Amnicythere sp. 1

RAUSCH, LEA, STOICA, MARIUS & LAZAREV, SERGEI, 2020, A Late Miocene - Early Pliocene Paratethyan Type Ostracod Fauna From The Denizli Basin (Sw Anatolia) And Its Palaeogeographic Implications, Acta Palaeontologica Romaniae 16 (2), pp. 3-56 : 35

Amnicythere sp. 1

Fig. 22 a-n

Description. The carpace is elongated in lateral view and uniformly covered with a pitted pattern that is more or less fine pronounced. The dorsal margin runs straight and continues smoothly onto the broadly rounded anterior end. The ventral margin is slightly concave at mid-length. The anterior border is well rounded and the posterior end slightly narrower and mid-posteriorly more angular. The entire surface is uniformly covered with fine to medium sized pits that sometimes have the tendency to be arranged in polygonal nets that further developed a weakly pronounced secondary recticulated ornamentation. In the coarser ornamented specimens, a short ridge can be observed running in the median area of the valve. In the finer pitted specimens, the ridge is thinner and usually accompanied by other parallel or concentric ridges. Along the anterior border 3-4 conules pores are displayed. The inner lamella is well developed, both anteriorly and posteriorly, extending also along the ventral margin. On the RV, the hinge is pronounced as a long, thin and smooth bar with two elongated, slightly divided teeth at both ends. Some specimens are noticeably shorter (k-n) and have, apart from the same ornamentation pattern, 2-3 postero-ventral tubercles that are not covered by ornamentation. We interpret this as sexual dimorphism and we consider these female specimens. Dimension: L = 0,46 – 0,63 mm, H = 0,22 – 0,28 mm, the minimum sizes include juveniles too.

Remarks. This species shows a highly variable ornamentation. The shape and general aspects of the valves surface resemble those described of Amnicythere oforta (Livental) (in Agalorova et al., 1961). The original handdrawing however is not accurate enough and a closer determination was not made possible. Similar other forms including Leptocythere nata Markova (in Yassini, 1986), Amnicythere polymorpha ( Olteanu, 1989) and Amnicythere aff. ebersini Scheidaeva , show similarities but due to the high variation in ornamentation it is difficult to assign the present species to either one of them.

Figures

Fig. 22a-n Amnicythere sp. 1; a, c, e, g LV, external view, ♂; b, d, f, h RV, external view, ♂; i LV, internal view, ♂; j RV, internal view, ♂; k, m LV, external view, ♀; l RV, external view, ♀; n RV, internal view, ♀; (all specimens from section A; a-j from sample 35,5 m; k-n from sample 32 m).