Hi Cjd
Yes, Minkus did list them. I cannot comment on whether they are speculative or not but only have to assume Scott is correct. I have the Banco Central albums that depict all Ecuador stamps in color (use them as reference) and they are not shown. Thus leading one to believe that maybe they were speculative.
---------------- From Minkus 1980 ----------------1886. Official; 1881 values
handstamped in black and red
1980 values, multiply by 8 to get approximate 2013 value
Calculated by: (Scott 2013 Minimum .25 / Minkus 1980 minumum .03)
black ovpt red ovpt
---------- ----------
15 1c yellow brown .60 .60 3.75 3.75
16 2c lake .80 .80 3.75 3.75
17 5c deep blue 1.20 1.20 2.00 2.00
18 10c yellow orange .80 .80 2.50 2.50
19 20c gray blue .90 .90 5.00 5.00
20 50c blue green 2.75 2.75 3.50 3.50-------------------------------------------------------------
Stanley Gibbons Part 20 (South America)
also lists them as O20 - O25
I believe Michel also lists them but my German is pretty much nil and cannot confirm this.
Jerry B