Subsequently, it was validly published by Royle. Therefore, its scientific name would be correctly written as:

1. Cerasus cornuta Wall. in Royle
2. Cerasus cornuta Wall. emend Royle
3. Cerasus cornuta Wall. ex Royle
4. Cerasus cornuta Wall. [Royle]

   Cerasus cornuta Wall. ex Royle is the correct scientific name format.​

   Detailed Nomenclature Explanation

   In botanical nomenclature (ICN, Articles 46-50), when one botanist (Wallich) proposes/identifies a taxon name but fails valid publication (missing Latin diagnosis, type, etc.), a later author (Royle) validly publishes it with description. The “ex” preposition credits the original identifier before the validating author: Author1 ex Author2.

   • Wallich: First named but invalid (nomen nudum).

   • Royle: Provided valid publication, becoming the authority.

   Option Analysis

   1. Cerasus cornuta Wall. in Royle: “In” denotes bibliographic citation (e.g., publication location), not authorship—ICN Note 1 discourages without full reference.

   2. Cerasus cornuta Wall. emend Royle: “Emend.” (emendavit) means later correction/modification of original valid description (e.g., updated diagnosis), not initial validation.​

   3. Cerasus cornuta Wall. ex Royle: Correct—Standard for pre-1953 cases where earlier author is cited but later provides validating elements (Article 46).

   4. Cerasus cornuta Wall. [Royle]: Brackets indicate basionym authorship for new combinations, not valid publication of original name.​

   Introduction
   Cerasus cornuta Wall. ex Royle follows ICN protocol when Wallich first proposed the name invalidly, but Royle validly published it. The “ex” distinguishes the identifier (Wall.) from the publishing authority (Royle), essential for precise taxonomic citation.​

   ICN Author Citation Rules

   Citation	Meaning	Example Use
   A ex B	A named; B validly published	Wall. ex Royle ​
   A in B	Bibliographic (avoid standalone)	Publication context ​
   A emend. B	B corrected A’s valid name	Taxonomy updates
   A [B]	B made new combination	Genus transfers ​

   Common Pitfalls

   • Post-1958: Both names connected by “/” (Wall. / Royle).

   • No “ex” if Royle ascribes description to Wallich alone.

   • Always abbreviate standard author names (Wall. = Wallich).​

   Taxonomy Exam Tips

   Memorize: Invalid proposer ex validator (pre-1953). Critical for NEET/UGC-NET botany questions on historical naming.​