What is the UML analogue to the Data Flow Diagram from Structured Analysis?

UML 2 has a very good analogue to a data flow diagram: the "information flow diagram".

Information flow diagrams are explained here: https://web.archive.org/web/20121118061853/http://www.uml-diagrams.org/information-flow-diagrams.html

Note that UML 2.5 has information flows and information items, but the term "information flow diagram" is not part of official UML 2.5 diagram taxonomy. So formally, you just create a class or component diagram with lots of information flows in it to obtain your "information flow diagram". I do this all the time, using information items of UML to represent my data.

Probably the closest thing is the activity diagram. It's not quite the same; more influenced by flow chart than dfd. However: you can do some of the useful things in DFDs, e.g. ADs do support concurrency and differentiate control flow from dataflow.

More details on comparisons & differences in this question.

[fwiw, I still use DFDs: they're simpler and more elegant in many circumstances]

hth.