Sunday Protist - A sampling of Cercozoa Part I

This post grew out of proportion, so I'm splitting it into two or three parts, to cater to our ever-shortening attention spans (mine included)...

[Warning: Taxonomy. Of the harshest kind: involves Cavalier-Smith]

At the moment, among my favourite supergroups is Rhizaria (tree). Rhizaria is generally where all the obscure, interesting, and outright weird eukaryotes get sent by molecular data these days. The group itself is fairly recent, having been formally spewed out declared by Cavalier-Smith in 2002, as a fusion of Cercozoa and Retaria(=forams and 'radiolarians'), as well as Heliozoa and Apusozoa, apparently because they had "a centrosomal core or radiating microtubules and two microtubular roots and soft surface, typically with reticulopodia." (TC-S 2002 IJSEM:297) Don't worry, I don't really know what that means either. That is, those are fairly common traits in many non-Rhizarians, even according to the TC-S 2002 classification.

The name derives from the group's inclusion of many members of the then-defunct "Rhizopods" ('root-feet' - members typically had thin, branchy pseudopodia). Since then, Heliozoa died a horrible death with its limbs strewn all over the tree (Nikolaev et al. 2004 PNAS) and [many] Apusozoa now seem to enjoy their privileged life as the putative basal Opisthokonts (or their sisters). Ironically, many of the "Heliozoa" did return to Cercozoa later. Obligatory TC-S Diagram:

The birth of Rhizaria. As the young supergroup struggles to open its eyes to the world for the first time, it is confronted by the glaring faces of frustrated readers threatening to ban the author from ever birthing another taxon, for the sake of global sanity. Yet, despite its weak, fragile synapomorphies, the newborn supergroup, heavily-medicated by state-of-the-art molecular phylogenies, rises to become a bona fide citizen of the taxonomic world. For now. As all other life forms on earth, the higher taxa themselves are mortal. (diagram slightly modified (red box added) from Cavalier-Smith 2002 IJSEM)

"Radiolarians" (Acantharians+Taxopodids+Polycystines) and Forams (more generally, Granuloreticulosea) are massively diverse, complicated and awesome, but Cercozoa are more obscure to non-protistologists, and are a rather weird assemblage of stuff. I think the Amoebozoan taxon "Variosea" would have been quite fitting for them, were it not taken by amoebae instead. Cercozoa is older than Rhizaria, but not by much - it was formally established by Cavalier-Smith in 1998 (Biol Rev) as a modified successor of Rhizopoda:

"The recently revised phylum Rhizopoda is modified further by adding more flagellates and removing some ‘ rhizopods ’ and is therefore renamed Cercozoa" (TC-S 1998 BiolRev:203)

Of course, that was Tom's version of Rhizopoda to begin with. Taxonomy gets very fun when different people at different times mean different things by the same name. Can't seem to find the etymology of Cercozoa, but the formal description reads pretty much like 'miscellaneous eukaryotes with thin pseudopodia'. And that they are.

While Cercozoa was initially based loosely on morphology and sketchy data from the dawn of molecular phylogenetics, it mostly survived intact over the years, and grew further (with various things shaved off too, of course). The original members were Phytomyxids (incl. the plant pathogen Plasmodiophora), Reticulofilosa (basically, Chlorarachniophytes) and Monadofilosa (Cercomonas, Gymnophrys, Euglypha and Spongomonas are given as original examples). Curiously, all of them survived the onslaught of molecular reality (or so we hope...). Stuff has been added, like Ascetosporea (paramyxids and haplosporidia; added in TC-S 2002 IJSEM) and the gromiids, as well as various obscure incertae sedis orphans and a few refugees from 'Heliozoa'.

Eventually, the Cercozoa got 'sistered' to the forams (Keeling 2001 MBE) by ACTIN phylogenies, which got taxonomically recognised in the TC-S 2002 IJSEM revision of The Book of Tom by declaring the holy union of Retaria (forams and rads) and Cercozoa as Rhizaria. Going overboard as usual by adding in Heliozoa and Apusozoa, of course. We're talking about the mad taxonomist here ;-) (now someone needs to make that into a pop culture phenomenon to rival mad scientists..."And along comes the evil mad taxonomist...and RENAMES EVERYTHING!" *cue spooky music*) The group still lacks any solid synapomorphies (shared derived characters); the situation is such that even the use of obscure ultrastructural elements has been attempted, such as Cavalier-Smith's "transitional nonagonal fibre" (TC-S 2008 Protist) – even one of his own past students has no idea what he meant there!

