The mini killie history is very interesting & has been confused with other sp. along the years.First of all it's not a true 'mini' form at all. The name was applied due to unknown circumstances.
I have laid down below, information I have referenced from BKA & AKA newsletters & information supplied to me by the people maintaing them between 1969 - 1976 (more or less the active period for this form)

In May 1970 an article appeared in the AKA Journal. The original import into the USA was in 1969 where fish were sent to Rosario la Corte from Walter Foersch in Germany. A photo appeared in the article which looked very close to Eymojok.

Walter Foersch wrote an article in the AKA Journal of October 1970 & included 3 photos in black & white of the 'mini killie' being kept in Germany. Although not in colour they looked remarkably like a golden form of gardneri (similar to the gold Nsukka strain). The photos in these 2 articles do not look to be the same fish at all.

One contact reported 'the "Mini Killie" was a commercial importation
(probably through Aquarium Imports of Long Island)'.

In the July 1971 BKA Killie-News ( No. 71) Fred Wright (then Technical Editor) wrote on the 'mini-killie' saying that he had received them from another BKA member (Terry O'Brien). It was reported as being 'not very well known among members'. Fred considered these fish to be the Cameroon population of A.gardneri from Eymojok. He gives the size attained of 2 & a quarter to 2 & a half inches for males & 2"+ for females. He refers to 'a very good black & white picture of this sp. which can be seen in ROTOW 1 p 226'. This is not the actual 'mini-killie' import as it came in after the publication of the book. Fred used this photo only as a guide to what the sp. looked like.

Fred later compiled his 'potted history' of the form in BKA newsletter No.82, June 1972. In this article he considered the purity of the form to be questionable. Fred obtained pairs from the USA from various sources all labelled 'mini-killie'. All pairs were kept seperated & the offspring were 'to say the least, remarkable as the offspring varied fantastically in regard to colour pattern & variation'. Other stock obtained from other countries (not given in the article) also showed this variability. In some instances Fred identified 5 different colour patterns.
It was considered that these fish were crossed before he got them. I hesitate to write the following for fear of being flamed but it is relevant to the sum of information. Fred wrote 'I understand from reliable information that the practice of using a female of any population to a definate male of a recognised population is common practice in the States'. I would add here that I'm sure this is not the practice nowadays as we all know the importance of keeping blood lines pure.
What Fred was saying is that their was a good chance this form was crossed either in Germany or the States unintentionally or otherwise..
The form resembling the Eymojok photo in ROTOW 1 was bred by Fred who reported they bred true.