42.1. The names of a genus and a species may be simultaneously validated by provision of a single description (descriptio generico-specifica) or diagnosis, even though this may have been intended as only generic or specific, if all of the following conditions obtain: (a) the genus is at that time monotypic; (b) no other names (at any rank) have previously been validly published based on the same type; and (c) the names of the genus and species otherwise fulfil the requirements for valid publication. Reference to an earlier description or diagnosis is not accepted as provision of such a description or diagnosis.
Ex. 1. Nylander (1879) described the new species "Anema nummulariellum" in a new genus "Anema" without providing a generic description or diagnosis. Since at the same time he also transferred Omphalaria nummularia Durieu & Mont. to "Anema", none of his names were validly published. They were later validated by Forsell (1885).
42.2. For the purpose of Art. 42, a monotypic genus is one for which a single binomial is validly published, even though the author may indicate that other species are attributable to the genus.
Ex. 2. The names Kedarnatha P. K. Mukh. & Constance (1986) and K. sanctuarii P. K. Mukh. & Constance, the latter designating the only species in the new genus, are both validly published although a Latin description is provided only under the generic name.
Ex. 3. Piptolepis phillyreoides Benth. (1840) was a new species assigned to the monotypic new genus Piptolepis published with a combined generic and specific description, and both names are validly published.
Ex. 4. In publishing "Phaelypea" without a generic description or diagnosis, P. Browne (Civ. Nat. Hist. Jamaica: 269. 1756) included and described a single species, but he gave the species a phrase-name and did not provide a valid binomial. Art. 42 does not therefore apply and "Phaelypea" is not a validly published name.
42.3. Prior to 1 January 1908 an illustration with analysis, or for non-vascular plants a single figure showing details aiding identification, is acceptable, for the purpose of this Article, in place of a written description or diagnosis.
42.4. For the purpose of Art. 42, an analysis is a figure or group of figures, commonly separate from the main illustration of the plant (though usually on the same page or plate), showing details aiding identification, with or without a separate caption.
Ex. 5. The generic name Philgamia Baill. (1894)
was validly published, as it appeared on a plate with analysis
of the only included species, P. hibbertioides Baill.,
and was published before 1 January 1908.