Looks like vivax, the spotty culm sheaths and hairdo kind of suggest it. So does the later shooting period.
Make sure you save a few culm sheaths to look at the way they are formed.

I don't know what it is, but I don't think it's vivax. Here's one of my vivax shoots and you can see the difference in the amount of dark color and spotting, as well as how the leaf blades at the top are crinkly and appear to be striated differently from yours.

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I'll take a look at what I have shooting later today and see if I can get a match. I would think that something unidentified on eBay would be a more common bamboo.

Might be decora aka manni if not vivax. They come up later than many of the others too.

I agree about the crinkled leaves being related to vivax- these are defnitely straight and no auricles/fimbriae/ligules that I can see. What clues should I look for in the culm sheaths?

After looking through the Bambouseraie catalog the closest match I can find is Meyeri. It was bought online through ebay so who knows at this point, I was hoping it was "Moso" like the title of the auction stated. Would you be able to identify Moso at a young age(about two years old) or do the defininig characteristics of the plant become more evident after several years?

Definitely not a Moso shoot, which are "fuzzy" and shoot early. My experience is that they need a lot of water and are difficult to grow here in Central TX. I have killed two already, I think due to the hot dry winds we get at times.

Mike near Brenham TX

A couple of possibilities:

Phyllostachys nuda has spots on the culm sheath and does not have the auricles or ciliae. However the spots are usually larger on the nuda than are shown on your pictures.

Phyllostachys kwangsiensis in the link below looks similar to your pictures. It also has spots on the culm sheaths.

Here is a link that might be useful: Phyllostachys kwangsiensis

Thanks for the attempts to ID this one- whatever it is it likes it here. It's putting up more shoots now; five in the past few days. I'll be anxious to see what the more mature form of it looks like once it's filled out later this summer.

Try to note if the culms take on a serious blue tint after the culm leaves begin to fall away. This would suggest Makinoi, as do the shoots, but it is not so common that I'd think you would have grabbed one off the internet.

Vajdak-
My Ph. aurea just started shooting and the shoots seem a very close match to yours. Just a light amount of spotting on the sheaths, almost straight leaf blades (with a little waviness), and just a hint of lighter color at the outer edges of the leaf blades. Aurea often has compressed nodes at the base, but not on all culms. Take a look at these and tell me what you think. (The first two I took when I had the sum backlignting the leaf blades, so they're a little lighter seeming than they really are.)

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Kudzu, those pics of the aurea shoots look close to the ones I have, thanks for posting them. It could be the environment/conditions here but the shoots I have seem a bit lighter in color, however the rest of it looks real similar. I really hope it's not golden, this stuff seems to grow wild around here and I was looking for something different. Well I'll keep an eye on the nodes near the base and see if any of the new shoots take on the characteristic compression of golden.

Vajduk-
I don't know how much variability there is in, say, culm darkness or lightness when you have the same species in two different environments. I did tweak the first two photos a little with photo software and that may have darkened mine a bit. The third photo didn't need tweaking and I think you can see that the shoots vary somewhat in darkness: for example, the one furthest right is lighter than some of the others. I'll be interested to hear if you get any more insights (like compressed nodes). The one other cynical thought I had was that an unknown bamboo purchased online is not likely to be exotic, and that increases the chances of getting something like aurea.

Scott,
Before this message drops off I thought I would add two more possibilities and some comments. I was expecting someone who was more expert than I would probably give you a more positive ID. I do not have the two bamboo listed below so would appreciate any additional comments on these possibilities.

If this was sold to you as a "giant bamboo," it might be Madake, Ph, bambusoides, 6"OD X 72'high (I do not think it will get that big in Central TX unless very well watered). I do not have this, but it was shooting at Zilker in Austin around the same time as yours, and as I recall looked similar. I do have Ph. b.'Castillon' but am drawing a blank on what the shoots look like.

There is also something about your shoots that remind me of my 'Robert Young'. It is not 'R Y' which shoots with much lighter green culms, at least mine do. Could it be the generic Ph, viridis, which I do not have, but does very well here. The culms are supposed to feel rough and have a pigskin like surface. Ph. vivax on the other hand has vertical ridges on the large culms that you can feel with your thumb nail.

Mike near Brenham TX

Looks like Phyllostachys bambusoides to me. Golden bamboo has been called P. bambusoides var. aurea in Japan, so it's consistent with that interpretation that a specimen of golden bamboo would look similar to yours.

Thanks for the help with this one. The only thing that has eliminated most of the suggestions so far is the apparent lack of oral setae. The nodes did compress just a little near the lower portion of the culm but nothing extreme like P. Aurea. I'll check again but am pretty sure the surface of the dark-green culms are mostly smooth.