Welleria cf. aequiconvexa Olempska, 1974

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 : 14

Welleria cf. aequiconvexa Olempska, 1974

(Pl. I: Figs. 2 a, 2b, 3)

cf. 1974 Welleria cf. aequiconvexa nov. sp.; Olempska: 524–525, pl. XXIV, figs. 1–3. 2013 « Kozlowskiella » sp. P1; Maillet: 35, pl. II, figs. 10a, b and 11.

Material. 17 specimens (12 C, 2 V, 3 F).

Description. Large preplete and equivalve carapace. Hmax at 1/3 anterior; Lmax at 2/5 dorsal; Wmax median. Very slight overlap of the larger RV over the LV dorsally. Straight dorsal margin and hinge line. Carapace inflated along the hinge line, especially anteriorly, in dorsal view. Cardinal angles of about 125°. Well rounded free margins. Carapace slender posteriorly. Anterior margin wide and regularly convex. Anterior part of the carapace higher than the posterior one. Carapace flattened along the free margins, more widely in the anterior part. No velum along ventral margin. Two distinct dorsal lobes, one anterior and one posterior, separated by a mid-dorsal sulcus. Surface entirely papillose.

Discussion. All the ornamental features of the carapace described above are less marked but can also be observed in juveniles (Pl. I: Fig. 3 ). By the size and the general morphology of their carapaces, showing two distinct dorsal lobes, these specimens belong to the genus Welleria . Only tecnomorphs and juveniles specimens have been collected, whose morphology well remind W. aequiconvexa Olempska, 1974 . However, specimens from the Candás Fm show a wider carapace in dorsal view and have a less marked adductorial sulcus.

Occurrence. Middle Givetian (Candás Fm, mb B), Asturias (Peran-Perlora section).

Figures

FIGURE 2. Simplified stratigraphical column of the Candás Formation, standard conodont zonation and chronostratigraphy (according to García-Alcalde et al. 1979; García-López 1986 and García-López et al. 2002).

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.