Typically the Studio will paint models not just for the webstore images, but for codicies and other rule books, so when you look at the new Tyranid Toxicrene, look under the creatures foot
A BLOOD ANGELS TERMINATOR
And to prove this is not just fancy conversion work by a maverick studio artist, here is the Toxicrene Sprue. Look on the bottom left.
Now since it doesn't to seem to have chapter specific icons, that leads me to believe that it was a conscious decision to make it specifically a Blood Angel. Why would that be the chapter of choice? (Other than they are amazing) Well simple: they need pictures for the forthcoming "Shield of Baal" release of Tyranids vs Blood Angels.
To back this claim up further is the fact that the Toxicrene with the Blood Angel in it is painted in Hive Fleet Leviathan colors, where as the new Maleceptor is painted in Hive Fleet Kraken colors and does NOT feature a Blood Angel. Why is this important? Well the new campaign book is supposedly "Shield of Baal: Leviathan" and is a continuation of Tyranid dataslates featuring Corbulo and a force of BA. Check out the Bundle Deal from GW to quickly compare the schemes (how it is a bundle when it is just 2 kits for the exact same price of two kits separately is a separate story).
Just my theory, but all the pieces fit IMO. What do you think?