Article 47. Nominotypical taxa.
47.1. Definition. When a species is considered to contain subspecies, the subspecies that contains the name-bearing type of the nominal species is denoted by the same species-group name as the species, with the same author and date [Art. 46.1]; this subspecies is termed the nominotypical subspecies.
47.2. Change of nominotypical subspecies. If the species-group name in use for a species, and hence for its nominotypical subspecies, is unavailable or invalid it must be replaced by the name valid under Article 23.3.5; the subspecies then containing the name-bearing type of the valid nominal species becomes the nominotypical subspecies.
Example. Hemming (1964) noted that the butterfly name Papilio coenobita Fabricius, 1793 is a junior primary homonym of Papilio coenobita Cramer, 1780, and established Pseudoneptis ianthe Hemming, 1964 as a new replacement name (nom. nov.) for Pseudoneptis coenobita (Fabricius). However, Stoneham (1938) had established a subspecies Pseudoneptis coenobita bugandensis, so that the valid name of the species is Pseudoneptis bugandensis Stoneham, 1938. The nominotypical subspecies is Ps. bugandensis bugandensis. The name ianthe denotes a different subspecies, Ps. bugandensis ianthe Hemming, 1964.