Not being introduced to the team – should I ask for it?

In all larger teams I've worked in, the boss leads by giving them a brief space at a meeting to say hi. In very small teams it's more likely implicit that the people already there will introduce themselves to you, and you introduce yourself to them at the same time, because the team is only half a dozen people in the same room.

I wouldn't go longer than 30 seconds or so though. Say who you are and what you're doing there on which project/area, and that's mostly it. If it's relevant or interesting, or just plain cool, a sentence or two about what you've done before might be appropriate too. Really you're mostly trying to make sure people have a name for the face, and a name/face that they can take issues to which relate to that project/area.

Be strong. On a meeting, about 3-5 people is actively watching. It does not matter, how big is the meeting itself.

If you have 50 people on the meeting, still only 3-5 will actively watch.

There are some exceptions. For example, if there are rumors about a possible mass layoff, and then your CEO calls a whole-company meeting with the subject "About the future of our company", then yes, very likely everyone will watch. But that is exception.

There are sometimes teams where really everyone thinks that listening 8 people an hour long will all have important content and they all watch. Also that is rare, but possible.

Having yet another new guy in a 50 team is nothing new.

Be strong. Even if you had this introduction, no one had remembered you on the next meeting.

If you get a word next time, you might introduce yourself politely in some word. Roughly so:

Boss: "Maybe @user169063, please talk about the XYZ"

You: "Thanks. This is the first time I get the word by the company. Before I start, first I would introduce me. I am a ..., since ... by the company as ... (so the usual introduction text). And now about XyZ... (that is what the boss asked for)"

I say not to ask you boss for a late official introduction, for two reasons.

#1 is that employees are quickly divided into those who bug the boss with nonsense, and ones who don't. In other words, you quickly get known as someone who can be trusted to handle minor issues, or as someone who likes to waste other people's time. For why a missing intro is nonsense:

#2 introductions at big staff meetings are fun, but almost always useless as far as job duties go. Most people assume they won't be working with you, or that they'll talk to you at smaller meetings where it's more appropriate to see where you fit in. I almost never even remember people's names introduced to the entire group.

Your job now is to find out who you'll be working with, doing exactly what, for or with them. Do that and introduce yourself as needed.