RBMO 45 - Suppl. 1: 635-657.
Article
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The Clupeocephala re-visited: Analysis of characters and homologies
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Gloria Arratia1,2
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1Biodiversity Research Center, The University of Kansas, Dyche Hall, Lawrence, Kansas 66045-7561, U.S.A.
2Department of Geology, Field Museum of Natural History, Chicago, Illinois, U.S.A.
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The characters supporting the monophyly of Clupeocephala are revised. The re-evaluation of these characters demonstrates that: 1) several characters as previously interpreted, are not unique, but homoplastic occurring elsewhere in non clupeocephalans (e.g., †crossognathiforms and osteoglossomorphs); 2) other characters are absent in most basal clupeocephalans; 3) some are variably present in basal clupeocephalans; 4) other characters seem to be wrong; and 5) several characters as previously defined, represent ambiguous homologies. Nevertheless, the present study reveals that the monophyly of Clupeocephala is supported by several unambiguous characters. Three of them are, apparently, uniquely derived novelties (early ossification of autopalatine; hyoidean artery piercing ventral hypohyal; toothplate of last pharyngobranchial or pharyngobranchial cartilage 4 corresponds to growth of only one toothplate), and seven are homoplastic, but are interpreted here as independently acquired in the different teleostean subgroups where they occur (e.g., anguloarticular present; retroarticular excluded from articular facet for quadrate; toothplates on pharyngobranchial 1 absent; six or fewer hypurals present). One character previously interpreted as a clupeocephalan synapomorphy (neural arch of ural centrum 1 [polyural terminology] reduced or lost) is proposed as a euteleostean synapomorphy. Additionally, the results reveal the need for further developmental, morphological, ontogenetic and phylogenetic studies, including many basal and advanced elopomorph, osteoglossomorph, and clupeocephalan species, to understand the meaning and distribution of the homoplastic characters and to test those interpreted as unique novelties of teleostean subgroups.
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Key words: Fishes, Teleostei, monophyly, synapomorphies, homoplasies
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