Triassicindivisia tibetinella Crasquin, 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 : 258-259

Triassicindivisia tibetinella Crasquin n. sp. ( Fig. 5 J-M)

TYPE MATERIAL. — Holotype: one complete carapace (P6M2631; Fig. 5J ); paratype: one complete carapace (P6M2632; Fig. 5K ).

ETYMOLOGY. — From Tibet , type locality.

MATERIAL EXAMINED. — 8 complete carapaces.

DIMENSIONS. — L = 460-825 µm; H = 250-420 µm. Holotype: L = 460 µm; H = 253 µm. Paratype: L = 714 µm; H = 385 µm.

TYPE HORIZON. — Sample 06Ti35, Unit VI, Tulong Formation, Anisian, Middle Triassic.

TYPE LOCALITY. — Tulong section, Southern Tibet .

OCCURRENCE. — Tulong section, Southern Tibet . Samples 06Ti07, 06Ti20, 06Ti31, 06Ti33 and 06Ti35, units III to VI, Smithian-Anisian, Early-Middle Triassic.

DIAGNOSIS. — A species of Triassicindivisia n. gen. with elongated carapace (H/L = 0.52), AB and PB have small radius of curvature.

DESCRIPTION

Carapace with long straight to gently convex DB; cardinal angles clearly expressed, equivalent and very obtuse (≈ 145 to 150°); AB with small radius of curvature, maximum of convexity located at mid-H or a little below; VB regularly curved with maximum of convexity (H maximum) in front of mid-L; BP with small radius of curvature, maximum located high at upper ⅓ of H; free margins compressed laterally; RV overlaps LV all along free margins; surface smooth, no primary nor secondary ornamentation; H/L = 0.52.

REMARKS

This new genus and the type species are reminiscent of Paraparchitoidea by the absence of primary and secondary ornamentation. Internal characters, e.g., muscle scars, were not observed so the superfamily is uncertain for the time being.

of a complete carapace (P6M2643); I, Microcheilinella sp. B., right lateral view of a broken carapace (P6M2630); J, Acratia goemoeryi Kozur,1970 ,right lateral view of a complete carapace (P6M2644); K, Urobairdia? sp.,right lateral view of a broken carapace (P6M2645); L, Bairdia cf. cassiana rotundidorsata Monostori, 1995, right lateral view of a complete carapace (P6M2646); M, Bairdia sp. E, right lateral view of a complete carapace (P6M2647). Scale bars: 100 μm.

Figures

FIG. 5. — Specimens from Tulong section (Tibet), stored at the Pierre et Marie Curie University Collections (Paris, France): A, Bairdia balatonica Méhes, 1911, right lateral view of a complete carapace (P6M2621); B, Acratia sp. A., right lateral view of a complete carapace (P6M2622); C, Hungarella? sp., right lateral view of right valve (P6M2623); D, E, Bairdiacypris anisica Kozur, 1971; D, right