In 1975, David E. Fairbrothers et al. first suggested a link between chemical properties and certain morphological groupings, based on the theory that morphologically similar plants produce chemical constituents with similar therapeutic effects.
The planktonic foraminifera appear polyphyletic, falling in at least 4 separate areas of the tree, consistent with the morphological groupings of the spinose (Globigerinidae and Hastigerinidae), non-spinose macroperforate (Globorotaliidae & Pulleniatinidae), non-spinose microperforate (Candeinidae), and the non-spiral planktonic foraminifera (see [ 71]).
The morphological partition supported several groupings found by previous morphological studies but contradicted by most molecular studies, including Balaenoidea [ 2, 38, 39], Physeteroidea + Ziphiidae [ 2, 9, 10], Platanista + Lipotes [ 2], and the grouping of Orcinus orca within Globicephalinae [ 6].
The taxonomy of Pocillopora is currently regarded as tenuous, e.g., some 16 species have been defined on the basis of morphological features, but cladistic groupings defined by molecular sequence data are not always congruent with these morphologically defined taxa (e.g., [ 31]).
We also found morphological support for two novel groupings, Balaenoidea + Balaenopteridae and Monodontidae + Delphinidae.
This grouping has largely remained robust to molecular phylogenetic analyses (although chaetognaths and lophophorates are no longer considered deuterostomes), as opposed to the protostomes in which many groupings based on morphological similarities have not been supported by molecular data.
Traditional classification of Culicidae based on the phenetic framework of Edwards [ 7] resulted in arbitrary groupings reflecting intuitive interpretation of morphological similarities.
Despite the strength of the phylogenetic signal and the high resolution of reconstructed species relationships, the mtDNA phylogeny contains several groupings in striking conflict with morphological, ecological and behavioral similarities.
Despite topological conflict among the broader-scale groupings examined, only the tree based on morphological data showed statistically significant differences.
Considered together, our analyses provide a consistent signal of deep platyhelminth interrelationships, demonstrating a combination of groupings familiar from the eras of classical morphological systematics and rRNA phylogenetics, as well as several novel but nonetheless well-supported clades, whose provenance and broader evolutionary significance we now consider.
In summary, levels of molecular divergence within the P. chusua s.l. group are sufficient to suggest that several species are present, but the molecular groupings do not correspond well with species circumscriptions based on morphology; a detailed and comprehensive revision, integrating molecular, morphological and ecological data, is clearly needed.
