Creating legend for different shapes and colors written with rule in one layer

Question

I have following problem: I have diffrent locations where I found amphibians. Now I want to create a map where the form/shape of the point illustrates the specific species (waterfrog, common toad, etc.) and the fill color the stadium (adult, juvenile, etc.). I find a way doing that by using the expression string filter.

I created following codes for the geometry:

CASE
   WHEN "Art" IS  'TM'  THEN 'circle'
   WHEN "Art" IS  'WF'  THEN 'square'
   ELSE 'triangle'
END

and for the color

CASE
WHEN "Stadium" =  'ad'  THEN  '#fce8d5' 
WHEN "Stadium" =  'juv'  THEN  '#ffd3el'
WHEN "Stadium" =  'Larve'  THEN  '#85b66f'
ELSE  '#0a97b0'
END

The problem now is that I want to create a legend where the diffrent forms/shapes and colors are listed as well (so far only the layer itself is listed).

So I either need a tip how to fix my legend or I need a diffrent approach to get my forms and colors.