Bairdia McCoy, 1844

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 : 653-655

Genus Bairdia McCoy, 1844

TYPE SPECIES. — Bairdia curta McCoy, 1844 , by subsequently designated by Ulrich & Bassler (1923: 320).

Bairdia khaokanaensis Chitnarin , n. sp.

( Figs 3 A-D; 4)

TYPE MATERIAL. — Holotype: one complete carapace (SUT-09- 2226; Fig. 3A ); paratypes: two complete carapaces (SUT-09-2223; Fig. 3B and SUT-09-2231; Fig. 3C ).

MATERIAL EXAMINED. — One damaged and one complete carapaces.

DIAGNOSIS. — Species of Bairdia with long carapace, ventral outline broadly arched, AB nearly vertical, AVB and PVB of both valves long and convex, VB slightly concave, short and convex DB.

ETYMOLOGY. — From the type locality, the Khao Kana section. DIMENSIONS. — H = 0.23-0.57 mm, L = 0.51-1.28 mm, H/L = 0.43-0.47, Holotype: H = 0.563 mm, L = 1.22 mm; Paratypes: H = 0.322, L = 0.726 ( Fig. 4; both paratypes of the same size).

TYPE HORIZON. — Sample 07 PB 03-3, Khao Kana section, Pha Nok Khao Formation, Sakmarian, Early Permian.

TYPE LOCALITY. — Khao Kana section (16°04’12’’N, 100°54’20’’E), Phetchabun Province, Central Thailand.

OCCURRENCES. — Samples 07 PB 03-1, 07 PB 03-3 and 07 PB 03-5, Khao Kana section, Phetchabun Province, Pha Nok Khao Formation, Early Permian, Central Thailand.

DESCRIPTION

Carapace long; dorsal outline regularly arched; DB short (30% of L); ADB nearly straight, angle with DB is 150°; AB round with moderate radius of curvature, maximum convexity located just below mid H; angle between AB and ADB is 150°; AVB long and convex; VB slightly concave; PVB long and convex; posteroventral region flattened; PB round with small radius of curvature, maximum convexity located below mid H; PDB nearly straight, angle with DB of 140°; LV slightly overlaps RV all around the carapace, except at AVB and PVB; maximum H located at mid L.

REMARKS

This species can be compared to Bairdia subfusiformis Hamilton, 1942 from the Guadalupian, Middle Permian of Texas ( Hamilton 1942) in general outline, but it can be differentiated by its shorter and more convex DB, the longer and more convex AVB and PVB. Bairdia khaokanaensis Chitnarin , n. sp. can also be compared to B. girtyi Sohn, 1960 from the Early Permian of South China ( Chen & Bao 1986: 115, pl. 2, figs 6, 7) in lateral outline but they can be differentiated by the longer and flat DB and the moderate overlapping at DB of the latter species. AVB and PVB of B. khaokanaensis Chitnarin , n. sp. are longer and more convex.

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.