And a whole bunch of other stuff happened but I think that was enough Historical Taxonomy (would make the most popular course evar, srsly) for...the month. Ok, so have we lost everyone yet? Or have the wiser ones employed the high art of The Scrollbar and skimmed accordingly? In any case, I'd like to very briefly and shallowly run over a few of the major cercozoans to give you a taste of the phylum, and just how diverse and varied it is. Things will be skipped, including, quite possibly, The Most Interesting Thing Ever Because You Studied it for the Past Ten Years. Apologies in advance. TMITEBYSiftPTY will get its chance, someday.

Some phylogeny and taxonomy sources: TC-S & Chao 2003; Bass & TC-S 2004; Bass et al. 2005; Pawlowski & Burki 2009; Chantangsi et al. 2010.

(L: Pawlowski & Burki 2009; R: Chantangsi et al. 2010)

To be continued in Part II – Endomyxa.

References
Bass D, & Cavalier-Smith T (2004). Phylum-specific environmental DNA analysis reveals remarkably high global biodiversity of Cercozoa (Protozoa). International journal of systematic and evolutionary microbiology, 54 (Pt 6), 2393-404 PMID: 15545489

BASS, D. (2005). Polyubiquitin Insertions and the Phylogeny of Cercozoa and Rhizaria Protist, 156 (2), 149-161 DOI: 10.1016/j.protis.2005.03.001

CAVALIER-SMITH, T. (1998). A revised six-kingdom system of life Biological Reviews of the Cambridge Philosophical Society, 73 (3), 203-266 DOI: 10.1017/S0006323198005167

Cavalier-Smith T (2002). The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa. International journal of systematic and evolutionary microbiology, 52 (Pt 2), 297-354 PMID: 11931142

Cavalier-Smith, T., & Chao, E. (2003). Phylogeny of Choanozoa, Apusozoa, and Other Protozoa and Early Eukaryote Megaevolution Journal of Molecular Evolution, 56 (5), 540-563 DOI: 10.1007/s00239-002-2424-z

CAVALIERSMITH, T., LEWIS, R., CHAO, E., OATES, B., & BASS, D. (2008). Morphology and Phylogeny of Sainouron acronematica sp. n. and the Ultrastructural Unity of Cercozoa Protist, 159 (4), 591-620 DOI: 10.1016/j.protis.2008.04.002

Chantangsi, C., Hoppenrath, M., & Leander, B. (2010). Evolutionary relationships among marine cercozoans as inferred from combined SSU and LSU rDNA sequences and polyubiquitin insertions Molecular Phylogenetics and Evolution, 57 (2), 518-527 DOI: 10.1016/j.ympev.2010.07.007

Keeling PJ (2001). Foraminifera and Cercozoa are related in actin phylogeny: two orphans find a home? Molecular biology and evolution, 18 (8), 1551-7 PMID: 11470846

Nikolaev, S. (2004). From the Cover: The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes Proceedings of the National Academy of Sciences, 101 (21), 8066-8071 DOI: 10.1073/pnas.0308602101

PAWLOWSKI, J., & BURKI, F. (2009). Untangling the Phylogeny of Amoeboid Protists Journal of Eukaryotic Microbiology, 56 (1), 16-25 DOI: 10.1111/j.1550-7408.2008.00379.x

The long-awaited TC-S paper IS OUT!!!

OMG, yes, it's finally out, in February, just like he said...! Wheeeeee! Featuring that very famous heartwarming diagram style of his! *drools*

*does a happy dance*

The paper I've been dying to read since no less than a YEAR ago...
(TC-S 2009 Biol Direct: Origin of the cell nucleus, mitosis and sex: roles of intracellular coevolution) (Alternative title must be "Sex, the universe, and everything")

No, seriously, I've even ranted about it before -- who the hell cites papers from the future?

(TC-S 2010 Biol Direct) My two great fetishes in one diagram -- cell biology and evolution. See, at least someone understand me! Well, would understand if he were even half-aware of my existence... that latter part really needs to be fixed ASAP. Maybe if I magically wake up one day at an ISEP meeting. One can dream...

