Amnicythere striatocostata ( Schweyer, 1949 ), 1990

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 : 30

Amnicythere striatocostata ( Schweyer, 1949)

Fig.21 a-i

1949 Cythere striatocostata sp. n. - Schweyer, p.27-28, pl. 9, fig. 8.

1961 Leptocythere striatocostata (Schweyer) - Agalarova et al., p. 108, pl. 68, fig. 1-3a-b.

1976 Leptocythere striatocostata (Schweyer) - Yassini & Ghahreman, p. 182, pl. 2, fig. 4.

1978 Leptocythere striatocostata (Schweyer) - Olteanu, p. 1019, pl. 4. fig. 7.

1986 Leptocythere striatocostata (Schweyer) - Yassini, p. 31, pl. 11, fig. 8-10.

1989 Amnicythere striatocostata (Schweyer) - Olteanu, pl. VI, fig. 9.

2010 Amnicythere striatocostata ( Schweyer, 1949) Stancheva, 1990 - Boomer et al, p. 129, pl.1, fig. 10.

2013 Leptocythere striatocostata (Schweyer) - Ter Borgh et al., p. 106, fig. 8, 20.

2016 Amnicythere striatocostata (Schweyer) - Van Baak et al., p. 66, fig. 3b, 13-14.

Description. The carapace has an elongated shape in lateral view and is ornamented with more or less pronounced parallel running, narrow ribs that run longitudinally from the posterior margin and fade towards the anterior half of valve. The ribs in some cases merge and form longitudinally, elongated polygons. The anterior part of the valves surface is smooth and thin. Small, wide spaced conulus pores are displayed along the anterior-and posterior borders. The dorsal margin slopes gently towards the posterior that is broadly rounded but slightly compressed. The ventral margin is slightly concave midlength and continues smoothly onto the rounded anterior margin which is flattened but wider than the posterior. The marginal area is broad and pierced by widely spaced branching pore canals. The inner lamella is broadly developed, especially along the anterior border. The RV carries a long smooth bar along the internal part of the dorsal margin, bordered by two pronounced teeth. The LV has a middle ventral snap-pit. Dimension: L = 0,50 – 0,76 mm, H = 0,29 – 0,39 mm, the minimum sizes include juveniles too.

Chronostratigraphical and geographical distribution. The species has been mentioned as a taxon of Pannonian origin ( Olteanu, 1989) and has been described from the late Miocene (Pannonian) of the Pannonian Basin (Fruška Gora inselberg, northern Serbia) ( Ter Borgh et al., 2013). In the Eastern Paratethys, L. striatocostata has been reported from the Pontian (Adzhiveli section, Azerbaijan) (Van Baak et al., 2016) and upper Aspheronian (Hajigabul section) ( Lazarev et al., 2019) of the South Caspian Basin. It is also a common faunal element of middle – upper Quaternary and Holocene deposits from Azerbaijan, Turkmenistan and northern Iran ( Mandelstam et al., 1962; Yassini, 1986).

Ecology. The recent living species in the Caspian- and Black Sea have been reported from salinities ranging from 4 – 12,7 ‰ (Yassini, 1986; Stancheva, 1989). During the Pannonian, L. striatocostata was mentioned as part of an assemblage that was dominated by brackish to freshwater species inside Lake Pannon.

Figures

Fig. 21a-i Amnicythere striatocostata; a LV, external view, ♂; b RV, external view, ♂; c LV, external view, ♀; d RV, external view, ♀; e RV, internal view, ♀; f LV, internal view, ♀; g RV, external view, A1 juvenile; h RV, external view, A2 juvenile; i RV, external view, A3 juvenile; j-n Amnicythere aff. striatocostata; j LV, external view,?♀; k, l RV, external view, ♀; m RV, internal view,?♀; n. RV, external view,?♂; (all specimens from section A, samples 0 m – 35,5 m).