Joseph Clemens, the CP database is not entirely correct in some cases and should not be treated as a 100% correct source of information when it comes to taxonomy. I have met Jan Schlauer, a brilliant man who deserves the utmost respect, especially for his efforts on the CP Database. However, it is just him that manages that site and one man cannot keep up with the onslaught of academic publications that are coming up nowadays and as a result there are sometimes mistakes in it. You are better off comparing databases such as Tropicos, iPlant, Biodiversity Heritage Library, IPNI, Hortus III, Index Kewensis, and JStor. Which is what I did to provide my response.
So let's begin
Heliamphora tatei var. parva Maguire 1978 and Heliamphora neblinae var. parva Maguire 1978 were published together in the Memoirs of the New York Botanic Garden 29: 59, f. 49: G–H, 50: A–C. 1978.
In 1984, Steyermark described Heliamphora tatei var. neblinae f. parva as a stat. nov. making this a synonym of H. neblinae var. parva Maguire 1978. Oddly enough, he didn't use H. tatei var. parva Maguire 1978 as the basionym (epithet bringing name)
instead choosing H. neblinae which is a completely and very distinct species from H. tatei.
Side Note: from a hobbyist perspective Steyermark would be considered a lumper while McPherson, et al. would be considered splitters when it comes to Heliamphora.
McPherson et al. elevate H. neblinae var. parva Maguire 1978 to species status giving it the name H. parva (Maguire) S. McPherson, A. Fleischm., Wistuba & Nerz 2011. They ignore H. tatei var. neblinae f. parva (Maguire) Steyerm. 1984 as a basionym and explain that all the authorities mentioned previously in this post agree that this plant deserves to be a distinct taxon but the level at which it should be named is questionable. Because Steyermark described it as an infraspecific forma of H. tatei, McPherson et al. decided that there were significant morphological differences that distinguish this plant from H. tatei and decided that Steyermark's work is not correct and should not be followed.
I often find it helpful to look at the taxonomic history of a plant to determine what is the correct name. In a way there are two lineages for this taxon so I agree that this is an unresolved taxon; however, I think McPherson et al. are correct based on my personal knowledge of Heliamphora and their argument made the most sense to me when compared to Steyermark's reasoning.
1978- H. neblinae var. parva Maguire
1984- H. tatei var. neblinae f. parva Steyerm.
or....
1978- H. neblinae var. parva Maguire
2011- H. parva S. McPherson, A. Fleischman, Wistuba & Nerz
Which is correct is a matter of opinion at this point. I thought it might be helpful to present all the facts though to help others form their own opinion.