Correct notation for unknown species at phylum level?

If I sample a flatworm, but cannot get the ID beyond Platyhelminthes, is the correct notation:

  1. Platyhelminthes

  2. Platyhelminthes sp.

in the context of “Three species were only observed once (Platyhelminthes sp., Stylocheilus longicauda, and Diffalaba opiniosa)”


The ‘sp.’ notation is only used when you’ve gotten down past genus level and are trying to bring it to species.

Everything above species (eg: genus, family, order class, phylum, kingdom, domain, and all the sub-divisions) should be noted by a single word.

An example:

  • You come across what’s obviously a great ape, but you don’t know what species, or even what genus.
    That would be * Hominidae*, the family. It would be left at one word.

  • Maybe you’re sure it’s a chimpanzee of some sort, but don’t know which type.
    That would be Pan, which is the genus, and left at one word.

  • Maybe you’re an expert in chimpanzees and can tell that it’s not Pan paniscus (bonobo) or Pan troglodytes (common chimpanzee), but something new and, as yet, undescribed/named (edit: or something that made you uncertain about which species).
    That would be Pan sp. to indicate that it’s an unknown Pan species and not one of the two known species, or at least there is something that makes you question just exactly what weird kind of chimpanzee this is.


Thanks for that, much appreciated. Yeah, I was essentially unsure if you could attach ‘sp.’ to a rank above genus.

With your examples, is it actually the rule that ‘sp.’ is only used for an undescribed or similar case?? I’ve always used Genus sp. (or Genus spp. for plural of course) to refer to a specimen from your second example, where I wasn’t really thinking something was undescribed, but was just unable to ID from the information I had.

E.g. Australian Dolomedes are really only IDable from genital dissection, so if I had a photo of a Dolomedes, referring to it as Dolomedes sp. would be incorrect?


It’s not formally correct to use sp. with the name of a higher rank. In my opinion your phrasing would still sound off if you just dropped the sp. because you open by saying you’re listing three species, not phyla.

I would recommend something like “an unknown platyhelminth” or “an unknown species of Platyhelminthes” (and stylistically that would probably sound best at the end of your list).

Re: your second comment
sp. is used any time you can’t or just don’t need to specify the species. It is not exclusively used for undescribed species (at least among botanists).


if I had a photo of a Dolomedes, referring to it as Dolomedes sp. would be incorrect?

No, that would be fine, as long as you were certain it was a Dolomedes.

You’ll see that often in field collection notes.

Pseudozizeeria maha
Anthene emolus
Nacaduba sp. 1
Nacaduba sp. 2

sp. 1 and sp. 2 to indicate that it was clearly two different species of Nacaduba that were seen, but the observer was unable to identify them to species at the time.

This sort of notation is important for species counts. Without the 1 and 2 notation a different person going over the data later might not know that it was 2 different species seen and count them both as one species (2 observations) for the purposes of species counts.


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