Vaticinaria Dall 1901

Vaticinaria Dall, 1901 Vaticinaria Dall, 1901 [22 August]. Type species (subsequent designation Chavan 1969): Cryptodon moseleyi E. A. Smith, 1885. South Atlantic. Description. Shell thin, subquadrate to subovate; inequilateral, longer anteriorly; sculpture of commarginal striae; periostracum translucent to light yellow or olive, adherent; hinge plate narrow, edentulous, slightly thickened on each side of umbones, in some; ligament internal, short, extending obliquely posteriorly from beaks; adductor muscles small, subovate, subequal, ventral to animal midline; anterior portion of mantle edge greatly thickened; ctenidium of a single, large inner demibranch. Remarks. In his study of Challenger Expedition (1872–1876) material, E. A. Smith (1885) placed several small putative thyasirids and lucinids in the genus Cryptodon Turton, 1822. The anatomy of Cryptodon moseleyi and Cryptodon luzonicus E. A. Smith, 1885 was described by Pelseneer (1888) who noted several differences between these species and other lucinoideans. Dall (1901) examined these species further and determined they did not fit any thyasirid or ungulinid genera, reluctantly assigning them to Lucinidae and erecting the new genus Vaticinaria. Chavan (1969) designated Vaticinaria moseleyi (Fig. 2 A) as the generic type species but placed the genus in synonymy with Leptaxinus Verrill & Bush, 1898. Vaticinaria moseleyi was subsequently placed in Montacuta by Knudsen (1970) and then in Axinodon Verrill & Bush, 1898, by Huber (2015). After remarking on its galeommatoidean affinities, Dall described Aligena borniana Dall, 1908, (Fig. 2 B – D) from the deep South Pacific and placed it in Aligena H. C. Lea, 1843. Huber (2015) noted similarities in size, morphology, and habitat between A. borniana and V. moseleyi, identifying them as congeneric and placing them in Axinodon as thyasirids. We agree that borniana and moseleyi are congeneric, but little of borniana ’ s anatomy suggests it is a member of Thyasiridae Dall, 1895. We herein place borniana in Vaticinaria in Galeommatoidea (Vaticinaria borniana comb. nov.). Station data for all known members of Vaticinaria are found in Suppl. material 2. Comparisons. As discussed above, Vaticinaria and its component species have an uncertain, alternating placement between Lucinida J. E. Gray, 1854 and Galeommatoidea, driven in large part by its members’ thin, inflated, edentulous valves. As such, Vaticinaria ’ s proper placement is best determined by comparing it to similar genera from several families. The genus Vaticinaria was long synonymized with Aligena H. C. Lea, 1843, a genus of small bivalves with a similar history of containing species later assigned to Galeommatoidea and Thyasiridae. Aligena striata H. C. Lea, 1843, the type species of the genus, has a small cardinal tooth in each valve (Fig. 2 F) and thus differs significantly from Vaticinaria, which is edentulous (Fig. 2 C, D). This condition also clearly sets Vaticinaria apart from the superficially similar Kelliola Dall, 1899 (with anterior cardinals in each valve); separate from Kelliopsis Verrill & Bush, 1898 (anterior cardinal and posterior ridge in each valve); and unlike either Montacuta Turton, 1822 (anterior cardinal in each valve) or Syssitomya Oliver, 2012 (anterior cardinal in right valve and anterior lateral in left valve). The genus with shell morphology most similar to Vaticinaria is the enigmatic Axinodon Verrill & Bush, 1898, erected for the deep-Atlantic Axinodon ellipticus Verrill & Bush, 1898 (Fig. 2 G, H). Both genera possess thin valves with a greatly expanded anterior, an internal oblique ligament, and a hinge with no clear dentition. Axinodon differs in having more prominent umbones and lacking the shallow resilifer and silky periostracum of Vaticinaria. In terms of shell characters, Axinodon resembles a thyasirid, but without further analyses of its soft anatomy, the genus’ placement remains uncertain.