I had read your post some time ago and was equally baffled by this question. By pure chance, I was reading an article this morning on Wikipedia about the Quechua language and came across this:
A number of Quechua loanwords have entered English via Spanish, including coca, cóndor, guano, jerky, llama, pampa, puma, quinine, quinoa, vicuña and possibly gaucho. The word lagniappe comes from the Quechua word yapay ("to increase; to add") with the Spanish article la in front of it, la yapa or la ñapa, in Spanish.
Lagniappe looked familiar and I knew that there was a question about -legnia here on Textkit.
I'm by no means claiming etymological expertness, and I would think it strange that a Quechua verb could enter the English scientific vocabulary, but I thought it was an interesting connection nonetheless.
An article posted on Chris Jones's http://www.latinlanguage.us blog led me to look up Quechua.
Anyway, if nothing else I hope this keeps the discussing going!
Rufus
