Dicrorygma (Orthorygma?) dimorpha Weiss, 1996, 1962

Tomé, Maria Emilia, Araripe, Rilda, Oliveira, David, Barreto, Alcina, Prado, Ludmila, Pedrosa, Flavia, Pereira, Priscilla, Nascimento, Luiz Ricardo & Ng, Christiano, 2022, Early Cretaceous Ostracoda (Crustacea) from south-centralAraripe Basin, Brazil with descriptions of seven new species, Zootaxa 5159 (4), pp. 535-557 : 548-549

Dicrorygma (Orthorygma?) dimorpha Weiss, 1996

Fig. 5G–I

1990 Ostracoda gen. et sp. indet,—Zihrul: 89, Taf. 6, Fig. 60.

1996 Dicrorygma ( Dicrorygma ?) n. sp. a—Weiss: 119, Abb. 10 Fig. 7–8; Tar. 1, Fig. 10–15; Taf. 2, Fig. 8.

2022 Dicrorygma ( Orthorygma ?) dimorpha —Araripe et al., p 7, fig. 5 (6a–b).

Illustrated material. Adult carapace, Nº. DGEO-CTG-UFPE-1524 ( Fig. 5 G–I )

Dimension. Nº. DGEO-CTG-UFPE-1524 ( Fig. 5 G–I ); L= (LV) 0.426 / ( RV) 0.396 mm, H= 0.233 mm, and W= 0.213 mm.

Comparison. It was not possible to compare with reference collection materials. Dicrorygma ( Orthorygma ?) dimorpha was compared to illustrations in Michael Weiss (1996); both species are very small, with a smooth surface and subtriangular carapace. The posterior end is sharp, joining the small caudal process in lateral view. The dorsal view is very similar, but the caudal process is smaller in the specimen found. We also compared the species studied with the illustrations of the species Parataxodonta inornate Kaye 1965 , but they are different in the dorsal view.

Occurrence and associated fauna. It was recorded in the Santo Antônio section, exclusively at following depth (from base to top) of 5.65 m. Dicrorygma ( Orthorygma ?) dimorpha occurs with D. grandiensis and Dicrorygma cf. minuta, which occurs throughout most of the section.

Observations. Dicrorygma ( Orthorygma ?) dimorpha and Dicrorygma cf. minuta comprise the first record of this genus in the Araripe Basin (Aptian). Weiss (1996), characterized the sexual dimorphism for this species, and the specimen found is similar to the male described by this author. It is worth pointing out that it is a very small species, and like the species belonging to the genus Perissocytheridea Stephenson, 1938 , they are only recovered in the smallest sieves and in the sorting process in the finest granulometry, thus requiring greater attention and persistence to recover.

Stratigraphic distribution. NW-German Kimmeridgian, Upper section (sample 5/7a), Lower Kimmeridge (ostracod-zone 10, Kimmeridgian) ( Babinot et al. 2007). Brazil, Araripe Basin, Romualdo Formation, upper Aptian (this work).

Figures

FIGURE 5. (A–C) Perissocytheridea florisdorsalis sp. nov., nº DGEO-CTG-UFPE-1521, depth 4.05m, (A) right side view, (B) left side view, (C) dorsal view. (D–F) Dicrorygma cf. minuta (Kaye, 1963); (D and E) nº DGEO-CTG-UFPE-1522, depth 3.1m, (D) right side view, (E) left side view; (F) nº DGEO-CTG-UFPE-1523, depth 0.3m, dorsal view. (G–I) Dicrorygma (Orthorygma?) dimorpha Michael Weiss 1996, nº DGEO-CTG-UFPE-1524, depth 5.65m; (G) vista dorsal, (H) right side view, (I) left side view. (J–L) Microceratina retangularis sp. nov., nº DGEO-CTG-UFPE-1525, depth 3.10m; (J) right side view, (K) left side view, (L) dorsal view. (M–O) Alicenula cf. leguminella (Forbes in Lyell 1855), depth 0.3m; (M) dorsal view; (N) left side view; (O) nº DGEO-CTG-UFPE-1526, right side view. (P–R) Theriosynoecum cf. quadrinodosum Krömmelbein & Weber, 1971; nº DGEO-CTG-UFPE-1528, depth 3.1m; (P) dorsal view; (Q) right side view, (R) left side view. The depth reference is from the bottom to the top. Scale bars are equivalent to 100µm.