[Taxacom] FW: Class Rosopsida (4 Subclasses)

[Ken Kinman]

Dear All, >       While I have access to a computer, I wanted to send you this post. Since posting my new classification of angiosperms (Phylum Magnoliophyta) here on Taxacom in February 2004 (in which I first recognized three Classes instead of the traditional two), I've been working on the classification of Class Rosopsida off and on ever since. And since then I have found that splitting it into four subclasses makes it MUCH easier to remember and wrap my mind around (in the traditional systematist's sense), rather than one rather long cladistic sequence.> >         So I offer my present classification here now for those who also find such classifications extremely useful, as an alternative to mere "cladifications" which tend to suffer from generating many more subclasses (and thus muddling the fundamental purposes of utilitarian classification in the broad and traditional sense). However, notice that each of these four Subclasses is individually coded cladistically, although the first two subclasses are paraphyletic overall.  I continue to recognize fewer Orders than traditional classifications, but more Orders than the APG classification (where I feel they lumped too much).> >         After switching to this division into 4 subclasses, I was somewhat surprised how similar it was to the 4-part subdivision of tetrapod vertebrates into four Classes. Subclass Ranunculidae is basically the amphibian equivalent, with Subclass Dilleniidae as the obvious (doubly paraphyletic) equivalent of reptiles (giving rise to two other major taxa). Much as with the reptiles, uncertainty plagues the classification of what I have called the "dilleniid" mess". My cladistic coding of Dilleniidae is thus the least certain, but such cladisto-eclectic coding can be easily modified to reflect new phylogenetic topologies. Also see the note following the classification about uncertainties concerning the cladistic relationships within Subclass Rosidae. Anyway, just wanted to offer this before I return again to "lurking" mode (although I do still catch up on Taxacom discussions when I can). > > Class Rosopsida (eudicots)>     1 Subclass Ranunculidae%>             1  Ranunculales>             2  Sabiales>             3  Proteales >             4  Trochodendrales>             5  Buxales>             6  Gunnerales >             7  {{"Core Eudicots"}} (Dilleniidae, etc.) > >   _1_ Subclass Dilleniidae%%>             1  Saxifragales>             B  Vitales>             C  {{Rosidae}}>             2  Berberidopsidales
>             3  Santalales>             4  Dilleniales  
>             5  Caryophyllales>             B  Polygonales>             C  Nepenthales>             6  Balsaminales>             B  Polemoniales>             C  Primulales>             D  Styracales>             E  Theales>             F  Ericales>             7  Cornales>             8  {{Asteridae}} > >    _a_ Subclass Asteridae (euasterids)>             1  Aquifoliales>             B  Asterales>             C  Apiales>             D  Dipsacales >             2  Garryales>             3  Gentianales>             4  Lamiales>             ?  Boraginales>             5  Solonales > >   _b_ Subclass Rosidae (rosids)>             1  Geraniales>             2  Myrtales>             3  Crossosomatales>             B  Sapindales>             C  Huerteales>             D  Malvales>             E  Brassicales>             4  Zygophyllales>             B  Fabales>             b  Rosales>             C  Fagales>             D  Cucurbitales>             5  Celastrales>             6  Oxalidales>             7  Linales >             8  Ochnales>             B  Hypericales>             9  Malpighiales>             ?  Balanopales>           10  Euphorbiales>           11  Violales > --------------------------------- > NOTE: The cladistic coding of Subclass Rosidae still has two main> uncertainties. The first is the exact interrelationships of clades 7-11> (which APG lumps into one large Order Malpighiales). Lumping them> together into one huge Order really solves nothing, and it just> unnecessarily confuses those who wish to use the more traditional> ordinal groupings (Violales in particular). The second uncertainty is> whether the "fabid" grouping (clades 4-11) is holophyletic (i.e.> strictly monophyletic) or paraphyletic. The fabids are coded as> holophyletic here, but it could well turn out to be paraphyletic. If> so, clade 4 (the nitrogen-fixation clade) should be shown splitting just> before (NOT just after) clade 3 (called the "malvids" or Rosid II> clade). Anyway, thankfully botanists had the foresight to continue> informally naming such uncertain clades, such as fabids/Rosids I (which> may not really be clades at all). Vertebrate paleontologists, on the> other hand, seem intent on formally naming almost every conceivable> "clade" in a race to establish priority for their favorite names and> "clades" (sometimes even giving certain clades two or more different> formal names). We'll see if the third PhyloCode conference this year> brings even more of the same.> 



Shed those extra pounds with MSN and The Biggest Loser! Learn more. 
_________________________________________________________________
Connect and share in new ways with Windows Live.
http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_012008