Diaphus biatlanticus (Weiler, 1959)

Nyctophus biatlanticus 1959 Nyctophus biatlanticus - Weiler: figs 9, 10.

Diaphus biatlanticus 2013 Diaphus biatlanticus (Weiler, 1959) - Schwarzhans and Aguilera: pl. 11, figs 1-8 (see there for further synonymies).

Material.

7 specimens; 5 specimens (figured specimen SMF PO 101.145), Miya River at Numa, Tsuyama City, Okayama Prefecture, Takakura FM, levels MS 27, MS 52, h, late Burdigalian, diatom zones 3A-3B ; 2 specimens (SMF OP 101.144), Okuna, Mizunami City, Gifu Prefecture, Oidawara FM, early Langhian, diatom zone 4A .

Discussion.

Diaphus biatlanticus has thus far only been reported from the early to middle Miocene of tropical America (Trinidad and Venezuela). Its otoliths are characterized by a very regular oval outline, a short rostrum, a short antirostrum and a minute excisura, a relatively long ostium compared to the cauda (OCL:CCL = 2.0-2.4), and a convex inner face combined with a flat to slightly concave outer face. The rare occurrence of the species in the middle Miocene of Japan indicates that it had a much wider geographical distribution than previously believed.