Dear Sayed,

Go through the following from ICN:

Art. 46.10 Authors publishing nomenclatural novelties and wishing other persons’ names followed by “ex” to precede theirs in authorship citation may adopt the “ex” citation in the protologue.

o Ex.41. In validly publishing the name Nothotsuga, Page (1989) cited it as “Nothotsuga H.-H. Hu ex C. N. Page”, noting that in 1951 Hu had published it as a nomen nudum; the name is attributed to either Hu ex C. N. Page or C. N. Page.

o Ex.42. Atwood (1981) ascribed the name of a new species, Maxillaria mombachoensis, to “Heller ex Atwood”, with a note stating that it was originally named by Heller, then deceased; the name is attributed to either A. H. Heller ex J. T. Atwood or J. T. Atwood.

Look for other aspects too. Assure that the name has not been given to any different species in the past, etc.

If you wish you can give a name of your choice too.

With best wishes,

Subir.

Sayed:

Have a look at this link for insights:

Best

Syed

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

The nomen nudum designation is a view of (previous) taxonomist, which must by based on something. Depending on argument, why it was declared nomen nudum, you can see, if this was a mistake (so - it was never nomen nudum, just it was perceived like that - but it can be proved that the name is valid and usable in fact), you can obviously use the original name with original author. You will have in such case bring an evidence, that as nomen nudum it was classified incorrectly.

Thanks all. In my case the name has become invalid because 1) it exists only on specimens not in literature in other words there is no description with that name it is restricted only to some specimens 2) the species has been misunderstood that is why the previous workers have declared it nomen nudum. more comments needed on the authority of the reinstated name.

One can supplement the description for such nomen music and validate it.  However the priority of that name changes. 

ICN. Art.46

The following example is helpful

Ex.41. In validly publishing the name Nothotsuga, Page (1989) cited it as “Nothotsuga H.-H. Hu ex C. N. Page”, noting that in 1951 Hu had published it as a nomen nudum; the name is attributed to either Hu ex C. N. Page or C. N. Page.

H.-H. Hu is responsible only for the scheduled taxon name Nothotsuga, not for the description of its morphological characteristics.  C.N. Page is the author of Nothotsuga, since he has described it.

In mentioning the name Hu in his description  C.N.Page connects the type of Nothotsuga to Hu's collection.

a name designated as nomen music doesn't have a description.  Such name  can be validated by providing a description.  However it's priority will be from the date when it is validly published with a valid description 

Dear Sayed,

You can validate the nomen nudum including the description of the taxon, the citation of types, etc, and using "ex". It is clear that the name is nomen nudum based on your explanation number one , but regarding number two ("...the species has been misunderstood that is why the previous workers have declared it nomen nudum...") is not clear. What do you mean by "misunderstood"? If there is confusion or disagreement about the limits of one taxon among its genera is a different matter that the nomenclatural one. Maybe is a better idea to use a different name and describe it as a new species, mentioning the presence of a nomen nudum associated with this new species. 

Dear Carlos,

The first author just wrote the species name on some specimens without description because after one year 2nd author described another species but mistakenly illustrated the first author's samples. So the first author was doubtful but he did not correct the problem in a publication but wrote a sentence about the problem on his samples labels. This made the first authors name numen nudum because he did not validly publish it. A third author mistook the samples again for another species further complicating the problem. Therefore, I agree with the first author as he was right in giving his samples a true identity but unfortunately he could not publish it. Therefore, I want to acknowledge his work by reinstating and validating his given name to the species rather than describing it a new species. Please comment if there is space for more improvement.

The question by Sayed is aptly answered by Dr Suchandra Dutta. The person who validly publishes the name (in Sayed's words 'new describer') will be the author of the plant name, but the original author also gets the credit. For example, Schiffner named a specimen of the genus Notothylas as Notothylas levieri, butdid not provide a description. Later, Stephani published it validly by providing a description to it. So the authority of the species is Notothylas levieri Schiffner ex Stephani.

You seem to imply that the name in question has never been published. If this is so, it has no status in scientific nomenclature and is NOT a nomen nudum. A nomen nudum is a name that HAS been published, but without the criteria that make it available. If you wish to use this name and publish it with criteria that make it available, you (and any co-authors) are the author(s) with no formal indebtedness to any predecessor. You might feel it right to mention them, but you alone receive credit for the name. In view of this, you might consider it more ethical to offer the author of the name the chance to set the record straight, perhaps in a collaborative paper. If this is impractical for whatever reason, it might be better to use a different name.

Your answer is appreciated Douglas Brandon-Jones. The name is arround 166 years old and I deem it more appropriate to mention the earlier author's name followed by "ex".

Yes !!  If published in literature (!) the old author ought to not be forgotten !

Best,   Hans

Nomenclature is a specialty; the rules about names and naming change from time to time. The current rules can be found by visiting www.ipni.org. It will get you pointed in the right direction.

I have had the experience of discovering a nomen nudum in a flora and called the attention of the editor to it.  Since the species description had not been published in a widely distributed journal, it was "unpublished" = in. ed. No type specimen was deposited in a herbarium available for examination, the name was invalid, a name without a plant, totally off limits thereafter. I published the species under a new name. If you're trying to get the plant into the literature, the problem is to know that the new name attaches to the same plant as did the nomen nudum. To sum up: nomen nudum is a specific condition of a name; another condition for a name is unpublished (in.ed.) and a third is valid/invalid. Differences between these terms might be very important systematically. I recommend that you become acquainted with the rules of naming. 

First of all I am giving the explanation of nomen nudum from the Glossary of the Code.

nomen nudum (nom. nud.). A designation of a new taxon published without a description or diagnosis or reference to a description or diagnosis (Art. 38 Ex. 1, Rec. 50B).

In this case  "The first author just wrote the species name on some specimens". So the name was never published and cannot be nomen nudum.

So the manuscript name can be validly published by citing 'name of the original author who proposed the name ex the name pf the author who will validly publish the name '  or  just name pf the author who will validly publish the name. Both type of author citations are acceptable.

What do you think of the expression  "in sched." (in schedula = on the label), which I have seen here and there in paratype lists (and elsewhere) ? Lacking reference to herbarium specimens you have a way of citing a name very non-committedly.