Acropora ID mini-class

[EricHugo]

Acropora florida group - A. florida, A. sarmentosa
growth form - modified robust hispidose, with even small branches around heavy main branch
radials - evenly sized, appressed tubular, thick labelate lower wall and round openings, radials contribute equally with axials to branch thickness.
cornosteum - reticulate without much spinule development at all between radials, costate or reticulo-costate on radials.
habitat - varies
range - Indo-Pacific, but not Central Pacific

Acropora hyacinthus group - A. hyacinthus, A. tanegashimensis, A. anthocercis, A. cytherea, A. microclados, A. paniculata, A. indonesia
growth form - tables or plates, central or side attachment, thickened stalk; juveniles are digitate before the mature table or plate forms (elaborate horizontal branching/anastomoses with short thin vertical projections)
radials - even sized, labellate, uppper wall absent, lower wall lip is rectangular
coenosteum - reticulate with simple spinules between radials, costate on radials
habitat - most reef zones but often shallow
range - depends on species

Acropora latistella group - A. latistella, A. subulata, A. nana, A. aculeus.
growth form - corymbose, slender branches, varies with depth, can form plates or tables
radials - evenly sized, appressed tubular, round openings, contribute equally with axials to branch diameter, spacing varies with depth
coenosteum - uniform reticulate with well-spaced simple spinules between radials, reticulate to reticulo-costate on radials.
habitat - broad depth range

Acropora horrida group - A. horrida, A. vaughani, A. tortuosa, A. abrolhosensis, A. microphthalma, A. kirstyae, A. derawanensis, A. halmaherae
growth form - highly variable, even within a colony, indeterminate
radials - evenly sized, simple tubular, round openings
coneosteum - simple to elaborate spinules, coenosteum sometimes partly fused, reticulate to costate between and on radials
habitat - variable, usually protected and lower water flow
range - variable

Acropora plumosa group - A. plumosa
growth form - irregular, flat-topped arborescent tables to twisted arborescent, branches 3-15mm diameter up to 50mm long; horizontal branchlets 3-4 mm diameter, sometimes anastomosing, the loose, open tables can form multiple tiers, cream to yellow-brown, yellow-grey, brown color
axials - 1.2-2.1mm OD, 0.6-1.2 ID, primary septa to 2/3 radius, secondary cycle absent or barely developed
radials - even, not touching; tubular; round, oval or dimidiate openings, primary septa to 1/4 radius; secondary cycle absent or barely developed
coenosteum - reticulate to reticulo-costate on radials with laterally flattened spinules, reticulate between radials with laterally flattened spinules between, sometimes in rows
habitat - deep slopes and walls below 40 feet
range - Indonesia and Papua only

4 groups to go...

 

[EricHugo]

Acropora elegans group - A. elegans, A. pichoni, A. tenella, A. walindii, A cardenae, A. torihalimeda, A. russelli
growth form - mostly horizontal branching with sparse flattened
branches
radials - evenly sized, tubular or appressed tubular; most species reticulate withs ome forming rows or being nearly costate with elebaorate spinules.
coenosteum - moderate to dense with eleaborate spinules
habitat - deeper calm water, mainly below 60 feet
range - localized to Indonesia or Australia, depending on species.

Acropora loripes group - A. loripes, A. squarrosa, A. chesterfieldensis, A. willisae, A. lokani, A. granulosa, A. speciosa, A. suharsonoi, A. caroliniana, A. desalwii, A. jacquelineae, A. simplex
growth form - various, depending on secondary branching of hispidose or corymbose colonies with a whitish glow
radials - evenly sized, rounded appressed tubular; some branches may lack radial develpment; mostly reticulate but some species develop costate aspects
axials - prominet and major contributor to branches
coenosteum - densely arranged eleborate spinules
habitat, frequently deep or shaded reef slopes
range - varies according to species, but most localized to Indonesia

Acropora echinata group - A. echinata, A. batunai, A. subglabra, A. carduus, A. awi, A. elseyi, A. longicyathus, A. turaki
growth form - well developed hispidose colones; evenly arranged secondary branchlets around primary branches
radials - sparse; evenly sized, "pocket-like" appressed tubular
axials - prominent; major contributor to colony development. Colonies have many axials and few radials and axials may be mistakenly be considered radials.
coenosteum - uniform; costate, or rows of simple to slightly elaborate spinules
habitat - protected areas (lagoons, deep slopes, sheltered bays); often form large fields with species intermixed
range - varies with species, some narrow, some wide, but centered around Indonesia.

Isopora subgenus - A. palifera, A. cuneata, A. crateriformis, A. brueggemanni (A. palmata in Caribbean)
growth form - thick, often wedge-shaped branches (except A. brueggemanni which is arborescent)
radials - absent, except in A. brueggemanni
axials - multiple
coenosteum - dense, meandorid arrangement, elaborate spinules on and between axials - most elaborate spinules in Acropora genus
habitat - variable
range - variable

So, now, the trick is to assign your coral to a group.

