Macunhaella posteroaltis, Almeida-Lima & Guzmán & Maia & Jesus & Piovesan, 2024

Almeida-Lima, Débora Soares De, Guzmán, Juliana, Maia, Renata Juliana Arruda, Jesus, Ariany De & Piovesan, Enelise Katia, 2024, New Non-Marine Ostracod Genera And Species Of Aptian Age From Araripe Basin, Northeast Brazil, Zootaxa 5496 (3), pp. 401-416 : 408-409

Macunhaella posteroaltis sp. nov. ( Fig. 4G–J ; Fig. 5B )

2022 Gen. et. sp. indet. 3—Guzmán et al., p.16, fig. 9M–P.

2023 Gen et. sp. indet. 3—Guzmán et al., p. 27, fig. 7E–F.

Zoobank-link: urn:lsid:zoobank.org:act:EF74575E-5FE5-4F14-9AA5-1D5E1B134DAA

Holotype: LMA-00042, L: 0.62 mm, H: 0.32 mm, W: 0.19 mm.

Material: Seven carapaces.

Derivation of name: In reference to the highest region.

Type locality: Top of the Barbalha Formation to the base of the Crato Formation, Santana Group, Araripe Basin, Ceará State, Brazil.

Type horizon: Top of the Barbalha Formation to the base of the Crato Formation, Santana Group, Araripe Basin, Brazil. Outcrop samples 3BAr06c–e, (Batateira River).

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

Diagnosis: Sub-rectangular outline in lateral view and fusiform in dorsal view, without ornamentation. RV overlapping LV at the anteroventral and posterodorsal regions.

Description: Carapace smooth and sub-rectangular in lateral view; fusiform in dorsal view. Ventral margin straight; dorsal margin straight and slightly sloping towards the anterior region; posterior margin rounded and equicurvated; anterior margin sub-rounded and truncated. RV larger than LV, subtly overlapping at the anteroventral and posterodorsal regions. Greater height at posterior cardinal angle, greater length at mid-height and greater width at the median region. Anterior and posterior cardinal angles obtuse. Sexual dimorphism and internal features not observed.

Remarks: The Macunhaella posteroaltis sp. nov. shows a reverse overlap pattern, RV larger than LV. This type of overlap has already been observed in other species that also show a normal overlap pattern (VL larger than RV) and this behavior has been interpreted as ecophenotypic responses of individuals to environmental stress events (e.g. Bergue et al. 2011; Almeida-Lima et al. 2022). Although all the specimens recovered in the material analyzed have reversed valve overlap, this is not a reliable diagnostic feature for distinguishing species and should be observed with parsimony in future identifications, since Macunhaella posteroaltis could be showing this type of overlap in response to unidentified stress.

Figures

FIGURE 4. New taxa of Ostracoda. A–C (right view, left view and dorsal): Batecypris reticularis sp. nov. noded; D–F (left view, right view and dorsal): Batecypris reticularis sp. nov. unnoded; G–J (left view, right view, dorsal and detail of the muscle scars): Macunhaella posteroaltis sp. nov.; K–M (RV, left view and dorsal): Timiriasevia aratra sp. nov.; N–P (left view, right view and dorsal): Theriosynoecum favus sp. nov.; Q–S (right view, left view and dorsal): Wolburgiopsis magnafossa sp. nov. Scale bar: 100 μm.

FIGURE 5. Detailed illustration of the outline and ornamentation of the new species. A (left view): Batecypris reticularis sp. nov. noded; B (right view): Macunhaella posteroaltis sp. nov.; C (right view): Timiriasevia aratra sp. nov.; D (right view): Theriosynoecum favus sp. nov.; E (left view): Wolburgiopsis magnafossa sp. nov. Scale bar: 100 μm.