Kuqaia concentrica Li, 1993

Peng, Jungang, Slater, Sam M., McLoughlin, Stephen & Vajda, Vivi, 2023, New species of Kuqaia from the Lower Jurassic of Sweden indicates a possible water flea (Crustacea: Branchiopoda) affinity, PLoS ONE (e 0282247) 18 (6), pp. 1-20 : 8

Kuqaia concentrica Li, 1993

Fig 5A–5E

Material. NRM X12701; NRM X12702.

Description. Shell reniform in lateral view; elliptical in dorso-ventral view. Concentric ridges well-developed, 21–27 ridges on one valve, blade-shaped, or widened to 2–3.5 μm. Radial ridges weakly developed on the dorsal and lateral sides on one specimen. Collar-shaped margin poorly preserved on one specimen, c. 22 μm high. Back inconspicuous on these laterally preserved specimens. Caudal spine damaged.

Comparison. This species is distinguished from other species by its pronounced concentric ridges.

Dimensions. Length 444(451)457 μm; width 171(202)233 μm (two specimens).

Remarks. Two specimens are assigned to Kuqaia concentrica based on the ornamentation dominated by concentric ridges ( Fig 5A–5E ). One specimen is characterized by distinct blade-shaped concentric ridges on the shell, with weak radial ridges ( Fig 5A and 5B ). The other specimen is characterized by wider concentric ridges with modestly developed radial ridges in the dorsal and lateral parts ( Fig 5D and 5E ), resulting in a weakly developed pattern of chequered ridges similar to that in Kuqaia quadrata ( Fig 5F and 5G ). Nevertheless, the dominance of concentric ridges in the shell ornamentation of this specimen favours assignment to Kuqaia concentrica .

Occurrence, unit and age. 57.00– 56.50 m and 46.97– 46.07 m, Kävlinge BH-928; Katslösa Member, Rya Formation; Pliensbachian.

Figures

Fig 5. Scanning electron micrographs of Kuqaia species from the Pliensbachian of Skåne. (a)–(e) Kuqaia concentrica Li, 1993; (a) whole specimen (NRM X12701), and (b) enlargement of concentric ridges; Kävlinge BH-928 core depth 57.00–56.50 m; (c) whole specimen (NRM X12702); (d) and (e) enlargement of concentric ridges; Kävlinge BH-928 core depth 46.97–46.01 m. (f) and (g) Kuqaia quadrata Li, 1993; (f) whole specimen in oblique compression (NRM X12703), and (g) enlargement of intersecting concentric and radial ornament; Kävlinge BH-928 core depth 46.97–46.01 m. Scale bars = 100 μm, unless otherwise stated. https://doi.org/10.1371/journal.pone.0282247.g005