Johnius sp.

Jirapatrasilp, Parin, Cuny, Gilles, Kocsis, László, Sutcharit, Chirasak, Ngamnisai, Nom, Charoentitirat, Thasinee, Kumpitak, Satapat & Suraprasit, Kantapon, 2024, Mid-Holocene marine faunas from the Bangkok Clay deposits in Nakhon Nayok, the Central Plain of Thailand, ZooKeys 1202, pp. 1-110 : 1-110

Johnius sp.

Fig. 32

Referred material.

CUF - NKNY - 16.2 (Fig. 32 A – D ) (1 right sagitta otolith).

Description.

Thick otolith with a smooth external surface, whereas the internal surface bears a sulcus characteristic of the genus. The ostium is shallow, vertically positioned, higher than long, and it widens ventrally. The anterior and horizontal portion of the cauda is short and shallow, then opening posteriorly into a deep caudal funnel with an external circular shape.

Taxonomic remarks and comparisons.

Otoliths of Johnius are unique and have distinct characteristics that make them easily distinguishable from those of other sciaenids or teleosts ( Schwarzhans 1993). There are 21 species of Johnius in Southeast Asia ( Froese and Pauly 2024), and most of them inhabit shallow coastal waters and estuaries but some species are capable of entering rivers. They are also known from the fossil records in Japan ( Ohe 1976) and Taiwan ( Lin et al. 2022).

Figures

Figure 32. Sciaenid otolith of Johnius sp., specimen CUF - NKNY - 16.2, right sagitta otolith in A inner B external C anterior and D posterior views.