Any hybrids between Lemon and Grapefruit?

[SoCal2warm]

Is anyone here aware of any hybrids between lemon and grapefruit ?
Or citron and pomelo (or any other of these type of combination) ? I thought I would ask the citrus experts here.

I know that orange has a little bit of pomelo in its genome, and lemons are descended from sour orange and citron, so technically a lemon is sort of like a cross between these two (citron and pomelo), but that's not really what I mean, since the pomelo heredity is so low, and it has more C. reticula (mandarin) heritage mixed in than the other two.

You see citron/lemon hybrids and grapefruit/pomelo hybrids all the time, but they are most often mixed with mandarin. Citron-lemon hybrids exist (Ponderosa lemon) and Grapefruit-pomelo hybrids exist (Oroblanco) but I've never read of a Grapefruit-lemon hybrid.

It seems these two groups are too far on the fringe for anyone to have considered combining them together. Oranges (and to a lesser extent mandarins which are not so dissimilar) are the mainstay of citrus and everything else is an outlier. There are lemons and then there are grapefruits, but no one really thinks about combining these two families together.

Would such a fruit have any desirable attributes, do you think?

[Millet]

There are probably some grapefruit/lemon hybrids , probably private hybrids.  I would think such a hybrid would result in a grapefruit even more bitter then normal, or a lemon that was somewhat washed down in taste.  But you never now.

[Ilya11]

Is anyone here aware of any hybrids between lemon and grapefruit ?
Or citron and pomelo (or any other of these type of combination) ? I thought I would ask the citrus experts here.

There are several candidates for Citron x grapefruit hybrids  the closest is  Damas citron
https://academic.oup.com/aob/article/117/4/565/2195970/Phylogenetic-origin-of-limes-and-lemons-revealed

You see citron/lemon hybrids and grapefruit/pomelo hybrids all the time, but they are most often mixed with mandarin. Citron-lemon hybrids exist (Ponderosa lemon) and Grapefruit-pomelo hybrids exist (Oroblanco) but I've never read of a Grapefruit-lemon hybrid.

Ponderosa and Bitrouni lime have genes only from  Citron and Pomelo , although not in proportion of 50:50
Fourny lemon is probably a direct hybrid between these two species.

[SoCal2warm]

According to one genetic study
Citrus sp. Bitrouni lime
C. sp. Hybride Fourny lemon
C. pyriformis Ponderrosa lemon
C. lumia sp. Jaffa lemon
appear to be all C. maxima and C. medica

I don't know about Ponderrosa, that's supposed to be a hybrid between citron and regular lemon (itself sour orange x citron). Maybe the specific markers they were looking for for mandarin got eliminated from the hybridization.

In addition, the Kulu lemon had very little C. reticula in its genome. It's worth pointing out that the Kulu lemon has been observed to be highly cold tolerant, during temperatures down to 18 F.