Bairdia (Bairdia) cf. siliklensis Rozhdestvenskaja, 1962

Maillet, Sebastien, Milhau, Bruno, Vreulx, Michel & Posada, Luis-Carlos Sánchez De, 2016, Givetian ostracods of the Candás Formation (Asturias, North-western Spain): taxonomy, stratigraphy, palaeoecology, relationship to global events and palaeogeographical implications, Zootaxa 4068 (1), pp. 1-78 : 51-52

Bairdia (Bairdia) cf. siliklensis Rozhdestvenskaja, 1962

(Pl. IV: Fig. 1 )

cf. 1962 Bairdia siliklensis nov. sp.; Rozhdestvenskaja: pl. 32, figs. 1–2.

cf. 1985 Bairdia cf. siliklensis Rozhdestvenskaja ; Coen: pl. 9, figs. 1–4.

2013 Bairdia (Bairdia) cf. siliklensis Rozhdestvenskaja ; Maillet: 160, pl. XXIV, figs. 18–19. aff. 2013 Bairdia cf. siliklensis Rozhdestvenskaja ; Maillet et al.: fig. 4R.

aff. 2013 Bairdia cf. siliklensis Rozhdestvenskaja ; Casier in Casier & Préat: 488, pl. V, fig. 9.

Material. 11 specimens (7 C, 2 V, 2 F).

Description. Large carapace, biconvex in dorsal view, suboval in lateral view. Pronounced overlap of the larger LV over the RV ventrally, posteriorly and especially dorsally. Overlap slighter in the antero-dorsal part. Bow-shaped projection in ventral view. Hmax at 2/5 anterior; Lmax slightly dorsal; Wmax slightly anterior. Dorsal margin of the larger LV slightly convex, both anteriorly and posteriorly oblique. Dorsal margin of the smaller RV straighter in its middle part and also both anteriorly and posteriorly oblique. Ventral margin of the larger LV slightly convex, more arched at its extremities. Ventral margin of the smaller RV slightly concave in its middle part and convex at its extremities. Middle part of the ventral and dorsal margins almost parallel. Well rounded, regularly convex anterior and posterior margins. Anterior and posterior margins forming an angle of about 130° respectively with the anterior part and the posterior part of the dorsal margin. Sharp posterior end. Anterior part of the carapace clearly higher than the posterior one. Surface smooth.

Discussion. These specimens are too badly preserved to be identified at a species level without doubt. However, size, global outline and features of the carapace well remind B. siliklensis Rozhdestvenskaja, 1962 . This species, whose features are a short hinge line, a pronounced overlap and a regular convexity of the dorsal margin, is sometimes confused in literature with B. plicatula Polenova, 1952 . Mural pores have not been observed on the carapaces of our specimens due to bad preservation.

Occurrences. Middle Givetian (Candás Fm, mbs A, B and C), Asturias (Peran-Perlora section).

PLATE IV. Ostracods from the type-area of the carbonate Candás Formation. For samples stratigraphic position, see Figure 3. 1 . Bairdia (Bairdia) cf. siliklensis Rozhdestvenskaja, 1962 , A9, RV (C. O.F.L.S. 1063); 2. Bairdia (Bairdia) sp. P1, O 5, RV (C. O.F.L.S. 1067); 3. Bairdia (Bairdia) sp. P2, II1, RV (C. O.F.L.S. 1068); 4. Bairdia (Bairdia) sp. P3, A9, LV (C. O.F.L.S. 1069); 5. Bairdia (Bairdia) sp. P4, A9, RV (C. O.F.L.S. 1070); 6. Bairdia (Cryptobairdia) cf. singularis Krömmelbein, 1954 , B10, RV (C. O.F.L.S. 1074); 7–8. Bairdia (Rectobairdia) paffrathensis Kummerow, 1953 , juvenile (7), B10, RV (C. O.F.L.S. 1082); adult (8), I6, RV (C. O.F.L.S. 1083); 9. Bairdia (Rectobairdia) sp. P5, N2, RV (C. O.F.L.S. 1087); 10. Bairdiacypris antiqua ( Pokorńy, 1951) , G1, RV (C. O.F.L.S. 1096); 11. Bairdiacypris sp. P1, P6, RV (C. O.F.L.S. 1099); 12. Orthocypris cf. cicatricosa Coen, 1985 , Q8, RV (C. O.F.L.S. 1105); 13. Orthocypris ? sp. indet. A, Q8, RV? (C. O.F.L.S. 1109).

Figures

FIGURE 1. Location maps of the studied area. A. Devonian deposits cropping out in the Cantabrian Zone (adapted from García-Alcalde et al. 2012); B. Simplified geological map of the Luanco-Candás area showing the Naranco, the Candás and the Piñeres Fms (modified from García-López et al. 2002), with location of the Peran-Perlora and Carranques sections; C. Detailed location map of the Peran-Perlora section (adapted from García-López et al. 2002); D. Detailed location map of the Carranques section (adapted from Fernández et al. 1996).

FIGURE 3. Stratigraphical distribution of ostracod taxa through the Candás Formation in the Peran-Perlora and Carranques sections. Samples numbers are replaced on a detailed stratigraphical column of the series, on which macro- and microfaunas’ occurrences are indicated.