Quasillites (Jennillites) ambiguus Becker, 1989

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 : 44-45

Quasillites (Jennillites) ambiguus Becker, 1989

(Pl. III: Figs. 5 & 6 )

1980 Jenningsina sp.; Becker: 764.

1985 Punctomosea sp. B; Casier: 836–837, pl. 1, figs. 13–14.

1989 Quasillites (Jennillites) ambiguus nov. sp.; Becker: 148, pl. 5, figs. 6–7. 1996 Gen. indet. sp. B ( Guerichiella ?); Milhau: 74–75, pl. 2, fig. 13.

1996 Punctomosea sp. B Casier; Milhau: 74–75.

2004 Quasillites (Jennillites) ambiguus Becker ; Becker in Becker et al.: 53, pl. 4, fig. 8, pl. 5, figs. 1, 10, 14. 2010a Quasillites (Jennillites) ambiguus Becker ; Casier in Casier et al.: 43, pl. 3, fig. 18. 2013 Quasillites (Jennillites) ambiguus Becker ; Maillet: 126, pl. XVI, figs. 23–25. 2013a Quasillites (Jennillites) ambiguus Becker ; Maillet et al.: pl. 1, fig. 16.

Material. 13 specimens (3 C, 10 V).

Diagnosis. Becker (1989, p. 148).

Description. Medium-sized elongated carapace, sub-rectangular in lateral view. Slight dorsal overlap of the LV over the smaller RV at free margins of the carapace. Hmax median; Lmax at 1/3 dorsal; Wmax slightly dorsal. Almost straight to very slightly convex dorsal margin. Slightly convex ventral margin. Ventral and dorsal margins almost parallel. Regularly convex anterior margin. Posterior margin very arched in the dorsal part, oblique anteriorly in the ventral part. Anterior part of the carapace slightly higher than the posterior one. Surface finely reticulated. Reticles orientated longitudinally. Marked vertical ridge in the posterior part of the carapace, possibly prolonged by spines. Carapace globally inflated, except a clear flattening in the postero-dorsal part posteriorly to the vertical ridge.

Discussion. The elongation of the carapace, its fine reticulation and the very marked vertical ridge in its posterior part are features of this species, both in juveniles and adults.

Occurrences. Upper Emsian to Middle Givetian (Chefar el Ahmar Fm), Saoura (Km 30 section), Middle Givetian (Candás Fm, mbs A and B), Asturias (Peran-Perlora section) and Palencia, Middle/Upper Givetian, Mouthoumet Massif (Berco Petito section); Givetian, Ardenne and Morocco.

Figures

FIGURE 6. Faunal relations and Middle Devonian palaeogeographic reconstruction. Abbreviations: Ard: Ardenne (Namur and Dinant Synclinoria); Arm: Armorican Massif; Bhm: Bohemian Massif; Bln: Boulonnais; CcA: Carnic Alps; Ctz: Cantabrian Zone; Dvs: Devonshire; Grm: Germany (Eifel, Ruhr, Sauerland, Bergisches Land, Thuringia, Harz); IbC: Iberian Cordillera; Mth: Mouthoumet Massif; MtN: Montagne Noire; NMc: North Morocco (Doukkala, Meseta); OMZ: Ossa Morena Zone; Pld: Poland (Holy Cross Mountains, Pomerania); Ptd: Pontides; Rus: Russia (Volga and Urals areas; Baschkiria); Sao: Saoura; SMc: South Morocco (Anti-Atlas, Tafilalt); Tns: Tunisia; Trd: Taurides; Ygv: Ex-Yugoslavia (Serbia). For the reviewed literature on Givetian ostracods of those areas, see text. A. Faunal affinities between the Cantabrian Zone and other places in Europe and neighbouring areas during the Givetian; B. Middle Devonian palaeogeographic reconstruction (adapted from Blakey 2007).