Tyrrhenocythere sp. 1

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

Tyrrhenocythere sp. 1

Fig. 5D 1 , D 2 .

Material.—One incomplete RV, length 0.77 mm, with the dorsal part broken.

Description.—Ornamentation: polygonal fossae with smooth solum connected by ribs starting in the centre and extending toward the outer margin; ventral and anterior ribs highly visible; short, weak ribs developed on AM between anterior rib and ordinary polygonal fossae; the ribs represent reinforced outer lamellae where the main canal joins the distal MPC; similar ribs are developed on PVM.

Discussion.—The specimen differs from other hemicytherids from Pezinok with its brush−like Tyrrhenocythere arrangement of MPC; each with 7 to 10 short canals on AM and with 3–4 on PVM. A comparison of the outline with other species is problematic because1/3 of the valve is missing. The polygonal fossae may indicate that Tyrrhenocythere sp. 1 is related to the Lower Pannonian Hemicytheria sp. (setosa) from Serbia (sensu Krstić 1985: 141), Pontian and Pliocene Tyrrhenocythere pontica from the Eastern Paratethys ( Krstić 1977: 401; Tunoglu 2001: 135), Dacian T. filipescui , T. azerbaidjanica (Livental, 1939) and T. sp. 1 of Olteanu, 1982 from Romania ( Olteanu 1982: 8, 1995: 300). However, the fossae of Tyrrhenocythere sp. 1 are connected by ribs, in contrast to the aforementioned Tyrrhenocythere .

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.

Fig. 1. A. Palaeogeographical map of Europe in the upper Miocene (9.5 Ma) (after Steininger and Rögl 1985). B. Lake Pannon in a time of maximum flooding surface in Pannonian zone E (Spiniferites paradoxus Biochron) (after Kováč 2000).

Fig. 2. Geographical sketch (A) and lithological col− umn (B) of Pezinok clay pit (Pipík 1998). C. Detail of the sequence with Tyrrhenocythere mirror swamps and shallow water sedimentation on the bord of freshwater− /miohaline lake (Baráth et al. 1999).