Tyrrhenocythere sp. 2

Pipík, Radovan, 2007, Phylogeny, palaeoecology, and invasion of non-marine waters by the late Miocene hemicytherid ostracod Tyrrhenocythere from Lake Pannon, Acta Palaeontologica Polonica 52 (2), pp. 351-368 : 361-362

Tyrrhenocythere sp. 2

Fig. 5F .

Material.— One adult right valve.

Description.—RV: AM symmetrically rounded; DM tapered, rounded without a visible anterior angle; DM straight before mid−length and sloping slightly anteriorly, tapered above central muscle scars then straight and sloping toward the posterior; posterior angle tapered; PM curved, slightly oblique

N l h h/l RV ♀ 1 0.74 0.44 0.595

and lower than AM; strongly rounded PVM with distinctive posterior process; VM right, slightly concave before the mid−length; outline subcircular; maximum height above central muscle scars.

Ornamentation: surface covered with small circular puncta; a weak ventral rib; anterior short ribs at the position of MPC, perpendicular with AM; weak and short ribs developed on the entire AM representing reinforced outer lamellae at the position of main canal joining distal MPC; eye tubercle smooth.

Marginal zone: inner lamella large with a series of parallel striae; inner margin parallel with outer margin; brush−like Tyrrhenocythere arrangement of MPC.

Discussion.— Tyrrhenocythere sp. 2 could be related to the group of semicircular forms with smooth, punctate to fossate species described by Krstić (1985: 399). The puncta of Tyrrhenocythere sp. 2 are deeper and regularly distributed throughout the surface without any sign of reticulation as it is visible in T. donetziensis , species with similar punctate surface ( Boomer et al. 1996: 80, fig. 3A, B, D, E).

Stratigraphical and geographical range.—Pannonian clay deposits in Pezinok.

Figures

Fig. 5. Late Miocene hemicytherid ostracods from the layer 36+37A in Pezinok, Slovakia. A–C, I, L. Tyrrhenocythere transitivum sp. nov. A. RV♂, paratype, SNM RP27−21, external lateral view. B. LV♂, paratype, SNM RP27−18, external lateral view. C. LV♀, paratype, SNM RP26−4−4, external lateral view. I. LV♀, paratype, SNM RP27−19, internal lateral view; I1, central muscle scars; I2, detail of hinge. L. RV♀, paratype, SNM RP27−22, internal lateral view, detail of hinge. D. Tyrrhenocythere sp. 1, RV, SNM RP27−2, external lateral view; D1, SEM photo; D2, valve in transparent light. F. Tyrrhenocythere sp. 2, RV♀, SNM RP28−2, external lateral view. G, J. Tyrrhenocythere pezinokensis (Jiříček, 1985). G. LV♀, SNM RP27−8, internal lateral view, G1, central muscle scars; G2, detail of hinge. J. RV♀, paratype, SNM RP27−5, internal lateral view, detail of hinge. E, H, K. Tyrrhenocythere rastislavi sp. nov. E. RV♂, paratype, SNM RP26−16−1, external lateral view. H. RV♀, paratype, SNM RP27−15, internal lateral view; H1, central muscle scars; H2, detail of hinge. K. LV♀, paratype, SNM RP27−12, internal lateral view, detail of hinge.