Ceratoscopelus brevis, Schwarzhans & Ohe & Tsuchiya & Ujihara, 2022

Schwarzhans, Werner, Ohe, Fumio, Tsuchiya, Yuki & Ujihara, Atsushi, 2022, Lanternfish otoliths (Myctophidae, Teleostei) from the Miocene of Japan, Zitteliana 96, pp. 103-134 : 103

Ceratoscopelus brevis sp. nov.

Fig. 6F-M

Etymology.

From Ceratoscopelus brevis (Latin) = short, referring to the compressed shape of the otoliths.

Holotype.

SMF PO 101.117 (Fig. 6J-M ); Miya River at Numa, Tsuyama City, Okayama Prefecture, Takakura FM, level MS 15, late Burdigalian, diatom zone 3A-3B.

Paratypes.

3 specimens (SMF PO 101.118), same location as holotype, levels MS 07, MS 22, MS 52.

Tentatively assigned specimens.

2 poorly preserved specimens from Osedani, Toyama City, Toyama Prefecture, Higashibessho FM, level H 21 may also represent this species and are tentatively assigned.

Diagnosis.

OL:OH = 1.25-1.35. Rostrum moderately long with rounded tip, 18-22% of OL. Dorsal, posterior and ventral rims all continuously curved. OCL:CCL = 1.8-2.5. Outer face with radial furrows close to rims and smooth, slightly bulged central region set off by circular furrow.

Description.

Small, delicate otoliths reaching about 2.25 mm in length (holotype 1.8 mm). OH:OT = 3.6-3.8. Dorsal rim gently curving without marked angles, continuously curving into rounded posterior and ventral rims around posterior reaches of otolith. Rostrum massive, broad, moderately long (18-22% of OL), with rounded tip; no or minute antirostrum and excisura. All rims slightly undulating.

Inner face nearly flat, with long, distinctly supramedian, shallow positioned sulcus; OL:SuL = 1.25. Ostium about twice as long as cauda (OCL:CCL = 1.8-2.5), straight and slightly wider. Caudal colliculum oval, underlain by slightly anteriorly shifted pseudocolliculum. Ventral furrow variable in expression and position; dorsal depression narrow, indistinct except towards crista superior. Outer face slightly convex with radial furrows along rims and characteristic smooth central area set off from rest of outer face by distinct circular furrow.

Discussion.

Otoliths of C. brevis are typical of those of Ceratoscopelus otoliths with the flat inner face and the long rostrum paired with minute antirostrum and excisura. Ceratoscopelus brevis differs from the three extant species by being more compressed and the regularly curving and undulating rims and characteristic aspect of the outer face. Its proportions are similar to those of the earlier C. richardsoni Schwarzhans, 2019 from New Zealand but differ in the very regularly curving posterior rim section of the otolith (vs. presence of a distinct obtuse postdorsal angle). An otolith found in situ and described as C. miocenicus Bedini, Francalacci & Landini, 1986 from the late Miocene of Italy is even more compressed and shows a pointed rostrum. Otoliths described as Ceratoscopelus sp. from the late Burdigalian of Chile ( Schwarzhans and Nielsen 2021) differ in the pronounced postdorsal angle at the junction with the posterior rim, the oblique posterior rim, and the lack of any marginal crenulation of the rims. It appears that the Miocene Epoch featured a greater diversity of the genus than that observed today ( Linkowski 1997).

Figures

Figure 6. A-D: Bolinichthys higashibesshoensis sp. nov., holotype, SMF PO 101.116, Fuchu machi, Toyama City, Higashibessho Formation, level H 20; E: Bolinichthys distofax Johnson, 1975, coll. Schwarzhans, Recent, Walter Herwig R / V, station 459 - 71; F-M: Ceratoscopelus brevis sp. nov., Tsuyama City, Takakura Formation; J-M: holotype, SMF PO 101.117, level MS 15; F-I: paratypes, SMF PO 101.118, levels MS 7, MS 52; N-Q: Lampadena exima sp. nov., holotype, SMF PO 101.119, Tsuyama City, Takakura Formation, level MS 36; R-U: Lampadena speculigera Goode & Bean, 1896, Recent; R: coll. Schwarzhans, Walter Herwig R / V, 38 ° S, 54 ° W; S: MCZ 169474; T-U: MCZ 96917; V-X: Taaningichthys sp., SMF PO 101.120, Tsuyama City, Takakura Formation, level MS 27.