Acratia mongkoli 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 : 676-677

Acratia mongkoli Chitnarin , n. sp.

( Figs 21 J-M; 23)

Bairdia galei – Crasquin-Soleau & Baud 1998: pl. 3, fig. 18 (nec Croneis & Thurman 1939: 325, pl. 7, fig. 21).

TYPE MATERIAL. — Holotype, one complete carapace (SUT-09- 2058, Fig.21K ); paratypes, two complete carapaces (SUT-09-2063, Fig. 21L and SUT-09-2062, Fig. 21M ).

ETYMOLOGY. — In honour of Assistant Professor Dr Mongkol Udchachon, Mahasarakham University, Thailand.

MATERIAL EXAMINED. — Ten complete carapaces.

DIMENSIONS. — H = 0.29-0.54 mm, L = 0.56-1.01mm, H/L = 0.50- 0.53, Holotype: H = 0.38 mm, L = 0.79 mm; Paratype ( Fig. 21M ): H = 0.38 mm, L = 0.77 mm; Paratype ( Fig. 21L ): H = 0.30 mm, L = 0.66 mm ( Fig. 23 ).

TYPE HORIZON. — Sample 07 PB 04-2, Nong Phai section, Pha Nok Khao Formation, Asselian-Sakmarian, Early Permian.

TYPE LOCALITY. — Nong Phai section (16°01’06’’N, 100°58’59’’E), Pha Nok Khao Formation, Phetchabun Province, central Thailand.

OCCURRENCES. — Early Permian of Hydra Island , Greece (Crasquin- Soleau & Baud 1998) ; sample 08LO07-2, Sak Chai quarry section, Pha Nok Khao Formation , Chaiyaphum Province, northeast Thailand, Early Permian ; sample 07 PB03-3 , Khao Kana section, Pha Nok Khao Formation, Phetchabun Province, central Thailand, Early Permian ; sample 07 PB04-2 , Nong Phai section, Pha Nok Khao Formation, Phetchabun Province, central Thailand, Early Permian ; sample 08 PB02-12 , Phu Phra That section, Tak Fa Formation , Phetchabun Province, central Thailand, Middle Permian ; sample 08LB01-1, Khao Som Phot section, Tak Fa Formation , Lopburi Province, central Thailand, Middle Permian .

DIAGNOSIS. — Species of Acratia with diamond shape carapace, with laterally flattened and tapering AB, AB points horizontally, AVB makes an angle of 140° with VB, PVB make an angle of 170° with VB, PB tapering.

DESCRIPTION

Carapace with diamond shape in lateral view; dorsal outline broadly arched at LV, angulated at RV; DB of RV inclined at 30° rearward; ADB with an angle of 140° with DB; AB tapering and flattened, pointing horizontally, with maximum of curvature located above mid H; AVB long and straight, making an angle of 140° with VB; VB straight; ventral area flattened; PVB short, angle of PVB and VB is 170°; PB tapering with maximum of curvature located very low; greatest H located at mid L; surface smooth; LV larger and overlapping RV at DB; carapace fusiform in dorsal view.

REMARKS

Acratia mongkoli Chitnarin , n. sp. can be distinguished from A. chongpani Chitnarin , n. sp. (see above) by the smaller radius of curvature of AB, the tapering PB, and the angle between AVB and VB. It can be compared with A. subfusiformis Wang, 1978 from the Late Permian of South China ( Crasquin et al. 2010a: figs 23I-L), however, the AB of the present species is more tapering. It can be compared to A. pulchra Posner, 1951 from the Early Carboniferous of Moscow Basin, Russia ( Posner 1951: 98, pl. 21, fig. 8) by the small radius of curvature of AB and PB but is differentiated by the position of AB and the angle between AVB and VB.Noteworthy, the specimens documented from the Early Permian of Greece by Crasquin-Soleau & Baud (1988) have been attributed to the Bairdia galei Croneis & Thurman, 1939 sensu Chen & Bao (1986) . However, Bairdia galei is not mentioned neither figured by Chen & Bao (1986).

Figures

FIG. 21. — Ostracods from the limestones of the 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-G, Acratia chongpani Chitnarin, n. sp.; A, holotype,right lateral view,SUT-09-2006,sample 07PB03-3;B, dorsal view,SUT-09-2018,sample 07PB03-5;C, ventral view,SUT-09-2042,sample 07PB03-2; D, right lateral view,SUT-09-2036,sample 07PB03-2;E, paratype,right lateral view,SUT-09-2001,sample 07PB03-5;F, paratype,right lateral view,SUT-09-2013, sample 07PB03-5; G, left lateral view, SUT-09-2020, sample 07PB03-3; H, Bairdiidae indet. sp. B, right lateral view, SUT-09-2567, sample 08LB01-2; I, Acratia sp., left lateral view, SUT-09-2055, sample 08LB01-3; J-M, Acratia mongkoli Chitnarin, n. sp.; J, ventral view, SUT-09-2067, sample 07PB04-2; K, holotype, right lateral view, SUT-09-2058, sample 07PB04-2; L, paratype, right lateral view, SUT-09-2063, sample 07LB09-1; M, paratype, right lateral view, SUT-09-2062, sample 07LB09-1; N-P, Baschkirina cf. huzhouensis Forel, 2010; N, left lateral view, SUT-09-2531, sample 08LB01-1; O, left lateral view, SUT-09-2528, sample 08LB01-1; P, right lateral view, SUT-09-2530, sample 08LB01-1. Scale bars: 100 μm.

FIG. 23. — Height (H)-length (L) diagram of Acratia mongkoli Chitnarin, n. sp. Scale bar: 100 µm.