Osteoglossomorpha: phylogeny, biogeography, and fossil record and the significance of key African and Chinese fossil taxa

Abstract

AbstractThe Osteoglossomorpha are a clade of primitive teleostean fishes with modern representatives in five biogeogeographic regions and fossil representatives on six continents. The centre of modern diversity is in Africa but the centre of fossil diversity is in E Asia. Key fossil taxa include: †Phareodus, †Joffrichthys, and †Ostariostomain N America; †Lycoptera, †Paralycoptera, and †Huashiaamong others in E Asia; †Brychaetusand possibly †Thaumaturusin Europe; †Palaeonotopterus, †Singida, and †Chauliopareionin Africa; †Tavernichthysin India; and †Musperiain SE Asia.Morphological phylogenies to date have disagreed on three main points: the relationships of †Lycoptera, ofPantodon, and of Notopterids and Mormyrids. Molecular phylogenies have similarly differed on the last two points. In this study a combined set of morphological data was generated from previous studies, including data from three recently described or redescribed taxa (the African †Singidaand †Chauliopareionand the Chinese †Xixiaichthys) and maximum parsimony was used to generate a revised hypothesis of relationships. Our analysis recovered †Lycoptera, †Paralycoptera+ †Tanolepis, and †Xixiaichthysas stem-group osteoglossomorphs, †Singidaas sister toPantodonwithin Osteoglossidae, †Chauliopareionas a stem osteoglossid, †Ostariostomaas a stem osteoglossiform, and Notopteridae as sister to Mormyroidea and †Palaeonotopterus.These results do not lend themselves to easy explanations of osteoglossomorph biogeography involving either dispersal from a centre of origin or vicariant division of a widely distributed ancestor. Recent suggestions of an ancient (Palaeozoic) origin for osteoglossomorphs are flawed. The evidence, instead, is consistent with an origin within the Mesozoic and the biogeographic explanation involves extensive extinction of clades from continents where they occurred in the past.