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I'm creating humanoid specie with two subspecies

• Hairy races - roughly based on humans, chiss, mirialans, with standard males & females sexes


• Tentacle races- roughly based on asari, twilek, togruta hermaphrodites with sex organs like futanari from Japanese manga

They could all interbreed between each other, with children getting DNA from both parents. However race is determined strictly by the mother, due to subspecies specific genes being encoded in mitochondrial DNA.

Is it possible for different subspecies to be with & without separate sexes?

Some background which I don't know is it important for answering.

Hairy races discriminate against tentacle ones, while modern hairies start to accept them as equals or at least say they do, the traditionalists which are majority of population still keep them as slaves and quite often castrate or even emasculate them. This behaviour was even more pronounced in the past when nearly all tentacle races were enslaved and castrated/emasculated. There were small number or free members of the tentacle races plus some runaways.

In the present tentacled are mainly kept as domestic servants and attractive ones for pleasure. The rest are becoming less economically valuable so they are slowly started to be freed. Most of them have few skills and turn to lowest payed jobs and prostitution to survive.

Technically, it's possible, but they're pretty far from humans.

You can achieve this via a rather convoluted genetic mechanism. However, the resulting species is majorly different from humans in terms of reproductive mechanism. Your question kind of requires this.

The following conditions would create the effect you want:

• The information related to subspecies is stored on the X chromosome


• Female (2 X chromosomes) embryos are not viable and die in the womb without exception. This is because vital information is stored on the Y chromosome.


• Both races are hermaphroditic, but the hairy race develops either one set of genitals or the other randomly in the womb, like a birthmark. This information is stored on the X chromosome.


• Both races produce egg cells with both X and Y chromosomes, but the X chromosome is necessary for egg development, so the ones with Y chromosomes die immediately.


• Sperm cells, however, can survive without an X chromosome.


• The X chromosome is really heavy, due to all of the extra information stored on it. This means that sperm cells containing an X chromosome are too heavy to swim as fast as the Y chromosome sperm. This ensures that virtually all babies are born XY.

The effects of this are:

• Every child gets the XY genotype, making them all genetically male


• Hairy fetuses develop either testes or ovaries (maybe these organs are in the same place, so only one can form?), which produces either female or male hormones, depending (the alien equivalent of estrogen and testosterone). This means that they appear and act either male or female, despite being genetically male


• Tentacle fetuses develop both sets of sex organs


• When members of different species mate, the mother is the one that provides the egg cell. This cell contains the subspecies-determining X chromosome, so the mother's race is taken on by the child.


• The other chromosomes determine the other aspects of the body appearance, so both parents give DNA.

Possible issues with this:

• Fertility is a little lower than in humans, because embryos with XX die in the womb.


• Birth defects in the hairy species are common, where both sets of genitals manifest on top of each other. This probably leads to the fetus dying, but that's up to you, the author.

I can't see this happening by natural evolution: there are too many difficulties on the way there. More likely, they were created by genetic engineering. Maybe a species found a better way to adapt to their environment, say learning to space travel, by messing with there genes, and they created this?

children getting DNA from both parents. However race is determined strictly by the mother.

This is the part that makes little to no sense at all. If they get DNA by both parents, race, being determined by genetics, also comes from both parents. If they didn't need the genetic contribution of the father, why bothering with sexual reproduction, when much simpler alternatives are available?

What you depict sounds much more as an extreme case of sexual dismorphism than subspeciation.

I am assuming by "is it plausible" you are wondering if it this species can occur by natural selection. The snide answer is "anything is possible, as long as it is evolutionarily favorable," but the more complicated reality is that "is it possible" calls for a justification of how it could happen. That could be more difficult.

From a biological perspective, you really have two different body types, which are at least as different as male and female in H. sapiens. That's a strange balance. You'll want a justification for why they stay in balance. You mention their history, but you're going to want to go into pre-history. How is it that, for millions of years, both body types were evolutionary advantageous enough that one type did not completely replace the other due to being more fit.