And I'm late to class. And other obligations. *sob* I won't be able to get to it until tonight. I mean, I'm gonna tend to my actual obligations tonight, yeah, totally...

But today is going to be a great day! The first thing I saw in Google Reader was that paper, so it must be a good sign, right?

Anyone wanna read this along with me, and then we can chat about it? Lab Rat, I'm looking at you =P

Oh and I'm really late to class now... I doubt the prof knows TC-S (or has read his papers anyway), and would therefore be unable to understand and sympathise with me. Sigh, such depraved souls they are, those non-evolutionary biologists. Poor things. If only they'd read from the Book of Tom, and see the light...

Another epic TC-S quote

‘I think it best to put forward simple, detailed and specific hypotheses, since these have a better chance of stimulating (and being refuted or corroborated by) future research than are vague or unnecessarily complicated ones.’ (Cavalier-Smith 1993a p. 339.) (quoting himself in TC-S 2010 Biol Lett supplementary data PAPER.) [emphasis mine]

Can't...hold...in...laughter...AHAHAHAAAA!!

I'm gonna have to do a live blogging of a reading from the Book of Tom someday. I think that would be epic entertainment!

For those who are confused, may I refer you to:

Simple! (TC-S, 2006 Biol Direct; open access)

Disclaimer: Again, for those 'out of the loop' (so lucky...), this is not an attack against Cavalier-Smith or anything. If I didn't find his stuff interesting and worthwhile, I wouldn't be reading it in the first place. Just sayin', in case someone randomly scolds me for being mean to Tom. Which in itself is a rather humorous concept...


Speaking of which, lemme crudely summarise what the latest TC-S "Eozoa crisis" is about in a couple trees:

Note the Excavates (Euglenozoa+Percolozoa+Metamonads). Left image based on TC-S 2009 JEM(free access), right image on TC-S 2010 Biol. Lett.; some taxa translated to terms people actually use. And yes, I was having too much fun with phylo software again, this time TreeView...

Basically, Tom apparently now thinks the root of Eukarya is in the bikonts, more specifically: between Euglenozoa (eg. Euglena, Trypanosomes) and the rest of Eukaryotes. He renames Excavata to Eozoa, and all other eukaryotes to Neozoa. Some other shit happens, but basically he thinks Euglenozoans are too special. However, it is their 'derivedness' that kind of worries me there -- more special != outgroup (of course he knows that), and perhaps all other things equal, rare 'weirder' things are less likely to be basal than more 'normal' things.

What bugs me here is that he actually MAKES SENSE. This hypothesis is utterly bizzare, strange and absurd. But on the other hand...reading more about it...it might not be. Grrr. This is the main problem with Tom: he says ridiculous things, but throws out some pretty complicated and substantial evidence that takes considerable effort to reject. Even when he's obviously wrong (and probably knows it too). Thus, unlike the low-grade crazies that put out shitty hypotheses that you can throw out in a second and ignore, Tom's craziness is quality. It takes effort to deal with, and a very worthwhile effort.

Until you do a word count on one of his papers (eg. TC-S 2006 Biol Direct) and find out it to be 40K words. Holy shit.

I'll cover this in more detail once the dust in my head settles a little, and once I can slowly start rebuilding my understanding of early eukaryotic evolution after this massive blow. What a way to start off a new year!


PS: Off topic, but go check out this amazingly well-written newspaper article on dinoflagellates -- I'm impressed with the quality of research the author has done! Seldom seen in popular science writing these days...

Divine masterpiece of a diagram...

In my quest to conquer as many TC-S papers as humanly possible, I came across this masterpiece of visual presentation*:

Love the "missing link" in the most prominent location. This is gonna be good...! (none other than TC-S, 2006 Biol Direct; open access)

83 page paper. 4 exams ahead. Tom's paper, wild hypotheses, bold assertions, *drools* cellular evolution. Exams, marks, future career. Hmmm. Damn you, Tom, I think you win this time...I will only read a few pages. The rest will be read over the holidays. I shall set my limit to...6 pages max until after the biochem final. And practise self-control. I CAN abstain from alcoholism drugs sex TC-S papers, I can! OMG, I has TC-S addiction... o_O

People in that field call me crazy. I can't quite figure out why...

