Hubertschenckia Takeda, 1953

Kiel, Steffen, Amano, Kazutaka & Goedert, James L., 2023, New taxa, records, and data for vesicomyid bivalves from Cenozoic strata of the North Pacific region, Acta Palaeontologica Polonica 68 (2), pp. 297-320 : 314-315

Genus Hubertschenckia Takeda, 1953

Remarks.—A species named Hubertschenckia quisquiliae Hu, 1995 , was reported from Eocene–Oligocene strata in south-central Taiwan, near Yakou village along Nankeng road ( Hu 1995: 2020–2021, pl. 369: 1, 5; pl. 370: 9, 16; pl. 371: 1, 6, 8, 9). The shell was described as follows: “The shell is unequal triangular in shape, moderately swollen, with a short and concave front, a long and slight arc in the back, and a slightly boat-bottom-shaped ventral side. The umbo is located in front of the vertical midline, protruding and slightly inclined to the front. The front end of the shell is short and small, and the rear end is long and round. The surface is sculptured by evenly spaced commarginal ribs.” ( Hu 1995, translated from Chinese by Liping Liu).

The illustrated specimens, some of which were examined by SK in the National Museum of Natural Sciences in Taichung (NMNS 007556), bear some resemblance to Hubertschenckia ezoensis in outline, showing a large, round anterior adductor muscle scar and reaching 70 mm in length. Some have distinctive, equally spaced commarginal ribs with smooth, rounded surfaces (similar to those of an Astarte ). Although these ribs match those on the sketch reconstruction by Hu (1995: 2021, text-fig. 7), several illustrated specimens are far more elongated (like H. ezoensis ) than on Hu’s (1995) sketch reconstruction. Whether all of those specimens belong to the same species, and whether any of the specimens belong to Hubertschenckia , remains questionable.

Hubertschenckia snatolensis Sinelnikova in Sinelnikova et al., 1991, was described from the middle Eocene Snatol Formation in western Kamchatka ( Sinelnikova et al. 1991: 157, pl. 39: 14, pl. 40: 20). The species was described as “Shell elongate, flat, rather small, with almost parallel dorsal and ventral margin, and much anteriorly located umbo. Umbo very wide and weakly bending. Sculpture only consisting of growth lines. Hinge ill-preserved, but two cardinal teeth well visible on each valve. Pallial sinus wide, very short and high, with round top, located near muscle scar. Measurements (in mm); length = 35, height = 19, thickness = 8. Comparison; This species is distinguished from Hubertschenckia ezoensis (Yok.) by having much smaller size, longer and more flat shell.” ( Sinelnikova et al. 1991, translated from Russian by KA).

The description and illustrations of this species are insufficient to accept or reject affinities to Vesicomyidae . Considering its size and outline, the specimens resemble Squiresica rather than Hubertschenckia ; however, the reported two cardinal teeth in each valve would preclude a placement in either of these genera.

As noted in the discussion of Pleurophopsis thieli , an unidentified species questionably assigned to Hubertschenckia was listed from upper Oligocene to Lower Miocene localities in the Katalla Formation on Kayak Island, Alaska ( Plafker 1974).