Orthobairdia jeanlouisi, Forel, 2012

Forel, Marie-Béatrice, 2012, Ostracods (Crustacea) associated with microbialites across the Permian-Triassic boundary in Dajiang (Guizhou Province, South China), European Journal of Taxonomy 19, pp. 1-34 : 20-21

Orthobairdia jeanlouisi sp. nov.

Fig. 11 T-X

Diagnosis

Species of Orthobairdia with preplete carapace, sharp angles between PDB, DB and ADB (~150°) and large radius of curvature at AB and PB.

Etymology

Personal dedication to Jean-Louis Forel.

Material examined

Holotype

One carapace ( Fig. 11T ), sample 05PAJ43, collection number P6M3077.

Paratype

One carapace ( Fig. 11V ), sample 05PAJ43, collection number P6M3079.

Other material

13 carapaces, several fragments. The species is known from its type locality only.

Type locality

Daye Formation (samples 05PAJ43-45), Dajiang section (25°33’56’’N- 106°39’41’’E), Guizhou Province, South China, Griesbachian, Early Triassic.

Measurements ( Fig. 12 )

L = 422 – 918 μm; H = 250 – 546 μm; H/L = 0.50 – 0.75.

Description

Carapace subtriangular in lateral view; surface smooth; LV overlapping RV all around the carapace, dorsal overlap thicker; angles between PDB, DB and ADB ~ 150° at both valves; PDB straight with steep backward slope; DB and ADB long, together ~ 60% of Lmax; DB straight at both valves, bent backward; ADB straight at LV, slightly convex at RV, less steep than PDB; VB concave; AVB long and gently rounded; PVB shorter, gently rounded; AB subtriangular, with large radius of convexity, maximum located above mid-H; PB subtriangular, sharply pointed, with narrower but still large radius of curvature, maximum located slightly below mid-H; carapace preplete; Lmax located at mid-H or slightly below.

Remarks

Orthobairdia jeanlouisi sp. nov. can be compared to Orthobairdia texana (Harlton, 1927) sensu Shi & Chen, 2002 from the Late Permian of Heshan and Yishen, Guangxi Province, South China ( Shi & Chen 2002) but here the species is shorter, posterior maximum of convexity is clearly situated more dorsally, anterior part is more elongated, ADB steeper. Orthobairdia jeanlouisi sp. nov. is also close to Orthobairdia exilimarginata Chen, 1987 from the Changhsingian (Late Permian) of the Meishan section, Zhejiang Province, South China ( Shi & Chen 1987), but the new species is less elongated and its DB is shorter and bent backward. This species can also be related to Orthobairdia meishanensis Chen, 1987 from the Permian of the Meishan section, Zhejiang Province, South China ( Shi & Chen 1987), however, Orthobairdia jeanlouisi sp. nov. has the PB located higher, a shorter DB and a less steep PDB.

Figures

Fig. 11. Ostracods from the Dajiang section, South China. — A–B. Bairdiacypris sp. 8. A. Carapace, right lateral view, P6M3058. B. Carapace, right lateral view, P6M3059. — C–D. Bairdiacypris sp. 9. C. Carapace, right lateral view, P6M3060. D. Carapace, right lateral view, P6M3061. — E–F. Bythocypris? sp. 1. E. Carapace, right lateral view, P6M3062. F. Carapace, right lateral view, P6M3063. — G. Bythocypris sp. 2, carapace, right lateral view, P6M3064. — H. Bythocypris? sp. 3, carapace, right lateral view, P6M3065. — I. Fabalicypris parva Wang, 1978, carapace, right lateral view, P6M3066. — J–N. Liuzhinia antalyaensis Crasquin–Soleau, 2004. J. Carapace, right lateral view, P6M3067. K. Carapace, left lateral view, P6M3068. L. Carapace, left lateral view, P6M3069. M. Carapace, right lateral view, P6M3070. N. Carapace, right lateral view, P6M3071. — O.?Liuzhinia antalyaensis Crasquin– Soleau, 2004, carapace, left lateral view, P6M3072. — P. Liuzhinia sp., carapace, right lateral view, P6M3073. — Q–S. Liuzhinia sp. 2. Q. Carapace, right lateral view, P6M3074. R. Carapace, left lateral view, P6M3075. S. Carapace, right lateral view, P6M3076. — T–X. Orthobairdia jeanlouisi sp. nov. T. Holotype, carapace, right lateral view, P6M3077. U. Carapace, left lateral view, P6M3078. V. Paratype, carapace, dorsal view, P6M3079. W. Carapace, right lateral view, P6M3080. X. Carapace, right lateral view, P6M3081. – Scale = 100 µm.

Fig. 12. Height/length diagram of Orthobairdia jeanlouisi sp. nov.