Petasobairdia collini Forel, 2011

Forel, Marie-Béatrice & Crasquin, Sylvie, 2011, In the aftermath of Permian-Triassic boundary mass-extinction: new ostracod (Crustacea) genus and species from South Tibet, Geodiversitas 33 (2), pp. 247-263 : 253-254

Petasobairdia collini Forel n. sp. ( Fig. 4 I-M)

TYPE MATERIAL. — Holotype: one complete carapace (P6M2615; Fig. 4M ); paratype: one complete carapace (P6M2619; Fig. 4J ).

ETYMOLOGY. — Dedicated to Dr Pierre-Yves Collin, Université Pierre et Marie Curie, Paris.

MATERIAL EXAMINED. — 18 complete carapaces and 20 isolated valves.

DIMENSIONS. — L = 630-1140 µm; H = 350-700 µm. Holotype: L = 1030 µm; H = 680 µm. Paratype: L = 848 µm; H = 546 µm.

TYPE HORIZON. — Sample 06Ti30, unit VI, Tulong Formation, Early Anisian, Middle Triassic.

TYPE LOCALITY. — Tulong section, Southern Tibet .

OCCURRENCE. — Tulong section, Southern Tibet . Samples 06Ti21, 06Ti25, 06Ti30, 06Ti32, 06Ti33, Tulong Formation, units V and VI, Spathian-Anisian, Early- Middle Triassic.

DIAGNOSIS. — A species of Petasobairdia with slight dorsal blade at LV, PB with very small radius of curvature and fingerprint ornamentation of fine ribs.

DESCRIPTION

RV: PDB, DB and ADB straight; DB quite horizontal compared with VB; AB with medium radius of curvature, maximum of curvature at mid-H; VB nearly straight to gently concave; PB with very small radius of curvature and maximum of curvature located at mid H;

LV: dorsal and ventral parts regularly arched; DB being more or less one third of length; presence of a dorsal blade.

Carapace laterally compressed at AB, AVB, PVB and PB; LV overlaps RV on dorsal and ventral margins with maximum on DB; carapace ornamented by a very fine reticulation organized in fingerprint of fine ribs parallel to margins.

REMARKS

Petasobairdia collini Forel n. sp. is close to two Late Permian species from South China. Petasobairdia nantongensis Chen, 1982 (in Chen & Shi 1982) has a shorter VB, overlap less important on ADB and PDB, AB and PB are smaller. Petasobairdia subnantongensis Chen, 1987 (in Shi & Chen 1987) has a longer DB particularly on LV and has a ventral “blade”.

Figures

FIG. 4. — Specimens from Tulong section (Tibet), stored at the Pierre et Marie Curie University Collections (Paris, France): A, Bairdia fengshanensis Crasquin-Soleau, 2006, right lateral view of a complete carapace (P6M2608); B, Bairdia sp. C, right lateral view of a complete carapace (P6M2609);C, Acratia? sp.B, right lateral view of a complete carapace (P6M2610);D, Bairdia anisicaforma Monostori, 1994, right lateral view of a complete carapace (P6M2611); E, Bairdia sp. F, right lateral view of a complete carapace (P6M2612);