Malakichthys sp.

Lin, Chien-Hsiang, Wu, Siao-Man, Lin, Chia-Yen & Chien, Chi-Wei, 2023, Early Pliocene otolith assemblages from the outer-shelf environment reveal the establishment of mesopelagic fish fauna over 3 million years ago in southwestern Taiwan, Swiss Journal of Palaeontology (23) 142 (1), pp. 1-40 : 29

Malakichthys sp.

Figure 16e–g

2021 Malakichthys sp. —Lin et al.: Fig. 5b–d [ Taiwan].

Remarks Te otoliths of Malakichthys are characterized by their massive and thickset structure as well as their high-bodied and pentagonal outline. Tey share some similarities of the sulcus with the otoliths of Acropoma , particularly in juveniles (see above). However, one distinguishing feature of Malakichthys otoliths is that the ostium appears to bend upwards more strongly. In Taiwan, there are four known species of Malakichthys (Shao, 2023) , but their otoliths exhibit subtle or no distinct differences that can be used for species-level identification (Lin & Chang, 2012: pl.319). Terefore, it is challenging to assign these otoliths to a specific species within the genus based on their morphology alone.

Figures

Fig. 16 Fish otoliths from the Lower Pliocene Gutingkeng Formation,southern Taiwan. Scale bars =1 mm. Images are inner views unless otherwise indicated. a–b Acropoma hanedai Matsubara, 1953, Site 2, ASIZF 0100686–687.c–d Acropoma japonicum GÜnther, 1859, Site 5, sand layer, ASIZF 0100688–689.e–g Malakichthys sp., Site 2, ASIZF 0100690–692. h Synagrops japonicus (Döderlein, 1883), Site 5, sand layer, ASIZF 0100693.i Serranidae indet., Site 5, sand layer, ASIZF 0100694.j Upeneus sp., Site 2, ASIZF 0100695.1, ventral view; 2, inner view

Fig. 5 Extant Neoscopelus otoliths from Taiwan. Scale bars=1 mm. Images are inner views. a–d Neoscopelus macrolepidotus Johnson, 1863, a 25 Mar.2022,110.61 mm SL,CHLOL 15935, b 25 Mar.2022,75.78 mm SL, CHLOL 16588, c, 25 Mar. 2022, 75.55 mm SL,CHLOL 15902, d, 25 Mar. 2022, 60.10 mm SL, CHLOL 16592. e–h Neoscopelus microchir Matsubara, 1943, e, 21 Jan. 2021, 171.07 mm SL, CHLOL 3283, f 21 Jan. 2021, 116.36 mm SL, CHLOL 3287, g 19 Feb. 2020, 60.75 mm SL,CHLOL 819, h 29 Jul.2021,95.46 mm SL, CHLOL 8208. i–l Neoscopelus porosus Arai, 1969, i 24 Jan. 2021, 120.58 mm SL, CHLOL 2127, j 29 Dec. 2021, 100.18 mm SL, CHLOL 13389, k 24 Jan. 2021, 55.30 mm SL,CHLOL 2136,l 19 Feb. 2020,78.81 mm SL, CHLOL 824