Speaking of which, might anyone happen to have TC-S 2004 The membranome and membrane heredity in development and evolution in Organelles, genomes, and eukaryote phylogeny: an evolutionary synthesis in the age of genomics Eds.: Hirt & Horner?
or his other chapter "Chromalveolate diversity and cell megaevolution: interplay of membranes, genomes and cytoskeleton"? We actually don't have that book, and there are no accessible PDFs out there, apparently. Alternatively, I could order it through inter-library loan, but I think I've harassed them enough for this year...

*His diagrams are 'special' enough to be featured on journal covers...

On a more personal note, I will try to abstain from blogging excessively over the next few weeks. Finals, etc, you see. 'tis the season to be cramming, lalala lala la la la la. Which is why I'm sitting here reading about eukaryotic megacell megaevolution. So if I'm falling behind on my posting obligations, that's why. In reality, I'm gonna be procrastinating my ass off, but we don't talk about that here. Perhaps I should write 1001 Things I'd Rather Do Instead of Cramming for Biochem Final. Would be such a bestseller. I mean, the possibilities are truly ENDLESS!

After finals, I'll have very sparse internet access until 04 Jan. Blogging will resume normally then.

That said, watch my post rate increase two-fold all of the sudden. And marks drop accordingly...

Speaking of marks, there's a guy in our lab who spent 5 years studying biology, and proudly brags about NEVER having stepped foot in a library all those years. His marks are really good.

"The anus was a prerequisite for intelligence" TC-S quote anthology 01

Still working on the Sunday Protist; it's the last week of classes, finals start next week, and I have to sort out some last minute stuff for the seminar we're running next term (finally got it officially up and running in terms of registration!). As you can see, I'm rather swamped here. Also, staying up till 4am working on the Sunday Protist last night was definitely not a splendid idea. I blame TC-S for distracting me with his elaborate hypotheses...

Speaking of which, I've started my very own personal collection of TC-S (Cavalier-Smith, for ye strangers) quotes. When you read most papers, there's just information being spat out and chewed up in more or less mechanistic technical language completely devoid of any human voice. Sometimes the monotony can be interrupted by a burst of "Holy fucking shit did they seriously just write that!? Who the flying fuck gave them a faculty position?" or "This sounds fishy". In contrast, Tom's stuff goes something like:

Looks interesting, let's do this! Ok, so this paper reviews...everything. *cringe* arggghhhh...dense...massive...life-changing hypothesis...crammed into...half a paragraph... OMG ROFLOLOLOL!!!! ...how could you postulate that? Eeeeek, shaky evidence there... dude, you just cited yourself like 10 times in a row!... omg, DEAD ON, YOU GET 'EM TOM! aaaahh....what is that supposed to mean... LOL!!! Wait, did he just write that in a research paper? You cheeky bastard you! ...wow, he reads paleogeology papers!? aaaah ANOTHER DENSE PARAGRAPH OF DOOM! o_O

And so on. See, it's never boring. Which is why despite being notoriously difficult, I actually find his papers easier to work through -- they appeal to my rather-easily dulled attention span. As soon as you begin drifting off somewhere, either you realise you actually needed to thoroughly understand every single sentence to follow along and get hopelessly lost, or you come across something like "The anus was a prerequisite for intelligence", and definitely pay more attention. Which is why he gets an entire label to himself here.

Here's some lines that made me chuckle:
"There was no spinach in the Archaean." (2006 Phil Transac R Soc B, p995 last paragraph)
"But it is not." (concise disagreement) (2006 PTRSB, p997 first paragraph)
"Assumptions that such a neomuran prokaryote existed for hundreds of millions of years are science fiction." (ouch!) (2006 PTRSB, p997 second last paragraph)
"Very likely this anal breakthrough ca. 550 GYr ago stimulated the long-puzzling Cambrian explosion." (2006 PTRSB, p998 second last paragraph)
"The anus was a prerequisite for intelligence; without it, heads and brains would not have evolved." (2006 PTRSB, p998 second last paragraph)
"I consider Brachiozoa, bivalves, Bryozoa [...] were not secondarily beheaded." (2006 PTRSB, p998 second last paragraph)
"Overstatements of gradualism asserting that megaevolution is simply the accumulation of large numbers of small mutations of the same kind as predominate at lower evolutionary levels are simply wrong and must be abandoned." [emphasis mine] (2006 PTRSB, p1000 first paragraph)
"[...] but have been partially forgotten and need restating each generation." (isn't that how science works?) (2006 PTRSB, p1000 last paragraph)
"When I spoke frequently on skeletal DNA over 20 years ago, a common reaction was why not make the nuclear skeleton of protein? One sometimes felt that one's critics would prefer any material but DNA - protein, chitin, even steel, or teflon." (and yes, he refers to himself as 'one' here...) (2005 Annals of Botany, p152 second paragraph)

