Tyrrhenocythere pezinokensis ( Jiříček, 1985 )

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 : 356-358

Tyrrhenocythere pezinokensis ( Jiříček, 1985)

Figs. 4A–F, 5G 1 , G 2 , J, 6F .

1985 Hemicytheria pezinokensis sp. nov.; Jiříček 1985: 405, pl. 56: 10–12.

1998 Tyrrhenocythere pezinokensis ( Jiříček, 1985) ; Pipík 1998: pl. 2: 5, 6.

Remark.—The original description is incomplete, hence a description of the hinge, muscle scars and marginal zone is given based on the material collected in Pezinok clay pit, the layer 36+37A.

Material.— 30 adult valves, 1 juvenile.

Description.—Muscle scars: a vertical row of six scars (the second and the third of the “standard” row of four each divided in two), with three additional anterior scars ( Fig. 5G 1 ).

Hinge (amphidont): The hinge ( Fig. 5G 2 , J) of the LV is composed of a rhomboidal anterior socket; a square tooth that continues into a smooth bar; a posterior socket with an elongate opening toward the interior; a tiny tooth in the middle of the posterior socket. The hinge of the RV has a strong, elongated tooth divided into two lobes; a socket that passes into a slightly curved, smooth groove; a posterior elongated, kidney−shaped tooth composed of 3 tiny elements.

Marginal zone: inner lamella large, with a series of parallel striae; inner margin parallel with outer margin; 5 fully developed brush−like marginal pore canals (MPC); 6 to 8 MPC on ADM ( Fig. 6F ); AVM are separate or incompletely fused; simple MPC on VM; large zone of fusion; drop−like space between the “brushes” on AM; irregular, sinusoidal line of concrescence on AM.

Stratigraphical and geographical range.—The species, first described by Jiříček (1985: 405) from the Pannonian clay deposits in Pezinok, is still known only from its type locality.

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).

Fig. 6. Marginal pore canals on anterior margin and their transformation from straight Hemicytheria arrangement to brush−like Tyrrhenocythere one. A. Hemicytheria reniformis (Reuss, 1850), Hemicytheria folliculosa (Reuss, 1850), Hemicytheria omphalodes (Reuss, 1850), original by author. B. Hemicytheria biornata (Zalányi, 1944), original by author, Hemicytheria maeotica Olteanu 1989 after Olteanu and Vekua (1989). C. Hemicytheria major Sokač, 1972. D. Hemicytheria marginata Sokač, 1972 after Sokać (1972). E. Tyrrhenocythere transitivum sp. nov. F. Tyrrhenocythere pezinokensis (Jiříček, 1985). G. Tyrrhenocythere rastislavi sp. nov. original by author.