Loxoconcha ex. gr. eichwaldi ( Livental, 1929 )

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 : 41

Loxoconcha ex. gr. eichwaldi ( Livental, 1929)

Fig. 26 a-k

1929 Loxoconcha Eichwaldii nov. sp. - Livental, p. 34, pl. 1, figs. 42, 43.

1961 Loxoconcha eichwaldi Livental- Agalarova et al., p. 141, pl. 79, figs. 4a–b.

1967 Loxoconcha eichwaldi Livental- Agalarova, pl. 20, figs. 3a,b.

1978 Loxoconcha eichwaldii Livental- Carbonnel, p. 114, pl. 1, fig. 4.

1999 Loxoconcha eichwaldi Livental- Gliozzi, p. 198, pl. 1, fig. d.

2007 Loxoconcha eichwaldi Livental- Faranda et al., p. 306, fig. 3, 3-4.

2016 Loxoconcha eichwaldi Livental- Stoica et al., p. 865, pl. 6, fig. 10-14.

2016 Loxoconcha eichwaldi Livental- Van Baak et al., p. 67, fig. 4a, 13, 14.

Description. The carapace is oval to rhomboidal in shape and has a distinct punctuate pattern, varying sligthly in size but generally becoming finer towards the marginal area. Like many other species of this genus, L. ex. gr. eichwaldi has a distinguishable eye-spot in the dorsoanterior corner. The dorsal margin is straight and passes smoothly onto the broadly rounded anterior margin. At the posterior end, especially visible in the RV of females, the dorsal margin passes in an obtuse angle onto the posterior boarder, forming a weakly pronounced ledge. The otherwise rounded posterior is inflated and wider than the anterior end, especially in males. The inner lamella is well developed and contains several simple marginal pore canals. The central muscle scar consists of a vertical row of four adductor scars and a V-shaped frontal scar. The hinge is amphidont and made of a crenulated bar that has two separated posterior teeth and one at the anterior end on the RV. Dimension: L = 0,57 – 0,68 mm, H = 0,34 – 0,43 mm, the minimum sizes include juveniles too.

Chronostratigraphical and geographical distribution. The species has been reported from several successions in the Eastern Paratethys. It is known from the Pontian to the Akchagylian - Bakunian interval of Azerbaijan, Turkmenistan, Crimea, Caucasus, Moldavia ( Agalarova et al., 1961; Agalarova 1967; Van Baak et al., 2016; Lazarev et al., 2019) and the Pontian of the Zheleznyi Rog section in Russia ( Stoica et al., 2016). In the Central Paratethys it has been described from the Pannonian and Pontian of Serbia ( Krstić, 1972) and the Pontian of Bosnia ( Sokač, 1967). Outside the Paratethys it has been mentioned from the late Miocene of Corsica, Italy, the Pliocene of the Rhone Valley ( Carbonnel, 1978) and the Messinian of the Vicenne Basin in the central Apennines in Italy ( Gliozzi, 1999). L. eichwaldi has further been described from the Pontian of the Eastern Black Sea region in Turkey ( Tunoğlu, 2001).

Ecology. Together with Loxoconcha muelleri (Méhes) and Cyprideis agrigentina Decima , L. eichwaldi has been described from low mesohaline environments ( Grossi et al., 2015). Recent living Loxoconcha species are reported from mesohaline to euryhaline waters worldwide ( Gliozzi, 1999). Some forms are occurring in stenohaline environments and are limited to marine littoral habitats ( Loxoconcha multifora (Norman)) . Others have euryhaline distributions ( Loxoconcha rhomboidea (Fischer) ( Neale, 1988)) .

Figures

Fig. 26a-k Loxoconcha ex. gr. eichwaldi; a-d RV, external view, ♀; e LV, external view, ♂; f RV, internal view, ♀; g LV, external view, A1 juvenile; h LV, external view, A2 juvenile; i RV, extermal view, A2 juvenile; j, k LV, external view, A3 juvenile; (all specimens from section B, samples 2 m, 19 m and 23 m).