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The genus Hexabathynella (Crustacea, Malacostraca, Bathynellacea) is revised in the sense of the phylogenetic systematics and four new species are described from South Africa ( H. monoaethetasca sp. nov. and H. africana sp. nov. ) and America ( H. schrieveri sp. nov. and H. virginiae sp. nov. ). A comparative analysis of all observable outer structures distributed in 18 known and four new species resulted in a re-evaluation of 18 characters and character states. The phylogenetic analysis using the program PAUP yielded one most-parsimonious tree, which suggests the grouping of ( H. decora (( H. halophila + H. aotearoae ) + ( H. pauliani ( H. monoaethetasca + H. africana )))) + ( H. knoepffleri ( H. nicoleiana ( H. hebrica , H. tenera , H. longiappendiculata , H. breviappendiculata , H. nestica ) + H. virginiae (( H. minuta ( H. valdecasasi + H. otayana )) + ( H. hessleri + H. muliebris ))) + H. paranaensis ( H. szidati + H. schrieveri )). The tree is 57 steps long and has a consistency index of 0.6140, a retention index of 0.7982 and a rescaled consistency index of 0.4901. The result does not agree with the previous analyses on the genus. In terms of sampling and coding, the characters used in the previous study are critically assessed. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 147 , 71–96. 相似文献
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A. I. Camacho T. Torres C. J. Puch J. E. Ortiz Antonio G. Valdecasas 《Biodiversity and Conservation》2006,15(11):3527-3541
An analysis was made of the micro-distribution patterns of five phylogenetically closely related species belonging to the
genus Iberobathynella, a group of subterranean aquatic crustaceans (Syncarida, Parabathynellidae). The two-step model of colonization and speciation
seems to provide a valid explanation for the current distribution of a large number of stygobiontic taxa of marine origin
(thalassoid). However, with respect to the Iberobathynella, only the colonization of the subterranean environment at the mesoscale level can be explained. The second phase of the model,
marine regression, can only explain the colonization of the region by the ancestor; the subsequent evolution and speciation
at a smaller scale remain to be explained. Local geological constraints – Upper Triassic gypsiferous mudstone deposits plus
faults and thrusting linked to the Alpine Orogeny – are responsible for the appearance of local palaeogeographic phenomena.
These may have been the vicariant processes responsible for the geographical and genetic isolation of the ancestral populations
of this group, which eventually led to clade divergence. Together with small-scale passive dispersion (11 dispersal events)
and local extinction, these processes could be responsible for the current distribution of the five sister taxa inhabiting
the caves of the Sierra de la Collada, Spain. A plausible palaeogeographical scenario is offered to explain their present
distribution, that clearly came about through chance events. 相似文献
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