Gabriel:

A new species of a plant or an animal must be published as per the rules of ICBN or ICZN, respectively, and should be published and not be in preparation or in press.

Best

Syed

Hello Gabriel:

No, is not accepted. Acording to the Rules of  Zoological Nomenclature, a new species in order to be available, a name must have been published in a scientific journal in a way to satisfy the requirements detailed in Arts. 8-20. The term available, as used in the code means " legitimate" or " effectively published". A name published without satisfying the conditions of availability is generally called a nomen nudum, particularly if its fails to satisfy the conditions of Arts. 12-16. A Nomen nudum has no standing in zoological nomenclature and is best never recorded.

Regards,

Luis Miguel

A summary of the process can be found here http://iczn.org/content/how-can-i-describe-new-species :-)

Dear Gabriel,

If the author of the another new species is known to you, you can think of publishing the two new species in a single paper with comparison.

Although the second author can effectively not reffer to the other species by its name (as not validly published) he can use available information to compare the two new species. And write something like "a species to be described (XXX, com.pers." has this and this feature". It should be with the agreement of XXX.

You must be quite careful. If you apply a name and meet certain criteria of "description," your citation of the "in prep" or "in press" description may well constitute the official description. It is much better to cite as under development, but without mentioning a name. And as one of the other respondents mentioned, the best thing to do is to work with the other researcher, if--of course--that is possible. ATP

You can compare your new species with another taxon still in preparation, as an unnamed "sp." only, without a scientific name until the latter will be formally published.

I do not know the importance of comparing your species with another undescribed. But, you do not need to do this to describe validly your new species. Surely you can indicate diagnostic characters by comparison with other species of the genus.

If you consider it important to compare your new species with another as yet undescribed species, you could resort to mentioning, in the taxonomic discussion, materials similar to your new species, still in study, from a particular locality or area, and listing the differential characters. Without mentioning the new name not yet published.

The rules of the ICZN only apply to the name. Of course you cannot use the name of something that is not even described. But if both of you are working together you still can use the morphological data without using a name.

Morphological or whatever, I said morphological thinking on paleontology :P

Simply, a nomen nudum will be produced. 

Dear Gabriel,

Each of new species must be first published according to the Code to establish their names. In the paper publishing the new species, each of you describers must give a differential diagnosis in relation to already described closely related species, if you both want to be exclusive authors who described the new species in concern. If you would publish a common paper, both of you would be describers of both species. So, comparison between the two new species should be a second step, a separate paper then. You can also accomplish the revision and compare your two new species with all other related (in the genus) species. So, there is a variety of possibilities, dependent on what would you like.

Hello Gabriel,

You must not cite any name not formally published (in prep), as said above this will create a nomen nudum. Nomen nudum creates a lot of confusion and is not attached to a formal species description, type material, etc. So its impossible to rescue the identity of the specimens associated to that name.  In other words,  that name was never published so it cannot be cited as it was. If the paper with the taxon description is formally accepted and in press, it usually is already available as in press and has an online version, with a DOI number associated, then its published online and can be cited as in press using the DOI as reference to the publication.

All the Best,

Ana

There is nothing wrong with using the specimens in comparisons in the respective descriptions but no taxonomic act pertaining the other specimen/species is to be featured in both publications. You and your college don't want to create a nomen nudum. You can be close to an identification using wording like "... in a yet undescribed specimen [here  collection number could be entered] tentatively identified as a member of [enter higher taxonomic group like family here, or a sister taxon to ...] (personal observation or personal comminication) ...".

I hope this helps.

Under the zoological code at least, there's nothing formally wrong with creating a nomen nudum. But of course I recommend avoiding it.

You must be quite careful. If you apply a name and meet certain criteria of "description," your citation of the "in prep" or "in press" description may well constitute the official description.

This is no longer the case, at least under the zoological code, where a new name must now be explicitly called new and must be accompanied by a diagnosis in order to be valid. Explicitly ascribing a new name to another work means the name is not being erected in your publication.

I recommend describing both species in a joint publication. It is not the case that both of you would automatically be the authors of both species names; if that's not what you want, you can make this explicit by adding "Novaes e Fagundes sp. nov." after the name of "your" species in the Systematics section of the paper, and analogously with your colleague's name for the other species.

yes! you can. But it depends on the journal which your MS will be submitted to.