Phylogenetic Interrelationships of Ginglymodian Fishes (Actinopterygii: Neopterygii)

The Ginglymodi is one of the most common, though poorly understood groups of neopterygians, which includes gars, macrosemiiforms, and ‘‘semionotiforms.’ ’ In particular, the phylogenetic relationships between the widely distributed ‘‘semionotiforms,’ ’ and between them and other ginglymodians have been enigmatic. Here, the phylogenetic relationships between eight of the 11 ‘‘semionotiform’ ’ genera, five genera of living and fossil gars and three macrosemiid genera, are analysed through cladistic analysis, based on 90 morphological characters and 37 taxa, including 7 out-group taxa. The results of the analysis show that the Ginglymodi includes two main lineages: Lepisosteiformes and {Semionotiformes. The genera {Pliodetes, {Araripelepidotes, {Lepidotes, {Scheenstia, and {Isanichthys are lepisosteiforms, and not semionotiforms, as previously thought, and these taxa extend the stratigraphic range of the lineage leading to gars back up to the Early Jurassic. A monophyletic {Lepidotes is restricted to the Early Jurassic species, whereas the strongly tritoral species previously referred to {Lepidotes are referred to {Scheenstia. Other species previously referred to {Lepidotes represent other genera or new taxa. The macrosemiids are well nested within semionotiforms, together with {Semionotidae, here restricted to {Semionotus, and a new family including {Callipurbeckia n. gen. minor (previously referred to {Lepidotes), {Macrosemimimus, {Tlayuamichin, {Paralepidotus, and {Semiolepis. Due to the numerous taxonomic changes needed according to the phylogenetic analysis, this article also includes formal taxonomic definitions and diagnoses for all generic and higher taxa