One answer might be location. Consider H. sapiens. Scientists steadfastly refuse to use the term "subspecies" to denote race, because the term "subspecies" comes with far too much baggage, but we can look at it that way ("Subspecies" is actually a very poorly defined word in science, referring to rather arbitrary distinctions. Within a species, scientists don't always agree as to which lines to draw to create subspecies). So, without stepping on too many toes, I'd suggest looking at our races as prior art. The most obvious example is the amount of melanin we find in those societies which stayed in Africa versus those which moved to Europe. In Africa, there was a massive survival boon for having dark skin to protect against the scorching sun. In Europe, that melanin was far less valuable, so not worth the metabolic cost to produce, so skins became lighter.

If we look at our own history, we see that such tiny changes in genetics were more than sufficient to justify desires for slavery. Many efforts, such as Phrenology, were developed to further justify this by demonstrating particular races were objectively inferior, though we now find all of them to be totally bunk.¹ If such small changes were sufficient to justify slavery, it would not be unbelievable for larger differences to do the same. All you would need is to define what environment lead to the tentacled and hairy races/subspecies to develop their distinctive features.

That approach calls for segregation, and differences in environment. Another approach might be collaboration. In the second paragraph, I mentioned that this balance was at least as strange as the balance of male and female in H. sapiens. Think about it... how the heck is that balance valuable in our species? The answer is that the male and female halves of our species work together to solve common problems. They are specialized in ways which dovetail nicely to solve the greater issues of how to propagate a species. Neither side takes over because the ideal answer is a balance, not a domination.

Of course, you want domination, so we may need to come up with a less equitable balance to support your culture. As a hypothetical, what if your tentacled race expressed genes in a visible way, perhaps in the shape of their tentacled features, which would otherwise be hard to see.² The colors and twists of the tentacles might act as a living microscope into the genetics of the individual. Control of this would be to peer into one's own genome itself. It would be a powerful tool for a powerful race, and rapidly promote the enslavement of one half of the species. As a neat added bonus, an enslavement of this sort would be an incredibly dark societal structure. To keep such a culture running, there would need to be an equally incredible lightness somewhere in the society. You, as the creator of the world, could put said lightness wherever it is convenient for your story.³

As a final thought, mitochondrial DNA is a very hard place to store such a fundamental division in a species. It evolves very differently than the rest of the DNA, as it is basically an asexual selection process, with no mixing from the male side. Thus it would evolve much slower. Instead, I'd recommend relying on a hormonal solution. As the baby grows, the mother releases hormones that lead the embryo to settle on one subspecies or the other. You could set it up such that too much or too little hormone would be fatal, making it very difficult to artificially select a subspecies by injecting hormones. This would be a delicate balance of the mother's body listening to that of the gestating child, and adapting her hormone secretions to match. Frankly, when you look at how a mother's body cares for her child's body in womb, this would not be all that far from the truth. Frankly, it's magic, and I'm happy to leave it that way.

^{1. I was going to say we found all of them to be totally bunk, except "white men can't jump," because that's the truth, but folks like Patrik Sjöberg demonstrate that it's not people with my skin color that can't jump... it's just me. Maybe I should, you know, practice or something.}

^{2. Why have the tentacled one express this? Anthropomorphic bias. As someone that looks human, the tentacled one is "the other side." For a fun mental challenge, flop this around, and have those hairy apes express the genes and see what the tentacle side does with said power!}

^{3. Or, for a twist, make this power into the lightness. If there is an even darker force threatening the species as a whole, this might be the lightness. This could lead to a tremendous amount of pride in the tentacled ones as they manifest what will save the essence of their species. Just as an alternative to the, you know, slavery and prostitution and all.}

So as mentioned, Sub-Species are very hard to define. Even within H. Sapiens, there is some debate as to whether we are a seperate species of the Genus Homo from H. Neanderthalis (spelling) or if Neanderthalis is a Human sub-spiecies (H. Sapien Neaderthalis) that inter-bred due to co-location with humans outside of Sub-Saharan Africa.

Sub-Species are generally seen as a location based phenomena in a species (okay, I'm going to do this and reference Pokemon... but Generation 7 introduced regional variants which are essentially sub-species of first generation characters. If we assume that a Kanto Vulpix (P. Vulpicus Kanto) and an Alolan Vulpix (P. Vulpicus Alola), the only genetic difference between the two is their typing (Kanto is a fire type and Alolan is an Ice type). However they are compatible and will produce an offspring that is also a (P. Vulpicus)... the typing and moves learned from the parents will vary but it is still of the same species as both parents, despite both parents being different sub-species.).

