Benthosema Goode & Bean, 1896

Genus Benthosema Goode & Bean, 1896 View in CoL

Remarks Benthosema otoliths typically exhibit certain characteristics, including a robust antirostrum and a specific arrangement of ventral denticles. Tis arrangement consists of 1–3 anterior denticles separated from a single, strong posterior denticle by a smooth gap along the ventral margin (Schwarzhans & Ohe, 2019; Schwarzhans, 2019a). However, we found that the presence of a consistent smooth gap may vary within species such as Benthosema pterotum (Alcock, 1890) . Tese intra-specific variations are mainly attributed to ontogeny ( Fig. 7 View Fig ).

Tree species of Benthosema , B. fibulatum , B. pterotum , and B. suborbitale (Gilbert, 1913) , are known in Taiwanese waters today (Shao, 2023). Among them, the otoliths of B. suborbitale exhibit distinct characteristics, including a salient depression on the postero-dorsal rim and two consistently spaced ventral denticles separated by a smooth gap ( Schwarzhans, 2019a: Fig. 49–4). Te otoliths of B. fibulatum feature a more pronounced posterior rim that extends further backward and a gently curved ventral rim ( Fig. 7a–c View Fig ). Te otoliths of B. pterotum are characterized by equal dorsal and ventral areas with both rostrum and antirostrum similar in size

( Fig. 7d–h View Fig ). Juvenile otoliths of B. pterotum are more rounded ( Fig. 7h View Fig ), while in adults, the otoliths are semirectangular and elongated ( Fig. 7d View Fig ). Te presence of a smooth gap on the ventral margin may become more evident in larger specimens.