And a line that makes me feel all warm, fuzzy and happy on the inside: "Understanding microbial megaevolution requires cell biology -- not just biochemistry." (2006 PTRSB, p1000 second last paragraph)

And 'one' must agree with this nice summary of how science academia the world works:

"[...] is not that we do not understand mutations well enough, but that the solution I have offered, and develop further here, is a synthesis drawing upon cell and molecular biology, population and evolutionary biology, developmental biology and ecology; evaluating such a complex synthesis is tough to a specialist in just one area. Population geneticists might prefer to be able to solve evolutionary problems strictly in their own terms and ignore detailed cell biology; cytologists might prefer to do the same and ignore abstruse population genetic arguments; molecular biologists might prefer to sequence DNA and ignore both the cell biology and population biology. But for a deeper understanding we must make the effort to combine the explanatory modes of all relevant disciplines." (2005 Annals of Botany, starting last line of p147)

Despite come across as a bit arrogant there (probably not his intent), he does have a great point. There is so little interaction and integration between the various clans and tribes of biology that one guy can go ahead and monopolize a nice chunk of an integrative field just like that. People complain, but what are they doing about the little issue of each department/discipline burying themselves into a nice comfy hole somewhere, never to venture outside and explore the world beyond. And then the occasional traveler ventures into a foreign burrow, only to be appalled at how horribly their own field gets abused there. Forget the monkeys, a ground squirrel can engage in better interdisciplinary integration =P

Anyway, enough for the first installment. I'm aware some of you guys also have nice TC-S quote collections -- feel free to contribute! There was one Opisthokont had that was oozing Tom-ness all over, can't find it at the moment... *nudge*

And this is definitely getting filed under ResearchBlogging =P

And the Neomuran eukaryogenesis post will be underway after I finish a couple more 70-page reviews of Everything. Well, actually, I should just start writing, probably. Although I did want to read some competing 50 page reviews of 'everything' by other people, although theirs are much more focused.

EDIT 18:26 03.12.09: If you think about it, the "anus was a prerequisite for intelligence" quote actually does make sense: The anus allowed Bilateria to evolve, since the input and output no longer had to be in the same place, thereby drastically altering the fundamental body plan. This freed up one end of the organism to specialise in obtaining food, which is aided by rather elaborate sensing systems. The mouth-containing head end was the focus of increasing cephalisation, eventually resulting in brains. Thus, in a way, the anus is responsible for allowing heads and brains to evolve. Just adding this in to point out that there IS good substance to that quirky TC-S quote, it's not just him going insane or anything (not this time anyway) ^_~

References:
CAVALIER-SMITH, T. (2005). Economy, Speed and Size Matter: Evolutionary Forces Driving Nuclear Genome Miniaturization and Expansion Annals of Botany, 95 (1), 147-175 DOI: 10.1093/aob/mci010

Cavalier-Smith, T. (2006). Cell evolution and Earth history: stasis and revolution Philosophical Transactions of the Royal Society B: Biological Sciences, 361 (1470), 969-1006 DOI: 10.1098/rstb.2006.1842

Citing papers from the future

Ok. I'm getting rather annoyed. SOMEONE keeps on citing papers from the future. HIS OWN papers from the future. Now I know that it's common practice to cite "Bob accepted" or "Bob in review", but "submitted for publication"?! What the fuck? What next, we're gonna have "Smith et al. in preparation" or "Smith et al. writing grant proposal"!?

I really really REALLY want this paper. And I've been waiting for it. Almost the entire year. This one:

Cavalier-Smith T. Intracellular coevolution and the origin the cell nucleus and sex, submitted for publication.