Can you do it? If so, please list which group, and we will go down to species level for each example.

 

[piercho]

pics of coenosteum?

pics of coenosteum?

I still need help finding the correct terms to describe the coenosteum on my piece. Would it be possible to get images showing what the terms descibe? That is a lot of typing you have been doing so I hate to ask for more...

 

[JB NY]

Here is what I've got.

Growth Form
caespitose-corymbose

axials
Septa: six primary. No secondary.
Septal lenght: mostly equal
Cycles of septal: One cycle
Septal height: not exsert
septal dentition: forms comb rows (not 100% on this as it's hard to see)
Paliform structures: absent

Radials
One type of radial corallite
Radial corallites are 'appressed'.
Radial corallite opening is dimidiate.
Radial corallite shape is nariform.


Coenosteum
Coenosteum between radials is costate or broken costate.
Top edges of the costae contain spinnules that are shark-like.

Grouping
Acropora latistella

Based of the above I picked the Acropora latistella group. I came down to that and the Acropora echinata group. But in echinata the radials were different and the also the radials are similar to the axials, which is not the case on my branch.

click for larger image

 

[EricHugo]

ok..here is the coenosteum image (Wallace 1999 as reviously referenced)

 

[EricHugo]

Joe:

I think the latistella group is a good option for yours. Do your radials have one or two cycles of septa? You might want to look at a number of them to se if there is any development - also, how far in do they protrude (both axial and radial septa) - try to be as accurate as possible on this, because these four species are very hard to distinguish - Wallace mentions that latistella and aculeus may sometimes only be distinguished in the lab...and IMO, the others are darn close, too.

 

[firefish15]

how far in do they protrude (both axial and radial septa)

Do you measure this at the top of the corallite? The septa on my coral protrudes further the deeper into the corrallite you go.
Paul

 

[Mantis]

I have a coral that I believe is one from the latistella group as well. My rough ID has always been aculeus. My question is are there any corals in that group whose axials are oval or flattened instead of round. As this coral continues to grow it appears to be getting more pronounced. It seems like this would be a distinguishing characteristic, any thoughts

Here is another pic

http://reefcentral.com/gallery/showphoto.php?photo=10658&papass=&sort=1&thecat=500

 

[EricHugo]

Paul: good question. Some septa are arched, and many corallites are not tubular and so, for example, in a nariform with straight septa, you basically have a cone and the septa would naturally project further at the bottom than towards the open end. I really don't even know how to answer the question "officially" but I would I would probabbly judge it from near the opening unless there is a strong arc, in which case I would estimate from the high point of the arc.

Mantis, I cannot see the characters of this coral. That has rather been the point of this excercise is that without analysis of the morphological features, once cannot in the majority of cases know what species of Acropora it is. As for the group, I have thus far listed the characteristics of the groups...have only listed species characters for two...toganensis and plumosa. If you cannot identify the characters, I cannot even tell you which group unless it is distinct.

It's like soft corals...certain things have to be known for many soft corals before even assigning a genus...species is not possible in soft corals without much greater effort than we have gone to so far in this Acropora example.

The answer to your question: what do you mean the axials are oval or flattened instead of round? Oval and round are characters of the opening. What is flattened? What are the radial and coenosteum characters? I see that the openings on some are oval shaped, but in this case, since I cannot see much of anything in the photo except basic growth from which is a common type, and also highly variable and basically unhelpful, I would have to go through several hundred species, many many books and look at all the conceivable or known variations to even guess what this might be. It would take weeks to do this, and the character might still be a result of the tank environmental conditions. No offense, but I'm not going to do this!

 

[JB NY]

I only have a 8x mag to look at the radials and it's not strong enough to notice any septa. I ordered a 20x loop that should be here today. But if I don't have time to look tonight I will not get a chance until Sunday, due to a quick trip I need to take Friday and Saturday. I'll also try and get some measurements, as close as I can.

I bought the Wallace book and it arrived the other day. Last night I spent some time with it and I think this coral also fits into the Nasuta group. After looking at it for some time I think that this group might be a better fit than the latistella group I had chosen previously.

 

[EricHugo]

No worries...take your time. Now that you have the book, we can really rock on yours! It shows the variations and features much better than Veron's Corals of the World (which might be a good thing or a bad thng, depending on your view or effort!). It has less variations than he and Wallace's earlier book (Scleractinia of E. Australia), but many of those corals may not be quite correctly ID'ed according to both him and her.

I think many aquarists avoid this book because of the limited color photos of living corals, but if you love Acropora, it is a must-have. It's sort of like those who are really into the lighting apparatus of their tanks (bulbs, ballasts, reflectors,etc. who spend thousands of dollars on this aspect, but will not spend $100 or so for a device to measure the light levels and yet also spend fifty dollars to measure ammonia and nitrite....Weird.

