Bolinichthys higashibesshoensis, 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

Bolinichthys higashibesshoensis sp. nov.

Fig. 6A-D

Etymology.

Named after the type formation Higashibessho FM.

Holotype.

SMF PO 101.116 (Fig. 6A-D ), Osedani, Toyama City, Toyama Prefecture, Higashibessho FM, level H 20, late Burdigalian to early Langhian, diatom zone 3A-4A.

Paratype.

One specimen, SMF PO 101.149, same location as holotype, level H 21.

Diagnosis.

OL:OH = 1.25. Ventral rim shallow with 4 denticles anteriorly; dorsal rim shallow, smooth. Rostrum inferior, long, rounded, distinctly longer than antirostrum, 18% of OL. OCL:CCL = 1.85. Inner face flat; outer face convex, smooth.

Description.

A well preserved and very typical otolith with rounded parallelogram-like outline of 1.8 mm length. OH:OT = 4.0. Ventral rim shallow, anteriorly pronounced and there with 4 broad, rounded denticles; dorsal rim shallow, smooth, with distinct, rounded postdorsal angle at junction with oblique, smooth posterior rim. Rostrum very broad, inferior, with rounded tip, distinctly longer than antirostrum. Antirostrum far dorsally shifted, short, pointed; excisura relatively deep, angular.

Inner face completely flat, with more or less centrally positioned, narrow and relatively shallow sulcus. Ostium nearly twice as long as cauda (OCL:CCL = 1.85). Dorsal margin of ostium straight, oriented slightly upward towards anterior; ventral margin of ostium distinctly concave and curved. Cauda slightly upward oriented; its pseudocolliculum extending forward beyond caudal colliculum. Ventral furrow weak, close to ventral rim of otolith. Dorsal depression large with indistinct boundary except towards sulcus with distinct crista superior. Outer face moderately convex, entirely smooth.

Discussion.

Bolinichthys higashibesshoensis is a typical species of the genus and cannot be confused with any of the few fossil species of the genus: the late Miocene B. italicus (Anfossi & Mosna, 1971) is characterized by a pointed rostrum and the lack of an excisura; B. kreffti Schwarzhans, 1986 from the early Pliocene differs in its outline and the more undulating and extended nature of the ventral rim and also shows a straight ostium. Both species have been found in sediments along the Mediterranean, and B. higashibesshoensis hence represents the only fossil species from the Pacific. Bolinichthys higashibesshoensis resembles extant otoliths of the genus but is more compressed than most of them, with the exceptions of B. distofax Johnson, 1975 (Fig. 6E ) and B. supralateralis (Parr, 1928) (see Brzobohatý and Nolf 2000 for figure), from which it differs in the relatively shorter rostrum, the deeper excisura, and the oscillating ventral margin of the ostium. The latter character is found in certain other extant Bolinichthys species, notably B. indicus (Nafpaktitis & Nafpaktitis, 1969) and B. longipes (Brauer, 1906), from which, however, it differs in the other abovementioned characters.

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.