It is only mentioned in ONE PLACE IN THE ENTIRE UNIVERSE: The references section of this wonderful Review of Everything: TC-S 2009 Int J Biochem & Cell Biol Predation and eukaryote cell origins: A coevolutionary perspective. A really nice paper, by the way, except for the whole 'citing papers from the future' drama. Heavily referring to that non-existent paper. Kind of like "Hang on a sec, I'll explain that in the next paper...sometime...eventually..." Note that it was published online in October 2008; I wonder if his Giant Review of Sex, the Universe and Everything has been rejected, considering it's been a year. Anyone happen to know of any updates on that paper?

The suspense is horrible. It's like watching part I of a movie, leaving off at a cliffhanger, and not knowing whether part II will ever come out. Of course, there's always fanfiction. o_O Academic fanfiction. TC-S fanfiction*...oh god, I think I've just discovered a genre that was never meant to exist. What have I done?

As for my Sunday Protist...it's, well, in preparation...

*That's right, I can write MY OWN damn TC-S Reviews of Everything. Ooooh, this could be kinda fun! I could heavily refer to events that would happen in the sequels. And then never write them. Prompting more fanfiction...

Someone gets it right: Cell biology -is- relevant!

I love you, Tom:

"Recent genome sequencing has fostered a simplistic
view of organisms as essentially aggregates of genes.
However, organisms are not simply a sum of their
genes nor, as some biochemists were once wont to say,
mere bags of enzymes. Genes and enzymes are both
fundamental, but play their vital roles as parts of
highly organized growing and dividing cells. Their life
depends on a mutualistic symbiosis of genes, catalysts,
membranes and cell skeleton" - TC-S 2002 Intl J Sys Evol Microbiol [emphasis mine]

=D Warm fuzzy feeling inside... an evolutionary biologist who doesn't neglect cell structure! Someone who didn't forget that there's more to life than nucleotide sequences! What we have before us here is an endangered species, a rare specimen of sanity... wait, Cavalier-Smith and sanity in one sentence? I must've fucked this up big time...

So who dares me to plow through all 70 pages of that review? It's tempting, and I have a holiday coming up... "Mom, leave me alone, can't you see I'm trying to read a TC-S paper here?!", but it's 70 pages of Tom's hypothesising. Wherein he will cite himself at least 50 times... *checks* nope, only 39 this time. It's an older paper. And holy shit, 58 own entries in his latest J Euk Microbiol paper... an entire page of references!

But it's a lot of fun to read... yes, I read TC-S papers for fun. Where do I put that on my CV?

(now if only he could go easy on the mega- and meta-, and if only he could read, absorb and obey Tufte's The Visual Display of Quantitative Information, life would be so perfect...)


And since when do I blog so frequently? Eeek...gonna set the expectations too high for the oncoming schoolyear!

A bit of a break...

Rather swamped with stuff right now - research, class (final next week x_x), other misc stuff. Probably would be best to stay away from the internet as much as I can for the next week or so... that may prove to be difficult. Oh well...

Oh and to top it all off, I think the star alignment is incorrect for PCR these days. May have to wait for them to shift a little so that the PCR prayer waves can reach their destination and make my Taq do its job. Or perhaps its governed by Chaos/Quantum whatever theory stuff BS. Srsly - exact same primers, reagents, temperature, program, machine... similar samples, and one day they work perfectly, the very next round there's no product. WTF? HELP! I need this to work like 3 days ago... argh.

For now, here's a random preview of a post I will finish eventually very soon ^.^

I de-Cavalier-Smithified and combined a couple of his diagrams into what may hopefully be read and understood by a normal human being. The protistology TA instructed me to avoid ever using Tom's diagrams in talks, even after I redrew it.

Here's one of the originals (very typical TC-S):

(Cavalier-Smith 2009 Predation and eukaryote cell origins: a coevolutionary perspective. Int J Biochem & Cell Biol 41:307-322; can't find free access pdf anywhere yet =( )

His phylogenies are even better...!

Hopefully explanation will soon follow...

PS: Just noticed something weird... why does Tom have animals and fungi branching out of 'Choanozoa'? Do 'Choanozoa' include nucleariids and ichtyosporeans too? What do those have to do with choanoflagellates anyway? As far as I know, that region looks something like this:

{Nucleariids + Fungi} {Ichtyosporea [Choanoflagellates + Animals]}; 'Choanozoa' would be a rather awkward group, no?

/pedantry; Damn, now I sound like a cladist...