What is the most fitting Identification for this Cactus?

[hegar]

I have two cacti growing side by side in one of my cactus flower beds. Image 1 shows both plants. The one in the foreground I am sure is an Echinocereus pentalophus. The other one, only a few inches away (flowering) is the one for which I cannot assign a species name and believe, that most likely this is a hybrid, perhaps between E. pentalophus and E. cinarescens.
As you can see, the "hybrid" is a sturdier plant with larger stems. Also, while the stems of E. pentalophus do change color during stress situations, e.g. frosty nights, very high temperatures, etc. the "hybrid" does stay green year round. In addition, it seems to flower later. The small E. pentalophus plant near it bloomed already on April 24th, the hybrid just opened its first blossom today. The blossoms also seem to be slightly different. Those of the "hybrid" remind me a bit of the flowers produced by my E. cinarescens.
Is there a cactus, which does fit the images and descriptions I gave, which falls into a species neither pentalophus or cinarescens? The latter does have a slightly different flower color and greatly larger stems than my "hybrid" plant.

E_pentalophus et al..JPG (156.69 KiB) Viewed 2626 times

E_pentalophus9.JPG (81.9 KiB) Viewed 2626 times

unknown hybrid2.JPG (113.56 KiB) Viewed 2626 times