Bairdia fontainei Chitnarin, 2017

Chitnarin, Anisong, Crasquin, Sylvie, Forel, Marie-Béatrice & Tepnarong, Prachya, 2017, Ostracods (Crustacea) of the Early-Middle Permian (Cisarulian-Guadalupian) from Central Thailand (Indochina Block): Part II, Orders Podocopida, Platycopida and Myodocopida, Geodiversitas 39 (4), pp. 651-690 : 659-660

Bairdia fontainei Chitnarin , n. sp.

( Figs 3 G-H, K-L; 5)

Bairdia cf. piscariformis Chen in Chitnarin, Crasquin, Chonglakmani, Broutin, Grote & Thanee et al. 2008: 347, 349, fig. 6 (1-2). n. syn.

TYPE MATERIAL. — Holotype, one complete carapace (SUT-09- 2187; Fig. 3G ); paratypes, two complete carapaces (SUT-09-2182; Fig. 3H and SUT-09-2178; Fig. 3L ).

ETYMOLOGY. — In honour of Dr Henry Fontaine, France.

MATERIAL EXAMINED. — Ten complete carapaces.

DIMENSIONS. — H = 0.44-0.48 mm, L = 0.87-0.92 mm, H/L = 0.48- 0.53, Holotype: H = 0.55 mm, L = 1.02 mm; Paratype ( Fig. 3H ): H = 0.43, L = 0.87; Paratype ( Fig. 3L ): H = 0.44, L = 0.91 ( Fig. 5).

TYPE HORIZON. — Sample number 07LB05-5, Ta Kli section, Tak Fa Formation, Artinskian, Early Permian.

TYPE LOCALITY. — Ta Kli section (15°19’05’’N, 100°22’46’’E), Nakhon Sawan Province, Central Thailand.

OCCURRENCES. — Sample 02TH46-07, Bung Sam Phan section, Tak Fa Formation, ( Chitnarin et al. 2008), Phetchabun Province, Middle Permian , Central Thailand ; sample 07LB05-05, Ta Kli section, Tak Fa Formation , Nakhon Sawan Province, Middle Permian, Central Thailand ; sample 07 PB05-3 , Ban Nean Sawan I section, Phetchabun Province, Tak Fa Formation , Middle Permian, Central Thailand ; samples 07 PB04-2 and 07 PB04-5 , Nong Phai section, Pha Nok Khao Formation , Phetchabun Province, Early Permian, Central Thailand .

DIAGNOSIS. — Species of Bairdia with spindle-shape carapace and a ventral ridge along VB of RV, DB and VB nearly straight and of equal length, H maximum at mid-L, distinct overlap of LV on RV at ADB and PDB.

DESCRIPTION

Spindle shape carapace in lateral view; DB and VB nearly straight and of equal length; at RV, ADB straight and has an angle of 150° with DB, ADB of LV slightly convex; AB rounded with medium radius of curvature, maximum convexity located at mid H; AVB of both valves straight, angle between AVB and VB is 150°; VB of RV slightly concave, VB of LV slightly concave to nearly straight; PVB of both valves straight, angle between PVB and VB is 150°; PB tapering, maximum convexity located at mid H; PDB of both valves straight, angle between PDB and DB is about 135°; surface smooth; presence of a ventral ridge along VB of RV; greatest H in the median region; LV strongly overlaps RV at ADB, PDB and VB, slightly overlaps at both ends.

REMARKS

Bairdia fontainei Chitnarin , n. sp. includes the species identified as B. cf. piscariformis Chen, 1958 from the Middle Permian limestone in Phetchabun area ( Chitnarin et al. 2008). However, it can be differentiated from B. piscariformis Chen, 1958 from the Early Permian of South China ( Chen 1958: 245, pl. 4, figs 9-10) by the nearly straight DB and VB, the equal length of both valves, the straight AVB and PVB and the presence of ventral ridge on RV. B. fontainei Chitnarin , n. sp. is close to B. guadalupiana Hamilton, 1942 from the Middle Permian of Texas ( Hamilton 1942) in general outline but the anterior part of the latter species is more rounded and with larger radius of curvature.

Figures

FIG. 3. — Ostracods from Indochina Block, Central Thailand. All specimens are stored at the Suranaree University of Technology Collections (Nakhon Ratchasima,Thailand), numbers SUT-09-xxxx. All the specimens are represented by complete carapaces.A-D, Bairdia khaokanaensis Chitnarin,n. sp.; A, holotype, right lateral view, SUT-09-2223, sample 07PB03-3; B, paratype, right lateral view, SUT-09-2226, sample 07PB03-3; C, paratype, right lateral view, SUT-09- 2231, sample 07PB03-3; D, left lateral view, SUT-09-2232, sample 07PB03-5; E, F, I, J, Bairdia incisedorsa Chitnarin, n. sp.; E, holotype, right lateral view, SUT-09-2216, sample 07PB05-3; F, paratype, right lateral view, SUT-09-2215, sample 07PB05-3; I, paratype, dorsal view, SUT-09-2221, sample 07PB05-3; J, ventral view, paratype, SUT-09-2220, sample 07PB05-3. G, H, K, L Bairdia fontainei Chitnarin, n. sp.; G, holotype, right lateral view, SUT-09-2187, sample 07LB05-3; H, paratype, right lateral view, SUT-09-2182, sample 07PB04-5; K, paratype, right lateral view, SUT-09-2183, sample 07PB05-3; L, right lateral view, SUT-09-2178, sample 07LB05-5; M-P, Bairdia songthami Chitnarin, n. sp.; M, holotype, right lateral view, SUT-09-2283, sample 07LB05-5; N, paratype, right lateral view, SUT-09-2278, sample 07PB05-4; O, paratype, left lateral view, SUT-09-2281, sample 07PB03-1; P, right lateral view, SUT-09-2284, sample 07LB05-A2. Scale bars: 100 μm.