Here's Michael Ronayne's description of what he does, in brief with references, from the ALA Forum:

"The best documented case of a Gambusia species where the female has a WZ sex chromosomes and the males ZZ is Gambusia affinis (Wooten et al, 1988). In Gambusia holbrooki the females have a pair of XX sex chromosomes, the males XY and melanic males XYm. The trick I am using to breed the Innes Gambusia, where both the males and females are black is to replace the WZ sex chromosomes with WYm, which codes for a black female. Black males can be ZYm or YmYm. Note that there is a secondary set of gender determining chromosomes in G. holbrooki and it is necessary to do a double backcross to G. affinis to obtain the desired results."

The Wooten paper is:

Genetic Variability and Systematics of Gambusia in the Southeastern United States
Michael C. Wooten, Kim T. Scribner, Michael H. Smith
Copeia, Vol. 1988, No. 2 (May 18, 1988), pp. 283-289
http://scholar.googl...amp;as_yhi=1988

The following paper contains information on karyotypes of Gambusia species.

Systematics and Biogeography of the Genus Gambusia (Cyprinodontiformes: Poecilidae)
by Mary Rauchenberger, 1989
http://digitallibrar...107/1/N2951.pdf

Somewhere on the ALA Forum is Ronayne's statement on his hybridization strategy for affinis/holbrooki.

Brooklampry, I have caught both black and speckled males and females Gambusia here in Savannah in the drainage ditches. I'm going after some more this weekend (I fed them all to my Frontosas). Just for my own info are you saying that G. affinis and G. holbrooki are separate species or are they actually named G. affinis holbrooki. Or are the black fish the dreaded "H" word. It would be interesting to know seeing as they were described by Innes (NOT an actually scientific book) ...Jim

My 2cents on the taxonomy is hide in a hole for a bit and when the dust settles maybe someone will make an authoritative decision..

G. holbrooki was described as it's own species and the subspecies was dropped (which I would think is valid but I'm not a taxonomist) Now it seems someone is just saying they are just G. Affinis so G. Holbrooki is an invalid junior synonym...which is correct I will differ to someone else better qualified in taxonomy... Neely maybe could chime in here on this.

For purpose here I'll just stick with calling the eastern fish G. holbrooki and the western G. affinis which was the accepted rule..

From my understanding on G. affinis and G. holbrooki populations, where they overlap, hybridization is actually rare and typically you find one or the other but not both. I do not think any of the black or spotted fish in the wild are the result of hybridization but rather just a population of one or the other that happens to express this special gene. Both can express this and just having a black pattern is not indicative of species or the presence of hybrid fish..

Ok it need new name for Innes gambusia before we killing each other. Any ideas?

Gambusia holbrooki x G. affinis (marbled hobby strain)

Marbled Mosquito Fish?

Marbled Mosquito Fish?

How about Ronayne's gambusia......Ok whatever... it should just be more clear that the fish is a cultivated strain and not a wild type fish...

Thanks Fundulus, I was getting curious about where the color variations were coming from. Its been a while since I actually got excited over the sientific desription of any fish. (they always change next week anyway). I've seen spotted and black gambusia most of my aquarium life (about 45 years) in the wild and never paid much attention to what they were...Jim

What the black western gambusia ans speckled western gambusia looks like?

To avoid arguements like brooklamprey started it, there will need to be specific subjects.

We are talk about Melanistic Eastern/western hybrids that's melanistic in both sexes.

Not full melanistic easterns or very rare melanistic westerns. There! Problem solved.

Through I want learn about these special population of all melanistic eastern and that black western that jimjim mentioned.
Teach me!

G. holbrooki was described as it's own species and the subspecies was dropped (which I would think is valid but I'm not a taxonomist) Now it seems someone is just saying they are just G. Affinis so G. Holbrooki is an invalid junior synonym...which is correct I will differ to someone else better qualified in taxonomy... Neely maybe could chime in here on this.

"Eschmeyers Catolog of Fishes" (supposedly the authority on which names are valid at the moment) does list holbrooki as a synonym of affinis. Though Im with you on this, I write holbrooki in my notebooks.

Online version of the catalog = http://www.calacadem...hcatsearch.html

"Eschmeyers Catolog of Fishes" (supposedly the authority on which names are valid at the moment) does list holbrooki as a synonym of affinis. Though Im with you on this, I write holbrooki in my notebooks.

