What is the name for the Mitsubishi A6M Zero's one-piece wing/fuselage?
The construction of the Zero was slightly different from that of its western counterparts. The aircraft had three major sub-assemblies:


wing/center fuselage
forward fuselage, and
aft fuselage.


The construction of the first sub-assembly was such that the both the wings were constructed as one piece integral with the cockpit. This is (presumably) what the author means in the article in question. Otherwise the wing was a semi-monocoque structure with two main spars, which is quite common. 

The image below shows the sub-assembly in question (the wing+cockpit section) from a recovered zero. It can be seen that there is no great difference in design, only in the choice of the sub-assembly (a wing+cockpit section, instead of wing + fuselage).



A6M Zero midsection; image from lasamurai.blogspot.in

The images below show the different sections of the aircraft (middle and rear sections) from a rebuilt Zero.



Cockpit+wing sub-assembly; image from j-aircraft.com



Rear fuselage assembly; image from j-aircraft.com

I'm not aware of any special name for this. It appears to be a normal semi-monocoque structure.