[Taxacom] Pteridophyta

[Mario Blanco]

For those interested in discussing the ins and outs of pteridophyte 
phylogeny and classification, I suggest the following read:

AR Smith, KM Pryer, E Schuettpetz, P Korall, H Schneider & PG Wolf. 
2006. A classification for extant ferns. Taxon 55: 705-731.

The phylogenetic classification proposed by these authors is not yet 
incorporated in either Catalogue of Life or Encyclopedia of Life. They 
treat the name Pteridophyta as an informal, paraphyletic group (made 
paraphyletic by the lycophytes). According to their studies, the rest of 
the pteridophytes form a monophyletic group sister to the seed plants, 
and the informal name Monilophytes is used for them (or, if you prefer, 
the awkward "Infradivision Moniliformopses"). Their classification 
divides the Monilophytes in 4 classes (Psilotopsida, Equisetopsida, 
Marattiopsida, and Polypodiopsida), each one subdivided into various 
orders and families (37 families in total).

We have adopted this classification scheme for our Plant Diversity course.

Citing from the article (p. 709): "Classifications may be better served 
by adopting 'floating', rankless names for clades above the rank of class."


-------- Original Message --------
Subject: 	[Taxacom] Pteridophyta
Date: 	Mon, 27 Jul 2009 11:17:45 -0500
From: 	kennethkinman at webtv.net (Kenneth Kinman)
To: 	taxacom at mailman.nhm.ku.edu



Dear All, 
       I finally figured out the confusion over
Pteridophyta. If you look at the Catalogue of Life, it lists four
separate phyla Equisetophyta, Lycopodiophyta, Psilophyta, and
Pteridophyta (each having just one Class). Many of us still use the
single paraphyletic Phylum Pteridophyta that brings all four of those
Classes together.  A PhyloCoder might call this group the
"non-spermatophyte tracheophytes". 
       Apparently some strict cladist didn't like the
paraphyletic Pteridophyta, and therefore split it up into four separate
Phyla (Divisions), and then very confusingly attached the name
Pteridophyta to just the true ferns. No wonder there is so much
confusion, and why?----once again it's that strictly cladistic aversion
to any paraphyletic taxon whatsoever. Anyway, the Pteridophyta sensu
stricto is probably monophyletic (holophyletic), but the Pteridophyta
sensu lato is definitely paraphyletic. If the Catalogue of Life wants to
separate these groups into separate phyla (and then further obscure
their relationship by alphabetizing them), so be it. But they would at
least avoid most of the confusion if they used another name for
Pteridophyta sensu stricto (perhaps Filicophyta?). 
              --------Ken Kinman 
P.S. And I don't know why Peter Hovenkamp would think that my
classification system doesn't deal with monophyletic taxa. If you look
at any of my classifications, the vast majority of taxa are monophyletic
(i.e. holophyletic) clades, and then I occasionally put in paraphyletic
taxa where it is appropriate to maintain stability and add in that extra
anagenetic/divergence information (also referred to as mother-daughter
or ancestor-descendant information). My classifications are full of
clades, but I don't restrict myself to clades ONLY.   Just look at the
Diptera classification I posted this morning. Everything there is widely
considered to be a clade except for just 3 paraphyletic taxa:  (1)
Nematocera% (mother group of exgroup Brachycera), (2) Orthorrhapa%
(mother group of exgroup Cyclorrhapa), and (3) Empididae% (mother group
of exgroup Dolichopodidae). They are clearly labelled with the % symbol
for paraphyly. 


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