Petasobairdia Chen, 1982

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 : 668-670

Genus Petasobairdia Chen, 1982

TYPE SPECIES. — Petasobairdia bicornuta Chen, 1982 by original designation.

Petasobairdia subnantongensis Chen, 1987 ( Fig. 15 A-C) Petasobairdia subnantongensis Chen in Shi & Chen, 1987: 47, pl. 8, figs 1-4, pl. 19, figs 8, 9. — Shi & Chen 2002: 75, pl. 14, figs 12- 14. — Crasquin et al. 2010a: 350, figs 13F-H.

Petasobairdia nantongensis Chen in Chen & Shi, 1982: 130, pl. 6, figs 7-9 (non figs 1-6). — Crasquin et al. 2008b: pl. 4, figs 16, 17.

MATERIAL EXAMINED. — 23 complete and six incomplete carapaces.

OCCURRENCES. — Jiangsu Province, latest Permian ( Chen & Shi 1982); Meishan section, Zhejiang Province, latest Permian ( Shi & Chen 1987; Crasquin et al. 2010a); Guangxi Province, South China, Late Permian ( Shi & Chen 2002); sample 07LB05-5, Ta Kli sec- tion, Tak Fa Formation, Nakhon Sawan Province, central Thailand, Early Permian; samples 07 PB 05-2 and 07 PB 05-3, Ban Naen Sawan I section, Tak Fa Formation, Phetchabun Province, central Thailand, Middle Permian; sample 08 PB 03-3, Phu Pra that section, Tak Fa Formation, Phetchabun Province, central Thailand, Middle Permian.

DIMENSIONS. — H = 0.45-0.62 mm, L = 0.81-0.96 mm, H/L = 0.61-0.64.

Petasobairdia campbelli Chitnarin , n. sp. ( Figs 12 J-P; 17)

TYPE MATERIAL. — Holotype, one complete carapace (SUT-09- 2568, Fig.12F ); paratypes, two complete carapaces (SUT-09-2570, Fig. 12N and SUT-09-2571, Fig. 12K ).

ETYMOLOGY. — In honour of Dr Hamish Campbell, GNS, New Zealand.

MATERIAL EXAMINED. — Nine complete carapaces.

DIMENSIONS. — H = 0.51-0.69 mm, L = 1.07-1.29 mm, Holotype: H = 0.57 mm, L = 1.18 mm; Paratype ( Fig.12N ): H = 0.51 mm, L = 1.07mm; Paratype ( Fig. 12K ): H = 0.55 mm, L = 1.28 mm ( Fig.17 ).

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

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

OCCURRENCES. — Sample 07LB05-5, Ta Kli section, Tak Fa Formation, Nakhon Sawan Province, central Thailand, Early Permian ; sample 07 PB05-5 , Ban Naen Sawan I section, Tak Fa Formation, Phetchabun Province, central Thailand, Middle Permian .

DIAGNOSIS. — Species of Petasobairdia with a long carapace, DB of LV nearly horizontal with an horizontal dorsal ridge ended by small spines at both ends, DB of RV convex underlined by a simple ridge, maximum H located in median region, ventral ridge at both valves.

DESCRIPTION

Long, subfusiform carapace; dorsal outline angulated, DB of RV convex underlined by a simple ridge, DB of LV nearly horizontal, underlined by a straight dorsal ridge ended by spines at both ends; ADB of RV concave, ADB of LV slightly concave, angle between AD and DB is 160°; AB rounded with small radius of curvature, maximum convexity located above mid H; AVB slightly convex, angle between AVB and VB is 150°; VB straight with a faint ventral ridge both valves; PVB long, slightly convex, making an angle of 155° with VB; PB tapering, with maximum of convexity located below mid H; PDB slightly concave on LV, concave on RV, angle between PDB and DB is 135°; maximum H all along DB; strong overlap of LV on RV along dorsal outline; in dorsal view carapace biconvex flattened laterally.

REMARKS Petasobairdia campbelli Chitnarin , n. sp. can be compared to P. levicornuta Chen, 2002 from the latest Permian of Guangxi in South China ( Shi & Chen 2002: 75, pl. 16, figs 1-7, pl. 17, figs 1-6) by its small dorsal ridge on LV with a backward-pointing spine. However, our specimens differ from P. levicornuta by the angular dorsal outline, DB of LV horizontal and presence of small spines at both ends of the horizontal dorsal ridge on LV.

Figures

FIG. 15. — 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-C, Petasobairdia subnantongensis Chen,1987;A, right lateral view, SUT-09-2578, sample 07PB05-2; B, right lateral view, SUT-09-2583, sample 07PB05-3; C, left lateral view, SUT-09-2581, sample 07PB05-2. D-F, Cryptobairdia seminalis (Knight) sensu Shi & Chen, 1982; D, right lateral view, SUT-09-2507, sample 07PB04-2; E, right lateral view, SUT-09-2508, sample 07PB04-2; F, right lateral view, SUT-09-2511, sample 07LB05-5. G, Cryptobairdia sp., right lateral view, SUT-09-2515, sample 07PB03-17. H, Fabalicypris sp. C, right lateral view, SUT-09-2527, sample 07LB07-17. I, Bairdia sp. K, right lateral view,SUT-09-2317, sample 08LO07-8. J, K, Bairdiacypris sp. D; J, right lateral view,SUT-09-2355, sample 07PB05-3; K, right lateral view, SUT-09-2353, sample 07PB05-3. L, N, O, Liuzhinia praeantalyaensis Forel, 2010; L, dorsal view, SUT-09-2099, sample 08LO02-5;N, right lateral view,SUT-09-2100,sample 08LO02-5; O, right lateral view,SUT-09-2099,sample 08LO02-5.M, Bairdiacypris longirobusta Chen,1958, right lateral view, SUT-09-2361, sample 07LB05-5. Scale bars: 100 μm.

FIG. 12. — 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-C, Bairdia deweveri Crasquin, 2010; A, right lateral view, SUT-09- 2165, sample 07PB04-2; B, right lateral view, SUT-09-2161, sample 07PB04-2; C, right lateral view, SUT-09-2169, sample 08LO02-10; D-F, Bairdia menardensis Harlton sensu Chen (1958); D, right lateral view, SUT-09-2140, sample 07LB05-B1; E, right lateral view, SUT-09-2147, sample 07LB05-D3; F, right lateral view, SUT-09-2148, sample 08LB01-6; G-I, Lobobairdia ventriconcava (Chen, 1958); G, right lateral view, SUT-09-2539, sample 07PB05-2; H, right lateral view, SUT- 09-2540, sample 07PB05-2; I, left lateral view, SUT-09-2541, sample 07PB07-3; J-P, Petasobairdia campbelli Chitnarin, n. sp.; J, holotype, right lateral view, SUT-09-2568, sample 07LB05-5; K, paratype,left lateral view, SUT-09-2571,sample 07LB05-5; L, dorsal view, SUT-09-2572, sample 07LB05-5; M, ventral view, SUT-09-2573, sample 07LB05-5; N, paratype, right lateral view, SUT-09-2570, sample 07LB05-5; O, left lateral view, SUT-09-2574, sample 07PB05-5; P, left lateral view, SUT-09-2575, sample 07PB05-5. Scale bars: 100 µm.

FIG. 17. — Height (H)-length (L) diagram of Petasobairdia campbelli Chitnarin, n. sp. Scale bar: 100 µm.