So, I think your choices in the nasuta group are pretty limited, but certainly possible...and you'll really have to consider those radials well on a species-by species level.
Look carefully at the photos of radials earlier in the book - those are quite helpful to keep referring to.

 

[firefish15]

I bought the Wallace book and it arrived the other day.

JB,
Where did you get the book? I could only find the CD version of the book online at Amazon. I orderded this but estimated delivery is end of june.
Paul

 

[JB NY]

Eric, your right about it being a great resource. At first I was surprised that almost all the photos are in black and white. After spending some time looking through it, I realized for what they are explaining B/W works better than color photos. It's goes into much greater depth than the Veron books did on Acropora.

So true on the light meter as well.


Paul, I ordered if from the publisher CSIRO, in Austrialia.

http://www.publish.csiro.au/pid/2187.htm

Took about 7 business days to receive. I'm on the east coat of the US. I bought both the CD and book. I found the Coral ID CD an excellent resource so I was hoping this would be the same. This CD seems to be the second half of the book. Not bad, but the Coral ID CD is so good I was hoping for a little more out of this one.

 

[Mantis]

Now I know how my students feel when they are unprepared for class.

No problem, I totally understand. I am having trouble getting a nice photo of my dead frag. I'll have to borrow a better digital camera. I was just curious if those flattened axial openings were a dead giveaway, common to many acro's, or possibly caused by environmental factors.

I should have known it couldn't be that easy.

 

[cabrerad]

I am sorry to jump in late, but I will try my best to catch up. The acropora sp. I have chosen was provided to me as several small frags glued to a small rock in various orientations. I have bleached a frag containing two branches and what appears to be two distinct axial corallites and at least one incipient axial corallite.

Here is what I could glean:

Growth form: Caespitose-Corymbose (a bit of a guess given this is a frag)

Axial structure:

Outer diameter: Mean: 2.6mm (range 2-3 mm). I did notice the axials are not perfectly round and one diameter is longer than the one perpendicular to it.

Inner diameter: Mean: 0.9mm (range 0.8-1 mm)

Septa: 12 (6 primary and 6 secondary, 2 cycles?): What I am calling primary septa are the longer ones and they extend about a third of the inner diameter. What I am calling secondary septa are about half the length of the primaries. The picture is blue corrected for contrast. It was the best I could do with a scope made to look at cells. I need to find a dissecting scope I can use to take pictures.

Radial structure:

Types of radials: Almost all the corallites appear tubular (but almost nariform at the very tip near the opening) There are a few appressed tubular and sub immersed radials.

Radials are appressed: roughly a 45 degree angle for most.

Opening shape: Oblique

Measurements:
Length: 3.5-5 mm ( the corallite I think is incipient is longer, 7 mm)
Outer Diameter: 1mm X 2mm
Inner diameter: the septa are oblique and run almost the entire length of the opening (0.8mm X 1.8mm). The measurements are consistent among corallites, with the shorter length radials having slightly smaller openings.


Septa: My pictures of the radials are horrible, Iââ"šÂ¬Ã‹Å“ll try to get some better ones. Many have no distinct septa that I can see and some appear to have 5-6 septa. Below is an example where I could not make anything out.

I am reasonably sure my measurements and estimates are kinda close to reality. I would like to obtain better pictures, but my equipment is rather limiting with coral identification (great for cells though). i will try to get a better picture of the bleached coral though.

David

 

[firefish15]

Paul, I ordered if from the publisher CSIRO, in Austrialia.

Thanks JB, I cancelled my Amazon order and ordered the book and CD from CSIRO.
Paul

 

[cabrerad]

Ok,

Last few bits to catch myself up:


Coenosteum (I found this one difficult)..some of the areas around the radials appear reticulate. Close to the radials and at the base of the coral, the coenosteum appears costate with spinnules.


Based on the information I have, I think my best fit is the A. robusta group.

Below are some preliminary pics with a dissecting scope I was able to find in a dark corner at work and "un-mothball". The micrometer on the slides is calibrated so that 100 units=50mm (so 1mm is 20 units).

Picture of axial and radials

And, side view of radials:

I am going to try to clean up the microscope and get some more illumination when I get time.

David

 

[EricHugo]

be with you all shortly..have to get to lab.

 

[Mantis]

Well I got creative and took my branch to a camera store and asked them if I could play around with a nice camera. Here's the result:

Growth form:
caespitose-corymbose

Axials:
Not sure how to describe, they are squished

Radials:
Seems like one type
Nariform rounded opening
Appressed

Coenosteum:
Uniform reticulate

My best estimate would be:
Latistella group

 

[Mantis]

I need to go ask the science department for some kind of magnification device so I can examine the septa.