Kuqaia scanicus, Peng & Slater & McLoughlin & Vajda, 2023

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 : 5-8

Kuqaia scanicus sp. nov.

Figs 2 and 3

Derivation of name. The specific epithet scanicus (Latin) refers to the discovery of this taxon in the southernmost province of Sweden, Scania (Skåne).

Holotype. NRM X12700 ( Figs 2 and 3 ).

Material. Only the holotype, lacking the caudal end, is available.

Type stratum and age. Katslösa Member, Rya Formation; Pliensbachian.

Diagnosis. A Kuqaia bearing long peduncles on the lateral sides of the postventral margin.

Description. Shell reniform in lateral view; elliptical in dorso-ventral view. Concentric ridges weakly defined on the posterior half, conspicuous in the central part represented by c. 10 ridges, indistinct towards the ventral, dorsal, and the anterior parts. Radial ridges, well-developed on the anterior half with c. 19 ridges, becoming less well defined in the central part, and indistinct towards the posterior. Concentric and radial ridges are never strongly raised. Collar-shaped postventral margin is poorly preserved. Two long peduncles initiate from the lateral part of the postventral margin, are thicker on the posterior side, pointed at the terminus, c. 1200 μm long, and c. 35 μm wide at the posterior side. Peduncles bear weak, parallel and transverse ridges that become indistinct towards the tip. Back inconspicuous. Caudal spine damaged.

Comparison. This species is distinguished from all other representatives in the genus based on its possession of long peduncles.

Dimensions. Length 443 μm; width 200 μm (one specimen).

Occurrence unit and age. 40.40– 39.60 m, Kävlinge BH-928; Katslösa Member, Rya Formation; Pliensbachian.

Remarks. The caudal spine of Kuqaia was initially emphasized as a primary morphological feature of this fossil group [ 18]. However, this slender structure is susceptible to breakage. On the single specimen stored in NRM, the central part of the postventral side of the shell is lacking due to incomplete preservation ( Figs 2A and 3E ). Since the other morphological characteristics of this species fall into the diagnosis of Kuqaia , we attribute the Swedish specimen to this genus, and infer that the caudal spine has been removed by physical damage.

Figures

Fig 2. Kuqaia scanicus sp.nov. Holotype, NRM X12700; Kävlinge BH-928 core depth 40.40–39.60 m. (a) Scanning electron micrograph of whole specimen at low magnification. (b) Enlargement (SEM image), showing surface ornamentation in central part. https://doi.org/10.1371/journal.pone.0282247.g002

Fig 3. Enlargement of the holotype (NRM X12700) of Kuqaia scanicus sp. nov. Kävlinge BH-928 core depth 40.40– 39.60 m. Scale bars = 100 μm, unless otherwise stated.(a) Well-developed radial ridges at the anterior (SEM image). (b) Weakly defined ridges at the posterior (SEM image). (c) Weak, parallel and transverse ridges on peduncles (SEM image). (d) Complex surface ornament revealed in UV-fluorescence microscopy. (e) Weakly defined ridges on peduncles evident in fluorescence microscopy. https://doi.org/10.1371/journal.pone.0282247.g003