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SCHWARZHANS, Werner:A comparative morphological treatise of recent and fossil otoliths of the order Pleuronectiformes1999. [in English] – 392 pp., 1021 figures. ISBN 978-3-931516-54-3 Euro 75.00 |
The following morphological study of otoliths of the order Pleuronectiformes (flatfishes) is the second part of a long term catalogue project mainly dealing with recent otoliths. Amongst teleost groups of comparable size, the otoliths of the order Pleuronectiformes are amongst the least well known. They are also not the easiest to work with morphologically and have never been subject of a comprehensive analysis. Taxonomic work with pleuronectiform otoliths is somewhat hampered by the often high degree of intraspecific variability, the low level of interspecific morphological differentiation and of course the ubiquitous effects of asymmetry.
For this treatise I have investigated otoliths of more than 300 recent species of the Pleuronectiformes (corresponding to more than 50 % of the known recent species of the order) covering 116 genera of the 133 currently recognized. In addition, the 124 nominal fossil otolith species of the Pleuronectiformes and 47 recent species that have also been described from fossil otoliths are being revised. For this revision I have investigated otoliths of the majority of the nominal fossil species, mostly including type-material. The results of other important revisions recently made have been incorporated. As a result of this revision, 26 species are removed from the Pleuronectiformes, 60 fossil species and 35 recent species recorded as fossils are regarded as valid. 18 species are described as new: genus aff. Rhombocitharus novaezeelandiae, genus aff. Brachypleura xenosulcis, Pseudorhombus weinfurteri, Cyclopsetta transitus, Syacium dominicensis, Etropus concaviventris, Grammatobothus awamoaensis, Grammatobothus radwanskae, Arnoglossus grenfelli, Arnoglossus quadratus, Caulopsetta arnoglossoides, Laeops rharbensis, Samaris validus, Microchirus wienrichi, Quenselia cornuta, Pseudopardachirolithus nolfi, Peltorhamphus flexodorsalis, Cynoglossus obliqueventralis. 3 new fossil genera are established, all in the family Soleidae: Granulithus, Praeachirolithus and Pseudopardachirolithus. The phylogenetic interpretations and conclusions from the character-analysis of the otolith-morphology are being discussed and compared to published ichthyological analyses. As a result of this several systematical reallocations within the Pleuronectiformes are being proposed. This includes:
1. The separation of the genera Tephrinectes, Paralichthodes and of the Ammotretis Group from their traditional allocations to a position near the Citharidae (as early pleuronectiform off springs).
2. Upgrading of the Brachypleuridae to a separate family next to the Citharidae.
3. Reallocation of the genus Azygopus from the Rhombosoleinae (sensu NORMAN, 1934) to the Samarinae.
4. Reallocation of the genus Peltorhamphus from the Pleuronectidae (Rhombosoleinae; sensu NORMAN 1934) to the Soleidae.
5. Reduction of the Rhombosoleinae (sensu NORMAN, 1934) to include only the two genera Pelotretis and Rhombosolea.
Possible relationships are being discussed between the various genera in the Bothidae, Pleuronectidae and Soleidae as well as between the two families Soleidae and Cynoglossidae. The descriptions and figures of the pleuronectiform otoliths are arranged in 40 informal "genus groups", distributed through 8 families and one group of genera of uncertain relationship, reflecting the results of the otolith analyses. This arrangement is not meant to represent a new formal subclassification of the order Pleuronectiformes.
With this second volume (as with the previous one) in the newly established Otolithi Piscium Catalogus format, I have put great emphasis on large and, I hope, clear and detailed drawings. Whenever possible, I tried to figure more than just one specimen of each species to document intraspecific variability, morphological asymmetry when and where it occurs and ontogenetic changes in morphology. Due to the nature of the flatfishes, special emphasis is paid to side dimorphism of their otoliths, which is reflected in depicting otoliths of both sides of the fishes as far as this was achievable.
With this monograph I hope to fulfill the following main objective: Present as many as possible detailed figures of recent and fossil pleuronectiform otoliths and thereby create a comprehensive basis for identification and correlation of otoliths for this order.
| Copyright © 2010 Verlag Dr. Friedrich Pfeil |