view, (B) general dorsal view, (C) general right view, (D) ventral view, anterior part, marginal pore canals; (E) LMA-00306, paratype 1, female carapace, general left view; (F–H) LMA-00334, paratype 2, juvenile carapace, (F) general right view, (G) general left view, (H) ventral view, anterior part, simple normal pore canals (types A’ and A”? of Puri & Dickau 1969 and A1 and A2? of Danielopol et al. 2018).