Histriabairdia, Forel & Grădinaru, 2020

Forel, Marie-Béatrice & Grădinaru, Eugen, 2020, Rhaetian (Late Triassic) ostracods (Crustacea, Ostracoda) from the offshore prolongation of the North Dobrogean Orogen into the Romanian Black Sea shelf, European Journal of Taxonomy 727, pp. 1-83 : 37

Histriabairdia gen. nov. sp. 1

Fig. 8 P–R

Material examined

ROMANIA • 1 RV; Black Sea , Romanian Continental Shelf , borehole 817LV, sample CM31C; Rhaetian, Upper Triassic; MNHN.F. F63240 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63241 .

Dimensions

RV: L = 570–800 µm; H = 275–570 µm; H/L = 0.48–0.54.

LV: L = 575 µm; H = 292 µm; H/L = 0.51.

Occurrence

Romanian Continental Shelf, Black Sea, Rhaetian, Upper Triassic (this paper).

Remarks

The two specimens of Histriabairdia gen. nov. sp. 1 have different dimensions and correspond to distinct ontogenetic stages. This species is characterized by its relatively slender carapace, long and straight to convex ADB and reticulate surface. The reticulate surface of Histriabairdia gen. nov. sp. 1 is reminiscent of that of Histriabairdia gemmellaroi (Crasquin in Crasquin et al., 2018) gen. et comb. nov. from the Late Carnian of Sicily ( Crasquin et al. 2018). However, Histriabairdia gemmellaroi gen. et comb. nov. is comparatively shorter (H/L = 0.61) with ADB shorter and concave, postero-dorsal angulation less expressed at both valves and small tubercles developed in the antero-dorsal and dorsal areas of the surface. Histriabairdia gen. nov. sp. 1 is very close to Histriabairdia tuningensis ( Beher, 2004) gen. et comb. nov. from the Sinemurian, Early Jurassic, of Germany and Switzerland ( Beher 2004), as shown by its similar elongation and long, straight ADB. However, the marginal compressions along AVB and PVB are narrower, anterior maximum of curvature is located lower and the surface is punctate rather than reticulate.

Figures

Fig. 8 (opposite page). SEM micrographs of ostracods from borehole 817 Lebăda Vest, drill core CM31, western portion of Black Sea shelf, Rhaetian, Late Triassic. All specimens are housed in the collections of the Muséum national d’histoire naturelle, Paris, France (MNHN). A. Fabalicypris cf. triassica Bolz, 1971, external view of a left valve, sample CM31A (MNHN.F.F63228). B. Hiatobairdia sp. 1, right lateral view of a carapace, sample CM31B (MNHN.F.F63229). C–E. Hiatobairdia sp. 2. C. Right lateral view of a carapace, sample CM31B (MNHN.F.F63230). D. Same specimen, dorsal view. E. External view of a left valve, sample CM31B (MNHN.F.F63231). F. Hiatobairdia sp. 3, right lateral view of a carapace, sample CM31B (MNHN.F.F63232).G–O. Histriabairdia pontuseuxinusensis Forel gen. et sp. nov. G. External view of a left valve, sample CM31C (MNHN.F.F63233). H. Right lateral view of a complete carapace, sample CM31C (MNHN.F.F63234). I. External view of a right valve, sample CM31C (MNHN.F.F63235). J. Right lateral view of a complete carapace, sample CM31C (MNHN.F.F63236). K. External view of a left valve, sample CM31C (MNHN.F.F63237). L. Holotype, right lateral view of a complete carapace, sample CM31B (MNHN.F.F63238). M. Same specimen, dorsal view. N. Paratype, external view of a left valve, sample CM31B (MNHN.F.F63239). O. Same specimen, inner view. P–R. Histriabairdia gen nov. sp. 1. P. External view of a right valve, sample CM31C (MNHN.F.F63240). Q. Right lateral view of a complete carapace, sample CM31C (MNHN.F.F63241). R. Same specimen, dorsal view. S–U. Histriabairdia gen. nov. sp. 2. S. Right lateral view of a carapace broken anteriorly and posteriorly, sample CM31C (MNHN.F.F63242). T. Right lateral view of a carapace broken anteriorly and posteriorly, sample CM31C (MNHN.F.F63243). U. External view of a broken right valve, sample CM31C (MNHN.F.F63244). Scale bars: 100 µm.