Browsing by Author "Britz, Ralf."
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Item Descriptive osteology of the family Chaudhuriidae (Teleostei, Synbranchiformes, Mastacembeloidei), with a discussion of its relationships. American Museum novitates ; no. 3418(New York, NY : American Museum of Natural History, 2003) Britz, Ralf.; Kottelat, Maurice.The little known earthworm eel family Chaudhuriidae consists of nine small to minute species of Asian freshwater fishes. In this paper, the osteology of seven representatives of the family is described in detail for the first time. We propose a list of 21 synapomorphies to support chaudhuriid monophyly. Reductive characters are: loss of basisphenoid, pterosphenoid, endopterygoid, dermopalatine, pars autopalatina, posttemporal, gill rakers, toothplate on pharyngobranchial two, distal pectoral radials, lateral line canals, dorsal- and anal-fin spines and their supporting pterygiophores, epurals, uroneurals, parhypural, and reduction in numbers of epicentrals and hypurals. Progressive characters are: presence of a long membrane bone process on autosphenotic, a boomerang-shaped ectopterygoid with a long preorbital extension, an anterior process of membrane bone of the metapterygoid, a unique arrangement of dorsal gill arch elements, separate foramina for the three trigeminal branches, and a ventromedian keel on the first vertebra. The new information is used to critically reevaluate previous hypotheses of chaudhuriid relationships. Finally, the issue of miniaturization in chaudhuriid fishes is addressed and discussed.Item Egg surface structure and larval cement glands in nandid and badid fishes, with remarks on phylogeny and biogeography. American Museum novitates ; no. 3195(New York, N.Y. : American Museum of Natural History, 1997) Britz, Ralf.Item Homology of intermuscular bones in acanthomorph fishes. American Museum novitates ; no. 3241(New York, NY : American Museum of Natural History, 1998) Gemballa, Sven.; Britz, Ralf.Myosepta of selected representatives of the following acanthomorph taxa were investigated: Polymixiiformes, Lampridiformes, Paracanthopterygii, Beryciformes, Atherinomorpha, and Percomorpha. A new technique, microdissection of alcohol-stored specimens and polarized-light microscopy, was applied to study the three-dimensional architecture of connective tissue fibers in epaxial parts of myosepta. Several invariable similarities were present in all taxa: an epineural series of tendons or bones and a tendinous series of lateral bands in the epaxial part of the myoseptum, and an epicentral series of tendons or bones in the horizontal septum. Patterson and Johnson's (1995) hypothesis that the single bony series of intermusculars in higher acanthomorphs is the homolog of epineurals of lower teleosts is tested. Our results contradict their hypothesis at essential points because we discovered epineural tendons in the normal epaxial position in different acanthomorphs that were considered to lack these. We conclude that the first intermuscular bone of Polymixia is an epicentral, the single series of intermuscular bones of Holacanthopterygii are epicentrals, and the neoneurals of some percomorphs are normal epineurals. Phylogenetic implications of our results are discussed.Item Ontogeny of the ethmoidal region and hyopalatine arch in Macrognathus pancalus (Percomorpha, Mastacembeloidei) : with critical remarks on mastacembeloid inter- and intrarelationships. American Museum novitates ; no. 3181(New York, N.Y. : American Museum of Natural History, 1996) Britz, Ralf.Item "Paradox lost" : skeletal ontogeny of Indostomus paradoxus and its significance for the phylogenetic relationships of Indostomidae (Teleostei, Gasterosteiformes). American Museum novitates ; no. 3383(New York, NY : American Museum of Natural History, 2002) Britz, Ralf.; Johnson, G. David.On the basis of an ontogenetic series of Indostomus paradoxus, we test characters that have been proposed for the phylogenetic placement of this enigmatic taxon. Contrary to previous authors, we found that the body armor of Indostomus differs from that of syngnathoids greatly and it closely resembles that of gasterosteoids in many unique details. The body plates originate from two different sources, that is, the endoskeleton (proximal-middle radials of dorsal and anal fin, neural and hemal spines, pelvic cartilages) and the exoskeleton (postcleithra, lateral body plates, sternal plate). The median bone in the ethmoid region develops from two centers and most likely represents the nasal bones that fuse during ontogeny with each other and with the vomer. Identity of the opercular bones is clarified, and it is demonstrated that Indostomus has an interopercle. The single pterygoid bone is the ectopterygoid. A parietal is lacking. There is only one cartilaginously preformed hypural element in the caudal fin. There is no parhypural, but a similar structure, termed the pseudoparhypural by us, develops as membranous outgrowths of the single hypural and the ural centrum. The pectoral radial plate fuses to the scapulocoracoid cartilage, and the pectoral radials ossify within that fused plate without prior fragmentation of the plate into individual radials, being specializations of the pectoral girdle that we think to be shared with all gasterosteoids. Indostomus shares with other gasterosteiforms the modification of the tripartite occipital condyle into an articulation of the basioccipital and the first centrum through loss of the articulation between exoccipitals and the first centrum in all developmental stages. Indostomus lacks distal radials in all pterygiophores supporting fin spines at all developmental stages, a character shared with other gasterosteiforms, mastacembelids, and probably other smegmamorphs. We conclude that Indostomus is a gasterosteoid gasterosteiform.