Online version of the catalog = http://www.calacadem...hcatsearch.html

ITIS lists it as well as a synonym:
http://www.itis.gov/...ch_value=165896

I've not had much luck in tracking down where this came about and when. I thought it was settled with the fifth edition of Common and scientific names of fishes from the United States, Canada, and Mexico.

The new version apparently changed this to Junior synonym status.

I've not had much luck in tracking down where this came about and when. I thought it was settled with the fifth edition of Common and scientific names of fishes from the United States, Canada, and Mexico.

The new version apparently changed this to Junior synonym status.

Yeah, I was a bit confused by this as well, I haven't been able to locate the paper which brought about the change in species status, i'll keep looking though.

Yeah, I was a bit confused by this as well, I haven't been able to locate the paper which brought about the change in species status, i'll keep looking though.

I am at a loss.. I was sure Wooten et al. and adoption by the AFS ended it...
Find anything please let me know....

Jimjim, do you saying you find affinis that colored peach right? Also you saying there's black gambusia and speckled gambusia isn't they are same color patterns?

Butch; I didnt say anything about peach color(these replys do run together don't they). I have found both speckled and black colored Gambusia for a long time, at least since the early sixties. There is a population of the speckled ones here in Savannah but the black ones are far and few between. It seems (not scientific, I know) that every year after it floods and then drys down to a trickle that one year its speckled the next its a preponderance of solid blacks (remember my mind is old;-))....Jim

Jimjim, do you saying you find affinis that colored peach right? Also you saying there's black gambusia and speckled gambusia isn't they are same color patterns?

I think you meant to address this to me (not only do the replies run together but jamjam and jimjim look similar). And yes I have collected some that have a somewhat peach color along the pectoral and pelvic regions. The rest of the body is usually a lighter version of the normal coloration (at least normal for the locations I collect them).

Also, these are not very common. I don't have an exact ratio of these to the normal colored ones, but it's probably one in several hundred.

Butch; I didnt say anything about peach color(these replys do run together don't they). I have found both speckled and black colored Gambusia for a long time, at least since the early sixties. There is a population of the speckled ones here in Savannah but the black ones are far and few between. It seems (not scientific, I know) that every year after it floods and then drys down to a trickle that one year its speckled the next its a preponderance of solid blacks (remember my mind is old;-))....Jim

That is some very interesting anecdotal information Jim..I think I have read a paper once that looked into temp being a factor in the expression or dominance of the Melanistic gene in Gambusia holbrooki..again Very interesting info.

Jamjam, can you collect these peach gambusia? And if they have black eyes then they are probably golden or peach but if its pink eyes its albino. I wanted that color to if I can line breeding them to produced nice color gambusia.

Jimjim, are full black gambusia still in the ditch, if so can you catch a pair or trio of full black gambusia?

I just wanted to breed a hardy gambusia for aquarium..my fancy guppies keeping died on me..

I think you meant to address this to me (not only do the replies run together but jamjam and jimjim look similar). And yes I have collected some that have a somewhat peach color along the pectoral and pelvic regions. The rest of the body is usually a lighter version of the normal coloration (at least normal for the locations I collect them).

Have to say your two user names have made me have to look twice a few times

On these peach colored fish. Posted below is a pic of a fish out of Eastern Alabama that I had that was very goldish yellow on the pectoral and pelvic are. Is this in any way similar to what you have observed???

Have to say your two user names have made me have to look twice a few times

On these peach colored fish. Posted below is a pic of a fish out of Eastern Alabama that I had that was very goldish yellow on the pectoral and pelvic are. Is this in any way similar to what you have observed???

Yes. The pattern of coloration is very similar. The color was less bright and metalic, more pastel and subdued.

More melanistic farther south

Since this topic is cooling down, I thought I would add a new branch.

From my personal experience, there are more melanistic male Gambusia affinis the farther south you go. Southern Florida panhandle seems to be the northern limit.

That is some very interesting anecdotal information Jim..I think I have read a paper once that looked into temp being a factor in the expression or dominance of the Melanistic gene in Gambusia holbrooki..again Very interesting info.

Could be temperature. Could be the strength of the sun.

What'cha think?

Could be temperature. Could be the strength of the sun.

What'cha think?

Interesting concept...Not sure how to ideally test it..
Good food for some critical thinking and research.