Splitting by adaptive traits in the Rhyacophila obscura species group (Trichoptera, Rhyacophilidae)

Abstract

The discovery of two new sibling species of the Rhyacophila obscura species group in the same population from the Fan-Si-Pan Mts. of Vietnam and the detected shape divergences of paraprocts with speciation trait function of repro-ductive barrier building initiated the survey of the entire species group. Character tree discordances inside the species tree motivated and justified us to survey briefly some aspects of splitting theory and practice. At all levels of taxonomic hierarchy there are genealogical discordances. Every homologous phenomic trait or nucleotide position may have their own true tree-like history. How taxonomists try to create nominal kinds most corresponding to the natural kinds along the iterative fractal splitting. Fractal is the nature‘s geometry and organises itself by the negentropy of integration and reticulation against the entropy of disintegration. Splitting along fractals and reticulation produces independent adaptive or neutral genealogically discordant trees; therefore, the reality of phylogenetic trees is highly questioned. Pheneticists work with large set of unweighted characters and without real hermeneutic analysis. Applying large number of unweighted adult, larval or molecular characters of independent tree histories and without hermeneutics we kill the reality of splitting. In the genealogy of Rhyacophila obscura species group we have applied weighted characters in lineage splitting by the hermeneutics of adaptive/neutral, commonality/generality, distribution/area and complexity/simplicity principles. Rhyacophila obscura, the ancestral species of the species group has (1) the most robust/complex adaptive epiproct and paraproct, the traits liable to adaptive divergences in reproductive isolation; (2) the most common/general distribution of the adaptive ancestral epiproct in the complex; (3) and the largest distributional area. This ancestral species was diverged to R. bidens, to the ancestor of the complex splitted by the reduction of epiproct to a small bilobed structure. The ancestral complex of R. obscura and the first splitted complex of R. bidens have been further splitted both by contemporary adaptive paraproct reduction and by neutral stochastic shape divergences of segment X and harpagones. During these splitting practices four new species were described: R. assamensis sp. nov., R. atlagos sp. nov., R. kurta sp. nov., R. sudar sp. nov.

Keywords

• Trait tree
• species tree
• splitting principles
• new species