Candona praevara Zhang & Zhang, 1982

Wang, Yaqiong, 2025, First report of the non-marine ostracod fauna from the Lower Cretaceous Xiaonangou Formation of the Baishan Basin, NE China, Zootaxa 5660 (4), pp. 560-572 : 566

Candona praevara Zhang & Zhang, 1982

Figs. 2 , 4I–R , 5A–B .

1982 Candona praevara —Zhang & Zhang: p. 365–366, pl. 2, figs. 4–5.

Material. More than one hundred carapaces.

Dimensions. L: 0.62–0.68 mm, H: 0.34–0.43 mm, W: 0.24–0.31 mm.

Description. Medium sized, elongated oval in lateral view. Maximum length at 2/3 of height, maximum height at 3/4 of length, and maximum width slightly behind mid-length. LV larger than RV; LV overlapping RV along all margins, including hinge margin. Anterior margin narrow and slightly supracurvate; anterior cardinal angle rounded. Posterior margin broader than anterior one, strongly infracurvate; posterior cardinal angle more rounded than anterior one. Dorsal margin arched, hinge margin long and gently slopes towards anterior margin but slopes more steeply towards posterior margin. Ventral margin nearly straight in LV, but somewhat concave in mid-length of RV. Surface smooth.

Remarks. The general morphology of specimens in this study is well matched with Candona praevara with an elongated oval carapace shape, maximum height at 3/4 of length in lateral view, LV overlapping RV along all margins, and a strongly infracurvate posterior margin.

Distribution. Xiaonangou Formation, upper part of the Fuxin Formation in western Liaoning ( Zhang 1985) and Quantou Formation of the Songliao Basin ( Zhang 1987).

Figures

FIGURE 2. Stratigraphic column for the ostracod-bearing sequence in the Guanghuanjie-Yumuqiaozi section (41°56'34.4"N, 126°34'18.6"E) of the Baishan Basin, showing the positions of the ostracod samples and abundances of ostracod species recovered from the Xiaonangou Formation.

FIGURE 4. A–F. Lycopterocypris sinuolata Zhang, 1985, A, left lateral view of carapace (NIGP 206917), sample 2024-XNG- 11, B, right lateral view of carapace (NIGP 206918), sample 2024-XNG-11, C, left lateral view of carapace (NIGP 206918), sample 2024-XNG-11, D, dorsal view of carapace, anterior to left (NIGP 206919), sample 2024-XNG-10A, E, right lateral view of carapace (NIGP 206920), sample 2024-XNG-11, F, left lateral view of carapace (NIGP 206920), sample 2024-XNG-11; G–H. Lycopterocypris sp., G, right lateral view of carapace (NIGP 206921), sample 2024-XNG-10A, H, left lateral view of carapace (NIGP 206921), sample 2024-XNG-10A; I–R. Candona praevara Zhang & Zhang, 1982, I, right lateral view of carapace (NIGP 206922), sample 2024-XNG-11, J, ventral view of carapace, anterior to left (NIGP 206922), sample 2024-XNG-11, K, left lateral view of carapace (NIGP 206923), sample 2024-XNG-11, L, dorsal view of carapace, anterior to left (NIGP 206923), sample 2024-XNG-11, M, dorsal view of carapace, anterior to left (NIGP 206924), sample 2024-XNG-11, N, right lateral view of carapace (NIGP 206925), sample 2024-XNG-11, O, left lateral view of carapace (NIGP 206925), sample 2024-XNG-11, P, left lateral view of carapace (NIGP 206926), sample 2024-XNG-10A, Q, left lateral view of carapace (NIGP 206927), sample 2024-XNG-10A, R, right lateral view of carapace (NIGP 206927), sample 2024-XNG-10A. Scale bars = 100 μm.

FIGURE 5. A–B. Candona praevara Zhang & Zhang, 1982, A, left lateral view of carapace (NIGP 206928), sample 2024- XNG-10A, B, right lateral view of carapace (NIGP 206928), sample 2024-XNG-10A; C–J. Candonidae gen. indet. sp., C, left lateral view of carapace (NIGP 206929), sample 2024-XNG-11, D, right lateral view of carapace (NIGP 206929), sample 2024- XNG-11, E, right lateral view of carapace (NIGP 206930), sample 2024-XNG-11, F, ventral view of carapace, anterior to left (NIGP 206930), sample 2024-XNG-11, G, right lateral view of carapace (NIGP 206931), sample 2024-XNG-11, H, dorsal view of carapace, anterior to left, (NIGP 206931), sample 2024-XNG-11, I, right lateral view of carapace (NIGP 206932), sample 2024-XNG-11, J, left lateral view of carapace (NIGP 206932), sample 2024-XNG-11; K–R. Cyclocypris invalida Zhang, 1985, K, right lateral view of carapace (NIGP 206933), sample 2024-XNG-11, L, left lateral view of carapace (NIGP 206933), sample 2024-XNG-11, M, left lateral view of carapace (NIGP 206934), sample 2024-XNG-11, N, right lateral view of carapace (NIGP 206934), sample 2024-XNG-11, O, ventral view of carapace, anterior to left (NIGP 206935), sample 2024-XNG-11, P, dorsal view of carapace, anterior to left (NIGP 206935), sample 2024-XNG-11, Q, left lateral view of carapace with anterior part of shell missing (NIGP 206936), sample 2024-XNG-11, R, right lateral view of carapace (NIGP 206936), sample 2024-XNG-11. Scale bars = 100 μm.