Two New Genera and Species of Oligocene Spikefishes (Tetraodontiformes: Triacanthodidae), the First Fossils of the Hollardiinae and Triacanthodinae

Abstract

Two new genera and species of spikefishes from the Menilitic Formation (late Tethys Sea) of the Upper Oligocene of Poland represent the first fossils of the two subfamilies of the tetraodontiform family Triacanthodidae. One of the new genera, <i>Prohollardia</i>, has a dome-like supraoccipital, the epiotics separated medially on the dorsal surface of the skull, the epiotics articulated anteriorly with the frontals, and a shaft-like posterior process of the pelvis, which are diagnostic features of the Hollardiinae. The other, <i>Carpathospinosus</i>, has a flattened supraoccipital with only a small crest anteromedially, the epiotics in contact medially on the dorsal surface of the skull, the epiotics separated from the frontals by the sphenotic, and a broad basin-like posterior process of the pelvis, which are diagnostic features of the Triacanthodinae. Some of these features of the Triacanthodinae are shown to be derived. The separation of the two subfamilies of Triacanthodidae took place no less than about 29 to 24 MYA. In an addendum, the Oligocene fish from Romania that was described in the dactylopteriform family Cephalacanthidae (Dactylopteridae) as <i>Cephalacanthus trispinosus</i> Ciobanu (1977) is referred to the Triacanthidae (the anatomically derived sistergroup of the Triacanthodidae) as a member of the triplespine genus <i>Acanthopleurus</i> Agassiz (1842). The single specimen is a juvenile and at least closely related to <i>A. serratus</i> Agassiz (1842) and A. <i>collettei</i> Tyler (1980), both from the Oligocene of Switzerland, and possibly identical to one or the other.