These new killifish species are part of the Melanorivulus dapazi group.  They are similarly tiny (~28mm / 1.1″ standard length) and have the same body form and common pigmentation.  But they are visibly different.  Their latin names are easy to remember because they are based on these differences.  M. ignescens has more red in its fins (“igenscens” means “inflamed”)  while M. flavipinnis has more yellow in its fins (“flavipinnis” means “yellow fins”).  M. regularis has regularly spaced banding on its caudal (tail) fin.

Melanorivulus regularis

Melanorivulus ignescens