However you do not have to be that close to breed as there are hybrids of genuses such as the Liger and the Tigon (The former is the offspring of a male lion and a female tiger, the later is a male tiger and female lion). These are not the same species (Panthera Leo and Panthera Tigris) but they are the same Genus (Panthera) which is genetically close enough for these purposes. This would be, to continue our Pokemon analogy the same as a Vulpix breeding with a Fennnik (another fire fox, P. Fennikus) and producing a viable offspring. These aren't hard rules, but it's a good line (It's thought that Humans and Chimps could make a hybrid offspring, but apperently no one's tried. And despite an extremely close genetic similarity, Chimps are no Homo... er... not of the Genus Homo... (I'm talking about the Human scientific name, let me have one joke).

Now that's a lot of stuff on genetics, Pokemon, and immature jokes about Gay apes, but there's something else that needs to be taken into account.

In Zoology, Hermaphrodites, especially as complex as vertebrates, are not normally simultaneously both genders. Typically that type of reproduction is observed in very basic sexual reproduction and flowering plants (usually confirs, but some flowering plants can self pollinate). Most vertebrate Hermaphrodites are capable of producing both gammetes but not at the same time, but within their life time. These species typically determine their gender based on dominance with the indivdual in a group that achieves dominants turning into the desired gender. A famous example of this is the Clown fish, which are typically born male and establish a pecking order among the other men. The top dog will become female, and remain so until she is killed, in which case her mate becomes the new female and the best man at their wedding becomes her new husband and the line moves down... except they don't wed... I'm ruining Finding Nemo enough, let me have it.

There are species of fish that do the reverse, and are born female (or first instance Male) and will become Male (or Terminal Male if already male) when the vacancy opens.

Finally there are bi-directional hermaphadites, which will transition from one gender to another and back again based on group dominance and needs for a gender. In this case, it's basically that scene from the Sandlot where the insult "You throw like a girl" is thrown out... but it actually might result in you throwing like a girl for real.

All this said, it's entirely possible that two species of the same genus could make a hybrid, with one of those two species having a bi-directional hermaphradidic nature. For best results, keep in mind that Hybrid individuals are often times steril and not capable of producing an offspring.

All known Neander DNA is associated w/ female lines. Presumably, only modern male / neander female couplings produced viable hybrid offspring.

You could thus say that those early hybrids, an incipient subspecies or the raw material of one, were sex-specific in the sense that only female neanders participated in gene flow with moderns (in Europe and Asia during the late pleistocene).

These creatures are different strains (races) of the same species.

Hairy races have genitalia like humans; easy.

I read the tentacle races are basically males and shemales. Tentacle races have genitalia like hyenas. https://en.wikipedia.org/wiki/Spotted_hyena#Female_genitalia

Female hyenas externally look like males but what appears to be a penis is an enlarged clitoris.

The genitalia of the female closely resembles that of the male; the
clitoris is shaped and positioned like a penis, a pseudo-penis, and is
capable of erection. The female also possesses no external vagina
(vaginal opening), as the labia are fused to form a pseudo-scrotum

It does not take a whole lot of evolution to move a female body type to one with an exaggerated clitoris; just hormone dose will do that for you.

Just as human races, these races are the same species - not that different from each other genetically biologically compatiable.

Re race determine by mother: your "race on mt dna" idea would work. If you want to get into the weeds another way this could work is genomic imprinting.

https://en.wikipedia.org/wiki/Genomic_imprinting

Genomic imprinting is an epigenetic phenomenon that causes genes to be
expressed in a parent-of-origin-specific manner. Forms
of genomic imprinting have been demonstrated in fungi, plants and
animals. As of 2014, there are about 150 imprinted genes known
in the mouse and about half that in humans.

Genomic imprinting is an inheritance process independent of the
classical Mendelian inheritance. It is an epigenetic process that
involves DNA methylation and histone methylation without altering the
genetic sequence. These epigenetic marks are established ("imprinted")
in the germline (sperm or egg cells) of the parents and are maintained
through mitotic cell divisions in the somatic cells of an organism.