Human Subspecies: Okay, no, since there are no humans. (Or, at least, none worth speaking of.) However, once the genetic engineers really got working, there are literally thousands of eldrae subspecies, galari subspecies, myneni subspecies, kaeth subspecies, esseli subspecies – although, with the esseli, it’s proceeded almost to the point that each individual is his very own species – and so on and so forth. People adapted to space, to alien planets, to some social ideal, to live underwater, to stand up under high gravity, to photosynthesize, to reproduce parthenogenically, to fly with their own set of wings, to breathe different atmospheres, to dwell in solar coronas, to… well, it’s a really long list.
Heavyworlder: Yes, but this universe is hard-SF enough that they do reflect the “compact, stout, and short” version of the trope. Of course, seeing as eldrae are all height-advantaged anyway, even the heavyworlder clades are still looking humans in the eye.
There are also lightworlders, of course, and Fan Service or no, they are that skinny.
Taxonomic Term Confusion: Taxonomy is even more of a mess than it used to be, having to deal with life originating separately (it is usually thought; see Panspermia) in a multitude of different ecologies, which then got intermingled by ancient and modern terraforming and accidents of star travel to produce the situation as we know it today.
Imperial taxonomy uses something that resembles our current system, but with an additional parameter right at the top of the tree to indicate the ecology which this particular species originated within (wherever it may be found now); i.e., adding to the classification of humans as kingdom Animalia, phylum Chordata, class Mammalia, order Primates, family Hominidae, tribe Hominini, genus Homo, species H. sapiens an initial level of classification along the lines of “ecology Terragenea“.
(Of course, not that this works perfectly even then: humanity – albeit not quite modern man – by virtue of ancient fossils turning up on Eliera with greenlife similarities, exists in the Imperial taxonomy as Pseudoeldrae archaea, ecology Cálenlethis; and in the event that they should discover us, I suspect we would take about as well to being reclassified as Pseudoeldrae novis about as well as they would take being shoved into genus Homo; which is to say, not at all well. This is the sort of thing over which wars, or at least vicious academic infighting and people being cut – as in “cut direct”, not as in “I CUT YOU”… well, at least most of the time – at professional conferences, start.
It also doesn’t help that the eldrae, E. alathis, E. anthalis, or E. kirsunar, are already a taxonomic mess by virtue of having at least as much claim to being in ecology Fidúrlethis [bluelife] as ecology Cálenlethis; hybrid engineered lifeforms are like that. And the continued production of neogens makes this problem worse by the day – while, yes, the Applied Biotics, ICC Bactry Template Organism EC-7 is descended from organisms in kingdom Bacteria, it’s descended from about a dozen of them, taken apart and the best bits kept. This is hard to classify in anything resembling the normal manner.)
There are also at least two alternative partial taxonomies in use simply because they’re useful: one, a classification of species by their biochemical features, simply because it’s useful for some purposes to have all the methane-breathers or all the silicon-based life, and so forth, classified together regardless of origin; and another more approximate classification by homology alone, because for non-biologists travelling between planets, it’s useful to have relatively simple terms to call all the avioids, the ichthyoids, the arboroids, and so forth even if they’re not related by anything but general similarity. (Which terms I still, despite this fine feature of the “original language”, I still “translate” as “bird”, “fish”, “tree”, etc. when writing just like the first set, because the clarity in the original language is the bloody-minded wordiness in English.)
On the use of “race” to mean “species” in particular: In formal speech they’re usually good at maintaining the race/species distinction, but then, the whole race concept is also a mess – inasmuch as it used to be that the former was used in much the same loose sense as we use it for natural phenotypic distinctions within a species, and then clade came to be used for artificial ones (as people started producing aquatic people, photosynthetic people, space-adapted people, etc., etc.), which are messy categories, because they overlap quite a lot (one clade can include all races; one race can include all clades), but some clades rewrite for perfectly good reasons the same phenotypic elements that were used to define races (for practical reasons: all naked-to-space-adapted-clades have high-melanin [etc.] skin for radiation protection, but all photosynthetic clades have to have low-melanin skin to avoid conflicting with the chloroplasts [etc.], for example), and some clades exist to be cosmetic phenotypes that are essentially new races in the casual sense, and aaarrrgh.
(It’s clade that’s used for classification, when relevant, because it’s the one that tends to be medically relevant, environmentally important, and so forth, on a regular basis.)